EXPERIMENTAL EPIDEMIOLOGY OF COCCIDIOIDOMYCOSIS: 1. EPIZOOTIOLOGY OF NATURALLY EXPOSED MONKEYS AND DOGS

Animals from constant populations of monkeys and dogs 24 of each divided among 3 exposure sites housed for 1 year in the open in a known endemic area for coccidioidomycosis Tucson, Arizona were removed - upon contracting infection with Coccidioides immitis - to air-conditioned quarters for further observation and were immediately replaced at the exposure sites with other susceptible animals. Periodic soil and air samples were obtained, and appropriate climatic data were recorded throughout the one-year period. Clinical and laboratory observations were continuously recorded for all animals, and complete necropsies were performed at the termination of the experiment. Approximately 15 534 of the monkeys housed 26 inches above ground and 58 2950 of the dogs allowed free run of 30 x 40 ft. pens became infected during the 1-year period, the majority 2534 during the cooler months November through March. Comparison of the pathogenesis of the disease in the naturally-infected monkeys with that in experimentally-infected monkeys indicated a natural, air-borne, infectious dose of probably less than 10 arthrospores. The infection rate, as well as the extent of disease, in the naturally-infected dogs was greater than in either the naturally-infected monkeys or the experimentally-infected dogs, and was attributed to their contact with the ground.