Q fever in Los Angeles County. Serological survey of human and bovine populations.

Q fever is endemic and enzootic in Los Angeles County. A serological survey conducted in 1949 is compared with a current survey. Infection in dairy herds is now almost universal, while the prevalence of positive complement fixation titers in man only increased from 1.2 percent to 2.3 percent (p <0.10). The relative stability in man is accounted for by the increase in temperature requirements for milk pasteurization, the decrease in consumption of raw milk and the decrease in the number of dairy farm foci.