Histoplasmosis Fact Sheet (English), 97-146

HISTOPLASMOSIS: Protecting Workers at Risk

Note: This document is superceded by NIOSH Publication 2005-109: Histplasmosis—Protecting Workers at Risk.

DHHS (NIOSH) PUBLICATION
NO. 97-146 SEPTEMBER 1997

Histoplasmosis Fact Sheet

What is histoplasmosis? Histoplasmosis is an infectious disease caused by inhaling spores of a fungus called Histoplasma capsulatum. Histoplasmosis is not contagious; it cannot be transmitted from an infected person or animal to someone else.

What are the symptoms of histoplasmosis? Histoplasmosis primarily affects a person's lungs, and its symptoms vary greatly. The vast majority of infected people are asymptomatic (have no apparent ill effects) or they experience symptoms so mild they do not seek medical attention. If symptoms do occur, they will usually start within 3 to 17 days after exposure, with an average of 10 days. Histoplasmosis can appear as a mild, flu-like respiratory illness and has a combination of symptoms, including malaise (a general ill feeling), fever, chest pain, dry or nonproductive cough, headache, loss of appetite, shortness of breath, joint and muscle pains, chills, and hoarseness. A chest X-ray can reveal distinct markings on an infected person's lungs. Chronic lung disease due to histoplasmosis resembles tuberculosis and can worsen over months or years. The most severe and rare form of this disease is disseminated histoplasmosis, which involves spreading of the fungus to other organs outside the lungs.

Who can get histoplasmosis? Anyone working at a job or present near activities where material contaminated with H. capsulatum becomes airborne can develop histoplasmosis if enough spores are inhaled. After an exposure, how ill a person becomes varies greatly and most likely depends on the number of spores inhaled and a person's age and susceptibility to the disease. The number of inhaled spores needed to cause disease is unknown. Infants, young children, and older persons, in particular those with chronic lung disease, are at increased risk for developing symptomatic histoplasmosis.
People with weakened immune systems are at greatest risk for developing severe and disseminated histoplasmosis. Included in this high-risk group are persons with AIDS or cancer and persons receiving cancer chemotherapy; high-dose, long-term steroid therapy; or other immuno-suppressive drugs.
A person can learn from a histoplasmin skin test whether he or she has been previously infected by H. capsulatum. This test, similar to a tuberculin skin test, is available at many physicians' offices and medical clinics. A previous infection can provide partial immunity to reinfection. Since a positive skin test does not mean that a person is completely immune to reinfection, appropriate exposure precautions should be taken regardless of a worker's skin-test status whenever disturbances of materials that might be contaminated with H. capsulatum occur.

What is the treatment for histoplasmosis? Mild cases of histoplasmosis are usually resolved without treatment. For severe cases, special antifungal medications are needed to arrest the disease. Disseminated histoplasmosis is fatal if untreated, but death can also occur in some patients even when medical treatment is received.

Where are H. capsulatum spores found? H. capsulatum grows in soils throughout the world. In the United States, the fungus is endemic (more prevalent) and the proportion of people infected by H. capsulatum is higher in central and eastern states, especially along the valleys of the Ohio, Mississippi, St. Lawrence rivers, and the Rio Grande. The fungus seems to grow best in soils having a high nitrogen content, especially those enriched with bat droppings or bird manure. Disturbances of contaminated material cause small H. capsulatum spores to become airborne or aerosolized. Once airborne, spores can easily be carried by wind currents over long distances.

How can someone know if soil or droppings are contaminated with H. capsulatum spores? To learn whether soil or droppings are contaminated with H. capsulatum spores, samples must be collected and cultured. Presently, the method used to isolate H. capsulatum is expensive and requires several weeks to complete. If not enough samples are collected, small but highly contaminated areas can be overlooked. Until a less expensive and more rapid method is available, testing samples for H. capsulatum will continue to be impractical for most situations. Consequently, when thorough testing is not done, the safest approach is to assume soil in endemic regions and any accumulations of bat droppings or bird manure are contaminated with H. capsulatum and take appropriate exposure precautions.

