Bovine coronavirus
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Bovine coronavirus (BCV) is as a member of the Coronaviridae family which are enveloped, single-stranded, positive-sense RNA viruses with a club-shaped surface. Infection causes 'Calf Enteritis' and contributes to the 'Enzootic Pneumonia complex' in calves. It can also cause 'Winter Dysentery' in adult cattle. It can infect both domestic and wild ruminants and has a worldwide distribution. Transmission is horizontal, via oro-fecal or respiratory routes.
Diagnosis
Infection normally occurs in calves between the ages of one week and three months. Gastrointestinal signs include profuse diarrhea, dehydration, depression, reduced weight gain and anorexia. Respiratory infection in the calf produces a serous to purulent nasal discharge. Clinical signs may worsen with secondary bacteria infection.
Infection in adults is normally subclinical, the exception being with Winter Dysentry, which affects housed cattle over the Winter months. Clinical signs include profuse diarrhea and a significant drop in milk yield is seen in Winter Dysentry outbreaks.
A presumptive diagnosis can be made based on the history and clinical signs. Definitive diagnosis of an enteric coronavirus infection is achieved by performing electron microscopy or an ELISA on a faecal or tissue sample. In respiratory disease, diagnosis is confirmed by performing a direct fluorescent antibody test on nasal washes - which identifies the viral antigen.
The haemagglutination inhibition test can be used to establish the strain of coronavirus.
Treatment
Animals should be treated symptomatically. The disease can be controlled by vaccinating the dam with a live vaccine (ATCvet code QI02) whilst she is pregnant as this provides antibodies to the virus in the colostrum. Additional management factors such as insuring adequate colostrum intake in newborn calves, using appropriate hygiene methods and ventilation of housing reduce disease incidence.