Epidemiology of Rotavirus Infection in Dairy Calves in Central Ethiopia

Rotavirus is a major pathogen responsible for diarrheal disease in calves and neonates resulting in loss of productivity and economic losses in dairy farms in developed and developing countries. In Ethiopia, the diarrheal disease caused by Rotavirus is not so far studied adequately. Across-sectional study was conducted from October 2019 to May 2020 to estimate the prevalence, assess associated factors, and isolate Rotavirus in calves below two months of age in the central part of Ethiopia, namely Holeta, Sululta, Bishoftu, and Sebeta. A total of 404 fecal samples, comprising 213 diarrheic and 191 non-diarrheic cases, were collected from calves of less than two months of age by simple random sampling technique. Rotavirus infection was detected using antigen detection Enzyme-linked immunosorbent assay technique. All samples positive for ELISA were propagated in Madin Darby bovine kidney cells. Data was analyzed using STATA version 13. Fisher's exact test and logistic regression analysis were used to determine the association between prevalence of rotavirus and potential risk factors. An overall rotavirus prevalence of 1.24% (95%CI 0.40 – 2.86%) was found. The prevalence of rotavirus in diarrheic calves (1.41%) was not significantly different from the prevalence of rotavirus in non-diarrheic calves (1.04%) (p>0.05). Similarly, the origin, breed, sex, age, management, and type of farm had no significant association with the prevalence of rotavirus infection of calves (p>0.05). After 3 subsequent passages, progressive cytopathic effect i.e. Cell swelling and obscure cell boundaries, detachment and floatation of cells, cytoplasmic vacuolationas, increased cell granularity and cytoplasmic stranding were observed in all samples. The presence of rotavirus in dairy calves might entail morbidity and mortality in calves. Moreover, rotavirus infection might also lead to zoonotic transmission. Therefore, further detailed molecular epidemiological studies are warranted. Good hygienic and husbandry practices are essential to limit the spread of infection.