ABSTRACT
An epidemiological study was conducted for investigation of bovine coronavirus by antigen Enzyme-linked immunosorbent assay kit in dairy calves from Central India (Madhya Pradesh and Chhattisgarh states) and North India (Uttar Pradesh state). Different epidemiological parameters like age, parity, colour and consistency of faecal materials and seasonal changes in a year were recorded. A total of 816 faecal samples were screened and out of which 7 (0.85%) animals were found to be positive for bovine coronavirus. The higher prevalence was recorded in north India followed by central India. Age wise higher prevalence was recorded below 2 month calves. Seasonally, the prevalence of coronavirus infection was higher in monsoon season and in first parity of calves as compared to other season and parity. Prevalence of coronavirus infection was higher in watery diarrhoea faecal materials than pasty yellow colour diarrhoea. The observations of the present study would provide the basis for further an effective explorative surveillance and epidemiological studies to know the real impact of coronavirus infection with associated risk factors in dairy calves of India.
ABSTRACT
Bovine rotavirus (BRoV) and bovine coronavirus (BCoV) are major enteric viral pathogens responsible for calve diarrhoea. They are widespread both in dairy and beef cattle throughout the world and causing huge economic losses. The diagnosis of these agents is very difficult due to non-specific nature of lesions and the involvement of some intrinsic and extrinsic risk factors. We performed postmortem of 45 calves, which was below three months of age. Out of 45 necropscid calves, three (6.66%) cases were positive for BRoV and four (8.88%) cases were found positive for BCoV, screened by reverse transcriptase polymerase chain reaction (RT-PCR). Further RT-PCR positive cases were confirmed by immunohistochemistry (IHC) in paraffin-embedded intestinal tissue sections. Three cases of enteritis caused by BRoV showed the hallmark lesions of the shortening and fusion of villi, denudation and infiltration of mononuclear cells in the lamina propria. The BRoV antigen distribution was prominent within the lining epithelium of the villi, peyer's patches in the ileum and strong immunoreactions in the lymphocytes and some macrophages of the mesenteric lymph nodes. Four cases in which BCoV was detected, grossly lesions characterized by colonic mucosa covered with thick, fibrinous and diphtheritic membrane. Histopathologically, jejunum showed skipping lesion of micro-abscesses in crypts. The BCoV antigen distribution was prominent within the necrotic crypts in the jejunum and cryptic micro-abscesses in the colon and ileum. It is the first report of BRoV and BCoV antigen demonstration in the jejunum, colon, ileum, Peyer's patches and mesenteric lymph nodes of naturally infected calves from India by using IHC.