What jobs and activities have risks for exposure to H. capsulatum spores? Below is a partial list of occupations and hobbies with risks for exposure to H. capsulatum spores. Appropriate exposure precautions should be taken by these people and others whenever contaminated soil, bat droppings, or bird manure are disturbed.

Bridge inspector or painter
Chimney cleaner
Construction worker
Demolition worker
Farmer
Gardener
Heating and air-conditioning system installer or service person
Microbiology laboratory worker
Pest control worker
Restorer of historic or abandoned buildings
Roofer
Spelunker (cave explorer)

How can exposure to H. capsulatum be controlled and histoplasmosis prevented? The best way to prevent exposures to H. capsulatum spores is to avoid situations where material that might be contaminated can become aerosolized and subsequently inhaled. This is especially important for persons with weakened immune systems.
Dust suppression methods, such as carefully wetting with a water spray, may be useful for reducing the amount of material aerosolized during an activity. For some activities, such as removing an accumulation of bat droppings or bird manure from an enclosed place such as an attic, wearing a NIOSH-approved respirator and other items of personal protective equipment may be needed to further reduce the risk of H. capsulatum exposure. However, only persons trained in the proper selection and use of personal protective equipment should undertake work where this equipment is needed.
Disinfectants have occasionally been used to treat soil and accumulated bat manure when removal was impractical or as a precaution before a removal process was started. Formaldehyde solutions are the only disinfectants proven to be effective for decontaminating soil containing H. capsulatum. Because of the potentially serious health hazards associated with formaldehyde exposures, this chemical should be handled only by persons who know how to apply it safely.

Where can I get more information about histoplasmosis? This histoplasmosis fact sheet was prepared by the National Institute for Occupational Safety and Health (NIOSH) and the National Center for Infectious Diseases (NCID), both of the Centers for Disease Control and Prevention. For answers to other questions about histoplasmosis or histoplasmin skin-testing, please contact your physician, your local health department, or NCID in Atlanta, Georgia, at (404) 639-3158. NCID's Internet address is http://www.cdc.gov/ncidod/ncid/ncid.htm. For other questions about worker health and safety precautions during disturbances of soil, bat droppings, or bird manure that might be contaminated with H. capsulatum spores, call NIOSH in Cincinnati, Ohio, at 1-800-356-4674.

