EPIDEMIOLOGICAL AND EXPERIMENTAL STUDIES ON CHICKEN INFECTIOUS ANEMIA IN ANDHRA PRADESH
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Date
2005-10
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SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA
Abstract
ABSTRACT:
In view of frequent disease outbreaks among vacinates, production losses, the chicken infectious anemia virus gained importance throughout the globe in the poultry industry. Because of immunosuppression, chicken infectious anemia virus is paving way for aplastic anemia, generalized lymphoid atrophy and further complicating the problem by secondary bacterial, viral and fungal infections. Hence a modest attempt has been made to study the chicken infectious anemia (CIA) in Andhra Pradesh in respect of epidemiological status, seroprevalence, experiment infection and electronmicroscopic study of the virus. A total of 375 pooled serum samples were collected from different poultry farms throughout Andhra Pradesh where there was a history of vaccination breaks inspite of regular vaccinations for different diseases. Serum samples were also collected from some of the healthy flocks. Commercially available CAV - antibody ELISA kit (IDEXX Laboratories) was employed for screening of serum samples. Based on the results of ELISA, it is confirmed that, there is high seroprevalence (upto 98%) of CIA in Andhra Pradesh in both broilers and layer flocks of different age groups. An outbreak suspected of CIA was investigated in one of the organized poultry farm in Tirupati (flock size of 23,000 aging 13 weeks). Convalescent serum samples from the affected flock were tested by ELISA and confirmed as CIA. The probable and suitable biological materials viz., bone marrow, thymus, bursa, spleen and liver suspensions were experimentally infected in three different groups of 70 birds each. Group I (70) chicks were inoculated with tissue suspension and betamethasone. Group II chicks (70) were inoculated with tissue suspension alone. Group III (70) chicks were treated as control by inoculating with distilled water. The affected chicks showed the signs of weakness, emasciation, weight loss, paleness of combs and wattles. The infection was further evidenced by aplasia of bone marrow with yellowish white gelatinous consistency, atrophy of thymus and bursa, paleness of liver and spleen were observed. The heparinated blood collected from experimental chickens from 7th to 35 days at different intervals of post inoculation for studying of hematological parameters viz., PCV & Hb% yielded 25-11 and 3-8% respectively, which is characteristics of chicken infectious anemia. While the tissues namely bone marrow, thymus, bursa, spleen and liver collected in 10% neutral buffered formalin revealed major histopathological changes that included depletion of bone marrow tissue, atrophy of thymus and bursa. Further bone marrow, plasma and liver samples collected from experimentally infected birds between 12-15 days PI were subjected to electronmicroscopy. Many viral particles of 20.2 to 26.2 nm were detected in bone marrow, plasma and liver in order of decreasing concentration. Serum samples were collected from experimentally infected chicks at weekly intervals and screened by using ELISA. Based on the results of ELISA the disease was confirmed as CIA.
Based on all these results, it was finally concluded that, there was high seroprevalence of CIA in Andhra Pradesh. Hence an appropriate immunization technique may be developed to safeguard the poultry industry from economic losses by providing suitable immune belt against
chicken infectious anemia in Andhra Pradesh.
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