Infection with the fungus Histoplasma capsulatum is known to be highly prevalent in some geographic areas, absent in others; but for many parts of the world little information is yet available on whether or not histoplasmosis has to be reckoned with as a significant health problem. The existence of an endemic focus of infection is suggested by cases of the disease diagnosed by culture of the organisms, particularly if the patients are lifetime residents of a particular locality; by cutaneous sensitivity to the antigen histoplasmin in the population; and by the correlation of histoplasmin sensitivity with X-ray evidence of pulmonary infiltrations or calcified residuals. The present paper brings together information from many different sources to draw as complete a picture as possible of the world-wide distribution of histoplasmosis and histoplasmin sensitivity as it appears today.
From the data currently available, histoplasmosis would appear to be primarily a disease of the Americas. It may also exist in endemic form, though presumably at a much lower prevalence, in some parts of Africa and southeastern Asia. There is little indication of the existence of infection with Histoplasma in Europe, the eastern Mediterranean, and those parts of Asia from which information is accessible.