# [Duck Viral Enteritis](/knowledge/bacteria/avian-bacteria/duck-viral-enteritis-clinical-diagnosis-management) (Duck Plague): Etiology, Clinical Signs, and Differential Diagnosis

## Key Takeaways

- Duck Viral Enteritis (DVE), or duck plague, is an acute, highly contagious herpesvirus infection caused by anatid herpesvirus 1 (AHV-1), primarily affecting waterfowl of the family Anatidae, leading to high morbidity and mortality.
- Clinical signs range from peracute sudden death to depression, anorexia, extreme thirst, ataxia, photophobia, and profuse, potentially hemorrhagic, diarrhea, with characteristic phallus prolapse in males.
- Gross pathology is marked by hemorrhagic and necrotic changes in the esophagus (diphtheritic membranes, hemorrhagic bands) and gastrointestinal tract, alongside splenic congestion and liver necrosis.
- Definitive diagnosis relies on laboratory confirmation via virus isolation in embryonated duck eggs, PCR for AHV-1 DNA, direct immunofluorescence for viral antigen, or serological tests like VN and ELISA to detect antibodies.
- Key differentials include highly pathogenic avian influenza, Riemerella anatipestifer infection, necrotic enteritis, fowl cholera, and coccidiosis, necessitating specific diagnostic testing for accurate differentiation.
- Control strategies focus on stringent biosecurity measures and vaccination with modified live virus (MLV) vaccines, alongside quarantine, depopulation, and disinfection protocols during outbreaks.

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## Introduction

[Duck viral enteritis](/knowledge/bacteria/avian-bacteria/duck-viral-enteritis-clinical-diagnosis-management) (DVE), also known as duck plague, is an acute, highly contagious herpesvirus infection of ducks, geese, and swans (family Anatidae) that causes high morbidity and mortality, particularly in adult waterfowl [<a href="#ref-1">1</a>, <a href="#ref-2">2</a>]. The disease is recognized worldwide and presents a major threat to commercial duck production, wild waterfowl conservation, and collection aviaries [<a href="#ref-1">1</a>, <a href="#ref-3">3</a>]. This article provides an exhaustive review of the etiology, clinical signs, pathology, diagnostic methods, and differential diagnoses for [duck viral enteritis](/knowledge/bacteria/avian-bacteria/duck-viral-enteritis-clinical-presentation-diagnosis), with emphasis on distinguishing this condition from other common [duck diseases](/knowledge/bacteria/avian-bacteria/duck-diseases-comprehensive-guide-health-issues-waterfowl).

## [What Is Ducks Disease](/knowledge/bacteria/avian-bacteria/duck-disease-comprehensive-veterinary-reference)? An Overview

In colloquial veterinary practice, the phrase "[what is ducks disease](/knowledge/bacteria/avian-bacteria/duck-disease-etiology-and-management-of-duck-viral-enteritis)" often refers to [duck viral enteritis](/knowledge/bacteria/avian-parasites/duck-viral-enteritis-clinical-signs-control), given its historical prominence and devastating impact [<a href="#ref-2">2</a>]. However, several infectious and noninfectious conditions may present with similar clinical signs, including hemorrhagic enteritis, depression, and sudden death [<a href="#ref-1">1</a>, <a href="#ref-3">3</a>]. A precise understanding of DVE etiology and pathogenesis is essential for accurate field diagnosis and implementation of control measures.

## Etiology

[Duck viral enteritis](/knowledge/bacteria/avian-bacteria/duck-viral-enteritis-clinical-signs-management) is caused by anatid herpesvirus 1 (AHV-1), a member of the subfamily Alphaherpesvirinae within the family Herpesviridae [<a href="#ref-1">1</a>, <a href="#ref-2">2</a>]. The virus possesses a double-stranded DNA genome approximately 160 kbp in length, enclosed within an icosahedral capsid and a lipid envelope containing glycoproteins essential for host cell attachment and entry [<a href="#ref-3">3</a>]. AHV-1 is antigenically distinct from other avian herpesviruses such as Gallid herpesvirus 1 ([infectious laryngotracheitis virus](/knowledge/viruses/avian-viruses/infectious-laryngotracheitis-virus)) and Meleagrid herpesvirus 1 (turkey herpesvirus) [<a href="#ref-1">1</a>].

The virus is relatively labile in the environment but can survive for several days in contaminated water and moist organic material at cool temperatures [<a href="#ref-2">2</a>, <a href="#ref-3">3</a>]. It is inactivated by heat (56°C for 30 minutes), lipid solvents, and common disinfectants including sodium hypochlorite and formaldehyde [<a href="#ref-1">1</a>, <a href="#ref-3">3</a>].

