Winter dysentery diagnosed by farmers in dairy herds in central Sweden: incidence, clinical signs and protective immunity
Tråvén, M.; Sundberg, J.; Larsson, B.; Niskanen, R.
Veterinary Record 133(13): 315-318
1993
ISSN/ISBN: 0042-4900 PMID: 8236667 Document Number: 411746
The occurrence of winter dysentery, diagnosed by farmers and defined as an outbreak of diarrhoea among at least 30% of adult cattle in a herd, was monitored in 256 dairy herds in an area of central Sweden. The cumulative incidence of winter dysentery between April 1988 and March 1989 was 28.5%. A typical outbreak lasted for 1 to 2 weeks and 74% of the outbreaks occurred between November and January. A decrease in milk yield was reported in 90% of the affected herds and the cows showed respiratory signs in 57% of them. There was a significant association between the occurrence of fever and coughing. In 31% of the outbreaks the farmer also noticed diarrhoea among the calves. One-third of the affected herds had experienced an outbreak within the previous 4 years and 18% had at least one further outbreak during the following 2 years. There was a significantly lower disease score in herds that had had an outbreak within the previous 4 years than in herds which had had an earlier or no previous outbreak, indicating the development of temporary immunity to the causative agent.