Evidence of a predominance of sexual transmission of HTLV-1 in Salvador, the city with the highest prevalence in Brazil

Several investigations in Latin America have monitored health problems in urban spaces using what is called “sentinel areas” On the basis of this strategy, we detected an overall HTLV-1 prevalence of 1.7% in a representative sample of general population in Salvador, Northeast Brazil. In order to evaluate the sexual transmission of HTLV-1 in the general population of the city of Salvador, Northeast Brazil, the study analyzed a collection of 3,451 serum samples obtained by a simple random sampling procedure without replacement. Samples were in 30 “sentinel areas” f the city of Salvador, Bahia, Northeast Brazil collected from May 1998 to July 2000. HTLV-1 Syphilis and HIV infection were tested as a sexual transmission marker. Overall prevalence of HTLV-1 was 1.48% (51/3,451; 95% CI: 1.10% – 1.94%). Sixty-two percent of the seropositive individuals were women and the majority (65.3%) earned two minimum wages or less. Overall prevalence of syphilis and HIV was 26.67% (45/3,451; 95% CI 1.08 – 2.25) and 0.6% (21/3,451), respectively. Syphilis was present in 12 out of 51 (23.53%) individuals infected by HTLV-1 (26% of males and 19.35% of females), while only one person was infected with HIV (4.76%). HTLV-1 infection was associated with family income (OR 2.25; 95% CI 1.12 – 4.08), age (OR 9.58; 95% CI 5.01 – 18.29) and syphilis (OR 38.63; 95% CI 15.08 – 98.94). In the logistic regression analysis stratified by sex, HTLV-1 infection remained associated with age and syphilis diagnosis in males and with age, income and syphilis diagnosis in females. These data strongly suggest a predominance of heterosexual transmission of HTLV-1 in Salvador, Bahia. Furthermore, the majority of infected individuals were poor, had low levels of education and lived in worse living conditions, confirming our previous results.