Histoplasmosis is an infection caused by breathing in spores of a fungus often found in bird and bat droppings. Histoplasmosis is most commonly transmitted when these spores become airborne, often during cleanup or demolition projects.
Soil contaminated by bird or bat droppings also can transmit histoplasmosis, so farmers and landscapers are at a higher risk of the disease. In the United States, histoplasmosis most commonly occurs in the Mississippi and Ohio river valleys.
Most people with histoplasmosis never develop symptoms and aren't aware they're infected. But for some people — primarily infants and those with compromised immune systems — histoplasmosis can be serious. Effective treatments are available for even the most severe forms of histoplasmosis.
Several types of histoplasmosis exist. The mildest form produces no signs or symptoms, but severe infections can be life-threatening. When signs and symptoms do occur, they usually appear three to 17 days after exposure and may include:
In some people, histoplasmosis can also produce joint pain and a rash. People who have an underlying lung disease, such as emphysema, may develop a chronic form of histoplasmosis that can additionally feature weight loss and a cough that brings up blood. Symptoms of chronic histoplasmosis sometimes can mimic those of tuberculosis.
When to see a doctor
Histoplasmosis is caused by the reproductive cells (spores) of the fungus Histoplasma capsulatum. The spores are extremely light and float into the air when dirt or other contaminated material is disturbed. Even if you've had histoplasmosis in the past, you can still get the infection again. However, if you contract histoplasmosis again, the illness will likely be milder than the initial infection.
The histoplasmosis fungus thrives in damp soil that's rich in organic material, especially the droppings from birds and bats. For that reason, it's particularly common in chicken and pigeon coops, old barns, caves and parks. Histoplasmosis isn't contagious, so it can't be spread from person to person.
The chances of developing histoplasmosis symptoms increase with the number of spores you inhale. Professions with a higher likelihood of spore exposure include:
Most at risk of severe infection
Histoplasmosis can cause a number of serious complications, even in otherwise healthy people. For infants, older adults and people with compromised immune systems, the potential problems are often life-threatening. Complications can include:
Preparing for your appointment
You're likely to start by seeing your family doctor. He or she might refer you to a doctor who specializes in infectious diseases. Depending on your symptoms and the severity of your infection, you may also see other doctors, such as a lung specialist (pulmonologist) or a heart specialist (cardiologist).
What you can do
Your time with your doctor is limited, so preparing a list of questions can help you make the most of your time together. List your questions from most important to least important in case time runs out. For histoplasmosis, some basic questions to ask your doctor include:
What to expect from your doctor
Tests and diagnosis
Diagnosing histoplasmosis can be complicated, depending on the area of the body being affected. While testing is not usually necessary for mild cases of histoplasmosis, it can be crucial to help choose appropriate treatments in life-threatening cases.
Each type of lab test for histoplasmosis has its limitations. Your doctor may suggest a combination approach to search for evidence of the disease in samples of:
Treatments and drugs
Treatment usually isn't necessary if you have a mild case of histoplasmosis. But if your symptoms are severe or if you have the chronic or disseminated forms of the disease, you'll likely need treatment with one or more antifungal drugs. Some of these medications come in pill form, but the strongest varieties are administered intravenously.
It's difficult to prevent exposure to the fungus that causes histoplasmosis, especially in areas where the disease is widespread. Even so, these steps can help reduce the risk of infection:
Last Updated: 2012-02-08
© 1998-2014 Mayo Foundation for Medical Education and Research (MFMER). All rights reserved. A single copy of these materials may be reprinted for noncommercial personal use only. "Mayo," "Mayo Clinic," "MayoClinic.com," "Mayo Clinic Health Information," "Reliable information for a healthier life" and the triple-shield Mayo logo are trademarks of Mayo Foundation for Medical Education and Research.
Terms and conditions of use