Histoplasmosis

Key Points
Infection caused by the histoplasma capsulatum fungus
Primary affects the lungs, but can affect the skin
Also known as Ohio River Valley fever
Symptoms could include rashes and skin nodules, which are more common in patients with a compromised immune system, such as those with HIV or who take medicines that suppress the immune system (these medications are often used by patients with common disorders such as lupus, Rheumatoid arthritis, and Psoriasis)

Histoplasmosis is a fungal infection that affects the lungs and occasionally the skin. The infection is common in certain areas of North America; it affects approximately 250,000 people a year. However, the majority who suffer the infection fill no ill affects. Those who do suffer from fever, chills, and cough, though other symptoms include rashes, joint aches, skin nodules, chest pains, or a stiff neck — symptoms develop 3-14 days after exposure. It’s most common in the southeastern, mid-Atlantic, and central states — or close to river beds (which is why it is also referred to as Ohio River Valley disease). It’s caused by a fungus called Histoplasma capsulatum, which can be inhaled. It grows in soil, although soil contaminated by bird or bat droppings can have a higher concentration of spores. It is not contagious.

The skin lesions of histoplasmosis are extremely variable, but often form small bumps or papules on the face or around the mouth, where they might be mistaken for a more common viral condition known as molluscum contagiosum. Unfortunately, the lesions can be so different from one patient to the next that diagnosis is rarely possible by visual skin inspection alone.

Fun Fact: Bob Dylan once suffered from the infection, and had to cancel several concerts, as a result.

Differential Diagnosis (Other conditions with similar appearance)
Pneumonia
Tuberculosis
Cryptococcosis
Blastomycosis

Diagnosis
Key Points
Detection is usually done through medical tests on the affected area(s)
Test for antibodies against Histoplasma in the blood may also reveal the infection

Detection of Histoplasmosis depends on the body parts involved. A doctor or dermatologist may examine the sputum, blood, skin, lung tissue, bone marrow, or even urine for signs of fungal spores. X-Rays may also reveal abnormalities in the lungs or lymph nodes for sufferers of histoplasmosis. It can also be diagnosed by a test for antibodies against histoplasma in the blood.

Treatment
Antifungal drugs
traconazole
*ketoconazole

Those who do not exhibit symptoms or who are otherwise healthy need not be treated; the infection should clear up on its own. Antifungal medications, such as amphotericin B, followed by oral Itraconazole, are used in the most severe cases. Treatment by Itraconazole may need to be prolonged.