Confirming Duck Viral Hepatitis: Choosing and Interpreting Diagnostic Tests

When young ducklings develop sudden mortality and liver lesions suggestive of duck viral hepatitis (DVH), how should the diagnosis be confirmed? Clinical presentation and necropsy findings can raise suspicion, but they cannot reliably establish the causative agent. Laboratory investigation is essential, particularly because several infectious and non-infectious conditions can produce similar clinical and pathological changes. 

RT-PCR for Detecting DHAV^[1] 

Reverse transcription polymerase chain reaction (RT-PCR) is considered the most sensitive and rapid method for detecting duck hepatitis A virus (DHAV) RNA. It provides molecular evidence of infection and helps distinguish DVH from conditions that produce similar hepatic lesions. 

For veterinarians investigating suspected outbreaks, molecular confirmation is particularly important when mortality progresses rapidly or the clinical picture is not sufficiently distinctive. A positive molecular result should be interpreted alongside flock history, clinical findings and pathological changes rather than in isolation. 

When Are Virus Isolation and Antibody Tests Useful?^[1],[2] 

Virus isolation in chicken embryos or cell cultures is another diagnostic option. Although it is less frequently used in routine diagnosis, it can support additional characterisation of the virus. 

Serological testing has a different role. Enzyme-linked immunosorbent assay (ELISA) can detect antibodies against DHAV and is particularly useful for population surveillance and assessing postvaccination immune status. 

However, timing matters. Antibodies may not have developed during the acute phase of infection. Consequently, a negative serological result in an acutely affected flock should not automatically exclude DVH. The timing of infection must be considered when interpreting antibody findings. 

Connecting Viral Detection with Liver Pathology^[1] 

Immunohistochemistry (IHC) can occasionally be used to identify viral antigens directly in liver tissue. This helps demonstrate the presence and distribution of viral antigens within hepatocytes and relate them to the observed tissue abnormalities. 

Histopathological examination also contributes to the diagnostic assessment by identifying hepatic necrosis and associated tissue changes. However, these lesions need to be interpreted with molecular and other laboratory findings. 

Investigating Alternative Causes of Mortality 

A diagnostic work-up should not focus exclusively on DHAV. Depending on the clinical and pathological findings, investigations may include bacterial culture, histopathology, and toxicological analysis. These help assess alternative explanations such as bacterial septicaemia and hepatotoxicosis. 

Clinical Bottom Line 

No single finding should replace an integrated diagnostic approach. RT-PCR offers rapid molecular detection, virus isolation supports further characterisation, serology helps assess population immunity, and IHC can demonstrate viral antigens in liver tissue. Combining these methods with flock history, clinical findings and pathology helps veterinarians reach a more reliable diagnosis and distinguish DVH from other causes of acute mortality.

References:

1. Nuradji H, Khairullah AR, Dharmayanti NL, Wiyono A, Noor SM, Saepulloh M, Adji RS, Ekawasti F, Fauziah I, Prihandani SS, Nurjanah D. Duck hepatitis A virus (DHAV): Pathogenesis, diagnosis, prevention, and control in duck production systems. Open Veterinary Journal. 2026 Sep 1;16(9):5905. https://www.researchgate.net/profile/Sutiastuti-Wahyuwardani-4/publication/413903277
2. Bing L, Qianqian W, Saisai Z, Xinhong M, Mian W, Chengguang L, Huihui L, Mingtian M, Suyun L, Zhanbao G, Zhengkui Z. Isolation and identification of duck hepatitis a virus type III and analysis of VP1 protein variation in China, 2021-2023. Poultry Science. 2025 Oct 17:105969. https://www.sciencedirect.com/science/article/pii/S003257912501209X