## Epidemiology

DVE primarily affects waterfowl of the order Anseriformes, including domestic ducks and geese, as well as wild mallards, wood ducks, swans, and other anatids [<a href="#ref-1">1</a>, <a href="#ref-2">2</a>]. Chickens, turkeys, and other gallinaceous birds are refractory to natural infection [<a href="#ref-3">3</a>]. Transmission occurs via direct contact with infected birds or indirectly through contaminated water, feed, equipment, and fomites [<a href="#ref-1">1</a>, <a href="#ref-2">2</a>]. Recovered birds can become lifelong carriers and intermittently shed virus in feces and oral secretions, particularly during periods of stress [<a href="#ref-2">2</a>, <a href="#ref-3">3</a>].

Outbreaks are most common in late spring and summer, coinciding with breeding and migration stress in wild populations [<a href="#ref-1">1</a>]. In commercial settings, introduction of carrier birds into naive flocks is the most common trigger [<a href="#ref-2">2</a>]. The incubation period ranges from 3 to 7 days in experimental infections, but can extend up to 14 days under natural conditions [<a href="#ref-3">3</a>].

## Clinical Signs

The clinical presentation of DVE varies with viral strain, host age, immune status, and environmental factors [<a href="#ref-1">1</a>, <a href="#ref-2">2</a>]. Peracute disease is characterized by sudden death without premonitory signs, often in adult birds [<a href="#ref-1">1</a>, <a href="#ref-3">3</a>]. Acute disease presents with depression, ruffled feathers, anorexia, extreme thirst, ataxia, and photophobia [<a href="#ref-2">2</a>, <a href="#ref-3">3</a>]. Oculonasal discharge is common, and a profuse watery diarrhea may be observed, which can become hemorrhagic in later stages [<a href="#ref-1">1</a>, <a href="#ref-2">2</a>].

Birds may exhibit prolapse of the phallus in males due to vascular congestion and necrosis of lymphoid tissues in the cloaca and bursa [<a href="#ref-3">3</a>]. In laying ducks, egg production drops sharply, and eggs may be misshapen or shell-less [<a href="#ref-1">1</a>]. Mortality rates can reach 90% in susceptible flocks, with death typically occurring 5 to 14 days after exposure [<a href="#ref-2">2</a>, <a href="#ref-3">3</a>].

Subacute or chronic forms occur in partially immune populations or with less virulent strains, with milder depression, transient diarrhea, and reduced egg production [<a href="#ref-1">1</a>].

## Pathology

Gross lesions are highly characteristic and include hemorrhagic and necrotic changes in the gastrointestinal tract and lymphoid organs [<a href="#ref-2">2</a>, <a href="#ref-3">3</a>]. The esophagus shows diphtheritic membranes and circular hemorrhagic bands, particularly at the esophageal-pharyngeal junction [<a href="#ref-1">1</a>, <a href="#ref-2">2</a>]. The small intestine and ceca exhibit diffuse hemorrhages, erosions, and ulcerations, often with luminal blood [<a href="#ref-1">1</a>, <a href="#ref-3">3</a>].

The liver may be enlarged with pale foci of necrosis scattered throughout the parenchyma [<a href="#ref-2">2</a>]. Other consistent findings include splenic congestion and mottling, petechiae on the heart and pancreas, and necrosis of bursal follicles and Peyer's patches [<a href="#ref-1">1</a>, <a href="#ref-3">3</a>].

Histopathologic examination reveals intranuclear inclusion bodies (Cowdry type A) in enterocytes, hepatocytes, and lymphoid epithelial cells, confirming the viral etiology [<a href="#ref-2">2</a>, <a href="#ref-3">3</a>]. These inclusion bodies are eosinophilic or basophilic and are surrounded by a clear halo [<a href="#ref-1">1</a>].

## Diagnostics

Presumptive diagnosis is based on history, clinical signs, and gross pathology, particularly the presence of esophageal and intestinal hemorrhagic rings and diphtheritic lesions [<a href="#ref-1">1</a>, <a href="#ref-2">2</a>]. Definitive diagnosis requires laboratory confirmation through virus isolation, molecular detection, or serology [<a href="#ref-3">3</a>].

### Table 1: Diagnostic Methods for [Duck Viral Enteritis](/knowledge/bacteria/avian-bacteria/duck-viral-enteritis-comprehensive-reference)

| Diagnostic Method | Sample Type | Target | Sensitivity | Specificity | Turnaround Time |
|---------|-------|----|-------|-------|--------|
| Virus isolation in embryonated duck eggs | Liver, spleen, cloacal swabs | Infectious virus | Moderate | High | 3-7 days |
| PCR (conventional or real-time) | Tissue homogenates, swabs | Viral DNA | High | High | 4-6 hours |
| Direct immunofluorescence | Cryostat sections of liver/spleen | Viral antigen | Moderate | High | 2-4 hours |
| Virus neutralization test | Serum | Neutralizing antibodies | Moderate | High | 3-5 days |
| ELISA | Serum | Anti-AHV-1 antibodies | High | Moderate | 2-4 hours |

Virus isolation is performed by inoculating 9- to 11-day-old embryonated duck eggs via the chorioallantoic membrane (CAM) route [<a href="#ref-3">3</a>]. Characteristic plaques appear on the CAM within 3 to 7 days, and the virus can be identified using specific antiserum [<a href="#ref-1">1</a>, <a href="#ref-2">2</a>].

