Abstract
Histoplasmosis was described over 50 years ago by S. T. Darling while he was a pathologist at Ancon (now Gorgas) Hospital in the Panama Canal Zone (20). During 1905-1906 three patients had entered the hospital terminally ill, constantly febrile, coughing, vomiting and suffering from diarrhea. Hepatosplenomegaly, anemia, and leukopenia were noted. Autopsy revealed lesions resembling tuberculosis in the lungs, spleen, liver and lymph nodes. However, on histologic study Darling found large numbers of small organisms packing the macrophages in these lesions, in the bone marrow, and in ulcers of the intestine as well. These organisms were round or oval with refractile rims and measuring 1-4 microns in diameter. He concluded that these were protozoa and named them Hlstoplasma capsulatum: calling the disease "histoplasmosis0. Not until 1926 was it heard of again when Riley and Watson reported a patient that had succumbed to the disease in Minnesota. By 1945 71 cases had been reported, almost all in the United States and involving all age groups. Since previous clinical experience had been of no consequence, histoplasmosis was still considered a fatal illness. However, the organism had been isolated and cultured in 1934 by De Monbreun (5), who had demonstrated that it was a fungus; thus cultural characteristics were known. In 1941 Zarafonetis and Lindberg (22) and others, introduced the histoplasmin skin test using a broth filtrate of H. capsulatura. It was shown that this test was positive within two to three weeks after onset of the disease. Since 1945 diagnostic antigens and serologic procedures have also been available. These diagnostic procedures gave an entirely new picture of the disease. Skin tests indicated that the disease is encountered over most of the world, and is one of the most widely distributed of the systemic mycoses (9). These tests revealed endemic areas in the United States where the incidence ranges from 70 to 90 percent in the Mississippi valley west of the Appalachian foothills to 0 to 10 percent elsewhere (see chart 1). Consolation is gained from the fact that most infections produced by H. capsulatura are asymptomatic or so slight in degree as not to necessitate medical attention.