Chicken anaemia virus (CAV, blue wing disease)
Species affected: Chicken.
Age affected: Young birds, 12-28 days.
Causes: Circo virus of 19-24nm in diameter.
Effects: 8-10 day incubation period. Anaemia, weight depression and up to 60% mortality may occur. Bluish discolouration of the wing can also occur (blue wing disease).
CAV is a circovirus of 19-24nm in diameter. It causes acute to chronic disease in young chickens. The virus is spread horizontally and vertically.
There is an 8-10 day incubation period. Signs include anaemia, weight depression and up to 60% mortality.
Lesions include thymic atrophy, the bone marrow is yellow or pink, bursal atrophy, swelling and mottling of the liver, and haemorrhages in the proventriculus and muscles. Bluish discolouration of the wing can also occur (blue wing disease).
An aplastic anaemia with gross lesions (swollen liver) is characteristic. Isolation of the virus from liver in MSB1 cells, identification with fluorescent conjugated antisera, and PCR are diagnostic. Serologic tests include virus neutralisation in MSB1 cells and ELISA.
Treatment & control
Chicks derived from immune (exposed) parent stock are immune.
Exposure of pullets to infected litter before egg production will produce protective maternal immunity in the progeny, but risks spreading other diseases to the birds. A live vaccine for breeders is available. It controls anemia in birds, but immunosuppression may till be evident in the progeny of vaccinated birds.