Causes and Risks:

Histoplasmosis is caused by a fungus found in the central and eastern United States (Mississippi and Ohio river valley), eastern Canada, Mexico, Central America, South America, Africa, and Southeast Asia. Most cases are mild or asymptomatic. Acute pulmonary histoplasmosis may occur in epidemics. Progressive or spreading (disseminated) and chronic disease can also occur. In disseminated disease, the infection is spread to other organs of the body from the lungs via the bloodstream. The liver and spleen are usually enlarged, and all body organs can be involved. Ulcerations of the mouth or gastrointestinal tract may occur. Risk factors are travel to or residence within the central or eastern United States and exposure to the droppings of birds and bats. The incidence is 1 out of 10,000,000 people.

Prevention:

Avoiding travel to areas where this spore is found would prevent it (but this is not practical). Avoid bird or bat droppings if you are in one of these areas, especially if you are immunosuppressed.

Symptoms:

• fever
• chills
• muscle aching and stiffness
• cough
• rash possible (erythema nodosum)
• joint pain
• skin lesions - papule, pustule, plaque
• headache
• visual changes (chorioretinitis)
• nausea, vomiting
• mental status changes

Signs and Tests:

A neurological examination may show abnormalities.

Tests used in the diagnosis of disseminated histoplasmosis may include:

• a CBC
• a biopsy of affected organ(s), bone marrow, liver, lymph node, open lung, skin
• an abdominal CT scan
• a MRI scan of the affected organ(s)
• an abdominal ultrasound
• a chest X-ray
• a histoplasma urinary antigen test

Treatment:

Antifungal medications are prescribed to control the infection. Amphotericin B is the drug of choice. In non-AIDS patients with milder disease, ketoconazole, itraconazole, or fluconazole used for at least 12 months can be effective. AIDS patients should receive chronic oral antifungal therapy (itraconazole is preferred) following initial treatment with amphotericin B.

Prognosis:

The disease may progress rapidly and death usually occurs. The fatality rate is 90%.

Complications:

Multiple organs are affected.

Call your health care provider if symptoms of disseminated histoplasmosis develop, particularly if you have been recently treated for acute or chronic histoplasmosis.

Emergency symptoms include mental status changes and rapid worsening of the condition of the affected person.