High prevalence of HTLV-1 among blood donors in southeastern Gabon (Central Africa): a major challenge for transfusion safety in a semi-rural area.

UNLABELLED: Sub-Saharan Africa is an endemic region for human T-lymphotropic virus type 1 (HTLV-1). While high prevalence rates have been reported across Gabon, systematic screening of blood donors has not yet been implemented at the national level. A cross-sectional study was conducted on 2,375 blood donations from 2,303 blood donors at the Amissa Bongo Teaching Hospital Center in Franceville. Serological screening was performed via ELISA, followed by Western Blot confirmation and PCR-based proviral DNA amplification of the env gene. The overall HTLV-1 seroprevalence was 2.1% (95% CI: 1.6%-2.7%) at the donation level and 1.8% (95% CI: 1.3%-2.5%) at the donor level. The seroprevalence in Franceville was significantly higher than at the national blood bank in Libreville (ORa = 2.52; 95% CI: 1.5-4.2). History of blood transfusion was the only risk factor significantly associated with HTLV-1 infection (OR = 3.73; 95% CI: 1.3-9). Molecular analysis revealed a predominance of the HTLV-1b subtype (32/33), alongside one HTLV-1d strain, a subtype primarily reported in non-human primates. The high HTLV-1 seroprevalence among blood donors in southeastern Gabon, combined with the identification of a history of transfusion as a significant risk factor, represents a major challenge for transfusion safety in a semi-rural area. These results underscore the urgent need to integrate systematic HTLV-1 screening into the transfusion safety algorithm in Gabon to interrupt the cycle of iatrogenic transmission.

IMPORTANCE: Human T-lymphotropic virus type 1 (HTLV-1) remains a major public health problem in Central Africa, with Gabon being a major endemic hotspot. This study addresses a critical issue for blood safety in semi-rural areas, where prevalence in the general adult rural population is exceptionally high, ranging from 7.3% to 8.7% according to previous studies. Here, we report a prevalence of 1.8% among blood donors in southeastern Gabon, a rate 2.5 times higher than that of blood donors in the capital. Moreover, a history of transfusion was identified as the only significant risk factor associated with HTLV-1 infection, directly demonstrating active iatrogenic transmission in the absence of systematic screening. Furthermore, the discovery of the rare HTLV-1d subtype highlights the persistent potential risk of zoonotic and human-to-human transmission in these forest-adjacent ecosystems. These results provide compelling evidence for the urgent integration of HTLV-1 screening in endemic rural areas of Gabon.