Persistent excretion of rotavirus by pregnant cows.

In a study of the epizootiology and prevalence of enteropathogens which may be involved in neonatal calf diarrhoea, 10 in-calf cows from a herd with a history of rotavirus-induced calf diarrhoea were monitored over a period of six to seven months. All the cows excreted rotavirus intermittently without showing any clinical signs, and 21.8 per cent of faecal samples contained rotavirus. Reoviruses were isolated from 87 per cent of the samples from the cows, and from all the 10 calves born to them. However, rotavirus was detected in only one calf, and diarrhoea developed only in this calf even though the calves were housed in communal pens. Campylobacter jejuni was isolated from six of the 10 dams and from five of the 10 calves, not including the calf with diarrhoea. Other potential enteropathogens such as cryptosporidium, salmonella, Clostridium difficile, coronavirus and other viruses were not found, but two cows and two calves shed enterotoxigenic Escherichia coli.