[Seasonal variation of allergy-causing fungi in the southern part of Mexico City].

The presence of mycotic flora in atmospheric medium has always been an interesting field for allergologists and ecologists interested in the problems of environmental contamination. In 1904 Saito in Japan demonstrated that certain spores of fungus when inhaled by susceptible individuals can produce severe respiratory processes. Since then many studies have been performed to determine the generic and species of causative fungus responsible for respiratory allergy, as well to understand its growth, movement and seasonal variations and its relation with the habits of man. Fungi which may produce allergy were investigated in 6 zones of the south of Mexico City, from November, 1981 to October, 1982. In each zone 108 samples were taken. Petri dishes containing Sabouraud medium were exposed during 10 minutes. The number of colonies per Petri dish; 27.6 per cent of the micro-organisms isolated corresponded to allergy producing fungi. The highest frequency of fungal isolation (6,512 colonies) was obtained in summer and the least (1,397 colonies) during winter. The principal genera isolated were: Rhodotorula: 2,418 (16.7%); Phialophora: 2,071 (14.4%); Penicillium: 743 (5.1%); Alternaria: 111 (0.7%). The most frequent species of the Aspergillus were: A. niger, A. fumigatus and A. flavus. The paper discusses the importance of the different factors which can influence the frequency and the seasonal variations of these fungi.