Molecular Diagnosis and Pathology of Chicken Infectious Anemia in Commercial White Leghorn Layer Flocks in Pakistan.

The present field study was conducted for confirmation of chicken infectious anemia (CIA) in White Leghorn (WL) commercial layer birds. A total of 60 farms were investigated. Birds from each farm ware necropsied for the presence of lesions on different visceral organs. Samples of blood and different tissues were collected for hematology, histopathology, DNA extraction and PCR amplification using specific primers for CIA virus. There was severe anemia indicated by low hematocrit values (10.9 to 17.2%) and hemoglobin concentration (5.3 to 6.7 g/dl). The petechial hemorrhages were present on subcutaneous tissue, epicardium, endocardium and gizzard mucosa. The liver and bone marrow were pale in appearance. The mortality ranged from 5 to 14 % on different farms. Samples of liver and spleen from 15 farms were subjected to PCR analysis for CIAV infection by amplifying the 186-bp region on highly conserved VP-2 coding gene using CAV1 and CAV2 primer pair. Presence of CIAV was confirmed in 67 and 33 percent samples of liver and spleen, respectively. A total of 13/15 farms (87%) were found positive for CIA. The results of present study confirmed the presence of CAV infection in WL commercial layer birds in current outbreak. It is concluded that extensive molecular epidemiological studies are required at national level to assess the prevalence of disease. Breeder flocks should be vaccinated to control CIA in commercial layer flocks. [ABSTRACT FROM AUTHOR]