Polymerase chain reaction (PCR) targeting the DNA polymerase or glycoprotein C gene is the most sensitive and rapid approach for direct detection of AHV-1 DNA in clinical samples [<a href="#ref-3">3</a>]. Real-time PCR methods allow quantification of viral load and are particularly useful for assessing shedding in carrier birds [<a href="#ref-2">2</a>].

Serological assays, including virus neutralization (VN) and enzyme-linked immunosorbent assay (ELISA), are used to detect antibodies in recovered or vaccinated birds [<a href="#ref-1">1</a>, <a href="#ref-3">3</a>]. A fourfold rise in VN titers between acute and convalescent sera confirms active infection [<a href="#ref-2">2</a>].

### Diagnostic Decision Tree for Suspected [Duck Viral Enteritis](/knowledge/bacteria/avian-bacteria/duck-viral-enteritis-disease-management)

```mermaid
flowchart TD
 A["Sudden death or hemorrhagic diarrhea in waterfowl"] --> B{"Postmortem lesions present?"}
 B -->|"Yes"| C["Examine esophagus and intestine"]
 C --> D["Esophageal rings / diphtheritic membranes?"]
 D -->|"Yes"| E["Collect liver, spleen, cloacal swab"]
 E --> F["Perform PCR for AHV-1"]
 F -->|"Positive"| G["Confirm DVE diagnosis"]
 F -->|"Negative"| H["Consider differentials: avian influenza, Riemerella, necrotic enteritis, coccidiosis, colibacillosis"]
 D -->|"No"| H
 B -->|"No"| I["Live bird: depression, diarrhea, ataxia"]
 I --> J["Collect serum for serology and cloacal swab for PCR"]
 J --> F
 G --> K["Report to authorities; implement quarantine, depopulation, disinfection"]
```

## Differential Diagnosis

DVE must be differentiated from several other infectious and noninfectious diseases that produce similar clinical signs and lesions in ducks [<a href="#ref-1">1</a>, <a href="#ref-2">2</a>]. The key differential diagnoses are summarized below.

### [Avian Influenza](/knowledge/bacteria/avian-bacteria/avian-influenza-cdc-global-surveillance) (Highly Pathogenic)

Highly pathogenic [avian influenza](/knowledge/bacteria/avian-bacteria/avian-influenza-cdc-guidelines-poultry-pandemic-preparedness) (HPAI) in ducks can present with sudden death, depression, respiratory signs, and hemorrhagic lesions [<a href="#ref-1">1</a>, <a href="#ref-2">2</a>]. Unlike DVE, HPAI often causes edema of the head, cyanosis, and rapid spread among multiple avian species [<a href="#ref-3">3</a>]. Laboratory differentiation relies on PCR or virus isolation for influenza A virus (matrix gene) and subtype determination [<a href="#ref-1">1</a>, <a href="#ref-2">2</a>]. See the article [Avian Influenza A Virus in Wild Birds and Poultry: Etiology, Epidemiology, Clinical Signs, Pathology, Diagnostics, Treatment, and Control](/knowledge/bacteria/avian-bacteria/avian-influenza-a-virus-wild-birds-poultry) for further details.

### [Riemerella anatipestifer](/knowledge/bacteria/avian-bacteria/duck-disease-riemerella-anatipestifer-waterfowl-clinical-overview-management) Infection

[Riemerella anatipestifer](/knowledge/bacteria/avian-bacteria/duck-disease-riemerella-anatipestifer-waterfowl-clinical-overview-management) causes septicemia and serositis in young ducks, characterized by fibrinous pericarditis, perihepatitis, and airsacculitis [<a href="#ref-1">1</a>, <a href="#ref-3">3</a>]. Neurologic signs such as tremors and torticollis are common [<a href="#ref-2">2</a>]. In contrast, DVE primarily affects older birds and does not produce fibrinous serositis [<a href="#ref-1">1</a>]. See [Riemerella anatipestifer Infection in Ducks: Septicemia and Serositis](/knowledge/bacteria/avian-bacteria/riemerella-anatipestifer-duck-septicemia-serositis).

