Outbreak of malaria among injectable-drug users

Abstract

Five cases of malaria were detected among cocaine users by the local health service in Bauru, a city with a population of 260,000, located 324 km from S. Paulo, Brazil, during the first three weeks of July 1990. Autochthonous malaria had not occurred in Bauru since 1978, and all the five cases denied having recently traveled to endemic areas. An extensive epidemiologic survey conducted from July 19 to September 13 revealed that the 5 cases were in fact part of a malaria outbreak among endovenous drug users. Moreover, at least 114 other people, who had in the last three months shared syringes and needles with one or more proved cases, were also involved in the outbreak. One hundred and two people were identified and interviewed orally. The examination of thick smears made from samples collected from 99 of them confirmed 21 cases of vivax malaria. Three people with negative blood smears had an indirect imunofluorescent assay positive to P. vivax antigen. Although the index case could not be discovered, the investigation suggested that one or more people who had recently traveled to the Amazon region might have introduced the disease. The control of the outbreak was achieved after offering treatment with chloroquine (10 tablets) to confirmed cases and contacts, followed by weekly suppresive chloroquine (2 tablets) until the last contact was detected. Malaria examination of 91 blood samples also revealed a high prevalence of hepatitis B virus infection (40%) and HIV infection (58%) among those involved in the outbreak. The strategy used to identify the cases and the contacts and the difficulties overcome in carrying it through are described. It is also suggested that malaria might become an endemic disease among endovenous drug users in the State of S. Paulo.