PREVALENCE AND INCIDENCE STUDIES OF HUMAN AND CANINE BLASTOMYCOSIS II. YEARLY INCIDENCE STUDIES IN THREE SELECTED STATES, 1960–1967

Furcolow, M. L (Dept. Community Medicine, Univ. of Kentucky, Lexington, Ky. 40506), J. F. Busey, R. W. Menges and E. W. Chick. Prevalence and incidence studies of human and canine blastomycosis. II. Yearly incidence studies in three selected states, 1960–1967. Amer. J. Epid., 1970, 92: 121–131.—Epidemiologic facets of blastomycosis are discussed, based on 5- or 6-year studies of the human and canine disease in Arkansas, Mississippi, and Kentucky, from 1960–1967. Based on these studies: a) The disease in both dogs and humans appears to be relatively uniformly distributed through the whole endemic area. b) The incidence of blastomycosis is probably much higher in both humans and canines than has been reported from any given area. Intensive studies in these 3 states suggest that statewide rates approximating 0.5 human cases per 100,000 population per year have been observed. This estimate approaches the average reported yearly number in Arkansas and Kentucky, but is exceeded by the average in Mississippi. Canine rates more than 10 times higher, or in the range of almost 6.5 per 100,000 per year, were observed in Arkansas where most careful studies were done. Thus, the true canine rate might well be essentially more than 10 times higher than the human rate. If one bases the observations upon the highest county rates observed in any of the three states, human rates in the range of 4 per 100,000 per year, or about 10 times higher than the state rates, do not appear unusual and are scattered throughout all three states. If rates this high were prevalent the reported number of cases would be far below the actual number in all three states. Based upon the highest rates observed in counties among canines, the true rates would appear to be in the range of 45 per 100,000 per year. This is almost 10 times higher than the highest observed state rates and suggests that the true incidence of the disease may be extremely high—in fact, about 10 times higher in both humans and canines to that observed, with tremendous underreporting of the disease.