Woah Listed Diseases

Overview and Taxonomy of WOAH-Listed Viral Diseases: Bluetongue and Infectious Hematopoietic Necrosis

The World Organisation for Animal Health (WOAH) maintains a critical list of notifiable diseases that pose significant threats to global animal health, food security, and international trade. Among this compendium, two viral pathogens, Bluetongue virus (BTV) and Infectious Hematopoietic Necrosis virus (IHNV), occupy positions of paramount importance due to their transboundary nature, their profound economic impacts on livestock and aquaculture industries respectively, and the substantial challenges they present for surveillance, control, and eradication. While BTV represents a vector-borne scourge of ruminants with global distribution and an expanding serotype diversity, IHNV exemplifies the devastating potential of viral pathogens in intensive aquaculture systems, where outbreaks can precipitate rapid and catastrophic mortality. An exhaustive understanding of their taxonomic classification, biological mechanisms, epidemiological dynamics, and evolutionary trajectories is indispensable for informing evidence-based diagnostic protocols, risk assessment frameworks, and strategic intervention measures.

Bluetongue Virus: Taxonomy and Virological Architecture

Bluetongue virus is the etiological agent of Bluetongue (BT), a disease classified by WOAH as a notifiable multispecies disease of domestic and wild ruminants [1]. Taxonomically, BTV is assigned to the genus Orbivirus within the family Reoviridae, a lineage characterized by a double-stranded RNA (dsRNA) genome architecture. The viral genome is organized into ten discrete linear segments (Seg-1 through Seg-10), which encode seven structural proteins (VP1–VP7) and four non-structural proteins (NS1, NS2, NS3, NS3A). The outer capsid is composed of VP2 and VP5, which together constitute the primary targets for neutralizing antibodies and the principal determinants of serotype specificity. The inner core, comprised of VP3 and VP7, encloses the transcriptionally active viral polymerase complex, VP1 (RNA-dependent RNA polymerase), VP4 (capping enzyme), and VP6 (helicase). This segmented genome is a hallmark of the Reoviridae and confers a formidable capacity for genetic reassortment, a mechanism that drives the emergence of novel strains with altered virulence, host tropism, and vector transmission efficiency. This property is of profound epidemiological significance, as reassortment between co-circulating serotypes can generate progeny viruses that evade pre-existing host immunity and challenge diagnostic detection systems [2].

The taxonomic complexity of BTV is reflected in the staggering diversity of serotypes recognized globally. To date, at least 29 distinct serotypes have been identified, with 17 serotypes isolated in China alone since the first report of BTV in 1979, specifically BTV-1, -2, -3, -4, -5, -7, -9, -11, -12, -14, -15, -16, -17, -20, -21, -24, and -29 [1]. This serotypic diversity is not merely a taxonomic curiosity; it represents a formidable obstacle to vaccine development and deployment, as immunity conferred by one serotype provides limited, if any, cross-protection against heterologous serotypes. The segmented nature of the genome further complicates control efforts, as the theoretical potential for reassortment is immense, particularly in regions where multiple serotypes co-circulate. The recent incursion of novel EHDV serotype 8 into European regions with recurrent BTV circulation underscores the dynamic and unpredictable nature of orbivirus emergence, highlighting the urgent need for pan-serotype and pan-orbivirus diagnostic tools, such as the validated TaqMan RT-qPCR pan-BTV/pan-EHDV assay described by Portanti and colleagues [2].

Bluetongue: Vector-Borne Transmission, Epidemiology, and Global Expansion

BTV is an arthropod-borne virus (arbovirus) transmitted almost exclusively by biting midges of the genus Culicoides (Diptera: Ceratopogonidae). The virus undergoes a critical replication cycle within the vector, a process that is exquisitely temperature-dependent and thus profoundly influenced by climatic variables. After ingestion of a viremic blood meal, the virus infects the midgut epithelium of the Culicoides vector, subsequently disseminates to the salivary glands, and is then transmitted to a susceptible ruminant host during subsequent feeding. This obligate vector-borne transmission imposes a distinct spatiotemporal pattern on disease occurrence: outbreaks are typically seasonal, coinciding with periods of peak vector activity, and are geographically constrained to regions where competent Culicoides species are endemic. In China, research has demonstrated that Culicoides are widely distributed, and studies are actively investigating climatic factors influencing their distribution and blood-sucking habits, which is critical for predictive modeling of disease risk [1].

The epidemiological landscape of Bluetongue has undergone a dramatic transformation over the past two decades. Historically considered a disease of tropical and subtropical regions, BTV has expanded its latitudinal range into temperate zones of Europe, North America, and Asia. This expansion is attributed to a confluence of factors, including climate change facilitating vector survival at higher latitudes, increased international trade in livestock and animal products, and the emergence of novel Culicoides species as competent vectors. The virus can infect a broad range of wild and domestic ruminants, including sheep, cattle, goats, deer, and camelids, although clinical disease severity varies dramatically among species. Sheep are generally considered the most severely affected, often exhibiting classical signs such as fever, oral erosions, coronitis, and pulmonary edema, while cattle frequently serve as subclinical reservoirs that sustain viral circulation within an ecosystem [3]. The World Health Organization (WHO) and the Food and Agriculture Organization (FAO) recognize Bluetongue as a disease of significant transboundary importance, and its inclusion on the WOAH list mandates immediate reporting of outbreaks to facilitate international coordination of control measures and inform safe trade practices.

Infectious Hematopoietic Necrosis Virus: Taxonomy and Genomic Organization

Infectious Hematopoietic Necrosis virus is the causative agent of Infectious Hematopoietic Necrosis (IHN), a WOAH-listed disease of finfish that is particularly devastating to salmonid aquaculture operations worldwide [4, 5]. IHNV is classified within the genus Novirhabdovirus of the family Rhabdoviridae, a family of enveloped, negative-sense single-stranded RNA viruses that also includes the notorious Rabies virus and Viral Hemorrhagic Septicemia virus (VHSV). The virion adopts a characteristically bullet-shaped or conical morphology, approximately 100–180 nm in length and 45–80 nm in diameter. The linear, non-segmented RNA genome, approximately 11,000 nucleotides in length, encodes six proteins in a conserved order: 3'-N-P-M-G-NV-L-5'. The nucleoprotein (N) encapsulates the genomic RNA, forming the ribonucleoprotein complex that serves as the template for transcription and replication. The phosphoprotein (P) and the large protein (L), which harbors the RNA-dependent RNA polymerase activity, constitute the viral polymerase complex. The matrix protein (M) is critical for virion assembly and budding. The glycoprotein (G) forms trimeric spikes on the viral envelope and is the principal target for neutralizing antibodies, making it the focus of vaccine development efforts, such as the novel ferritin nanoplatform-based vaccine (FerritVac) described by Ahmadivand and colleagues [4]. A unique feature distinguishing novirhabdoviruses from other rhabdoviruses is the presence of a non-virion (NV) gene, whose product is implicated in the modulation of host antiviral responses, particularly the inhibition of the interferon system and the suppression of apoptosis.

Phylogenetic analysis of IHNV isolates has resolved four major genogroups, designated U (upper), M (middle), L (lower), and J (Japanese), which generally correlate with geographic origin and host species. The M genogroup, for instance, is predominantly associated with rainbow trout (Oncorhynchus mykiss) in North America, while the U and L genogroups are more frequently isolated from Pacific salmon species. This genotypic diversity has implications for virulence, host range, and diagnostic assay performance. The detection of single nucleotide polymorphisms (SNPs) in the nucleoprotein (N) gene targeted by certain RT-qPCR assays has been documented to impair probe binding and lead to false-negative results, necessitating the continuous refinement of diagnostic protocols to account for viral genetic diversity [6].

Infectious Hematopoietic Necrosis: Pathogenesis, Host Range, and Epidemiological Context

IHNV exhibits a narrow host range, primarily infecting salmonid species, including rainbow trout, Chinook salmon (Oncorhynchus tshawytscha), sockeye salmon (O. nerka), and Atlantic salmon (Salmo salar). The virus is highly contagious and is transmitted horizontally via the waterborne route, with the portal of entry typically being the gills, skin, or gastrointestinal tract. Upon entry, IHNV exhibits a profound tropism for the hematopoietic tissues of the kidney and spleen, as well as the endothelial cells lining blood vessels. The virus replicates rapidly within these tissues, causing extensive necrosis and hemorrhage. Clinical signs are highly variable depending on host species, age, viral strain, and environmental conditions, but commonly include lethargy, exophthalmia, darkening of the skin, abdominal distension due to ascites, and petechial hemorrhages at the base of fins, in the peritoneum, and within the viscera. Mortality rates can approach 100% in naïve, susceptible populations, particularly in fry and fingerling stages, making IHN one of the most economically significant viral diseases in salmonid aquaculture [5].

Histopathological examination reveals organ-specific lesions that are pathognomonic for the disease. In the kidney, a pronounced necrosis of the hematopoietic interstitium is observed, with widespread cellular disintegration and pyknosis. The spleen exhibits similar necrotic changes in the splenic pulp, often accompanied by depletion of lymphoid elements. In the liver, focal to multifocal hepatocellular necrosis with hemorrhage is a common finding. These histopathological changes, while highly suggestive, require confirmation through virological or molecular methods, as they can overlap with other viral diseases such as Viral Hemorrhagic Septicemia. The WOAH Manual of Diagnostic Tests for Aquatic Animals provides standardized protocols for histopathological examination, but inconsistencies in lesion scoring and a lack of comparative histopathological analysis across different host species remain significant gaps in the literature [5]. The development and validation of improved molecular diagnostic tools, such as the one-step RT-qPCR assays incorporating an endogenous control system and refined probes to circumvent SNP-related binding issues, have been critical for enhancing the sensitivity and reliability of IHN surveillance and eradication programs globally [6]. Furthermore, innovative vaccine approaches, including the use of self-assembling ferritin nanoplatforms to deliver the viral glycoprotein, represent a promising frontier for developing safe, stable, and orally administrative vaccines against this devastating disease [4].

Molecular Pathogenesis of Bluetongue Virus and IHNV

The molecular pathogenesis of Bluetongue virus (BTV) and Infectious Hematopoietic Necrosis virus (IHNV) represents two distinct paradigms of viral-host interaction, each shaped by fundamentally different genomic architectures, transmission strategies, and host immune landscapes. BTV, a vector-borne Orbivirus within the Reoviridae family, and IHNV, a directly transmitted aquatic Novirhabdovirus within the Rhabdoviridae family, are both listed as notifiable diseases by the World Organisation for Animal Health (WOAH) due to their profound economic and animal health impacts [1, 5]. A deep understanding of their molecular pathogenic mechanisms is essential for developing targeted countermeasures, from diagnostics to vaccines.

