Epidemiological Characteristics of HTLV-I and II Co-Infection in Brazilian Subjects Infected by HIV-1

Serum samples from 895 HIV-1 infected individuals were tested for antibodies against HTLV-I and HTLV-II. The overall prevalence of the co-infection was high (16.3%). Epidemiological information was obtained from each subject including gender, age, intravenous drug use (IVDU), blood transfusion, previous diagnosis of sexually transmitted diseases (STD) and sexual behavior. The risks for acquiring retroviral infections other than HIV-1 were evaluated and the prevalence of co-infection was compared according to the AIDS clinical status. We detected seven cases (0.9%) of triple infection. HTLV-I co-infection was associated with blood transfusion (p=0.02), IVDU (p=0.0001) and female gender (p=0.0001). Co-infection by HTLV-II was primarily associated with a history of past blood transfusion (p=0.009). Women co-infected by HTLV-I or HTLV-II had a higher risk of AIDS than those infected only by HIV-1 (RR=2.04; 95% CI: 127-327, p=0.007 and RR=3.09; 95% CI: 1.07-8.91, p=0.04, respectively). These findings suggest that co-infection by HTLVI or II in Bahia, Brazil, may modify the clinical course of HIV-1 infection.