title: Systematic isolation of the genus Alternaria in the atmosphere of the "Grande Sao Paulo" area (Brazil).
abstract: The genus Alternaria has been isolated from the atmosphere of several countries and its spores are considered as having a strong allergenic power. The description of the genus isolation with a relative frequency was noted in the following countries: Mexico, the United States of America, Canada, Great Britain, Spain, South Africa, Denmark and Argentina. Many Brazilian authors have pointed out the rare incidence of this genus excluding Faria (5) who recorded in the city of Belo Horizonte, State of Minas Gerais, a frequency of 21.1%. Several authors have failed to detect Alternaria sp. spores in the atmosphere of the city of Sao Paulo. As we were studying in our laboratory the airborne fungi of a region called Greater Sao Paulo, where the collections were made in some boroughs of the main city and its neighborhood, we began to make findings of the Alternaria sp. This gave us the opportunity of studying its incidence in that area during a period of one year. We chose 11 areas of this region where we made weekly plate expositions performing 429 trials in all. The technique of collection was the usual one with the exposition of the Petri dishes containing Sabouraud Agar distributed 72 hours before. The collection was made from September 1973 to August 1974. The exposition period was of 5 minutes duration in the open air or in a protected place when it rained. The exposition height was 1 meter from the ground. The identification was made through the colony macroscopic morphology and through the Riddell technique. The Alternaria sp. was isolated in the mentioned area through all the months of the year with its highest frequency in August (35.8%) and its lowest in December 3.7%). The average relative frequency obtained was of 17%. The highest isolation frequency was attained in Winter, the lowest in Spring; in Summer and Autumn, it remained at a medium level. In relation to the studied areas, the Alternaria sp. was isolated in all of them with a minimum frequency of 8.3% in Campos Eliseos and with a maximum frequency of 28.9% in Osasco. The authors would like to emphasize this unusual finding because in the region studied the Alternaria sp. was previously considered absent.
mesh_terms: D000391:Air Microbiology; D000528:Alternaria / Q000302:isolation & purification*; D001938:Brazil; D003904:Mitosporic Fungi / Q000302:isolation & purification*; D013172:Spores, Fungal