Molecular Pathogenesis of Bluetongue Virus

BTV is a non-enveloped, double-stranded RNA (dsRNA) virus with a segmented genome composed of ten segments (Seg-1 through Seg-10), encoding seven structural proteins (VP1-VP7) and four non-structural proteins (NS1, NS2, NS3/NS3a, and NS4) [1, 2]. The molecular pathogenesis of BTV is a multi-step process that begins with the virus's entry into the ruminant host via the bite of an infected Culicoides midge [1, 7]. The outer capsid proteins, VP2 and VP5, are critical determinants of serotype specificity and cellular tropism. VP2 is the primary target for neutralizing antibodies and is responsible for binding to host cell receptors, while VP5 facilitates membrane fusion and viral entry [1, 2]. The remarkable genetic diversity of BTV, with at least 17 serotypes identified in China alone (BTV-1, 2, 3, 4, 5, 7, 9, 11, 12, 14, 15, 16, 17, 20, 21, 24, and 29), is a direct consequence of the high mutation rate and, more significantly, the capacity for genetic reassortment among co-infecting serotypes [1, 7]. This reassortment, particularly involving Seg-2 (encoding VP2) and Seg-6 (encoding VP5), drives the emergence of novel strains with altered virulence and antigenic profiles, complicating vaccine development and diagnostic surveillance [1, 7].

Once internalized, the virus uncoats, and the core particle, composed of VP3 and VP7, is released into the cytoplasm. The viral RNA-dependent RNA polymerase (VP1) and capping enzyme (VP4) are activated within this core, initiating transcription and replication entirely within the cytoplasm [1]. The non-structural protein NS1 is a key virulence factor, forming viral inclusion bodies (VIBs) that serve as the sites of viral replication and assembly. NS1 also inhibits host cell protein synthesis and modulates the interferon response, a critical aspect of immune evasion [1]. The NS3 protein, particularly NS3a, is essential for viral egress. It mediates the release of progeny virions from infected cells, primarily through a non-lytic budding mechanism, by interacting with host cellular proteins involved in the exocytic pathway [1]. This non-lytic release allows for persistent infection and dissemination without immediate cell destruction, contributing to the prolonged viremia observed in infected ruminants.

The pathogenesis of BTV is characterized by a profound vascular injury. The virus has a marked tropism for endothelial cells lining small blood vessels, particularly in the lungs, oral cavity, coronary band, and skeletal muscle [1]. Infection of these cells leads to endothelial damage, increased vascular permeability, and disseminated intravascular coagulation (DIC). This vasculitis is the primary driver of the clinical signs associated with bluetongue, including edema, hemorrhage, cyanosis of the tongue ("blue tongue"), and laminitis [1]. The severity of disease is influenced by viral strain, host species (sheep are most severely affected, while cattle often serve as asymptomatic reservoirs), and environmental factors [1]. The host's innate immune response, particularly the type I interferon system, plays a crucial role in controlling early viral replication. However, BTV has evolved mechanisms to counteract this, including the NS4 protein, which has been shown to antagonize the interferon response [1]. The molecular interplay between viral non-structural proteins and the host's antiviral machinery ultimately dictates the outcome of infection, ranging from subclinical to fatal hemorrhagic disease.

Molecular Pathogenesis of Infectious Hematopoietic Necrosis Virus

IHNV is an enveloped, negative-sense single-stranded RNA virus with a genome of approximately 11,000 nucleotides, encoding six proteins: the nucleoprotein (N), phosphoprotein (P), matrix protein (M), glycoprotein (G), non-virion protein (NV), and RNA-dependent RNA polymerase (L) [4, 5, 6]. The molecular pathogenesis of IHNV is a paradigm of a highly virulent, directly transmitted pathogen that causes a systemic, often lethal, disease in salmonid fish. The virus is a WOAH-listed pathogen and a major constraint to global salmonid aquaculture [4, 5, 8]. The G protein is the primary determinant of viral attachment and entry, binding to host cell receptors on the surface of susceptible cells, including hematopoietic tissues of the kidney and spleen [4, 5]. The G protein is also the major antigenic target for neutralizing antibodies, making it the primary component of subunit and recombinant vaccines [4].

Following entry via receptor-mediated endocytosis, the viral envelope fuses with the endosomal membrane, releasing the nucleocapsid into the cytoplasm. The viral RNA-dependent RNA polymerase (L protein) transcribes the viral genome, producing capped and polyadenylated mRNAs. The N protein encapsulates the nascent genomic RNA, while the P and M proteins are involved in replication complex formation and viral assembly [4]. A unique feature of IHNV, shared with other novirhabdoviruses, is the NV gene. The NV protein is a non-structural protein that plays a critical role in viral pathogenesis by modulating the host's innate immune response. It has been shown to inhibit the interferon (IFN) response, a key antiviral defense mechanism in fish [4]. This inhibition is crucial for establishing a productive infection, as the IFN system can rapidly induce an antiviral state that limits viral replication and spread.

The hallmark of IHN is a severe, necrotizing infection of the hematopoietic tissues, primarily the kidney and spleen, leading to profound immunosuppression and anemia [5]. The virus also targets the endothelial cells lining blood vessels, causing widespread hemorrhage and edema. The molecular basis of this tissue tropism is linked to the expression of specific host receptors and the ability of the virus to replicate efficiently in these cell types [4]. The pathogenesis is further characterized by a rapid and overwhelming viral replication, leading to high viral loads in target organs. The host's response, while initially inflammatory, is often insufficient to control the infection, and the virus-induced immunosuppression, mediated in part by the NV protein, exacerbates the disease [4]. Histopathological examination reveals extensive necrosis of the hematopoietic cells in the kidney and spleen, with pyknosis and karyorrhexis of cell nuclei [5]. In the liver, focal necrosis and hemorrhage are common, while the pancreas may show acinar cell necrosis [5]. The gills often exhibit lamellar fusion and hyperplasia, contributing to respiratory distress [5].

The molecular detection of IHNV has been revolutionized by real-time reverse transcription PCR (RT-qPCR), which offers high sensitivity and specificity compared to traditional cell culture methods [6]. However, the genetic diversity of IHNV, particularly within the N gene targeted by some RT-qPCR assays, has led to the emergence of single nucleotide polymorphisms (SNPs) that can impair probe binding and cause false-negative results [6]. This underscores the need for continuous molecular surveillance and assay redesign to maintain diagnostic accuracy. The development of novel vaccine platforms, such as self-assembling ferritin nanoplatforms displaying the IHNV G protein (FerritVac), represents a significant advance in IHNV control [4]. These nanovaccines are designed to be stable, biocompatible, and capable of inducing robust innate and adaptive immune responses, including the upregulation of key antiviral genes such as mx, vig1, ifit5, and isg-15 in host macrophages [4]. This approach aims to overcome the limitations of traditional inactivated or live-attenuated vaccines, offering a safer and more effective strategy for controlling this devastating disease.

Epidemiology and Vector Transmission Dynamics

The epidemiological landscape of WOAH-listed diseases is defined by a complex interplay of pathogen biology, vector ecology, host population dynamics, and anthropogenic factors that facilitate both local maintenance and transboundary spread. Understanding these transmission dynamics is not merely an academic exercise; it is the foundational prerequisite for designing effective surveillance systems, implementing targeted control measures, and predicting future emergence events. The diseases under WOAH listing span terrestrial livestock, aquatic species, and wildlife, each presenting unique epidemiological challenges that demand nuanced, evidence-based approaches.

The Culicoides Nexus: Orbivirus Transmission and Emerging Threats

Among the most extensively studied vector-borne disease systems within the WOAH framework are those caused by orbiviruses of the genus Culicoides, particularly bluetongue virus (BTV) and epizootic haemorrhagic disease virus (EHDV). These viruses exemplify the critical role of vector biology in shaping disease distribution and emergence. The epidemiology of BTV in China, as comprehensively reviewed by Xin et al. [1], illustrates a scenario of remarkable serotypic diversity and widespread vector distribution. Since the first report of BTV in China in 1979, a total of 17 serotypes have been isolated (BTV-1 through BTV-29, excluding several), and seropositive animals have been detected across most of the country’s provinces. This pattern is not random; it is driven by the broad ecological niche of Culicoides vectors, which are themselves widely distributed and influenced by climatic factors such as temperature, precipitation, and humidity. The blood-feeding habits of these midges, their host preferences, and their capacity for long-distance wind-borne dispersal are critical determinants of viral transmission intensity and seasonality.

The emergence of EHDV in Europe provides a compelling contemporary example of how vector-borne pathogens can rapidly expand their geographic range. Following the first identification of a novel EHDV serotype 8 strain in Tunisia in 2021, the virus was subsequently detected in cattle exhibiting BTV-like symptoms in Italy, Spain, Portugal, and France [2]. These are regions with recurrent circulation of multiple BTV serotypes, indicating that the ecological and vectorial infrastructure for orbivirus transmission is already in place. The co-circulation of BTV and EHDV in the same geographic areas, transmitted by the same or closely related Culicoides species, creates opportunities for viral reassortment and complicates differential diagnosis. This epidemiological reality has driven the development of multiplex molecular tools, such as the validated TaqMan RT-qPCR pan-BTV/pan-EHDV assay described by Portanti et al. [2], which enables simultaneous detection and differentiation of these two WOAH-listed pathogens. Such tools are indispensable for surveillance in regions where both viruses are endemic or emerging.

In China, the epidemiological picture for EHDV mirrors that of BTV in its complexity. Antibodies against EHDV serotypes 1, 2, 5, 6, 7, 8, and 10 have been reported, and strains of EHDV-1, -5, -6, -7, -8, and -10 have been isolated [7]. Critically, molecular analyses of the Seg-2, Seg-3, and Seg-6 sequences have revealed that Chinese EHDV serotypes -5, -6, -7, and -10 belong to the eastern topotype, while the emergence of a western topotype Seg-2 in EHDV-1 strains indicates that reassortment between eastern and western lineages is occurring [7]. This reassortment, a hallmark of segmented RNA virus evolution, can generate novel strains with altered virulence, host range, or vector competence, posing significant challenges for disease prediction and control. The isolation of a novel serotype strain, YNDH/V079/2018, further underscores the dynamic and poorly understood nature of EHDV evolution in Asia. The primary vector for both BTV and EHDV remains Culicoides, and controlling vector populations through environmental management, insecticide application, and reducing host-vector contact are central to prevention strategies [1, 7]. However, the sheer breadth of Culicoides distribution and the difficulty of achieving sustained vector control in extensive livestock systems mean that vaccination and robust surveillance remain the most viable long-term strategies.

