Spotted fever in Brazil: A seroepidemiological study and description of clinical cases in an endemic area in the state of Sao Paulo

During 1985-1995, illnesses clinically and epidemiologically compatible wit h Brazilian spotted fever were identified in 17 patients in the county of P edreira, in the state of Sao Paulo, Brazil. Spotted-fever group rickettsial infection was confirmed by serology and/or immunostaining of tissues in 10 of these patients. Immunostaining confirmed infection in a 37-year-old pre gnant patient, although rickettsial antigens were not demonstrable in the t issues of the fetus. A serosurvey was conducted in four localities in the c ounty to determine the prevalence of subclinical or asymptomatic infections with spotted fever group rickettsiae. Five hundred and twenty-five blood s amples were tested by an indirect immunofluorescence assay for antibodies r eactive with Rickettsia rickettsii. Twenty-two (4.2%) of these samples demo nstrated titers greater than or equal to 1:64. The results indicate that Br azilian spotted fever is endemic within this region of Brazil.