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Histoplasmosis

Background and Symptoms

Histoplasmosis is a fungal infection caused by Histoplasma capsulatum, a soil saprophyte that produces infective spores. Human infection results about 10 days (3-17) after the inhalation of airborne spores, which are dislodged from soils enriched with animal feces. Approximately 80% of those infected with histoplasmosis experience either a subclinical or acute benign form that is characteristic of a flu-like syndrome (headache, myalgia, malaise, and cough) and resolves without specific treatment.¹ Progressive or chronic disseminated and chronic pulmonary (cavitary) forms of histoplasmosis have a poor prognosis and are difficult to diagnose and treat. Avian habitats associated with domestic poultry, pigeons, roosting flocks of wild birds and zoological parks are considered to be especially suitable for proliferation of H. capsulatum.¹ Approximately 90% of all cases reported in the US come from the Ohio and Mississippi River valleys and some portions of Virginia and Maryland.²

Histoplasmosis in Florida

In Florida, histoplasmosis became a reportable disease in 1957. From that time through 1998, 150 confirmed human cases of histoplasmosis were reported. However, it was determined that less than one-third of Florida histoplasmosis cases were acquired in the state and all of those were derived from exposure to caves inhabited by bats.³ The first documented case of histoplasmosis in the state associated with caves and bats occurred in 1955.⁴ Since then, reported cases have been sporadic and rare, with a few cases reported in spelunkers in 1966 (1), 1972(3) and 1982(3).⁵ An unusual outbreak that involved 23 high school students attending a cave party, in 1973, has also been documented.⁶ Epidemiological studies have demonstrated that H. capsulatum can be recovered from the soil and bats (Myotis austroriparius and Pipistrellus subflavus) associated with the caves frequented by these cases.^3,6,7 In 1999, Histoplasmosis was removed from the list of reportable diseases within the state of Florida.

Prepared by Bill Bigler, PhD

DOH, Bureau of Epidemiology

10/26/99

Updated 9/15/05

For more information on histoplasmosis, visit the Centers for Disease Control and Prevention (CDC)

References

1. Friedman, L and Domer, JK. Systemic mycoses:histoplasmosis. In Diagnostic Procedures for Bacterial, Mycotic and Parasitic Infections. Balows, A and Hausler, WJ, (eds) Am. Pub. Hlth. Assn. 6th edition, 1981; pp. 959-64.

2. Larsh, HW. The epidemiology of histoplasmosis. In: The Epidemiology of Human Mycotic Diseases. Y. Al-Dorry ed. Charles C. Thomas Publishers, Springfield, Ill.

3. Hoff, GL, and Bigler, WJ. The role of bats in the propagation and spread of histoplasmosis:a review. J. Wildl. Dis. 1981; 17(2):191-96.

4. Tegeris, AS and Smith, DT. Acute disseminated pulmonary histoplasmosis treated with cortisone and MRO-112. Ann. Int. Ned. 1958; 48:1414-20.

5. Johnson, JE, Radimer, JE, Disalvo, AF, et al. Histoplasmosis in Florida: 1. Report of a case and epidemiologic findings. Am. Rev of Resp. Dis; 1970, 101:299-305.

6. Lottenberg, R, Waldman, RH, Ajello L, et al. Pulmonary histoplasmosis associated with exploration of a bat cave. Am. J. Epidemiol. 1979,110:156-61.

7. Disalvo, AF, Bigler, WJ, Ajello L. et al. Bat and soil studies for sources of histoplasmosis in Florida. Pub. Hlth. Rep., 1970; 85:1063-69.