Most people call it “the bird disease,” but we physicians call it histoplasmosis.  What is it?  It’s a fungus that lives in the soil.  It can cause disease in humans that ranges from a very mild illness to a relentless overwhelming infection leading to death. 

While the specific disease was not identified until 1905, the danger of fungi was recognized in ancient times and can even be traced back to the Old Testament (Leviticus 14:33-48). In that passage the term “affection” is used but it is clear that mold inside the home is being described along with very careful instructions to get the priest involved in order to rid the home of this problem; “If upon looking at the affection he finds that the affection on the walls of the house is in greenish or reddish patches, and that they have the appearance of being deeper than the surface of the wall, the priest shall come out of the house to the doorway of the house, and quarantine the house for seven days.”

Histoplasmosis is one of many fungi that inhabit our world. Like bacteria a fungus  has a single cell, but unlike bacteria it can grow like a plant with branching limbs and spores.  It is that structure that gives it the fuzzy fluffy appearance that we call mold or mildew.  Since its discovery in 1905 histoplasmosis has been studied extensively. It occurs worldwide but has a preference for river valleys. In the United States it is concentrated around the Ohio and Mississippi rivers from Iowa through Ohio in the north to Louisiana and Mississippi in the south. As mentioned above it lives in the soil but its favorite home is soil mixed with bird droppings. In soil without bird droppings there will be a low concentration of the fungus but in moist soil with bird droppings there will be a very high concentration. Birds don’t actually carry the disease.  Instead, it lives where they live which is why it is called “the bird disease.”

Willow Creek meanders through downtown Mason City.  In the 1960s its banks were overgrown with trees and brush and thousands of starlings lived there covering the banks with droppings.  In 1962 the city decided to clean up the mess with bulldozers and in the process created large clouds of dust that contained millions of histoplasma spores.  An epidemic followed in which two people died, about 30 became quite ill and hundreds more suffered a mild illness.

Histoplasmosis is contracted five to 15 days after inhalation of spores but is not contagious from person to person. While it most commonly infects the lungs it can travel to any organ including the eyes.  Although the illness can be life threatening it is generally mild and most people get better.  However some people develop the chronic progressive kind in which the person feels run down and the spots in the lung gradually enlarge. 

While we can treat histoplasmosis today with antibiotics the best treatment is prevention.  All one has to do to prevent the disease is avoid inhaling the spores.  There are two principles of avoidance.  The first is, don’t disturb an outdoor environment of histoplasmosis which can infect others.  The second is, if you have to clean or disturb an indoor environment of histoplasmosis such as a chicken coop, a bird sanctuary, an out building with droppings, an attic with droppings, etc. wear a respirator.  While cartridge respirators are the best, they are expensive, bulky and inconvenient.  A good quality paper respirator will do the job quite well.  I must emphasize good quality.  The paper thin dust masks with one strap are not as good as the thicker two strap respirators.  These respirators can be found at some hardware stores and most welding shops and elevators.

With proper precautions we can prevent histoplasmosis and free up our priests to turn their attention to more pressing human dilemmas.

Dr. Gary Levinson is a pulmonogist with Mercy Internal Medicine Clinic.

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