Chicken anemia virus (CAV), scientific name Gyrovirus chickenanemia, is a member of the Anelloviridae family which is found worldwide. which causes bone marrow atrophy, anemia, and severe immunosuppression. Clinical signs of CAV infection are predominantly found in young chicks due to vertical transmission from the breeder hens whose maternal antibodies have not yet formed following exposure. Clinical disease is rare today because of the widespread practice of vaccinating breeders, but the subclinical form of the disease—which normally affects birds more than two weeks of age following horizontal transmission of the virus via the fecal–oral route—is ubiquitous. The virus is very resistant in the environment, making elimination very difficult.
The disease and virus have many names including chicken anemia, blue wing disease, anemia dermatitis syndrome, chicken/avian infectious anemia, hemorrhagic aplastic anemia syndrome, infectious chicken anemia, chicken infectious anemia virus, and chicken anemia agent. When this virus was first discovered in 1979, it was named chicken anemia agent.
Clinical signs
Clinical signs only occur in chicks less than three weeks of age. Signs include a pale comb, wattle, eyelids, legs and carcass, anorexia, weakness, stunting, unthriftiness, weight loss, cyanosis, petechiation and ecchymoses, lethargy, and sudden death. Neurological signs include dullness, depression and paresis.
In older chickens, an infection with no apparent symptoms may cause reduced growth rates due to a poor feed conversion ratio. causing destruction of these cells via apoptosis.
This reduces the production of red blood cells (RBC) and white blood cells (WBC), leading to severe immunosuppression and anemia.