Associations between human and farm animal infections with Salmonella typhimurium DT104 in Herefordshire.

Reports of human infection with Salmonella typhimurium definitive type (DT) 104 have generated considerable interest. We undertook a descriptive study of infections with S. typhimurium DT 104 infection in humans and farm animals in Herefordshire between 1991 and 1993. Laboratory reports of human salmonellosis, sent to the consultant in communicable disease control, were compared with cases identified using Statutory Incident Reports of salmonella in animals, birds and their products, received from the Ministry of Agriculture, Fisheries and Food. Six separate associations of infection between farming families and their livestock were identified. Nine out of 23 human cases, including three family outbreaks, were associated with animal infection. This study suggests that occupationally acquired infection in farmers and their families may be contributing to the national increase in cases, and shows the value of drawing together data from human and animal sources for the surveillance, investigation, and control of human infection with S. typhimurium DT104.