In investigating six cases of blastomycosis in two school groups that had separately visited an environmental camp in northern Wisconsin in June 1984, we identified a large outbreak of the disease and isolated Blastomyces dermatitidis from soil at a beaver pond near the camp. Of 89 elementary-school children and 10 adults from the two groups, 48 (51 percent) of the 95 evaluated in September had blastomycosis. Of the cases, 26 (54 percent) were symptomatic (the median incubation period was 45 days; range, 21 to 106 days). No cases were identified in 10 groups that visited the camp two weeks before or after these two groups. A review of camp itineraries, a questionnaire survey, and environmental investigation showed that blastomycosis occurred in two of four groups that visited a beaver pond and in none of eight groups that did not. Walking on the beaver lodge (P = 0.008) and picking up items from its soil (P = 0.05) were associated with illness. Cultures of soil from the beaver lodge and decomposed wood near the beaver dam yielded B. dermatitidis. We conclude that B. dermatitidis in the soil can be a reservoir for human infection.
OBJECTIVES: This study estimated the magnitude of cryptosporidiosis-associated mortality in the Milwaukee vicinity for 2 years following a massive waterborne outbreak. METHODS: Death certificates were reviewed. RESULTS: During approximately 2 years before the outbreak, cryptosporidiosis was listed as an underlying or contributing cause of death on the death certificates of four Milwaukee-vicinity residents. In the approximately 2 years after the outbreak, this number was 54, of whom 85% had acquired immunodeficiency syndrome (AIDS) listed as the underlying cause of death. In the first 6 months after the outbreak, the number of death certificates indicating AIDS, but not cryptosporidiosis, as a cause of death was 19 (95% confidence interval = 12.26) higher than preoutbreak trends would have predicted. CONCLUSIONS: Waterborne outbreaks of cryptosporidium infection can result in significant mortality, particularly among immunocompromised populations. Any discussion of policies to ensure safe drinking water must consider the potential fatal consequences of waterborne cryptosporidiosis among immunocompromised populations.
Blastomycosis cannot yet be prevented or controlled, in part because the natural habitat of the causative fungus, Blastomyces dermatitidis, remains ill defined. In investigating 2 outbreaks of blastomycosis that occurred in the summer of 1985 among persons engaged in activities along rivers in contiguous central Wisconsin counties, we isolated B. dermatitidis from soil at one of the riverbanks. Blastomycosis developed in 7 (58%) of 12 residents and guests who had gathered at a pheasant farm on the Tomorrow River in early May, and in 7 (88%) of 8 boys and 1 adult who had visited a site on the Crystal River in early June. Of the 14 patients, 13 (93%) were symptomatic. Two patients visiting the sites only once became ill 23 and 78 days after exposure, respectively. We traced one outbreak to fishing from the bank of the Tomorrow River, and the other to climbing into an underground timber fort along the Crystal River. A culture of soil and organic debris from the fishing site yielded B. dermatitidis. From these and other outbreaks, and studies of endemic disease, we conclude that riverbanks can be a natural habitat of B. dermatitidis, and that the environment around waterways represents the most important site yet identified for transmission of B. dermatitidis.
Staphylococcal enterotoxin F (SEF) has previously been shown to be a marker for toxic-shock syndrome (TSS)-associated strains of Staphylococcus aureus, whereas the serologic absence of antibody to SEF (anti-SEF) has been shown to be a marker for susceptibility of persons to TSS. In this study, anti-SEF was measured by radioimmunoassay in 689 banked sera obtained from Wisconsin residents during 1960, 1970, and 1980. The prevalence of anti-SEF as estimated by logistic regression analysis was 47%, 58%, 70%, 88%, 96%, and 99% at ages one, five, 10, 20, 30, and 50 years, respectively. Evidence for the transplacental transfer of anti-SEF is also presented. Despite the reported increased incidence of TSS occurring during the past five years, with a preponderance of cases occurring among women, no significant differences in the prevalence of anti-SEF were noted between sexes or longitudinally between the years 1960, 1970, and 1980. These data enhance our understanding of the epidemiology of TSS and further identify the population that may be susceptible to TSS.
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