Disease outbreak investigation. Three case studies.

Three case studies of the investigation of outbreaks of disease or deviations from target performance are presented. The first is a study of a mastitis problem in a dairy herd, made evident by increased somatic cell counts. The pattern of the production problem is carefully analyzed and conclusions are reached that indicate an infection with environmental contaminant organisms, thus permitting control measures to be introduced. The second case study is an investigation of an outbreak of neonatal mortality in sheep. Analysis suggests a multiple etiology, with infection by border disease virus predominating. The third case study describes the investigation of foothill abortion in a beef herd in California and demonstrates the use of epidemiologic techniques to try to identify the source of infection in a subgroup of the study population, thus allowing specific control measures to be introduced.