Pathology of offbeat lesions in an outbreak of systemic histomoniasis in desi chickens Prasath N. Babu*, Selvaraj J., Thilagavathi K., Prabu P.C., Hariharan J., Janakipriya C., Velusamy R.1 Department of Veterinary Pathology, Veterinary College and Research Institute, TANUVAS, Orathanadu-614 625, Tamil Nadu, India 1Department of Veterinary Parasitology, Veterinary College and Research Institute, TANUVAS, Orathanadu-614 625, Tamil Nadu, India *Address for Correspondence: Dr N. Babu Prasath, Department of Veterinary Pathology, Veterinary College and Research Institute, TANUVAS, Orathanadu - 614 625, Tamil Nadu, India, E-mail: vetdrprasad@gmail.com
Online Published on 03 February, 2023. Abstract An outbreak of multisystemic histomoniasis in six weeks-old desi chickens from a rural based poultry farm holding 500 birds for commercial purpose associated with unusual visceral lesions and high mortality is reported. Birds were reported to have clinical signs of depression, loss of production, yellowish diarrhoea and high mortality. Cumulative mortality of the affected flock was reported to be 60% within a period of 7-10 days. Postmortem examination of the dead birds revealed enlargement of liver covered with pale whitish viscous membranous layer. Hepatic parenchyma showed multifocal, pale whitish to yellow, circular, press button like necrotic lesions varying from 0.3 to 0.5 cm diameter. Few of these lesions were coalescing and appeared as lesions of lymphoma. Spleen was slightly enlarged and congested. Bursa of Fabricius was distended and contained well organised, creamy white, firm mass exhibiting casting of bursal plicae. Kidney revealed multifocal greyish white foci (3-5 mm). Caecum showed moderate longitudinal corrugation of the mucosa. Microscopically, liver showed multifocal necrotic hepatitis with numerous scattered degenerative forms of histomonads surrounded by clear halo, having bull’s eye appearance within the necrotic areas. Mature trophozoites of invasive form of histomonads were also found in the hepatic sinusoids. Bursa of Fabricius revealed severe subacute to chronic cloacal bursitis associated with presence of histomonads within the follicle. Bursal follicles revealed severe lymphoid depletion and cystic degeneration. Multifocal myocarditis, pancreatitis, pneumonia and neuronal degeneration with satellitosis were the other associated lesions observed. Periodic-acid Schiff stained tissue sections revealed intense purple magenta-coloured degenerative forms of histomonads within the necrotic areas of liver, bursa of Fabricius and caecum. This report records the outbreak of naturally occurring multisystemic histomoniasis in layer-type desi chicken associated with unusual lesions including cloacal bursitis, myocarditis, pancreatitis and pneumonia. The present study also validates the earlier postulates of immunosuppression induced primarily by histomoniasis causing severe lymphoid depletion in bursa of Fabricius. Top Keywords Cloacal bursitis, Hepatitis, Histomoniasis, Myocarditis, Neuronal satellitosis, Typhlitis. Top |