Contribution to the epidemiology of paracoccidioidomycosis and histoplasmosis in the state of São Paulo, Brazil

Abstract

Bovines, ovines and equines from various counties in the state of São Paulo, Brazil, show a high incidence of paracoccidioidomycosis infection according to the results obtained with intradermic test standardized in experimentally infected bovines: 44·88%, 42·86% and 77·06% respectively for bovines, ovines and equines. The antigen chosen for this study was a suspension of P. brasiliensis yeast cells after extraction of lipidic substances by acetone and ether and extraction of the polysaccharide antigen by autoclavation. The volume used for the intradermic tests was 0·2 ml for the bovines and equines and 0·1 ml for the ovines. These quantities permitted formation of well-defined papules, indicating that the antigen had been correctly injected intradermically. Our results indicate that two readings should be taken, 24 and 48 hours after injection of the antigen. If only one reading is possible, the 24 hours reading is preferable. Positive reaction to the paracoccidioidin test was of the same magnitude in bovines and ovines and about two times that observed in humans from the same geographic area. Positive reaction in equines was about three times that observed in humans. Bovines, ovines and equines from different counries in the state of São Paulo, Brazil, show histoplasmosis infection at rates of 16.57%, 6·12% and 16·51% respectively. The antigen used in this intradermic test was a filtrate obtained from cultivation of just one strain of Histoplasma capsulatum, used in a concentration that corresponds to 100 times the concentration used in humans. Positive reaction to the histoplasmin test in bovines and equines was of the same magnitude as that observed in humans from the same geographic area, but of much lower magnitude in ovines. Intradermic cross reactions between paracoccidioidin and histoplasmin were observed in bovines. The principal conclusion of this study is that domestic animals are suitable for epidemiology study of paracoccidioidomycosis and histoplasmosis.