African Swine Fever: Unraveling a Sylvatic Cycle Involving Lice

African swine fever (ASF) presents a starkly different epidemiological paradigm, one characterized by extreme virulence, environmental persistence, and a complex transmission ecology that extends beyond direct contact. While the role of soft ticks of the genus Ornithodoros in maintaining sylvatic cycles in Africa is well established, recent evidence points to the potential involvement of other arthropod vectors. A groundbreaking study by Rajkhowa et al. [9] detected African swine fever virus (ASFV) in the hog louse Haematopinus suis collected from sows that died of acute ASF, and critically, in newly hatched nymphs derived from nits collected from the same source. This finding provides the first evidence for a potential new sylvatic cycle of ASFV involving lice and domestic pigs. The implications are profound: if lice can serve as a biological or mechanical vector, the virus could persist in pig populations even in the absence of tick vectors or direct contact, particularly in environments with high louse burdens and poor biosecurity. This could explain the seasonality of ASF outbreaks observed in some regions and the frustrating persistence of the virus in farms with high biosecurity standards [9]. The epidemiological significance of this finding demands urgent investigation into the vector competence of H. suis, the duration of viral persistence within the louse, and the efficiency of transmission from infected lice to naive pigs. Such knowledge is critical for refining control strategies, which currently rely heavily on early detection, strict biosecurity, and stamping-out policies in the absence of a commercially available vaccine [9, 10].

Aquatic Pathogen Dynamics: Co-infections, Trade, and Surveillance

The epidemiology of WOAH-listed diseases in aquatic animals presents unique challenges due to the fluid nature of the environment, the diversity of host species, and the globalized trade in live animals and their products. In shrimp aquaculture, pathogens such as white spot syndrome virus (WSSV), infectious hypodermal and hematopoietic necrosis virus (IHHNV), decapod iridescent virus 1 (DIV1), and acute hepatopancreatic necrosis disease (AHPND) cause catastrophic economic losses. Surveillance data from Karnataka, India, revealed a high prevalence of Enterocytozoon hepatopenaei (EHP) (28.6%) compared to WSSV (5.5%) in Penaeus vannamei farms, with co-infections also detected [11]. This pattern highlights the importance of multi-pathogen surveillance, as co-infections can exacerbate disease severity and complicate diagnosis. The development of high-throughput diagnostic tools, such as the quintuplex EvaGreen real-time PCR assay described by Lou et al. [12], which can simultaneously detect WSSV, IHHNV, DIV1, AHPND-causing Vibrio, and EHP with high diagnostic sensitivity (above 89.74%) and 100% specificity, represents a major advancement for epidemiological monitoring. Such tools enable rapid, cost-effective screening of large numbers of samples, facilitating early detection and informed management decisions.

The role of wild aquatic populations as reservoirs and sources of infection for farmed stocks is a critical but often understudied aspect of aquatic disease epidemiology. A study of wild Penaeus chinensis from the Yellow Sea revealed the presence of IHHNV, DIV1, yellow head virus genotype 8 (YHV-8), and oriental wenrivirus 1 (OWV1), with a notably high prevalence of co-infection between YHV-8 and OWV1 [13]. This finding raises serious concerns about the transmission risk between wild and farmed shrimp populations, particularly in regions where wild broodstock are used for aquaculture or where farm effluents discharge into natural waterways. The biosecurity implications are significant, as wild populations can serve as a persistent reservoir for pathogens that are difficult to eradicate once established.

For finfish, the epidemiology of WOAH-listed viruses such as infectious spleen and kidney necrosis virus (ISKNV) is increasingly shaped by international trade in frozen seafood products. A landmark study by Becker et al. [14] demonstrated that ISKNV remains infectious in frozen fish fillets stored at -20°C for seven days, and that challenge inocula prepared from skin-on fillet tissue caused infection and disease in rainbow sharks via both injection and bath immersion. The estimated median infectious dose (ID50) was just 42 genome equivalents, underscoring the high infectivity of this virus. This evidence directly challenges the assumption that frozen fish products pose negligible biosecurity risk and highlights a critical pathway for the transboundary spread of ISKNV, a pathogen that causes large-scale mortality in tilapia and mandarin fish aquaculture. These findings must inform import risk assessments and surveillance protocols for frozen aquatic commodities.

Drivers of Transmission: Wildlife, Trade, and Global Movement

The epidemiology of WOAH-listed diseases cannot be understood in isolation from the broader ecological and anthropogenic drivers that facilitate pathogen spread. Wildlife serves as a vast and often unrecognized reservoir for many listed pathogens. A comprehensive review by Smith et al. [15] identified 528 possible wild animal hosts for 73 OIE-listed terrestrial animal diseases, though not all host-pathogen relationships are epidemiologically significant. The expanding international wildlife trade, valued at over US $300 billion annually, represents a major pathway for the transboundary movement of pathogens, often with minimal surveillance or reporting. This is particularly concerning for diseases where wildlife can maintain transmission cycles independent of domestic livestock, complicating eradication efforts.

For highly pathogenic avian influenza (HPAI) H5Nx, the interplay between wild bird migration and poultry trade is a dominant driver of international spread. A sophisticated analysis by Awada et al. [16] using 10 years of WOAH, UN, and genetic data demonstrated that both poultry trade and migratory bird movements significantly contribute to viral spread, with geographic proximity between countries playing a particularly strong role. Crucially, the study found a protective effect of resources allocated to veterinary services and of border precautions, underscoring the importance of robust national surveillance and biosecurity infrastructure. These findings align with the WOAH standards for disease prevention and control, which emphasize the need for transparent reporting, timely notification, and scientifically sound risk management.

The global movement of animals and their products, combined with the effects of climate change on vector distribution, ensures that the epidemiology of WOAH-listed diseases will remain dynamic. The emergence of EHDV-8 in Europe, the detection of ASFV in lice, and the persistence of ISKNV in frozen fish are all reminders that our understanding of transmission pathways is incomplete. Continued investment in surveillance, molecular epidemiology, and vector biology research is essential to anticipate and mitigate future disease threats. The integration of data from systems like the World Animal Health Information System (WAHIS) with genetic, ecological, and trade data will be critical for developing predictive models and risk assessments that can inform evidence-based policy decisions [17].

Diagnostic Methods: Serological and Molecular Detection

The accurate and timely diagnosis of World Organisation for Animal Health (WOAH)-listed diseases is the cornerstone of effective surveillance, control, and international trade. The diagnostic landscape for these pathogens has evolved dramatically, moving from classical isolation and serotyping towards highly sensitive and specific molecular platforms capable of multiplex detection. For notifiable diseases, the choice of diagnostic method is dictated not only by the pathogen’s biology but also by the epidemiological context, the stage of infection, and the laboratory infrastructure available. A robust diagnostic regimen must integrate both serological methods, which reveal prior exposure and immune status, and molecular methods, which confirm active infection and viral load. The interplay between these two approaches defines the reliability of disease reporting under the WOAH framework.

Serological Detection Methods: Principles and Pitfalls

Serological assays remain indispensable for large-scale surveillance, particularly for pathogens where viremia is transient or where subclinical infections predominate. The WOAH Terrestrial and Aquatic Manuals provide standardized protocols for diseases such as bluetongue (BT), epizootic haemorrhagic disease (EHD), and brucellosis, yet the implementation of these guidelines in field conditions is often inconsistent.

For bluetongue virus (BTV), a multi-serotype orbivirus transmitted by Culicoides midges, serological screening relies heavily on the competitive enzyme-linked immunosorbent assay (c-ELISA) targeting the highly conserved VP7 protein. This assay offers high sensitivity and specificity across all 24 serotypes and is the recommended method for detecting anti-BTV antibodies in ruminants [1]. In China, a comprehensive review highlighted the deployment of agar gel immunodiffusion (AGID) alongside c-ELISA, though AGID is increasingly viewed as less sensitive and is being phased out in favor of ELISA-based platforms [1]. Similarly, for epizootic haemorrhagic disease virus (EHDV), Chinese researchers have developed an antigen-capture ELISA and a competitive ELISA targeting the VP7 protein, enabling serological differentiation from BTV in co-circulation zones [7]. The biological basis for this cross-reactivity is rooted in the shared orbivirus core protein architecture, necessitating the use of serotype-specific or competitive formats to avoid false positives.

In the case of brucellosis, a WOAH-listed zoonotic disease of livestock, serological diagnostics are notoriously complex. A systematic review of 349 studies across continents revealed that the Rose Bengal test (RBT) and indirect ELISA are the most utilized assays, yet remarkably, only 16% of studies adhered to WOAH-recommended protocols regarding sample type, assay interpretation, and confirmatory testing [18]. The RBT is valued for its simplicity and low cost in low-income settings, as demonstrated in Guinea where it achieved 94-95% concordance with multispecies ELISA kits [19]. However, the complement fixation test (CFT) remains the WOAH-prescribed confirmatory test for international trade, despite its technical demands and the risk of prozone phenomena. The problem of cross-reacting antibodies is particularly acute in mycoplasmal infections. For instance, in a German goat outbreak of Mycoplasma mycoides subsp. capri, some animals developed antibodies that cross-reacted with Mycoplasma mycoides subsp. mycoides, the causative agent of contagious bovine pleuropneumonia (CBPP) [20]. This serological overlap complicates differential diagnosis and underscores the need for culture or molecular confirmation when serology yields ambiguous results.

For fish pathogens, serological detection faces additional challenges due to the polkilothermic nature of hosts and the lower immunogenicity of certain viral antigens. While ELISA-based methods exist for viruses like infectious hematopoietic necrosis virus (IHNV) and viral hemorrhagic septicemia virus (VHSV), direct virus isolation in cell culture has historically been the gold standard. However, the WOAH Manual now prioritizes molecular detection over serology for active surveillance of these notifiable diseases [6].

Molecular Detection: The Paradigm of Nucleic Acid Amplification

The advent of polymerase chain reaction (PCR) and its real-time variants has revolutionized the diagnosis of WOAH-listed diseases, offering unparalleled sensitivity, specificity, and speed. Reverse transcription quantitative PCR (RT-qPCR) is now the method of choice for most RNA viruses, while conventional and real-time PCR are standard for DNA pathogens.

