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Subject: Veterinary Pathology × Author: MOUNIKA PENUBAKULA × End date: 2024 × Thesis Type: M.V.Sc. ×
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    ThesisItemOpen Access
    PATHOLOGICAL AND MOLECULAR DIAGNOSIS OF CHICKEN INFECTIOUS ANEMIA IN COMMERCIAL CHICKEN
    (SRI VENKATESWARA VETERINARY UNIVERSITY, TIRUPATI - 517 502. (A.P.) INDIA, 2024-02) MOUNIKA PENUBAKULA; SAMATHA .V (MAJOR); SUDHA RANI CHOWDARY .CH; SRIVIDYA .G
    In the present study, a total of 217 commercial chicken among 50 chicken flocks were suspected for CIA based on history and clinical signs. CIA was diagnosed in 135 birds including 116 layers (71.6%) and 19 broilers (34.5%) with an overall prevalence of 62.2% based on hematology, gross lesions, histopathology, electron microscopy and molecular studies. Out of 116 CIA cases in layers the highest prevalence was recorded in East Godavari (90.47%), followed by Chittoor (81.81%), Kakinada (80%) and lowest in Eluru (52.38%). The prevalence of CIA in broilers was found highest in East Godavari (39.1%) followed by Chittoor (38.88%) with lowest prevalence in Visakhapatnam (21.42%). In the present study, age wise prevalence of CIA in commercial chicken showed highest prevalence in layer growers of 5-16 weeks of age (79.8%) and the lowest prevalence in layer chicks aged ≤4 weeks age (27.2%). Concurrent infections with other bacterial (36.3%), viral (24.2%), protozoal (28.7%) infections were noticed with overall occurrence of 48.88%. Concurrent infections were confirmed in layer growers (55.17%), layer adults (42.30%) followed by broiler chicken (42.1%) and layer chick (33.33%). The commercial chicken affected with chicken infectious anemia exhibited pale comb and wattles, anorexia, generalised weakness, decline in egg production and ruffled feathers. Blood samples collected randomly from the birds suspected for CIA grossly appeared as watery contents and there was a significant decline in the Hemoglobin concentration (5.56 ± 0.29 g/dl), PCV (17 ± 0.79 %) and TEC (1.46 ± 0.09 x 106/µL) in CIA affected flock when compared to that of healthy flocks. Grossly, CIA affected chicken exhibited small, shrunken thymus and bursa. Pale pink to yellow discoloration of bone marrow of femur along with oily jelly to watery like consistency was observed. Atrophy of spleen was noticed in many cases whereas enlarged pale livers and swollen pale kidneys were observed in few cases. Petechiae to patchy hemorrhages on thigh muscle, breast muscles and in the oral cavity were also noticed. Cytologically, bone marrow collected from affected chicken revealed presence of vacuolar spaces due to replacement of hematopoietic tissue by adipose tissue. Thymus sections revealed multiple hemorrhages along with moderate to severe depletion of lymphocytes in cortex and medullary areas and apoptotic changes in nucleus like pyknosis and karyorrhexis in thymic lymphocytes whereas few lymphocytes exhibited the presence of eosinophilic, intranuclear inclusion bodies. All the sections from bone marrow of femur revealed aplasia of all cell types including granulocytic, agranulocytic and hemopoietic precursors along with complete replacement of bone marrow by adipose tissue in the form of vacuolar spaces. Hemocytoblast cells with more cytoplasm and large nuclei revealed eosinophilic, intranuclear inclusions. Bursa of Fabricius showed moderate atrophy of lymphoid follicles, cystic changes in bursal follicles. Spleen revealed moderate to severe lymphoid depletion in white pulp along with proliferation of macrophages, reticular cells and hemosiderosis. Severe congestion of blood vessels, multiple hemorrhagic foci and degenerative changes were noticed in tissue sections of liver and kidneys. In the present study, different concurrent infections were noticed in 66 CIA affected commercial chicken. Marek’s disease was confirmed in a total of 16 cases revealing neoplastic nodules on liver and heart. Tissue imprints revealed numerous pleomorphic cells and histologically, infiltration of neoplastic lymphoid cells in hepatic parenchyma and myocardium was noticed. Different bacterial diseases included fibrinopurulent serositis (12), gangrenous dermatitis (7) and Fowl Cholera (5). Protozoal infections like intestinal and caecal coccidiosis (19) were also recorded. Fibrinous pericarditis revealed fibrinous exudation along with inflammatory cell infiltration in pericardium and samples collected from these lesions yielded characteristic green metallic sheen colonies on EMB agar confirming E.coli. Gangrenous dermatitis appeared as dark, moist lesions at the base of the wing indicating blue wing. Necrotic and inflammatory changes were evident in subcutaneous tissue and lesions yielded Gram positive cocci suggestive of Staphylococcal infection. Multiple hemorrhagic foci on epicardium and numerous necrotic foci on liver were noticed in Fowl cholera. Microscopically, hemorrhages and necrotic changes were observed in heart and liver. Tissue imprints of heart revealed presence of bipolar organisms and swabs collected revealed non hemolytic colonies on blood agar suggestive of Pasteurellosis. Distended intestinal segments and caeca along with hemorrhagic and necrotic contents were suspected for coccidiosis. Intestinal and caecal mucosal scrapings revealed presence of different stages of coccidia suggestive of Eimeria Spp. Severe hemorrhages and necrosis in mucosa and submucosa along with presence of different stages of coccidia was evident. Five thymus and three bone marrow samples collected from CIA affected birds were subjected to TEM and revealed severe scarcity of cells and presence of apoptotic changes in the nuclei and intranuclear viral inclusions. Apoptotic thymocytes revealed chromatin aggregation as large, dark condensed masses that abut the nuclear membrane. Bone marrow samples revealed large adipose cells replacing the bone marrow whereas few electron dense viral aggregates in the nucleus of hemocytoblast are also observed. In the present study, molecular diagnosis of CIA disease in commercial chicken was carried out using thymus, bone marrow, spleen and liver tissue samples for amplification of VP1, VP2 and VP3 genes of Chicken infectious anemia virus by specific primers and yielded amplicons of size 1390 bp for VP1 gene, 713 bp and 367 bp for VP2 and VP3 genes respectively confirming the presence of CIA viral DNA in the samples. In conclusion, the present study has defined characteristic gross and microscopic features of CIA in commercial chicken and diagnosis was done based on PCR by amplification of VP1, VP2 and VP3 genes of CIAV.