Histoplasmosis is caused by a fungus

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Posted on Tue, Nov. 09, 2004

http://www.kentucky.com/mld/kentucky/living/health/10113889.htm

Fungus found in soil

If you grew up in Kentucky, there is a good chance you've been

exposed to the infection that robbed Mike Freholm of his eyesight.

But don't worry. In all likelihood you'll never know you came in

contact with histoplasmosis.

Histoplasmosis is caused by a fungus commonly found in the soil in

Kentucky and other parts of the Ohio Valley. Countless residents are

infected by inhaling or ingesting spores released by the fungus.

Dangerous, even fatal, histoplasmosis infections of the lungs or

other organs occur in a few cases. Fortunately, however, most people

never get sick. But for the rest of their lives, they might carry

tiny histoplasmosis lesions in their lungs or eyes.

Usually, the lesions never cause trouble. But sometimes blood

vessels start growing around histoplasmosis lesions under the retina

of the eye. If the vessels leak, a blister can form on the retina

and produce a blind spot. In some cases, leaks occur around multiple

lesions, causing many blind spots. This is what happened to Freholm.

Ophthalmologists can try to halt the process by treating the leaking

vessels with lasers or surgery. But lost vision can't be restored.

" For some reason, the center of the vision field tends to be

affected, " says Dr. Pearson, chairman of ophthalmology at the

University of Kentucky. " You lose a spot in the center of the

vision, but the peripheral vision may still be pretty good. "

The problem typically develops 20 or 30 years after the actual

exposure to histoplasmosis.

As a cause of blindness, " histo " ranks far behind conditions such as

diabetes or macro-degeneration. But Pearson notes that it often

strikes people in their 30s -- their peak working years -- while

other causes of blindness usually develop later in life.