The application of RT-qPCR for BTV and EHDV exemplifies the power of multiplex molecular diagnostics. A validated pan-BTV/pan-EHDV TaqMan assay, based on well-established primers targeting the highly conserved polymerase (Seg-1) and core protein (Seg-5) regions, allows simultaneous detection and differentiation of these two Culicoides-transmitted viruses [2]. This assay demonstrated high analytical sensitivity (down to 10 copies/μL) and 100% diagnostic specificity in field samples from Europe, where EHDV serotype 8 emerged in 2022 causing clinical signs indistinguishable from BT [2]. The ability to distinguish these pathogens in a single reaction is critical for rapid outbreak response, as they require different control measures and have distinct implications for trade.

For fish rhabdoviruses, IHNV and VHSV, the WOAH-recommended RT-qPCR protocols have undergone significant refinement. Hoferer et al. (2019) identified single nucleotide polymorphisms (SNPs) in the nucleoprotein gene of IHNV strains that compromised the binding of a commonly used TaqMan MGB probe, leading to false negatives [6]. By designing a new hydrolysis probe targeting a more conserved region, the improved one-step RT-qPCR achieved a technical sensitivity of 19 gene equivalents for IHNV and 190 for VHSV, with an analytical sensitivity of 2-7 TCID₅₀/mL [6]. This highlights a critical principle: molecular assays must be continuously updated to reflect the genetic diversity of circulating field strains. The same principle applies to spring viremia of carp virus (SVCV), where a whole-genome comparison of 24 strains covering all four genotypes (a-d) led to the design of a new primer-probe set targeting the L gene. This assay achieved a limit of detection of 1.28 copies/μL and a diagnostic sensitivity of 100% for cell-culture isolates [21].

Multiplex molecular detection has advanced to the point where quintuplex assays are feasible. Lou et al. (2025) developed an EvaGreen-based melting curve real-time PCR for the simultaneous detection of five major shrimp pathogens: white spot syndrome virus (WSSV), infectious hypodermal and hematopoietic necrosis virus (IHHNV), decapod iridescent virus 1 (DIV1), acute hepatopancreatic necrosis disease-causing Vibrio (VAHPND), and Enterocytozoon hepatopenaei (EHP) [12]. By exploiting distinct melting temperatures (Tm) of the amplicons, the assay could discriminate all five targets in a single tube, with a detection limit of 10 copies/μL and a diagnostic sensitivity above 89.74% across 800 clinical samples [12]. This approach is far more cost-effective than running five separate reactions and is ideal for regional surveillance programs.

Isothermal amplification technologies, particularly loop-mediated isothermal amplification (LAMP) and recombinase polymerase amplification (RPA), are bridging the gap between laboratory-based PCR and field-deployable diagnostics. For BTV, LAMP assays have been developed in China targeting the Seg-10 gene, offering results in under 30 minutes without the need for thermal cyclers [1]. For African swine fever virus (ASFV), which causes a devastating hemorrhagic disease of swine, real-time reverse transcription multienzyme isothermal rapid amplification (RT-MIRA) has been established. This method targets the Seg-7 gene of African horse sickness virus (AHSV) and achieves a limit of detection of 10 copies/μL, with results visible under blue light using a portable device [22]. The specificity was 100% against other equine orbiviruses, making it suitable for border screening.

For crustacean pathogens, the combination of RPA with lateral flow strips (LFS) represents a significant breakthrough. Mu et al. (2025) developed an RPA-LFS assay for DIV1 that amplifies the target gene in 18 minutes at 38°C, with visual readout within 3 minutes. The assay did not cross-react with WSSV, IHHNV, or other shrimp viruses, and its sensitivity (1.12 × 10¹ copies/μL) was comparable to WOAH-recommended qPCR [23]. Such assays are transformative for point-of-care diagnostics in shrimp farms, where laboratory infrastructure is often lacking.

Integration and Validation of Diagnostic Strategies

The WOAH diagnostic framework emphasizes a hierarchical approach: screening (serology or group-specific molecular assays) followed by confirmatory testing (virus isolation, sequencing, or species-specific PCR). For CBPP, caused by Mycoplasma mycoides subsp. mycoides, the recommended approach includes both serological screening (c-ELISA) and molecular confirmation via PCR targeting the fusA or dnaK genes, given the organism's fastidious growth requirements [24]. Similarly, for contagious agalactia in goats, molecular detection of Mycoplasma species using a multiplex PCR targeting the 16S-23S rRNA intergenic spacer region is essential to differentiate M. mycoides subsp. capri from other pathogenic mycoplasmas [20].

The validation of these assays is subject to rigorous standards. The SVCV RT-qPCR developed by Zhu et al. (2026) was validated across nine independent laboratories, demonstrating robust reproducibility and adherence to the WOAH Manual of Diagnostic Tests for Aquatic Animals [21]. For brucellosis, the WOAH reference laboratory in France employs a combination of RBT, CFT, and multispecies ELISA, yet the diagnostic accuracy of RBT in field hands can vary greatly, emphasizing the need for regular proficiency testing [19].

One emerging concern is the detection of nucleic acid from inactivated or non-viable pathogens. In the context of aquaculture feed biosecurity, PCR-based assays cannot distinguish infectious WSSV particles from degraded genomic fragments in extruded pellets. Mai et al. (2025) addressed this by developing a conventional PCR targeting a 980 bp amplicon, which was only produced from intact viral DNA, whereas shorter amplicons could arise from degraded templates [25]. This approach, combined with a real-time PCR for initial screening, provides a practical solution for assessing the biosecurity risk of formulated aquafeeds until a crustacean cell line becomes available.

The integration of serological and molecular methods in surveillance programs is exemplified by the work in China on BTV and EHDV. While serology identifies past exposure and defines the geographic distribution of serotypes, molecular detection confirms active infection and enables genotyping. The co-circulation of multiple BTV serotypes (17 isolated in China) and EHDV serotypes (1, 5, 6, 7, 8, 10) necessitates the use of multiplex RT-qPCR assays that can detect and differentiate these viruses simultaneously [1, 7]. This dual approach is essential for implementing targeted vaccination strategies and for the safe movement of livestock across borders.

Vaccine Platforms and Immunoprophylaxis Strategies

The development of effective vaccines and immunoprophylaxis strategies for WOAH-listed diseases represents one of the most formidable challenges in contemporary veterinary medicine. The extraordinary diversity of etiological agents, ranging from complex double-stranded DNA viruses like African swine fever virus (ASFV) to fastidious mycoplasmas and recalcitrant fungal pathogens, demands a correspondingly diverse arsenal of vaccine platforms. The biological complexity of these pathogens, coupled with the intricate host-pathogen interactions that characterize many WOAH-listed diseases, has necessitated a paradigm shift from traditional empirical vaccine development toward rational, structure-guided immunogen design. This section provides an exhaustive analysis of the current state of vaccine platforms and immunoprophylaxis strategies, examining both established approaches and cutting-edge technological innovations that are reshaping the landscape of disease prevention for these globally significant pathogens.

Traditional Vaccine Platforms: Inactivated and Attenuated Approaches

Conventional vaccine platforms, including inactivated (killed) and live-attenuated formulations, have historically formed the backbone of veterinary immunoprophylaxis for WOAH-listed diseases. For bluetongue virus (BTV), a vector-borne orbivirus affecting ruminants, both inactivated and attenuated vaccines have been extensively investigated, particularly in China where 17 serotypes have been isolated since 1979 [1]. Inactivated BTV vaccines offer the advantage of safety, as they cannot revert to virulence or be transmitted by Culicoides vectors, but they often require multiple doses and adjuvants to induce protective immunity. Conversely, live-attenuated BTV vaccines, while capable of eliciting robust and durable immune responses following a single administration, carry inherent risks including reversion to virulence, reassortment with field strains, and potential teratogenicity in pregnant animals [1]. The serotype-specific nature of BTV immunity further complicates vaccine development, as cross-protection between the 17 circulating serotypes in China is limited, necessitating multivalent formulations or the identification of conserved protective epitopes.

The challenges associated with traditional platforms are perhaps most starkly illustrated by African swine fever (ASF), a hemorrhagic disease of domestic and wild pigs caused by ASFV, a large, enveloped double-stranded DNA virus with extraordinary genomic complexity [10]. Despite decades of research, no safe and efficacious commercial ASFV vaccine exists, a failure that stems fundamentally from the virus's sophisticated immune evasion mechanisms. ASFV orchestrates a complex manipulation of host apoptosis and autophagy pathways, subverting innate immune surveillance to promote its replication and dissemination [26]. The virus encodes numerous proteins that interfere with interferon signaling, inhibit apoptosis, and modulate inflammatory responses, creating a formidable barrier to vaccine development. Early attempts at developing inactivated ASFV vaccines were uniformly unsuccessful, failing to protect against homologous challenge. Live-attenuated vaccines, generated through serial passage in cell culture or targeted gene deletion, have shown greater promise, with several candidates demonstrating protection against homologous virulent challenge. However, safety concerns persist, including the potential for residual virulence, reversion to pathogenicity, and the establishment of persistent infections. The identification of immunogenic viral antigens remains a critical bottleneck, as the protective immune response to ASFV is incompletely characterized, and the correlates of protection, whether antibody-mediated, cell-mediated, or both, remain subjects of intense investigation [10].

Recombinant Subunit and Virus-Like Particle Vaccines

The limitations of traditional platforms have catalyzed the development of recombinant subunit vaccines, which employ purified immunogenic proteins produced through heterologous expression systems. These platforms offer unparalleled safety, as they contain no infectious material, and can be designed to elicit precisely targeted immune responses. For classical swine fever (CSF), a highly contagious WOAH-listed disease of swine, the envelope glycoprotein E2 has been identified as the primary immunogen, capable of inducing neutralizing antibodies and protective immunity. A landmark study demonstrated the efficacy of a single-dose bivalent subunit vaccine co-formulating soluble CSFV-E2 (50 µg) and porcine circovirus type 2 ORF2 (100 µg) antigens with a porcine-specific CpG adjuvant [27]. This formulation induced significantly increased neutralizing and ELISA antibody titers against both viruses four weeks post-vaccination, and vaccinated pigs displayed no clinical signs or lesions following viral challenge, with markedly reduced viral loads in serum and tissues compared to controls [27]. The success of this approach highlights the potential of subunit vaccines for WOAH-listed diseases, particularly when combined with potent adjuvants that can compensate for the reduced immunogenicity of purified antigens.

