The Dillon Beach Project--a five-year epidemiological study of naturally occurring salmonella infection in turkeys and their environment.

A 5-year epidemiological study of naturally occurring salmonella infection in 2 basic strains of turkeys and their environment was completed. Multiple generations of these turkeys, free from salmonella infection, were raised on a new commercial breeding ranch (the Dillon Beach Ranch) in California during a 31/2-year period. Eight salmonella serotypes eventually gained access to the ranch. Egg transmission and prior contamination of the premises were ruled out as the source of these infections. The most likely means of their introduction was physical transport into the ranch by contaminated feed, personnel, and/or equipment. Several serotypes of salmonella were isolated from pelleted feed delivered to the ranch, demonstrating its role in introducing infection. The low isolation rate from feed samples and environmental samples taken from many buildings indicates the need for intensive sampling as a reliable indicator of infection. The most severe and consistently detected infection occurred in young birds grown in forced-air-ventilated buildings. A total of 17,858 bacteriological cultures representing about 102,756 environmental, feed, and bird samples, and 93,930 serological tests on 46,977 serum samples, were run during the study.