HTLV prevalence is no longer following the decreasing HIV prevalence - 20 years of retroviral surveillance in Guinea-Bissau, West Africa.

BACKGROUND: The HIV-2 and HTLV-1 prevalences in Bissau have followed similar trends in surveys from 1996 and 2006 with HTLV-1 prevalences of 3.6% and 2.3%, respectively. However, following the introduction of antiretroviral treatment (ART) and informative campaigns about HIV, the epidemics may have shifted. To evaluate the current HTLV prevalence and the continued association with HIV, we performed a third survey.

METHODS: A cross-sectional survey was performed from November 2014 to February 2016. In total, 2583 participants were interviewed, tested for HIV, and had blood samples collected. Samples were analysed for anti-HTLV using chemiluminescence and immunoblot assays. We calculated the HTLV prevalence for 2016 and examined risk factors for HTLV and associations with HIV using binominal regression.

RESULTS: The prevalence of HTLV was 2.8% (71/2583), 1.5% (16/1,089) for men and 3.7% (55/1,494) for women. Old age, female sex, HIV-2 infection and sharing a house with a HTLV- infected person were strong risk factors for HTLV. In contrast to previous studies, we found a non-significant increase in prevalence among the 15-24 year-olds since 2006, supporting ongoing transmission.

CONCLUSIONS: The HTLV prevalence in Bissau showed a non-significant increase. We found evidence supporting continuous vertical and horizontal routes of transmissions.