For infectious hematopoietic necrosis virus (IHNV), a rhabdovirus causing devastating losses in salmonid aquaculture, a novel self-assembling ferritin nanoplatform has been developed to overcome the stability and immunogenicity limitations of traditional subunit vaccines [4]. By genetically fusing the virus glycoprotein to Helicobacter pylori ferritin as a scaffold, researchers constructed FerritVac, a self-assembling nanovaccine that forms stable protein nanocages. Remarkably, these nanoparticles demonstrated excellent stability under diverse storage, pH, and temperature conditions, including those mimicking the harsh gastrointestinal environment of trout, the virus's primary host [4]. This thermostability is particularly significant for aquaculture applications, where cold chain maintenance is often logistically challenging. The nanovaccine upregulated expression of innate antiviral immunity genes, including mx, vig1, ifit5, and isg-15, in host macrophage cells, indicating potent immunostimulatory properties. The ferritin platform enables multivalent antigen presentation, mimicking the repetitive array of viral surface proteins and thereby enhancing B cell receptor cross-linking and humoral immune responses. This approach offers significant commercial potential for non-mammalian and enveloped viruses, addressing critical gaps in vaccine availability for WOAH-listed aquatic diseases [4].

Autogenous and Emergency Vaccination Strategies

For pathogens where commercial vaccine development has proven intractable, autogenous vaccination, the preparation of inactivated vaccines from farm-specific isolates, represents a pragmatic alternative. This approach was notably employed during an outbreak of Mycoplasma mycoides subsp. capri (Mmc) in a German goat flock, where the pathogen caused severe mastitis, arthritis, pleuropneumonia, and sudden deaths [20]. Although Mmc is considered an uncommon pathogen in Central Europe, the outbreak demonstrated that autogenous vaccination significantly improved animal health and welfare, even though complete eradication was not achieved [20]. This strategy is particularly relevant for mycoplasmal diseases, where the antigenic diversity of field strains often limits the efficacy of commercial vaccines. For contagious bovine pleuropneumonia (CBPP), caused by Mycoplasma mycoides subsp. mycoides, the development of safer, more effective, and thermostable vaccines, including DIVA (Differentiating Infected from Vaccinated Animals) and multivalent options, has been identified as a critical need [24]. The current live-attenuated CBPP vaccine, while providing some protection, has limitations including residual virulence and the inability to distinguish vaccinated from infected animals, complicating surveillance and eradication programs. The DISCONTOOLS database has highlighted these gaps, emphasizing the need for cost-effective intervention strategies combining vaccination with rational, regulated antibiotic use [24].

Emerging Platforms and Future Directions

The frontier of vaccine development for WOAH-listed diseases is being reshaped by platforms that leverage advances in structural biology, immunology, and nanotechnology. Self-assembling protein nanoparticles, as exemplified by the ferritin platform for IHNV, represent a particularly promising approach for enveloped viruses, where the presentation of conformationally intact glycoprotein spikes is critical for eliciting neutralizing antibodies [4]. These platforms offer the additional advantage of enabling oral administration, which would revolutionize vaccination logistics for aquatic species. The biocompatibility and stability of ferritin nanocages under gastrointestinal conditions make them ideal vehicles for oral vaccines, potentially eliminating the need for individual injection of millions of fish [4].

For diseases like ASF, where traditional approaches have failed, novel strategies are being explored, including the development of live-attenuated vaccines through targeted deletion of virulence genes involved in immune evasion. Understanding the molecular mechanisms by which ASFV manipulates host apoptosis and autophagy pathways, including the crosstalk between these processes, provides a rational basis for designing attenuated strains that retain immunogenicity while lacking pathogenic potential [26]. Similarly, for bluetongue virus, the development of recombinant vaccines expressing multiple serotype-specific antigens, potentially delivered through viral vectors or DNA vaccines, offers a path toward broad-spectrum protection against the diverse serotypes circulating in endemic regions [1].

The integration of vaccine development with improved diagnostic capabilities is essential for effective immunoprophylaxis strategies. The ability to differentiate vaccinated from infected animals (DIVA) is critical for surveillance and trade, particularly for diseases where vaccination is used as part of control programs rather than for eradication. For CBPP, the development of DIVA-compatible vaccines is a priority, enabling serological surveillance to continue during vaccination campaigns [24]. Similarly, for epizootic hemorrhagic disease (EHD), the development of multiple ELISA detection methods, including antigen capture and competitive ELISA, provides the diagnostic infrastructure necessary to support vaccination programs [7].

The economic and logistical realities of vaccine deployment in resource-limited settings must inform platform selection. For brucellosis, a zoonotic WOAH-listed disease, the Rose Bengal agglutination test (RBT) remains the primary diagnostic tool in low-income countries like Guinea, where logistics, equipment, competence, and cost limitations constrain diagnostic capacity [19]. Vaccine strategies for such settings must prioritize thermostability, single-dose efficacy, and affordability. The development of thermostable vaccines for CBPP and other mycoplasmal diseases of sub-Saharan Africa is therefore not merely a scientific challenge but a prerequisite for disease control in endemic regions [24].

In conclusion, the landscape of vaccine platforms and immunoprophylaxis strategies for WOAH-listed diseases is characterized by both remarkable progress and persistent challenges. Traditional inactivated and live-attenuated vaccines continue to play important roles, particularly for diseases like bluetongue where they have demonstrated field efficacy. However, the emergence of recombinant subunit vaccines, self-assembling nanoplatforms, and rationally designed live-attenuated candidates offers new hope for diseases that have historically proven vaccine-resistant. The integration of these platforms with improved adjuvants, delivery systems, and diagnostic tools will be essential for translating scientific advances into practical disease control. The ultimate success of these efforts will depend on sustained investment in basic research, translational development, and field implementation, guided by the recognition that effective vaccines are not merely biological products but essential tools for global food security, animal welfare, and public health.

Global Surveillance and Control Programs for WOAH-Listed Diseases

The architecture of global surveillance and control for WOAH-listed diseases represents a complex, multi-layered system that must simultaneously address the biological intricacies of diverse pathogens, the logistical realities of resource-limited settings, and the economic imperatives of international trade. The World Organisation for Animal Health (WOAH) has established a framework that relies on mandatory notification, standardized diagnostic protocols, and a tiered system of disease status recognition, but the practical implementation of these programs reveals significant heterogeneity across regions, host species, and pathogen types. This section provides an exhaustive analysis of the current state of global surveillance and control programs, examining the structural components, technological innovations, and persistent gaps that define the contemporary landscape.

The World Animal Health Information System as a Foundational Surveillance Platform

At the core of global surveillance efforts lies the World Animal Health Information System (WAHIS), which serves as the primary mechanism for collecting, analyzing, and disseminating data on WOAH-listed diseases across 182 Member countries [17]. This system obligates members to report outbreaks in a timely manner, generating one of the most comprehensive epidemiological datasets available for animal health research. The utility of WAHIS extends beyond simple case counting; the data have been instrumental in developing predictive models for disease spread, assessing risks associated with trade in animal products, and understanding the movement of vectors across international borders [17]. For instance, analyses of WAHIS data on foot and mouth disease (FMD) status suspensions between 1996 and 2020 revealed that implementing stamping-out policies or vaccination-and-removal strategies significantly shortened the time required to recover disease-free status compared to vaccination-and-retain approaches [28]. This finding has direct implications for control program design, demonstrating that the choice of intervention strategy has measurable consequences for trade recovery and economic impact.

The effectiveness of WAHIS, however, is contingent upon the quality and timeliness of national reporting, which varies considerably. A systematic review of brucellosis diagnostics across 349 studies found that only 16% of research followed WOAH-recommended protocols for sample selection, assay choice, and result interpretation [18]. This discrepancy between official reporting and actual diagnostic practice raises serious concerns about the accuracy of data submitted to WAHIS, particularly for diseases like brucellosis where serological cross-reactivity and variable test performance can lead to misclassification. The implications are profound: if countries are reporting disease status based on inadequate diagnostic algorithms, the entire edifice of global surveillance becomes compromised, potentially facilitating the international spread of pathogens through undetected infected animals or products.

Diagnostic Technology Integration into Surveillance Frameworks

The evolution of molecular diagnostics has transformed the capacity for surveillance, enabling rapid, high-throughput detection of multiple pathogens simultaneously. The development of a quintuplex EvaGreen-based real-time PCR assay for simultaneous detection of white spot syndrome virus (WSSV), infectious hypodermal and hematopoietic necrosis virus (IHHNV), decapod iridescent virus 1 (DIV1), acute hepatopancreatic necrosis disease-causing Vibrio (VAHPND), and Enterocytozoon hepatopenaei (EHP) represents a paradigm shift in aquatic disease surveillance [12]. This assay demonstrated diagnostic sensitivity above 89.74% for all five pathogens and 100% diagnostic specificity when tested against 800 clinical samples from Chinese shrimp farming regions [12]. The ability to screen for multiple WOAH-listed crustacean pathogens in a single reaction dramatically reduces the cost and time required for surveillance, making comprehensive monitoring feasible even in resource-constrained settings.

Similarly, the validation of a TaqMan RT-qPCR pan-BTV/pan-EHDV assay capable of simultaneously detecting and distinguishing bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV) addresses a critical need in regions where both viruses circulate [2]. Following the emergence of a novel EHDV serotype 8 strain in Tunisia in 2021 and its subsequent detection in Italy, Spain, Portugal, and France, the ability to differentiate between BTV and EHDV using a single assay has become essential for surveillance programs in European Mediterranean countries [2]. The assay’s high sensitivity, specificity, and reproducibility make it suitable for integration into national surveillance strategies, particularly given the significant cost reduction compared to running separate assays for each virus.

For diseases where rapid field detection is paramount, isothermal amplification technologies have emerged as powerful alternatives to PCR. The development of a recombinase polymerase amplification combined with lateral flow strip (RPA-LFS) assay for DIV1 detection enables amplification within 18 minutes at a constant temperature of 38°C, with results visible on the lateral flow strip within 3 minutes [23]. When tested against 110 field samples, the RPA-LFS assay produced results identical to the WOAH-recommended qPCR, demonstrating that field-deployable diagnostics can achieve laboratory-grade accuracy [23]. This technology is particularly valuable for surveillance programs in remote aquaculture areas where access to thermocyclers and skilled laboratory personnel is limited.

