Histoplasmosis - acute (primary) pulmonary
Acute pulmonary histoplasmosis is a respiratory infection that is caused by inhaling the spores of the fungus Histoplasma capsulatum.
Histoplasma capsulatum, the fungus that causes histoplasmosis, is found in the central and eastern United States, eastern Canada, Mexico, Central America, South America, Africa, and Southeast Asia. It is commonly found in the soil in river valleys. It gets into the soil mostly from bird and bat droppings.
You can get sick when you breathe in spores that the fungus produces. Every year, thousands of people worldwide are infected, but most do not become seriously sick. Most have no symptoms or have only a mild flu-like illness and recover without any treatment.
Acute pulmonary histoplasmosis may happen as an epidemic, with many people in one region becoming sick at the same time. People with weakened immune systems (see Symptoms section below) are more likely to:
- Get the disease, if exposed to the fungus spores
- Have the disease come back
- Have more symptoms, and more serious symptoms, than others who get the disease
Risk factors include traveling to or living in the central or eastern United States near the Ohio and Mississippi river valleys, and being exposed to the droppings of birds and bats. This threat is greatest after an old building is torn down, or when exploring caves.
Most people with acute pulmonary histoplasmosis have no symptoms or only mild symptoms. The most common symptoms are:
- Chest pain
- Joint pain and stiffness
- Muscle aches and stiffness
- Rash (usually small sores on the lower legs)
- Shortness of breath
Acute pulmonary histoplasmosis can be a serious illness in the very young, elderly, and people with weakened immune systems, including those who:
- Have HIV/AIDS
- Have had bone marrow or solid organ transplants
- Take medications to suppress their immune system
Symptoms in these persons may include:
- Inflammation around the heart (called pericarditis)
- Serious lung infections
- Severe joint pain
Exams and Tests
To diagnose histoplasmosis, the doctor needs to find the fungus or signs of the fungus in the body, or evidence that your immune system is reacting to the fungus.
- Antibody tests for histoplasmosis
- Biopsy of infection site
- Bronchoscopy (usually only done if symptoms are severe or you have an abnormal immune system)
- Complete blood count (CBC) with differential
- Chest CT scan
- Chest x-ray (might show a lung infection or pneumonia)
- Sputum culture (this test often does not show the fungus, even if you are infected)
- Urine test for Histoplasma capsulatum antigen
Most cases of histoplasmosis clear up without specific treatment. Patients are advised to rest and take medication to control fever.
Your doctor may prescribe medication if you are sick for more than 4 weeks, have a weakened immune system, or are having breathing problems.
When histoplasmosis infection is severe or gets worse, the illness may last for one to six months. Even then, it is rarely fatal.
Acute pulmonary histoplasmosis can become chronic pulmonary histoplasmosis (which does not go away).
Histoplasmosis can spread from the lungs to other organs through the bloodstream. This type of spread is usually seen in infants, young children, and persons with a weakened immune system.
Acute pulmonary histoplasmosis can get worse over time, or can become chronic pulmonary histoplasmosis (which doesn't go away).
Histoplasmosis can spread to other organs through the bloodstream (dissemination). This is usually seen in infants, young children, and patients with a suppressed immune system.
When to Contact a Medical Professional
Call your health care provider if:
- You have symptoms of histoplasmosis, especially if you have a weakened immune system or have been recently exposed to bird or bat droppings
- You are being treated for histoplasmosis and develop new symptoms
Avoid contact with bird or bat droppings if you are in an area where the spore is common, especially if you have a weakened immune system.
Deepe GS Jr. Hisoplasma capsulatum. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. Philadelphia, PA: Elsevier Churchill Livingstone; 2009:chap 264.
Kauffman CA. Histoplasmosis. In: Goldman L, Ausiello D, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 340.
Schmitt BH, Rosenblatt JE, Pritt BS. Laboratory diagnosis of tropical infections. Infec Dis Clin N Am. Jun 2012; 26(2):513-554.
Waht LJ, Freifeld AG, Kleiman MB, et al. Clinical practice guidelines for the management of patients with histoplasmosis: 2007 update by the Infectious Diseases Society of America. Clin Infect Dis. 2007; 45(7):807-825.
Reviewed By: Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.