Each farm was studied for at least ten months. Unlike the prevalence study, farms were not randomly selected. Selection was biased by the inclusion of twelve herds of known positive status. Six farms showed no evidence of shedding at any time. The researchers attempted to find out why by completing a farm management questionnaire at each visit.
More comprehensive analysis is ongoing.
Acknowledgements The almost universal willingness of farmers to allow their livestock to be sampled and to answer the questionnaires is a great credit to the agricultural industry. Colleagues in SAC Veterinary Science Division at Aberdeen, Inverness and Thurso contributed to these studies. Grampian University Hospitals Trust, Department of Medical Microbiology carried out the typing of isolates.