• What Is Histoplasmosis?

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    Reviewed By Ninel Z Gregori MD
    Sep. 29, 2020

    Histoplasmosis is a disease you can get when you breathe infected airborne spores into your lungs. The spores that cause it are from the fungus Histoplasma capsulatum. This microscopic fungus is sometimes called histo for short. It enters the air when people disturb soil when plowing fields, sweeping chicken coops, or digging holes.

    Histoplasmosis starts as a lung infection. Doctors think that the infection, even if mild, can later move to the eye through the blood stream. Once in the eye it can cause a serious eye disease called presumed ocular histoplasmosis syndrome (POHS). POHS is a leading cause of vision loss in Americans ages 20 to 40.

    Histoplasmosis Symptoms

    Histoplasmosis infection is often so mild that it produces no clear symptoms. Any symptoms are often like those from a common cold. In fact, if you had histoplasmosis symptoms, you might think you just had a cold or flu. This is because the body’s immune system normally beats the infection in a few days without treatment.

    POHS often has no symptoms in its early stages. You can have POHS without knowing it. Tiny scars called histo spots remain at the infection sites after the inflammation is gone. These histo spots can be the only way to tell you had the infection. Histo spots do not generally affect vision. Although ophthalmologists don’t know why, they can cause complications years or even decades later. We do know that there is a connection between histo spots and the growth of abnormal blood vessels underneath the retina.

    Histoplasmosis symptoms may appear if these abnormal blood vessels spread to areas of the retina that are vital for good vision. The symptoms for POHS are similar to macular degeneration symptoms.

    These symptoms include:

    • blank spots in your vision, especially your central vision
    • distorted vision, so that straight lines appear bent, crooked or irregular
    • size of objects may appear different for each eye
    • colors lose their brightness; colors do not look the same for each eye
    • central light flashes or flickering

    If you have any of the symptoms of histoplasmosis, you should see an ophthalmologist.

    Who Is At Risk for Histoplasmosis?

    People who have lived in states in the Ohio and Mississippi River Valley are at higher risk. Many people have been exposed to the fungus that causes histoplasmosis, but few go on to develop POHS. If you know that you had histoplasmosis, watch for vision changes that could signal the symptoms of POHS.

    Most people who have histoplasmosis don’t know it. Have your eyes examined for histo spots if you ever lived somewhere with high rates of histoplasmosis.