[Human leptospirosis - infection in inhabitants of the Aricanduva river valley, São Paulo city, Brazil, 1984-5; part. 1 - aspects related to the studied group and the environment].

The article approachs the investigation, from the epidemiological point of view, of one zone that had been flooded in 1983 by the Aricanduva river and its tributaries in the east side of the São Paulo city, Brazil. At that time, zone was affected by human leptospirosis, confirmed by laboratory tests. For the present survey, a population of 61 inhabitants of the region, who dwelled with subjects affected by leptospirosis was studied, in order to establish the level of infection of leptospira remaining in that population. In this paper, the author describes the aspects relatives to the studied group and their environment. It was found that eighteen months after the 1983 outbreak of the disease (1984-5) there still persisted in the environment, risk factors of leptospirotic infection such as floods and the presence of rats. In a next paper, the author will describe the sorological aspects of this investigation.