Chicken anemia virus infection in broiler chickens in Shahrekord, Iran: serological, hematological, and histopathological findings

Abstract

Chicken infectious anemia caused by a single-strand DNA circovirus is a disease in young chickens that is characterized by aplastic anemia, generalized lymphoid atrophy, and immunosuppression. In the present study, the presence of chicken anemia virus (CAV) infection and the hematologic and histopathologic changes in CAV seropositive broiler chickens in Shahrekord region, center of Iran, were investigated. Blood and lymphoid tissue samples were obtained from 271, 2–6-week-old chicks of 23 commercial broiler chicken flocks. Measurement of CAV antibody titers by enzyme-linked immunosorbent assay (ELISA) and differential leukocyte counts were carried out on serum and whole blood, respectively. The results of ELISA showed that all flocks of different ages were positive for anti CAV antibodies. Histological examination of lymphoid organs revealed lymphocytic depletion in 72 chicks, of which 66 cases were seropositive in ELISA. Twenty chicks had lymphocytic depletion in both thymus and bursa of Fabricius and 46 cases had only bursal lymphoid depletion. Macroscopic appearance of bone marrows and spleen were normal. The mean antibody titers, packed cell volumes (PCVs), and number of lymphocytes and heterophils of the chickens with both thymic and bursal lymphoid depletion were significantly different than antibody titers and PCVs of the other group. These results have demonstrated CAV infection and immunosuppressive effect of this virus in broiler chickens and the need for vaccination of breeder flocks in center of Iran.