Brucellosis in the United States. Past, present, and future.

The incidence of human brucellosis has declined in the United States since 1974, when 6,321 cases were reported, to 175 cases reported in 1973. A resurgence occurred in 1974 and 1975, when 247 and 328 cases were reported, respectively. This increase followed an increase in incidence of bovine brucellosis as indicated by an increase from 4.3 reactors per 1,000 market cattle in 1971 to 6.8 in 1974. Recurrence occurred in 15 states that had been free of the disease, and increased incidence occurred in other states. A total of 16,401 infected herds were identified in 1975, and 90% of these were in 11 states. Migration of infected cattle occurs through market channels. Effective control of brucellosis leading to local eradication, which could be national in scope, is biologically feasible. Physicians have a responsible role in this eradication.