*Rate per 100,000 population based on the U.S. Census Bureau’s population data as of July 1, 2004
Histoplasmosis is caused by Histoplasma capsulatum, a saprophytic soil fungus. The primary route of transmission is inhalation of infectious spores made airborne by the disturbance of contaminated soil. The presence of Histoplasma capsulatum has been associated with soil enriched with bird feces especially blackbirds, starlings, chickens, and pigeons. However, birds are not carriers of histoplasmosis, but accumulation of bird feces provide the organic enrichment needed for Histoplasma growth. Bat guano may also carry the organism.
Approximately 90 percent of Histoplasma capsulatum infections are asymptomatic. Clinically recognized histoplasmosis can be characterized into one of three forms:
1) acute, pulmonary histoplasmosis; 2) disseminated histoplasmosis; and 3) chronic, cavitary histoplasmosis. Symptoms of acute cases are flu-like with nonproductive cough, chest pains, and difficult breathing. More severe disease may result in fever, night sweats, weight loss, and bloody sputum. Severe cases may result in Histoplasma organisms being disseminated to many body organs.
In 2004, 55 confirmed cases of histoplasmosis were reported in Indiana for an incidence rate of less than one person per 100,000 population (Table 1). Figure 1 illustrates the number of cases by year for 2000-2004. Histoplasmosis occurred throughout the year in 2004 with the largest number of cases in the winter (Figure 2). Figure 3 displays the distribution of cases by age group. Age-specific rates were greatest among adults aged 30-79 years of age. Males (1.21) were twice as likely to be reported with histoplasmosis infection than females (0.57).
In 2004, two counties reported five or more cases of histoplasmosis in Indiana: Marion and Delaware. The incidence rates were 1.0 case per 100,000 population for Marion County and 4.2 cases per 100,000 population for Delaware County.
You can learn more about histoplasmosis by visiting the following Web sites:
CDC Website: Histoplasmosis