IMMUNOLOGICAL, GENETIC AND SOCIAL HUMAN RISK-FACTORS ASSOCIATED TO HISTOPLASMOSIS - STUDIES IN THE STATE OF GUERRERO, MEXICO

Immunologic and occupational aspects of the susceptible population exp osed to Histoplasma capsulatum, the causative agent of histoplasmosis were analyzed in the Mexican State of Guerrero. Three areas were studi ed, Juxtlahuaca, Olinala, and Coyuca; in the first two, their populati ons refer contact with bat guano and/or avian excreta, which contain n utrients for fungal growth, while the Coyuca population referred no co ntact with the above mentioned excreta. Previous infection with H. cap sulatum was determined by histoplasmin-skin test, and the response was higher in men than in women (93.87, 85.71, and 6.6% for men, and 78.9 4, 66.6, and 0% for women) in Juxtlahuaca, Olinala, and Coyuca, respec tively. Labor activities related to a persistent contact with the fung us were considered as an occupational risk factor, histoplasmin-skin t est reached 88.57 and 36.36% of positive response in individuals with high and low risk activities. A high percentage of histoplasmin respon ses was observed in subjects with constant contact with H. capsulatum, such as, cave-tourist guides, peasants, and game-cock handlers, and g enerally they developed the largest diameter of skin reactions. Geneti c risk factor was determined by studying the gene frequency of the Maj or Histocompatibility Complex antigens in a sample of individuals and their first degree relatives in Juxtlahuaca, Olinala, and Coyuca. Sign ificant differences were found for HLA-B22 and B17 antigens in Juxtlah uaca, and for HLA-B22 in Olinala, in comparison to the usual gene freq uency observed in the normal Mexican population. HLA results were impo rtant, considering that HLA-B22 was previously found to be possibly re lated to pulmonary histoplasmosis in Guerrero.