Description

Histoplasmosis is a disease caused by the fungus Histoplasma capsulatum. The fungus usually grows in soil enriched with accumulations of bat or bird droppings. The disease is acquired via inhalation of spores (conidia) from soil contaminated with bat or blackbird droppings. Ninety percent of infections are asymptomatic or result in a mild influenza-like illness. Some infections, however, cause acute pulmonary histoplasmosis as manifested by high-grade fever, headache, nonproductive cough, chills, weakness, and pleuritic chest pain. Symptoms occur 3 to 17 days after exposure and most people recover spontaneously 2 to 3 weeks after symptom onset. Dissemination, especially to the gastrointestinal tract and central nervous system, can occur in people with severe immune compromise (i.e., human immunodeficiency virus infection). Re-infection and reactivation can occur. Histoplasmosis is not transmitted from person to person.

Occurrence

In the United States, H. capsulatum var. capsulatum is found along the Ohio and Mississippi River valleys mostly in the central and southeastern states. Its occurrence has been described on every continent except Antarctica. Autochthonous human cases have been reported throughout Central America, the Caribbean, South America, eastern Asia ( Iran, Pakistan, India, China, Thailand, Indonesia, Vietnam, Malaysia, Philippines, Burma, and Japan), parts of Europe (northern Italy, Bulgaria, Spain, Hungary, Austria, France, Portugal, Romania, Turkey, the countries of the former Soviet Union, Great Britain, Ireland, and Norway), parts of Africa, and Australia. In May 2001, an outbreak of histoplasmosis occurred among college students vacationing in Acapulco.

Risk to Travelers

People who visit endemic areas and are exposed to accumulations of bat guano or bird droppings are at increased risk for infection. Exposures can occur during activities such as spelunking, mining, construction, excavation, demolition, roofing, chimney cleaning, farming, gardening, and installation of heating and air-conditioning systems. While in caves or mines, spending time close to the ground or kicking up dirt infested with bat guano containing H. capsulatum can increase the risk of infection. With sufficient exposure, persons can be reinfected with H. capsulatum.

Treatment
For people with acute, localized pulmonary histoplasmosis, specific antifungal treatment is not usually necessary because disease is self-limited. For people with severe or persistent symptoms, itraconazole can be given for 6 to 12 weeks. For those with underlying immune deficits or chronic disease, itraconazole may be given for longer periods. All people with severe disease, including diffuse pulmonary and disseminated histoplasmosis, should be treated with either itraconazole (available orally and intravenously) or Amphotericin B (available in intravenous form). Pregnant women should be given Amphotericin B.

Preventive Measures

People at increased risk for infection, especially for severe disease, should be advised to avoid high-risk areas, such as bat-inhabited caves. If exposure cannot be avoided, people should be advised to decrease dust generation in infested areas by watering the areas prior to engaging in dust-generating activities and to wear masks and special protective equipment. Further details about the protective equipment can be obtained from "Histoplasmosis: Protecting Workers at Risk".

No effective vaccine for histoplasmosis is currently available.

© Center for Disease Control

Credits: National Center for Infectious Diseases