Histoplasmosis

Histoplasmosis is a type of fungal infection in your lungs. You get it from breathing in the fungus Histoplasma capsulatum (H. capsulatum). The fungus lives in the soil in many parts of the world, including the U.S. It’s most commonly found where there are bird or bat droppings (poop) in the soil.

Types of this histoplasmosis

Types of histoplasmosis include acute pulmonary histoplasmosis, chronic cavitary histoplasmosis and progressive disseminated histoplasmosis. Healthcare providers diagnose the type of histoplasmosis based on how long you’ve had symptoms and whether it’s spread to the rest of your body. You can also have histoplasmosis that primarily causes symptoms in your brain (central nervous system histoplasmosis) or your eyes (ocular histoplasmosis).

Acute pulmonary histoplasmosis

Pulmonary histoplasmosis is the most common type of symptomatic H. capsulatum infection. In about 10% of people who are infected with the fungus, it causes symptoms similar to pneumonia, including fever, cough and shortness of breath. If you’re exposed to lower levels of the fungus, you could have milder (subacute) symptoms that last several months.

Chronic cavitary pulmonary histoplasmosis

Chronic cavitary pulmonary histoplasmosis is a long-lasting form of illness most commonly seen in people who have emphysema or chronic obstructive pulmonary disease (COPD). It can cause milder symptoms than those of acute pulmonary histoplasmosis, plus night sweats and weight loss. Symptoms can go on for months or years. It can look similar to tuberculosis. It causes damage to your lungs that gets progressively worse if left untreated.

Progressive disseminated histoplasmosis

Progressive disseminated histoplasmosis happens when H. capsulatum spreads from your lungs to many other parts of your body. It most often happens in people who have severely weakened immune systems, like those with advanced HIV. It can cause progressive shortness of breath, fatigue, weight loss and skin ulcers.

How common is histoplasmosis?

It’s estimated that about 75% of adults who live in areas where H. capsulatum is common have been infected before, even if they never had symptoms.

What does histoplasmosis do to your body?

The fungus H. capsulatum gets into your lungs when you breathe it in from the soil. There, it enters your white blood cells and changes from a mold into its infectious form as a yeast. In most people, your immune cells destroy it, or wall it off from your body with granulomas, before you ever notice any symptoms. In certain circumstances, it can make you sick:

• If you’re exposed to a lot of H. capsulatum at once, it can overwhelm your immune system and cause mild or severe flu-like symptoms and breathing problems.
• If you have certain lung diseases, like COPD, it can cause ongoing damage to your lungs.
• If you have a compromised immune system, it can use your immune cells to spread to other parts of your body. This can cause life-threatening complications.