Also known as: Haemorrhagic Enteritis — HE — Egg Drop Syndrome — EDS — Quail Bronchitis — QB — Pheasant Marble Spleen Disease — MSD — Inclusion Body Hepatitis — IBH
| Avian adenovirus | |
|---|---|
| Virus classification | |
| Group: | Group I (dsDNA) |
| Family: | Adenoviridae |
| Genus: | Aviadenovirus |
Contents |
Aviadenoviridae are viruses that affect birds - particularly chickens, ducks, geese, turkeys and pheasants - representing one of four genera of the family Adenoviridae, the others being Mastadenovirus, Atadenovirus and Siadenovirus. They are class I, non-enveloped, icosahedral viruses that are 74–80 nm in diameter, having a double stranded DNA genome of approximately 26–45 kilo–base pairs (kbp) and a guanine/cytosine content of 53–59%. The viruses causes specific disease syndromes such as Quail Bronchitis (QB), Egg Drop Syndrome (EDS), Haemorrhagic Enteritis (HE), Pheasant Marble Spleen Disease (MSD) and Inclusion Body Hepatitis (IBH).
Avian adenovirus has a worldwide distribution and it is common to find multiple species on a single farm. The most common serogroups are serogroup 1, 2 and 3. It is not a zoonoses.
The virus is mainly spread horizontally by the oro-fecal route, but vertical transmission can occur in serogroup 1. Once it has infected the bird the virus may remain latent until a period of stress, when it may then cause clinical disease.
Infections are normally subclinical, however clinical disease can occur - especially in young birds as maternal antibody levels begin to wane.
Clinical signs are related to the organ effected:
Signs of gastrointestinal disease (Haemorrhagic Enteritis) include diarrhea, anorexia, melena and hematochezia. Anaemia and dehydration may develop secondary to this haemorrhagic enteritis. Signs of reproductive disease (Egg Drop Syndrome) include low egg production/hatching and the laying of abnormal eggs (size, shape, colour, texture). Adenovirus infection may infect other organs, causing a splenitis, inclusion body hepatitis, bronchitis, pulmonary congestion ventriculitis, pancreatitis, or oedema, depending on the species of bird infected.
Diagnosis of aviadenovirus is by histopathology, electron microscopy, viral isolation and ELISA. In addition, virus antigen can be detected double immunodiffusion. Postmortem examination may reveal a variety of clinical signs relating directly to the organ affected. Specifically, Egg Drop Syndrome can be diagnosed by hemagglutinin inhibition and the virus causes haemagglutination in chickens and ducks.
Vaccines for HE and EDS are available (ATCvet codes: QI01AA05 for the inactivated vaccine, QI01AD05 for the live vaccine, plus various combinations). Disease incidence may be reduced by minimising stress levels, using appropriate hygiene measures and providing adequate nutrition.