Histoplasmosis is a dimorphic fungus infection caused by bird and bat droppings in the soil. (Dimorphic meaning two forms indicates that the fungus depending on the temperature at which it is grown can take the form of either a yeast like fungus in the body of a mammal or a mycelial fungus in the surrounding environment.) Histoplasmosis is endemic to midwestern and east central states in the United State in regions near the Mississippi River Valley and the Ohio River Valley.
According to an eMedicine article by Ryan C. Chang, MD (http://www.emedicine.com/MED/topic1021.htm),birds can not actually get or transmit the fungus but their droppings contribute to the richness of the soil for mycelial growth of the fungus, and make the ambient form of the disease more likely. Bats, on the other hand, can become infected with histoplasmosis, and pass on the fungus to the surrounding soil in their droppings.
The Center for Disease Control and Prevention reported on its website
People contract the illness by breathing the spores of the fungus when the soil is contaminated and then disturbed for some reason (e.g., digging). Histoplasmosis is not passed from person to person. Human beings who do not have AIDS or other immunological disorders and who are neither very young nor elderly are usually able to fight off histoplasmosis without its becoming disseminated – i.e., spreading to the lymph nodes and affecting body organs besides the lungs. However, in persons with insufficient immune systems the disseminated form of the disease can result in damage to the spleen, central nervous system, liver, eye and/or blood system, according to Chang's article. The disease can also take on the rheumatologic system, the article stated. People with emphysema are less likely to resist the fungus and more likely to develop chronic pulmonary histoplasmosis, it was noted in the article.
Although ninety percent of persons with histoplasmosis do not develop symptoms of the illness, the symptoms will appear in three days to two weeks if they are going to occur at all, stated both the CDC article and the Chang article. Common symptoms of the acute form of pulmonary histoplasmosis are chills and fever, headache, myalgia and stomach pains. Less common symptoms include joint pain, skin lesions, enlarged lymph nodes, shortness of breath, cough, pericarditis and/or chest pain.
According to the Chang article no treatment is needed for people with acute pulmonary histoplasmosis who do not show symptoms of histoplasmosis, but monitoring is necessary for those with mild symptoms, and medical treatment should be initiated for those with moderate to severe symptoms. Chronic pulmonary histoplasmosis should be treated in persons with impaired immune systems regardless of whether clinical symptoms are present. Treatment is to be initiated immediately for all cases of progressive disseminated histoplasmosis and those cases involving meningitis.
Sources
Center for Disease Control and Prevention website article on histoplasmosis
