Acute pulmonary histoplasmosis is a respiratory infection caused by inhaling the spores of the fungus Histoplasma capsulatum, which is commonly found in bird and bat droppings along river valleys.
Causes, incidence, and risk factors
Histoplasmosis is caused by a fungus found in the Central and Eastern United States, Eastern Canada, Mexico, Central America, South America, Africa, and Southeast Asia.
Most patients have no symptoms (asymptomatic) or experience a mild flu-like illness and recover uneventfully. Acute pulmonary histoplasmosis may occur in an epidemic, which is a widespread local outbreak of disease. Progressive and chronic disease can also occur, particularly amongst those with impaired immune systems, such as people with HIV.
Risk factors include travel to or residence in the Central or Eastern United States near the great river valleys, exposure to the droppings of birds and bats, and having a compromised immune system.
- Shortness of breath
- Muscle aching and stiffness
- Joint pain and joint stiffness
Signs and tests
- chest x-ray
- Sputum culture (often not positive)
- CBC (complete blood count)
- Bronchoscopy (usually only performed in patients with severe disease or abnormal immune systems)
- Antibody tests for histoplasmosis (serologies)
- Biopsy of site of infection
- Chest CT scan
Treatment for acute pulmonary histoplasmosis is usually not necessary. Amphotericin B, an antifungal medication, may be given for severe cases. Treatment with amphotericin B is given for 2 weeks to children under 2 years of age, because they are at risk for developing disseminated histoplasmosis. If additional therapy is needed, itraconazole and fluconazole may be given.
When severe and progressive, the illness may last for 1 to 6 months, but is rarely fatal. It can be a very serious illness in people with weak immune systems, such as those who have had bone marrow or solid organ transplants, or those who have AIDS.
Histoplasmosis can spread to other organs through the bloodstream (dissemination). This is usually seen in infants, young children, and immunosuppressed patients.
Acute histoplasmosis can progressively worsen or can become chronic histoplasmosis.
Calling your health care provider
Call your health care provider if symptoms of histoplasmosis occur, especially if you have an immune disorder, have been recently exposed to bird or bat droppings, or if you are being treated for histoplasmosis and new symptoms develop.
Avoiding travel to areas where this spore is found would prevent it but this is not practical. Avoid contact with bird or bat droppings if you are in one of these areas, especially if you are immunosuppressed.
by Martin A. Harms, M.D.
All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.