The real-time reverse transcription multienzyme isothermal rapid amplification (RT-MIRA) assay for African horse sickness virus (AHSV) detection provides another example of how isothermal technologies are expanding surveillance capabilities [22]. With a limit of detection of 10 copies/μL and no cross-reactivity with other equine viruses or orbiviruses, this assay matches the sensitivity of RT-qPCR while offering the advantages of portability, visualization under blue light, and operation without specialized equipment [22]. For a disease like African horse sickness, which can cause up to 90% mortality in naïve horses and is listed as notifiable by WOAH, the availability of rapid, field-deployable diagnostics is critical for outbreak response and containment.

Targeted Surveillance Programs for Terrestrial and Aquatic Diseases

The implementation of surveillance programs varies dramatically between terrestrial and aquatic animal sectors, reflecting differences in disease biology, production systems, and regulatory frameworks. In the Spanish aquaculture sector, application of the FAO Surveillance Evaluation Tool (SET) revealed important disparities between surveillance systems for trout versus marine fish species [29]. Trout surveillance scored 70.8% for institutional components, 91.7% for laboratory capacity, and 75.3% for surveillance activities, reflecting the presence of EU and WOAH-listed diseases for this species. In contrast, seabass and seabream surveillance scored only 50.0%, 47.2%, and 61.3% respectively, largely because no WOAH-listed diseases exist for these species [29]. This finding highlights a fundamental challenge in aquatic animal health surveillance: the absence of listed diseases does not equate to the absence of disease risk, and surveillance programs must be designed to detect emerging pathogens and abnormal mortality events even in the absence of specific regulatory requirements.

The WOAH Aquatic Animal Health Strategy (AAHS), launched in 2021, represents a concerted effort to address these gaps by ensuring scientifically sound standards for risk management, building capacity for aquatic animal health services, and coordinating regional and global responses [8]. The strategy recognizes that disease is currently a major limiting factor in the sustainable growth of aquaculture, which is increasingly critical for global food security. However, implementation faces obstacles including limited laboratory capacity in many producing countries, the high cost of diagnostic testing, and the challenge of developing standardized surveillance methodologies for diverse production systems and species [8].

For terrestrial diseases, participatory surveillance designs offer a cost-effective approach to achieving national-level coverage. A simulation study using the U.S. swine industry as a model demonstrated that a participatory surveillance system, where herd veterinarians and producers collect and submit samples for testing, could achieve a 90% probability of detecting a notifiable pathogen at 0.05% farm prevalence when farm-level sensitivity was at least 20% and producer participation was at least 40% [30]. The estimated cost ranged from $0.03 to $0.07 USD per pig in inventory, making this approach both affordable and practical for national surveillance programs [30]. This model is particularly relevant for diseases like African swine fever (ASF), where early detection is critical for containment but where the sheer number of farms makes traditional surveillance approaches prohibitively expensive.

Vector Surveillance and Integrated Control Strategies

For vector-borne WOAH-listed diseases, surveillance programs must extend beyond pathogen detection in hosts to include comprehensive monitoring of vector populations. In China, studies on bluetongue virus have examined climatic factors influencing the distribution and blood-sucking habits of Culicoides vectors, recognizing that vector ecology is a critical determinant of disease transmission risk [1]. The isolation of 17 BTV serotypes across China since 1979 underscores the need for ongoing vector surveillance, particularly as climate change alters the geographic range of Culicoides species and potentially introduces new serotypes into previously unaffected areas [1].

Similarly, surveillance for epizootic hemorrhagic disease in China has documented the circulation of multiple EHDV serotypes, including reassortant strains combining western and eastern topotypes [7]. The isolation of a novel serotype (YNDH/V079/2018) in 2018 highlights the ongoing evolution of these viruses and the importance of maintaining robust surveillance systems capable of detecting emerging strains [7]. Control recommendations include reducing Culicoides populations, minimizing host-vector contact, and continued monitoring of both virus and vector distribution across different ecological zones [7].

The discovery of African swine fever virus in Haematopinus suis (the hog louse) collected from sows that died of acute ASF, and in newly hatched nymphs from nits collected from the same source, introduces a potential new dimension to ASF surveillance and control [9]. This finding suggests the possibility of a sylvatic cycle involving lice and domestic pigs, which could complicate eradication efforts by providing an additional mechanism for viral persistence and transmission [9]. Surveillance programs for ASF may need to incorporate ectoparasite sampling, particularly in regions where biosecurity measures have failed to prevent recurrent outbreaks.

Challenges in Wildlife Surveillance and the One Health Interface

Wildlife populations present unique challenges for surveillance of WOAH-listed diseases, as they often serve as reservoir hosts without exhibiting clinical signs. A review of 73 WOAH-listed terrestrial animal diseases identified 528 possible wild animal hosts, though not all host-pathogen relationships indicate epidemiologically significant roles in disease transmission [15]. The expanding international wildlife trade, valued at over US $300 billion annually, represents a potential pathway for transboundary disease movement, yet surveillance and reporting of listed diseases in wildlife remain largely opportunistic [15]. This gap is particularly concerning for diseases like ASF, where wild boar populations can maintain the virus and serve as a source of infection for domestic pigs, complicating control efforts.

The role of wildlife in the epidemiology of WOAH-listed diseases in Europe has been the subject of recent analysis, with 25 selected pathogens identified as having significant impacts on wildlife conservation, livestock health, or human health [3]. These include bluetongue virus, West Nile virus, African swine fever virus, and various morbilliviruses, among others. The drivers of disease change and emergence in European wildlife appear to be multifactorial, involving climate change, land use patterns, and wildlife population dynamics [3]. Effective surveillance at the wildlife-livestock interface requires integrated approaches that combine molecular diagnostics, ecological monitoring, and cross-sectoral collaboration.

Control Program Implementation and the Path to Eradication

The success of control programs for WOAH-listed diseases depends on a combination of diagnostic capacity, vaccination strategies, biosecurity measures, and political will. For contagious bovine pleuropneumonia (CBPP), caused by Mycoplasma mycoides subsp. mycoides, eradication has been achieved in the USA, Australia, Europe, and parts of southern Africa through the application of drastic stamping-out policies [24]. However, the disease remains endemic in sub-Saharan Africa, where control efforts are hampered by limited diagnostic capacity, the absence of effective vaccines, and socioeconomic factors that make stamping-out policies impractical [24]. The DISCONTOOLS database has identified critical gaps in CBPP knowledge, including the need for better understanding of disease distribution and impact, mechanisms of transmission and persistence, molecular basis of pathogenicity, and development of affordable pen-side diagnostic tests [24].

In contrast, the control of brucellosis in southern Italy demonstrates how territory-specific One Health measures can achieve eradication even in challenging environments. In the provinces of Caserta and Salerno, stringent control measures tailored to the specific vulnerabilities of water buffalo breeding operations, including frequent flooding events and high animal density, led to a gradual decline in outbreak prevalence, with Salerno achieving zero positive heads by 2022 [31]. Key components of this program included strengthening biosecurity measures, implementing advanced animal traceability systems, continuous professional training for farmers, and promoting voluntary serological self-monitoring practices [31]. This case study illustrates that successful control programs must be adapted to local epidemiological, ecological, and socioeconomic contexts rather than applied as one-size-fits-all solutions.

For diseases where effective vaccines exist, vaccination strategies must be integrated into comprehensive control programs. The development of a single-dose PCV2/CSFV bivalent subunit vaccine for classical swine fever virus and porcine circovirus type 2 represents an advance in swine disease control, as it reduces the number of vaccinations required and improves compliance [27]. In CSF-endemic regions, such bivalent vaccines could be incorporated into national control programs to simultaneously address two significant pathogens, reducing both disease burden and vaccination costs [27].

The Role of International Standards and Trade Considerations

WOAH standards for disease surveillance and control are intrinsically linked to international trade, as disease-free status recognition facilitates the safe movement of animals and animal products. The analysis of FMD-free status suspensions between 1996 and 2020 revealed that territories bordering FMD-infected countries, those with lower Veterinary Service capacity, and those that took longer to implement control measures experienced longer recovery times [28]. These findings underscore the importance of investing in Veterinary Services and maintaining rapid response capabilities, not only for animal health but also for economic competitiveness in international markets.

The WOAH standard-setting process for bee health provides a model for how international standards can evolve to address emerging risks. Current standards limit recommendations to preserving the health of Apis species, extended to Bombus and stingless bees for one disease, but do not include standards for mitigating risks associated with international trade of other insects [32]. As the insect trade expands for food, feed, and other purposes, the development of comprehensive standards will be essential to prevent the introduction of WOAH-listed pathogens into new regions [32]. This aligns with the WOAH commitment to a One Health approach, recognizing that animal health, human health, and environmental health are interconnected.

Persistent Gaps and Future Directions

Despite significant advances in surveillance technology and control strategies, substantial gaps remain in the global capacity to monitor and manage WOAH-listed diseases. The lack of harmonized lesion scoring methods for viral disease histopathology in aquaculture finfish limits the comparability of diagnostic findings across studies and regions [5]. For diseases like infectious hematopoietic necrosis virus (IHNV) and viral hemorrhagic septicemia virus (VHSV), improved RT-qPCR procedures have been developed to address issues with probe binding due to single nucleotide polymorphisms in target sequences, but field validation remains essential to ensure that diagnostic assays keep pace with viral evolution [6].

The challenge of antimicrobial resistance (AMR) adds another layer of complexity to disease control programs. In the ASEAN region, limited collaboration between human health and other sectors has impeded the benefits that a One Health approach could achieve in addressing AMR [33]. For WOAH-listed diseases like CBPP, where antibiotics are used for treatment and control, the emergence of antimicrobial resistance poses a serious risk that must be monitored through integrated surveillance systems [24].

Looking forward, the integration of artificial intelligence and machine

Future Directions and Research Gaps

1. Critical Gaps in Vaccine Development and Immunoprophylaxis

Despite decades of research, the development of safe, efficacious, and globally accessible vaccines for numerous WOAH-listed diseases remains arguably the most pressing unmet need. The case of African swine fever (ASF) exemplifies this challenge with stark clarity. The absence of a safe commercial ASFV vaccine stems from fundamental unresolved questions regarding the identification of protective immunogenic viral antigens, the incomplete characterization of ASFV pathogenesis, and a limited understanding of the virus's sophisticated immune evasion mechanisms, particularly its orchestration of the autophagy-apoptosis crosstalk to subvert innate immune surveillance [10, 26]. Future research must prioritize the elucidation of ASFV's molecular strategies for host remodeling, as this knowledge is prerequisite for rational vaccine design. Similarly, for bluetongue virus (BTV) in China, while inactivated, attenuated, and recombinant vaccines have been investigated, a comprehensive prevention and control technology system remains nascent, hindered by ongoing serotype diversity (17 serotypes isolated to date) and the need for multivalent formulations that provide broad protection against co-circulating strains [1].

