Histoplasmosis is a disorder that affects the lungs. It is evolved by Histoplasma capsulatum fungi. Though a lot of people who are or maybe have been affected by H. capsulatum may not become ill, some humans in acute disease phases may have a fevere, dry cough, pains in the chest and they may also feel ill. There are several histoplasmosis types and they are the following: chronic, acute, disseminated and all these types have their subtypes.
Samuel Darling described H. capsulatum for the first time in the tissue cells of humans (known as histiocytes) in 1906. Katharine Dodd together with Edna Tompkins diagnosed histoplasmosis in a child for the first time in 1932. H. capsulatum can be found all over the world, but almost all of the cases occur in river valleys of the temperate regions as well as in equatorial Africa. Outbreaks often happen in people after visiting particular areas such as caves containing bat droppings. As for the US histoplasmosis appears to be endemic in the valleys of such rivers as the Mississippi, Ohio and Missouri.
Histoplasmosis belongs to the most often diagnosed endemic fungal infections in the US (almost 250,000 cases each year). H. capsulatum can appear in large concentrations in certain sources like bat and bird feces. Histoplasmosis may also affect other mammals including cats and dogs, though the disease is not spread from animals to people and to animals. Actually cats and dogs might have symptoms because of lung infections caused by H. capsulatum which can be confused with human histoplasmosis.
Histoplasmosis is often provoked by a dimorphic fungus under the name Histoplasma capsulatum. The name of the genus can be confusing; this fungus doesn’t have a capsule, though early researchers wrongly thought that it had. Mycelial phase that consists of mycelia spores and fragments may be inhaled and thus it can reach lung alveoli. Macrophages (people’s phagocytic cells in the immunity) surround and also engulf H. capsulatum that then turns into the yeast in the macrophages in fifteen – eighteen hours. Mostly the macrophage reaction destroys the yeast. If macrophages cannot kill the yeast, in this case a disease variation can develop as the yeast multiplies and attacks some other cells. So the bigger the mycelia and spores number to which a person is exposed, the more probably a person will get the symptomatic disease.