Occurrence: Worldwide. Species affected: Chicken. Age affected: Young birds, 12-28 days.

Causes: Circo virus of 19-24 nm in diameter.

Effects: 8-10 day incubation period. Anaemia, weight depression and up to 60% mortality can occur. Bluish discolouration of the wing can also occur (Blue wing disease). Immunosuppression, causing often secondary problems (eg Marek’s).

CAV is a circovirus of 19-24 nm 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).

Postmortem lesions and histopathology (widening of epiphyseal plate, hypertrophy and softening of the bone, and irregular patterns of cartilage and bone development in the primary and secondary spongiosa) are diagnostic.

It simulates other deforming leg weaknesses in poultry.

Control in chickens can be afforded by administration of a live vaccine orally or via drinking water. Exposure of pullets to infected litter before egg production will produce protective maternal immunity in the progeny.

A live vaccine for breeders is available.

None.

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