Conversely, promising avenues are emerging. The self-assembling ferritin nanoplatform (FerritVac) developed for Infectious Hematopoietic Necrosis Virus (IHNV) represents a paradigm shift in vaccinology for non-mammalian hosts. This platform demonstrates how genetic fusion of viral glycoproteins to bacterial ferritin scaffolds yields nanoparticles with exceptional thermal and pH stability, enabling oral administration and robust induction of antiviral innate immunity (mx, vig1, ifit5, isg-15) in trout macrophages [4]. Future work must scale this platform for field trials and explore its applicability to other enveloped WOAH-listed viruses, such as Viral Hemorrhagic Septicemia Virus (VHSV) and Spring Viremia of Carp Virus (SVCV). Additionally, the successful development of a single-dose PCV2/CSFV bivalent subunit vaccine for swine, incorporating a porcine-specific CpG adjuvant, demonstrates that rational antigen combination and adjuvant selection can overcome the limitations of monovalent approaches [27]. Research must now extend this principle to other WOAH-listed co-endemic pathogens, particularly in regions where polyvalent protection is critical for economic sustainability.

2. Diagnostic Innovations and Surveillance Infrastructure Deficits

A constellation of diagnostic gaps undermines global capacity for early detection and response. For brucellosis in livestock, a systematic review of 349 studies revealed that only 16% adhered to WOAH-recommended diagnostic protocols in terms of sample selection, assay choice, and result interpretation [18]. This alarming discordance between field practices and international standards yields an inaccurate epidemiological picture, delays control, and amplifies zoonotic risk. Future directions must include the development and deployment of affordable, field-deployable, and WOAH-validated point-of-care tests, particularly for low-income settings where the Rose Bengal test remains the sole tool despite its limitations [19]. For contagious bovine pleuropneumonia (CBPP), the need for pen-side tests that circumvent the requirement for cold chain and sophisticated laboratory infrastructure is acute, as is the requirement for DIVA (Differentiating Infected from Vaccinated Animals) vaccines and companion diagnostics to support eradication campaigns in sub-Saharan Africa [24].

The evolution of molecular diagnostics offers a partial solution but introduces new complexities. Multiplex real-time PCR assays, such as the quintuplex EvaGreen melting curve method for simultaneous detection of WSSV, IHHNV, DIV1, VAHPND, and EHP in shrimp, achieve diagnostic sensitivities above 89.74% and 100% specificity [12]. Similarly, the development of pan-BTV/pan-EHDV TaqMan RT-qPCR assays enables cost-effective, high-throughput surveillance for these Culicoides-transmitted viruses [2]. However, the Achilles' heel of molecular surveillance is the emergence of primer-probe mismatches due to viral evolution. Whole-genome comparisons of SVCV strains revealed critical mismatches in previously published RT-qPCR assays, leading to false negatives; a redesigned assay targeting conserved L-gene regions now achieves a detection limit of 1.28 copies/μL with 100% diagnostic specificity [21]. Future research must adopt a proactive, phylogenetically-informed approach to assay design, continuously cross-referencing global sequence databases to ensure primer-probe sets remain robust against emerging genotypes. The integration of recombinant polymerase amplification (RPA) with lateral flow strips (LFS) for DIV1 detection, achieving results within 21 minutes at constant temperature, underscores the potential for shifting diagnostics from centralized laboratories to farm-side or port-of-entry settings [23]. For African horse sickness (AHSV), the real-time reverse transcription multienzyme isothermal rapid amplification (RT-MIRA) assay provides a visual, equipment-free alternative to RT-qPCR, with identical sensitivity (10 copies/μL) and the ability to be read under portable blue light [22]. The critical research gap now lies in validating these isothermal platforms across diverse matrices (blood, tissue, vectors) and ensuring their performance matches WOAH standards under field conditions in endemic regions.

3. Unraveling Sylvatic Cycles, Vector Ecology, and Transmission Pathways

The discovery of African swine fever virus (ASFV) in Haematopinus suis lice collected from acutely infected sows, and critically, in newly hatched nymphs from nits, has profound implications [9]. This finding strongly suggests a potential sylvatic cycle involving lice as a biological vector capable of transovarial transmission, challenging the current dogma that ASFV transmission is primarily direct or via soft ticks (Ornithodoros spp.). Future research must rigorously characterize the vector competence of H. suis, quantify the viral load in lice during different stages of infection, and assess the epidemiological significance of this route in both free-range and intensive production systems. Such work would fundamentally alter risk assessments and biosecurity protocols.

For vector-borne diseases of ruminants, the intricate interplay between Culicoides midges, climate, and viral reassortment remains poorly parameterized. In China, the isolation of 17 BTV serotypes and the emergence of a novel EHDV strain (YNDH/V079/2018) highlight the pathogen's adaptive capacity, including the generation of reassortant strains containing both western and eastern topotype segments [1, 7]. Research must integrate high-resolution Culicoides distribution and blood-feeding habit data with dynamic climate models to forecast incursions under changing environmental conditions. The recent introduction and rapid spread of EHDV serotype 8 in the Mediterranean basin, causing clinical signs indistinguishable from BTV, underscores the urgency for integrated surveillance systems that simultaneously monitor both pathogens using validated pan-assays [2].

4. Strengthening Surveillance Systems and International Data Harmonization

The application of the FAO Surveillance Evaluation Tool (SET) to the Spanish aquaculture surveillance system exposed stark disparities: trout surveillance scored 75.3% for activities, while marine fish (seabass, seabream) scored only 61.3%, largely because no WOAH-listed diseases are designated for these species [29]. This gap is not unique to Spain. For Mediterranean aquaculture, a critical knowledge deficit exists regarding the disease situation for seabass and seabream, compounded by legislative frameworks that do not list these species as susceptible hosts for notifiable pathogens, thereby eliminating the obligation for systematic reporting [34]. Future policy directions must advocate for an expansion of host-species listings to encompass commercially significant marine finfish, enabling structured surveillance and risk analysis.

The potential of the World Animal Health Information System (WAHIS) as a tool for predictive modeling and risk assessment is enormous but underutilized. WAHIS data, combined with trade, migration, and genetic data, have been used to quantify time-dependent predictors of HPAI H5Nx international spread, revealing the protective effect of resources allocated to veterinary services and border precautions [17, 16]. However, the granularity and timeliness of reporting remain bottlenecks. Research must develop automated pipelines for real-time data integration from WAHIS, FAO, and IUCN to generate dynamic risk maps that can inform pre-emptive vaccination and biosecurity interventions. For wildlife, the current opportunistic surveillance for WOAH-listed diseases is a critical blind spot, given that the international wildlife trade represents a US $300 billion per year industry with over 500 potential wild animal hosts documented [15]. A standardized, risk-based wildlife surveillance framework, coupled with mandatory reporting of WOAH-listed diseases in traded wildlife, is an imperative for global health security.

5. Addressing Anti-Microbial Resistance (AMR) and the One Health Imperative

The emergence of AMR in the context of WOAH-listed diseases is a double-edged sword. For CBPP, where antimicrobial use remains a primary control tool in sub-Saharan Africa, the risk of resistance emergence is high, yet surveillance for AMR in Mycoplasma mycoides subsp. mycoides is essentially nonexistent [24]. Similarly, for brucellosis, the diagnostic challenges discussed above lead to misdiagnosis and inappropriate antibiotic use, further driving resistance [18, 31]. The application of a One Health approach, as advocated by the Quadripartite (FAO, WHO, WOAH, UNEP), is essential. Research must prioritize the development and validation of cost-effective intervention strategies that combine vaccination with the rational, regulated use of antibiotics, coupled with integrated AMR surveillance across human, animal, and environmental sectors [24, 33]. The success of local eradication programs for bovine brucellosis in Italian provinces, which required targeted biosecurity, animal traceability, and stakeholder engagement, demonstrates that context-specific One Health measures can be effective but require sustained financial investment and political commitment [31].

6. The Neglected Frontier: Protozoan Diseases, Honeybee Pathogens, and Fungal Infections

Surveillance gaps for WOAH-listed protozoan parasites in bivalve shellfish are starkly illustrated by the baseline assessment in Korean coastal waters, which found no detectable Perkinsus marinus, Bonamia ostreae, or Marteilia refringens in Pacific oysters and Mediterranean mussels from port-adjacent harbors [35]. However, the contrast with recent reports of these pathogens in other bivalve species (Ostrea denselamellosa) underscores that infections may be focal, host-specific, and transient. Future research must implement continuous, risk-based surveillance coupled with environmental DNA (eDNA) metabarcoding to detect cryptic introductions at ports of entry. For honeybees, the small hive beetle (Aethina tumida) remains a listed threat, yet effective surveillance methods are still evolving. The Mobile Divider method shows promise for concentrating beetles during hive inspections, but its effectiveness in high-infestation regions requires validation [36]. Finally, equine epizootic lymphangitis (EEL), caused by Histoplasma capsulatum var. farciminosum, persists in Mediterranean countries and Africa, yet its diagnosis is hampered by the slow growth of the organism and challenges in sample collection [37]. Research into rapid molecular diagnostics for EEL and the development of effective control measures, including fly control and wound management, are urgently needed to protect the livelihoods of equine-dependent communities.

