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Rotavirus and Coronavirus

Rotavirus and Coronavirus infections

Rotavirus and Coronavirus are ubiquitous viruses in cattle that are associated with the majority of diagnosed diarrhoea outbreaks in young calves.  Both viruses cause diarrhoea in calves on their own but are often detected in association with each other and other diarrhoea pathogens, like Cryptosporidium.

Rotavirus and Coronavirus can cause high-morbidity in calves less than 10 days of age. Rotavirus infection of the small intestine leads to loss of the upper third of the intestine villi with subsequent destruction and malabsorption of fluids and nutrients. Coronaviruses are slightly different from Rotavirus in that it infects not only the small intestinal mucosa, producing significant villous destruction, but also the colon, causing severe damage that can lead to death due to subsequent electrolyte disturbances. Mortality levels for Rotavirus and Coronavirus infections are variable mainly due vaccination status of dam, passive colostrum transfer, secondary bacterial infections and electrolyte imbalances.


When are calves infected?

Viral diarrhoea in calves occurs mostly between 5 and 14 days of age, and virtually always under 3 weeks of age. Rapid outbreaks with profuse watery yellow/green diarrhoea are characteristic of viral scours with the infection spreading rapidly among young calves in the group especially in housed calves. In most cases there is a build-up of infection a few weeks into the calving period.

The severity of the disease depends on:

·         Environmental conditions

·         Dam’s immune status.

·         Ingestion of adequate amounts of colostrum.

·         Age of the calf



Diagnosis of viral diarrhoeas of calves requires the support of the laboratory. The sample of choice is fresh faecal samples collected directly from the calves as close as possible to the onset of diarrhoea. Samples from more than one calf during the outbreak enhance the laboratory’s ability to establish a proper viral diagnosis.


Control and Prevention

Once a herd has experienced problems with Rotavirus-Coronavirus infection, annual vaccination of the cows is essential 1 - 3 months before their calving date. This will provide the protection needed to help prevent infectious scours caused by Rotavirus, Coronavirus and E. coli.

At Selwyn Rakaia Veterinary Services we can provide a comprehensive on farm investigation to determine the cause of your calf health issues and make best practice recommendations to control and prevent ongoing issues.