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What is histoplasmosis?	Histoplasmosis is an infectious disease caused by inhaling spores of a fungus called Histoplasma capsulatum. Histoplasmosis is not contagious; it cannot be transmitted from an infected person or animal to someone else.
What are the symptoms of histoplasmosis?	Histoplasmosis primarily affects a person's lungs, and its symptoms vary greatly. The vast majority of infected people are asymptomatic (have no apparent ill effects) or they experience symptoms so mild they do not seek medical attention. If symptoms do occur, they will usually start within 3 to 17 days after exposure, with an average of 10 days. Histoplasmosis can appear as a mild, flu-like respiratory illness and has a combination of symptoms, including malaise (a general ill feeling), fever, chest pain, dry or nonproductive cough, headache, loss of appetite, shortness of breath, joint and muscle pains, chills, and hoarseness. A chest X-ray can reveal distinct markings on an infected person's lungs. Chronic lung disease due to histoplasmosis resembles tuberculosis and can worsen over months or years. The most severe and rare form of this disease is disseminated histoplasmosis, which involves spreading of the fungus to other organs outside the lungs.
Who can get histoplasmosis?	Anyone working at a job or present near activities where material contaminated with H. capsulatum becomes airborne can develop histoplasmosis if enough spores are inhaled. After an exposure, how ill a person becomes varies greatly and most likely depends on the number of spores inhaled and a person's age and susceptibility to the disease. The number of inhaled spores needed to cause disease is unknown. Infants, young children, and older persons, in particular those with chronic lung disease, are at increased risk for developing symptomatic histoplasmosis. People with weakened immune systems are at greatest risk for developing severe and disseminated histoplasmosis. Included in this high-risk group are persons with AIDS or cancer and persons receiving cancer chemotherapy; high-dose, long-term steroid therapy; or other immuno-suppressive drugs. A person can learn from a histoplasmin skin test whether he or she has been previously infected by H. capsulatum. This test, similar to a tuberculin skin test, is available at many physicians' offices and medical clinics. A previous infection can provide partial immunity to reinfection. Since a positive skin test does not mean that a person is completely immune to reinfection, appropriate exposure precautions should be taken regardless of a worker's skin-test status whenever disturbances of materials that might be contaminated with H. capsulatum occur.
What is the treatment for histoplasmosis?	Mild cases of histoplasmosis are usually resolved without treatment. For severe cases, special antifungal medications are needed to arrest the disease. Disseminated histoplasmosis is fatal if untreated, but death can also occur in some patients even when medical treatment is received.
*Where are H. capsulatum* spores found?**	H. capsulatum grows in soils throughout the world. In the United States, the fungus is endemic (more prevalent) and the proportion of people infected by H. capsulatum is higher in central and eastern states, especially along the valleys of the Ohio, Mississippi, St. Lawrence rivers, and the Rio Grande. The fungus seems to grow best in soils having a high nitrogen content, especially those enriched with bat droppings or bird manure. Disturbances of contaminated material cause small H. capsulatum spores to become airborne or aerosolized. Once airborne, spores can easily be carried by wind currents over long distances.
*How can someone know if soil or droppings are contaminated with H. capsulatum* spores?**	To learn whether soil or droppings are contaminated with H. capsulatum spores, samples must be collected and cultured. Presently, the method used to isolate H. capsulatum is expensive and requires several weeks to complete. If not enough samples are collected, small but highly contaminated areas can be overlooked. Until a less expensive and more rapid method is available, testing samples for H. capsulatum will continue to be impractical for most situations. Consequently, when thorough testing is not done, the safest approach is to assume soil in endemic regions and any accumulations of bat droppings or bird manure are contaminated with H. capsulatum and take appropriate exposure precautions.
*What jobs and activities have risks for exposure to H. capsulatum* spores?**	Below is a partial list of occupations and hobbies with risks for exposure to H. capsulatum spores. Appropriate exposure precautions should be taken by these people and others whenever contaminated soil, bat droppings, or bird manure are disturbed. Bridge inspector or painter Chimney cleaner Construction worker Demolition worker Farmer Gardener Heating and air-conditioning system installer or service person Microbiology laboratory worker Pest control worker Restorer of historic or abandoned buildings Roofer Spelunker (cave explorer)
*How can exposure to H. capsulatum* be controlled and histoplasmosis prevented?**	The best way to prevent exposures to H. capsulatum spores is to avoid situations where material that might be contaminated can become aerosolized and subsequently inhaled. This is especially important for persons with weakened immune systems. Dust suppression methods, such as carefully wetting with a water spray, may be useful for reducing the amount of material aerosolized during an activity. For some activities, such as removing an accumulation of bat droppings or bird manure from an enclosed place such as an attic, wearing a NIOSH-approved respirator and other items of personal protective equipment may be needed to further reduce the risk of H. capsulatum exposure. However, only persons trained in the proper selection and use of personal protective equipment should undertake work where this equipment is needed. Disinfectants have occasionally been used to treat soil and accumulated bat manure when removal was impractical or as a precaution before a removal process was started. Formaldehyde solutions are the only disinfectants proven to be effective for decontaminating soil containing H. capsulatum. Because of the potentially serious health hazards associated with formaldehyde exposures, this chemical should be handled only by persons who know how to apply it safely.
Where can I get more information about histoplasmosis?	This histoplasmosis fact sheet was prepared by the National Institute for Occupational Safety and Health (NIOSH) and the National Center for Infectious Diseases (NCID), both of the Centers for Disease Control and Prevention. For answers to other questions about histoplasmosis or histoplasmin skin-testing, please contact your physician, your local health department, or NCID in Atlanta, Georgia, at (404) 639-3158. NCID's Internet address is http://www.cdc.gov/ncidod/ncid/ncid.htm. For other questions about worker health and safety precautions during disturbances of soil, bat droppings, or bird manure that might be contaminated with H. capsulatum spores, call NIOSH in Cincinnati, Ohio, at 1-800-356-4674.