### [Necrotic Enteritis](/knowledge/bacteria/avian-bacteria/necrotic-enteritis-poultry) (Clostridium perfringens)

[Necrotic enteritis](/knowledge/bacteria/avian-bacteria/poultry-necrotic-enteritis-pathogenesis-control) caused by Clostridium perfringens type A presents with severe intestinal necrosis and hemorrhagic diarrhea [<a href="#ref-2">2</a>, <a href="#ref-3">3</a>]. However, it lacks the esophageal lesions characteristic of DVE and is often associated with predisposing factors such as coccidiosis or dietary changes [<a href="#ref-1">1</a>, <a href="#ref-2">2</a>]. See [Necrotic Enteritis in Poultry: Etiology, Diagnosis, and Management](/knowledge/bacteria/avian-bacteria/necrotic-enteritis-poultry-etiology-diagnosis-management).

### [Fowl Cholera](/knowledge/bacteria/avian-bacteria/avian-cholera-fowl-cholera-in-poultry) (Pasteurella multocida)

[Fowl cholera](/knowledge/bacteria/avian-bacteria/avian-cholera-fowl-cholera) is an acute septicemic disease of waterfowl that can cause sudden death and hemorrhagic enteritis [<a href="#ref-1">1</a>, <a href="#ref-3">3</a>]. It is distinguished by the presence of bacteremia, petechiae on the heart and serosal surfaces, and focal hepatic necrosis, but not the esophageal diphtheritic membranes seen in DVE [<a href="#ref-2">2</a>, <a href="#ref-3">3</a>]. See [Fowl Cholera in Poultry: Etiology, Epidemiology, Clinical Signs, Diagnosis, and Control](/knowledge/bacteria/avian-bacteria/fowl-cholera-poultry-etiology-clinical-signs-control).

### Coccidiosis

Coccidiosis in ducks (primarily caused by Eimeria spp.) produces hemorrhagic diarrhea and thickening of the intestinal wall [<a href="#ref-1">1</a>]. However, esophageal lesions are absent, and oocysts can be identified in fecal smears [<a href="#ref-2">2</a>, <a href="#ref-3">3</a>]. See [Coccidiosis in Poultry: Etiology, Clinical Signs, and Therapeutic Management](/knowledge/parasites/avian-parasites/coccidiosis-poultry-etiology-clinical-signs-therapeutic-management).

### Other Viral Enteritides

[Duck astrovirus](/knowledge/viruses/avian-viruses/duck-astrovirus) and [duck circovirus](/knowledge/viruses/avian-viruses/duck-circovirus) may cause enteritis but lack the hemorrhagic esophageal lesions and high mortality typical of DVE [<a href="#ref-1">1</a>, <a href="#ref-2">2</a>]. Differentiation is achieved by specific PCR panels covering multiple [duck viruses](/knowledge/bacteria/avian-bacteria/duck-viruses) [<a href="#ref-3">3</a>]. See [Duck Astrovirus](/knowledge/viruses/avian-viruses/duck-astrovirus) and [Duck Circovirus](/knowledge/viruses/avian-viruses/duck-circovirus).

## Treatment and Control

No specific antiviral treatment is approved for DVE [<a href="#ref-1">1</a>, <a href="#ref-2">2</a>]. Supportive care, including clean water, nutrition, and protection from stress, may reduce mortality in mildly affected flocks, but is generally ineffective during acute outbreaks [<a href="#ref-2">2</a>, <a href="#ref-3">3</a>].

Control relies on prevention through biosecurity and vaccination [<a href="#ref-1">1</a>, <a href="#ref-3">3</a>]. Modified live virus (MLV) vaccines based on an attenuated strain of AHV-1 are available for use in domestic ducks and geese [<a href="#ref-2">2</a>, <a href="#ref-3">3</a>]. Primary vaccination is recommended at 4 to 6 weeks of age, with a booster prior to the laying period [<a href="#ref-1">1</a>]. Vaccination provides solid immunity but does not prevent latent infection in previously exposed birds [<a href="#ref-2">2</a>].

In the event of an outbreak, quarantine of infected premises, depopulation of affected flocks, thorough cleaning and disinfection of facilities, and restriction of bird movements are mandatory in many jurisdictions [<a href="#ref-1">1</a>, <a href="#ref-3">3</a>]. In waterfowl collections, surveillance and separation of wild and domestic populations are critical preventive measures [<a href="#ref-2">2</a>].

## References

<a id="ref-1"></a>[<a href="#ref-1">1</a>] Swayne D.E., Boulianne M., Logue C.M., et al. Diseases of Poultry, 14th Edition. Wiley-Blackwell, 2020.

<a id="ref-2"></a>[<a href="#ref-2">2</a>] Aiello S.E., Moses M.A. The Merck Veterinary Manual, 11th Edition. Merck & Co., 2016.

<a id="ref-3"></a>[<a href="#ref-3">3</a>] OIE (World Organisation for Animal Health). Manual of Diagnostic Tests and Vaccines for Terrestrial Animals, 12th Edition. OIE, 2023.

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