ISOLATION AND CHARACTERIZATION OF ROTAVIRUS ASSOCIATED WITH CALVES, IN CENTRAL PART OF OROMIA, ETHIOPIA
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2019-06
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Abstract
Rotavirus is a major pathogen responsible for diarrheal disease in calves resulting in loss of productivity and economy of farmers. However, various facets of diarrheal disease caused by rotavirus in calves in Ethiopia are inadequately understood. A cross sectional study was conducted with the aim of isolation and molecular characterization of rotavirus in calves from central part of Oromia (Bishoftu, Sebata, Holeta and Addis Ababa), Ethiopia from November 2018 to May 2019. The four study areas were purposively selected and fecal samples were collected by simple random sampling for diagnosis of rotavirus infection by using antigen detection Enzyme linked immunosorbent assay (Ag-ELISA) kit. In addition, this study was carried out to have insight in prevalence and associated risk factors of rotavirus infection in calves. Different farm levels (floor of the calf) and calf level (sex, age) factors were measured the level of association between variables. During the present study 83 diarrheic and 162 non-diarrheic fecal samples collected from calves less than 4 weeks of age were screened for rotavirus. Of the 83 diarrheic samples, 6 samples (7.2%) were found to be positive for rotavirus antigen (Ag) by Ag-ELISA. All the non-diarrheic samples were negative for rotavirus Ag. The overall prevalence of rotavirus infection in calves was estimated as 2.45% (6/245). All samples (6) of ELISA test positive were propagated in Madin Darby bovine kidney cells. After 3 subsequent passages, progressive cytopathic effect (CPE) i.e. rounding, detachment as well as destruction of mono-layer cell of four sample (66.7%) were observed. At the molecular stage, reverse transcriptase polymerase chain reaction (RT-PCR) technique was used to determine the presence of rotavirus nucleic acid by using specific generic primers for VP4 genetic regions in feces samples. The 4 samples that were rotavirus antigen positive by ELISA and develop CPE on cell culture were also positive on RT-PCR technique. Infection prevalence peaked have been obtained at 1st and 2nd weeks of age in male calves. Considering that diarrheal disease caused by rotavirus is a vital health problem in calves that interrupts production benefits with reduced weight gain and increased mortality, and its potential for zoonotic spread. So the present findings revealed rotavirus infection in calves in Ethiopia that needs to be addressed by practicing early colostrums feeding in newborn calves, using vaccine, or improving livestock management.
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Calf diarrhea, ELISA Test, Rotavirus