Health Encyclopedia

Histoplasmosis - chronic pulmonary

Definition

Chronic pulmonary histoplasmosis is a long-term respiratory infection caused by breathing the spores of the fungus Histoplasma capsulatum.

Alternative Names

Chronic cavitary histoplasmosis

Causes, incidence, and risk factors

Histoplasma capsulatum is a fungus found in the soil of the central and eastern United States (especially Mississippi and Ohio river valleys), eastern Canada, Mexico, Central America, and South America.

The infection occurs when a person breathes in the reproducing parts of the fungus, called spores. Those who have a healthy immune system usually do not have symptoms, or only mild ones.

This "acute" infection does not last, but can leave a person with small scars (granulomas). These scars are sometimes difficult to distinguish from growths in the lung.

However, the infection can cause severe illness right away, or redevelop years after the first exposure, if a person's immune system is weakened by:

Cancer
Chemotherapy
Immune-suppressing drugs
HIV infection

Risk factors for chronic pulmonary histoplasmosis include:

Living in or traveling to central or eastern United States
Exposure to soil or particles contaminated with droppings of chickens, bats, or blackbirds
Pre-existing COPD
Weakened immune system, such as in people who have AIDS

Symptoms

Chills
Cough that brings up mucus or pus
Fever
Joint stiffness
Shortness of breath
Skin involvement (erythema nodosum)
Unintentional weight loss

Signs and tests

Tests that may be used to diagnose chronic pulmonary histoplasmosis include:

Biopsy of infected tissue, such as open lung biopsy or bone marrow biopsy
Bronchoscopy with transbronchial biopsy or bronchoalveolar lavage
CBC
Chest CT scan
Chest x-ray
Histoplasma complement fixation titer
Histoplasma urinary antigen test
Immunodiffusion test
Sputum culture and stain

Treatment

The doctor will prescribe antifungal medications to control the infection within the lung.

Expectations (prognosis)

The infection usually goes away with antifungal medication, but scarring inside the lung often remains. Histoplasmosis is unusual enough that if you develop it, your health care provider should check to find out whether another disease is weakening your immune system.

Often, those who have had chronic pulmonary histoplasmosis must follow up with their doctor, who will check for signs of relapse.

In rare cases, a pulmonary histoplasmosis infection can spread through the blood to other organs. This is called disseminated histoplasmosis. People who have a suppressed immune system and very young children are more likely to develop this condition. If this occurs, the prognosis is less favorable.

Complications

Arthritis
Disseminated histoplasmosis
Lung scarring (fibrosis)
Pericarditis
Respiratory insufficiency

Calling your health care provider

Call for an appointment with your health care provider if you develop symptoms of chronic pulmonary histoplasmosis.

Call your health care provider if your symptoms continue despite treatment, or if you have breathing difficulty or symptoms of disseminated histoplasmosis.

Prevention

Be aware of your surroundings, especially if you are in a weakened state from another medical condition, or from immune-suppressing medications.

References

Goldman L, Ausiello D. Goldman: Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders; 2007.

Review Date:11/12/2007
Reviewed By:Andrew Schriber, M.D., F.C.C.P., Specialist in Pulmonary, Critical Care, and Sleep Medicine, Virtua Memorial Hospital, Mount Holly, New Jersey. Review provided by VeriMed Healthcare Network.

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