Is histoplasmosis contagious and transmitted from person to person?

No, histoplasmosis is not contagious and cannot be transmitted from person to person. You cannot contract the infection from an infected person or animal. Histoplasmosis infection occurs primarily by inhaling microscopic fungal spores of the fungus Histoplasma capsulatum found in the air. These spores are most often found in soil, especially soil contaminated with bird or bat droppings. When the soil is disturbed—such as during farming, construction, or landscaping activities—the spores can become airborne and be inhaled.

Although histoplasmosis typically begins as a lung infection, in some cases, it can travel through the bloodstream to other parts of the body, including the eyes, causing Presumed Ocular Histoplasmosis Syndrome (POHS). However, this transmission within the body does not mean it becomes contagious to others [1].

How does histoplasmosis infection occur?

Histoplasmosis infection occurs when a person inhales the fungal spores of Histoplasma. This fungus is common in the environment, especially in soil rich in bird and bat droppings [3]. These spores can be present on the feathers of chickens, pigeons, and blackbirds, and in the droppings of infected bats. Infection usually occurs after performing activities that disturb the soil and lead to the spread of spores into the air, such as digging, excavation, or cleaning cages or caves [1].

Common places for the histoplasmosis fungus to spread

The Histoplasma fungus is widely distributed in certain regions around the world. It is particularly common in the central and eastern parts of the United States, especially in the Ohio and Mississippi River valleys. It can also be found in parts of Central and South America, Africa, Asia, and Australia [3]. People who live in or visit these areas and come into contact with contaminated soil are at a higher risk of inhaling the spores [1].

Symptoms and progression of histoplasmosis

Often, a histoplasmosis infection is so mild that it causes no noticeable symptoms, and the infected person may think it is just a cold or the flu. The immune system usually fights off the infection within a few days without the need for treatment [1]. However, symptoms may appear within 3 to 17 days after inhaling the spores and may include fever, cough, fatigue, chills, headache, and body and chest pain [3].

In some cases, especially in individuals with weakened immune systems (such as AIDS patients, those who have undergone organ transplants, or those taking immunosuppressive drugs), the infection can develop into an acute or chronic form, or spread to other parts of the body such as the brain and spinal cord, which is known as disseminated histoplasmosis [3].

When should you seek medical attention?

If you have been exposed to an environment potentially contaminated with the histoplasmosis fungus and develop symptoms such as a persistent cough, fever, chest pain, or shortness of breath, it is important to consult a doctor. Laboratory tests, such as fungal cultures from blood, urine, or tissue samples, can help diagnose the infection [2]. If the infection spreads to the eye, symptoms may include blind spots in your vision, distorted vision, differences in the size of objects between the two eyes, loss of color brightness, or central light flashes. In these cases, you should visit an ophthalmologist immediately [1].

For more information about histoplasmosis, you can visit our comprehensive article: Histoplasmosis: A Hidden Fungal Infection in Soil and Lungs (Arabic).

Medical references

• What is Histoplasmosis?
• Histoplasmosis
• Fungal Culture Test