References

[1] Xin J, Ji X, Song Z, Zuo W, Yin S, Peng Y, et al.. Bluetongue in China: Current Status of Viruses, Vectors, Detection Methods, and Vaccines.. Transboundary and Emerging Diseases. 2026. DOI: https://doi.org/10.1155/tbed/5538034

[2] Portanti O, Ciarrocchi E, Irelli R, Palombieri A, Salini R, Melegari I, et al.. Validation of a molecular multiplex assay for the simultaneous detection and differentiation of bluetongue virus and epizootic haemorrhagic disease virus in biological samples.. Journal of Virological Methods. 2024. DOI: https://doi.org/10.1016/j.jviromet.2024.115064

[3] Yon L, Duff J, Ågren E, Erdélyi K, Ferroglio E, Godfroid J, et al.. RECENT CHANGES IN INFECTIOUS DISEASES IN EUROPEAN WILDLIFE. Journal of Wildlife Diseases. 2019. DOI: https://doi.org/10.7589/2017-07-172

[4] Ahmadivand S, Krpetić Ž, Martínez MM, Garcia-Ordoñez M, Roher N, Palić D. Self-assembling ferritin nanoplatform for the development of infectious hematopoietic necrosis virus vaccine. Frontiers in Immunology. 2024. DOI: https://doi.org/10.3389/fimmu.2024.1346512

[5] Kurapati Rb, Ramena G, Wanjala H, Gudapati S, Ramena Y. Viral Disease Histopathology in Aquaculture Finfish: Organ‐Specific Pathological Changes and Diagnostic Insights, Referencing the World Organisation for Animal Health: A Review. Reviews in Aquaculture. 2026. DOI: https://doi.org/10.1111/raq.70129

[6] Hoferer M, Akimkin V, Skrypski J, Schütze H, Sting R. Improvement of a diagnostic procedure in surveillance of the listed fish diseases IHN and VHS.. Journal of Fish Diseases. 2019. DOI: https://doi.org/10.1111/jfd.12968

[7] Xin J, Dong J, Li J, Ye L, Zhang C, Nie F, et al.. Current Knowledge on Epizootic Haemorrhagic Disease in China. Vaccines. 2023. DOI: https://doi.org/10.3390/vaccines11061123

[8] Bateman K, Paley R, Batista FM, Bass D, Peeler EJ. Advances in aquatic animal health within the framework of the World Organisation for Animal Health.. Revue scientifique et technique. 2024. DOI: https://doi.org/10.20506/rst.se.3571

[9] Rajkhowa TK, Jayappa K, Beithatlo AZ, Balakrishna CB, Khiangte L, Risatti GR. Detection of African Swine Fever Virus (ASFV) in Haematopinus suis : Evidence for a Potential New Sylvatic Cycle of ASFV Involving Lice and Domestic Pigs. Transboundary and Emerging Diseases. 2026. DOI: https://doi.org/10.1155/tbed/6675117

[10] Li Z, Wang B, Gao Y, Xian Y, Feng H, Jin H, et al.. Current state of knowledge about African swine fever: a review. Animal Health Research Reviews. 2025. DOI: https://doi.org/10.1017/S1466252325100054

[11] Kalaria KK, Girisha SK, Nithin MS, Puneeth TG, Kushala KB, Suresh T. Prevalence of disease outbreak from cultured whiteleg shrimp Penaeus vannamei farms located in Karnataka, India. emergent Life Sciences Research. 2022. DOI: https://doi.org/10.31783/elsr.2022.82240247

[12] Lou H, Li X, Wang G, Zhang K, Wang K, Tang Q, et al.. Simultaneous detection of five shrimp pathogens using a single-tube EvaGreen real-time PCR assay with differential melting temperature. Applied and Environmental Microbiology. 2025. DOI: https://doi.org/10.1128/aem.00591-25

[13] Qin J, Meng F, Wang G, Chen Y, Zhang F, Li C, et al.. Coinfection with Yellow Head Virus Genotype 8 (YHV-8) and Oriental Wenrivirus 1 (OWV1) in Wild Penaeus chinensis from the Yellow Sea. Viruses. 2023. DOI: https://doi.org/10.3390/v15020361

[14] Becker JA, Hick P, Megarani D, Siler HJ, Pierezan F, Gray SN, et al.. Risk of Spread of Megalocytivirus pagrus1 (Infectious Spleen and Kidney Necrosis Virus) From Frozen Fillets. Journal of Fish Diseases. 2025. DOI: https://doi.org/10.1111/jfd.70086

[15] Smith KM, Machalaba C, Jones H, Cáceres P, Popovic M, Olival K, et al.. Wildlife hosts for OIE‐Listed diseases: considerations regarding global wildlife trade and host–pathogen relationships. Veterinary Medicine and Science. 2017. DOI: https://doi.org/10.1002/vms3.57

[16] Awada L, Vrancken B, Thézé J, Ducrot C, Tizzani P, Dellicour S, et al.. Quantifying Time-Dependent Predictors for the International Spatial Spread of Highly Pathogenic Avian Influenza H5NX: Focus on Trade and Surveillance Efforts. Transboundary and Emerging Diseases. 2025. DOI: https://doi.org/10.1155/tbed/2020766

[17] Morales R, Weber-Vintzel L, Awada L, Cáceres P, Tizzani P, Meske M. The World Animal Health Information System as a tool to support decision-making and research in animal health.. Revue scientifique et technique. 2023. DOI: https://doi.org/10.20506/rst.42.3367

[18] Vection S, Laine C, Arenas-Gamboa Á. What do we really know about brucellosis diagnosis in livestock worldwide? A systematic review. PLoS Neglected Tropical Diseases. 2025. DOI: https://doi.org/10.1371/journal.pntd.0013185

[19] Vicente AF, Troupin C, Grayo S, Ellis-Bangoura I, Doukouré B, Camara A, et al.. Comparison of serological tools for reliable diagnosis of brucellosis circulation in the West-African context. BMC Veterinary Research. 2026. DOI: https://doi.org/10.1186/s12917-025-05183-z

[20] Wagner H, Heller M, Fawzy A, Schnee C, Nesseler A, Kaim U, et al.. Mycoplasma mycoides subspecies capri, an uncommon mastitis and respiratory pathogen isolated in a German flock of goats.. Veterinary Microbiology. 2024. DOI: https://doi.org/10.1016/j.vetmic.2024.109996

[21] Zhu P, Sun J, Liao L, Zuo Z, Rice A, Gui S, et al.. Development and partial validation of an RT-qPCR assay for the rapid detection of spring viremia of carp virus (SVCV). Frontiers in Microbiology. 2026. DOI: https://doi.org/10.3389/fmicb.2025.1726705

[22] Huang C, Wang J, Ruan Z, Wu J, Lin Y, Cao C, et al.. Real-Time Reverse Transcription Multienzyme Isothermal Rapid Amplification for Rapid Detection of African Horse Sickness Virus. Transboundary and Emerging Diseases. 2025. DOI: https://doi.org/10.1155/tbed/1852368

[23] Mu Q, Ding C, Xie Y, Zhen X, Wang X, Qi T, et al.. Rapid Visual Detection of Decapod Iridescent Virus 1 (DIV1) by RPA Combined With LFS.. Journal of Fish Diseases. 2025. DOI: https://doi.org/10.1111/jfd.70052

[24] Manso-Silván L, Amanfu W, Apolloni A, Comtet L, Heller M, Muuka G, et al.. Review and comprehensive analysis of knowledge, tools, and implementation gaps for the control of contagious bovine pleuropneumonia. BMC Veterinary Research. 2025. DOI: https://doi.org/10.1186/s12917-025-04979-3

[25] Mai H, Schofield PJ, Sealey WM, Baker TM, Dhar AK. Development of a PCR-Based Assay for Assessing Biosecurity Risk of Extruded Feed for White Spot Disease.. Journal of Fish Diseases. 2025. DOI: https://doi.org/10.1111/jfd.70008

[26] Zhang S, Zhang T, Cao Z, Yang Y, Lü P. Hijacking the Autophagy-Apoptosis Crosstalk: African Swine Fever Virus Orchestrates Immune Evasion via Host Remodeling for Viral Pathogenesis.. Microbial Pathogenesis. 2025. DOI: https://doi.org/10.1016/j.micpath.2025.107609

[27] Chen Y, Chung W, Chaung H, Huang Y, Chen C, Ke G. Development of an Effective Single-Dose PCV2/CSFV Bivalent Subunit Vaccine Against Classical Swine Fever Virus and Porcine Circovirus Type 2. Vaccines. 2025. DOI: https://doi.org/10.3390/vaccines13070736

[28] Cabezas AH, Mapitse N, Tizzani P, Sanchez-Vazquez M, Stone M, Park M. Analysis of suspensions and recoveries of official foot and mouth disease free status of WOAH Members between 1996 and 2020. Frontiers in Veterinary Science. 2022. DOI: https://doi.org/10.3389/fvets.2022.1013768

[29] Muniesa A, Ruiz‐Zarzuela I, Lamielle G, Dobschuetz Sv, Furones D, Rodgers C, et al.. Applying the FAO surveillance evaluation tool (SET) to assess the fish farming disease surveillance system in Spain. Frontiers in Veterinary Science. 2024. DOI: https://doi.org/10.3389/fvets.2024.1399040

[30] Munguía-Ramírez B, Trevisan G, Morris P, Silva GS, Zhang D, Wang C, et al.. Active Participatory Surveillance for Early Detection of Notifiable Pathogens: A Case Study of the U.S. Swine Industry. Viruses. 2026. DOI: https://doi.org/10.3390/v18040478

[31] Mazzeo A, Mascolo C, Maiuro L, Esposito M, Ferrara C, Rossi N, et al.. Brucellosis in cattle and buffalo in southern Italian provinces: trends in presence of territory-specific One Health measures. Frontiers in Microbiology. 2025. DOI: https://doi.org/10.3389/fmicb.2025.1609336

[32] Torres G, Diaz F, Okamura Y, Messori S, Hutchison J. The World Organisation for Animal Health - current and potential roles in safe international trade of bees and other insects.. Revue scientifique et technique. 2022. DOI: https://doi.org/10.20506/rst.41.1.3318

[33] Tiwari HK, Tan DK, Chinda C, My DNT, Hoang H, Keonam K, et al.. Challenges and opportunities for AMR research in the ASEAN following the One Health approach. One Health. 2025. DOI: https://doi.org/10.1016/j.onehlt.2025.101001

[34] Muniesa A, Basurco B, Aguilera C, Furones D, Reverte C, Sanjuan-Vilaplana A, et al.. Mapping the knowledge of the main diseases affecting sea bass and sea bream in Mediterranean.. Transboundary and Emerging Diseases. 2020. DOI: https://doi.org/10.1111/tbed.13482

[35] Kim J, Kajino N, Shin J, Choi HJ, Kwon M, Park C, et al.. Baseline Assessment of WOAH-Listed Protozoan Parasites in Wild Mediterranean Mussels Mytilus galloprovincialis and Pacific Oysters Crassostrea gigas from Port-Adjacent Coastal Waters of Korea in 2023. Animals. 2026. DOI: https://doi.org/10.3390/ani16101502

[36] Ruggiero CD, Gyorffy A, Artese F, Carolis AD, Simone AD, Pietropaoli M, et al.. The Mobile Divider Method: An Effective Strategy to Detect Small Hive Beetle (Aethina tumida) Adults in Honey Bee Colonies (Apis mellifera) in Calabria, Italy. Applied Sciences. 2025. DOI: https://doi.org/10.3390/app15094890

[37] . Equine epizootic lymphangitis: A synopsis and current development. German Journal of Veterinary Research. 2025. DOI: https://doi.org/10.51585/gjvr.2025.1.0117