HTLV-1 in rural Guinea-Bissau: prevalence, incidence and a continued association with HIV between 1990 and 2007

Abstract

BackgroundHTLV-1 is endemic in Guinea-Bissau, and the highest prevalence in the adult population (5.2%) was observed in a rural area, Caió, in 1990. HIV-1 and HIV-2 are both prevalent in this area as well. Cross-sectional associations have been reported for HTLV-1 with HIV infection, but the trends in prevalence of HTLV-1 and HIV associations are largely unknown, especially in Sub Saharan Africa. In the current study, data from three cross-sectional community surveys performed in 1990, 1997 and 2007, were used to assess changes in HTLV-1 prevalence, incidence and its associations with HIV-1 and HIV-2 and potential risk factors.ResultsHTLV-1 prevalence was 5.2% in 1990, 5.9% in 1997 and 4.6% in 2007. Prevalence was higher among women than men in all 3 surveys and increased with age. The Odds Ratio (OR) of being infected with HTLV-1 was significantly higher for HIV positive subjects in all surveys after adjustment for potential confounding factors. The risk of HTLV-1 infection was higher in subjects with an HTLV-1 positive mother versus an uninfected mother (OR 4.6, CI 2.6-8.0). The HTLV-1 incidence was stable between 1990-1997 (Incidence Rate (IR) 1.8/1,000 pyo) and 1997-2007 (IR 1.6/1,000 pyo) (Incidence Rate Ratio (IRR) 0.9, CI 0.4-1.7). The incidence of HTLV-1 among HIV-positive individuals was higher compared to HIV negative individuals (IRR 2.5, CI 1.0-6.2), while the HIV incidence did not differ by HTLV-1 status (IRR 1.2, CI 0.5-2.7).ConclusionsTo our knowledge, this is the largest community based study that has reported on HTLV-1 prevalence and associations with HIV. HTLV-1 is endemic in this rural community in West Africa with a stable incidence and a high prevalence. The prevalence increases with age and is higher in women than men. HTLV-1 infection is associated with HIV infection, and longitudinal data indicate HIV infection may be a risk factor for acquiring HTLV-1, but not vice versa. Mother to child transmission is likely to contribute to the epidemic.

Factors associated with HIV testing and receiving results during antenatal care in Tanzania

“…Most of the HIV burden is located in Sub-Saharan Africa though it is home to only 12% of the global population (Lozano, Naghavi et al 2012). Furthermore the prevalence of HIV is higher among women compared to men (van Tienen, van der Loeff et al 2010). Annually about 400,000 children are being infected with HIV of whom 90% (300,000) are due to mother to child transmission of HIV (MTCT) (Tudor Car, van-Velthoven et al 2011).…”

Maternal Proviral Load and Vertical Transmission of Human T Cell Lymphotropic Virus Type 1 in Guinea-Bissau

“…The upper age limit of children was chosen assuming that sexual activity has mostly not started by this age in this population. 10 The area of living was defined as central or peripheral as previous studies showed different prevalences of HIV and HTLV-1 in the central and peripheral areas of Caió . 10 Medical care was provided by the project's physician when needed.…”

“…10 The area of living was defined as central or peripheral as previous studies showed different prevalences of HIV and HTLV-1 in the central and peripheral areas of Caió . 10 Medical care was provided by the project's physician when needed. At the time of the study no anti-retroviral therapy was available in Guinea-Bissau.…”

“…In rural areas, where the current study was conducted, the adult prevalence was 4.9% in 2007. 10 The relative importance of different routes of transmission has not been established in this population but it is thought that sexual transmission is most common. 11 Two studies among adults in the capital Bissau found no relationship between HTLV-1 infection in mothers and their children and it was suggested that vertical transmission does not importantly contribute to the endemic HTLV-1.…”

“…14 An earlier study from rural Guinea-Bissau found a significantly higher prevalence of HTLV-1 infection among adult children of HTLV-1-positive mothers. 10 To study the role of MTCT in the HTLV-1 epidemic in Guinea-Bissau, factors associated with HTLV-1 infection in children from infected and uninfected mothers were examined.…”