Clinical and molecular evidences of HTLV-1 infection in inpatients diagnosed with diseases previously described as associated to this infection: A case series in Gabon, Central Africa

The Human T-cell Leukemia Virus Type 1 (HTLV-1) infection is endemic in Gabon, and despite the high prevalence, very few cases of HTLV-1 associated diseases are sporadically described. A cross-sectional study was conducted in the main teaching hospital of Gabon. Using serological and molecular techniques, plasma samples were tested and nucleic materials of all positive samples extracted from the buffy coat, then a polymerase chain reaction (PCR) was performed to detect fragments of 220 and 522-base-pairs of HTLV-1 Tax/Rex and Env genes, respectively. From March to September 2022, a total of 352 participants (51 median age, IQR 36-62) were recruited, consisting of 290 (82.4%) patients and 65 (17.6%) patients' family members. Of them, 36 (10.2%) samples were ELISA seropositive, and according to WB criteria, 22 were HTLV-1 positive (6.3%), 7 indeterminate (2%), 5 seronegative (1.4%) and 2 had HTLV seroreactivity (0.6%). The HTLV-1 infection was confirmed in 26 individuals (22 patients and 4 among their family members) with an overall prevalence estimated at 7.39% (26/352), and 3.7% (10/272) prevalence for diseases associated to HTLV-1, obtained from all clinical diagnoses. The link assessment between HTLV-1 infection and diseases' occurrence revealed 10.5% of cases of Adult T-cell Leukemia/Lymphoma (2/19), 55.6% of tropical spastic paraparesis/HTLV-1-associated myelopathy (5/9) and 60% of inflammatory myopathies (3/5). Most of the detected genotypes of HTLV-1 strains belonged to the central African HTLV-1b, four defined as HTLV-1a including a-Na, a-Wa and a-TC subclades, and one belonging to the HTLV-1d. Then, assessment of HTLV-1 intrafamilial transmission and risk factors reported one case of mother-to-child HTLV-1 transmission, and significant impacts of association between HTLV-1 infection with the gender and birthplaces were observed. Here, we discussed both the prevalence of HTLV-1 infection among patients and diseases previously described as associated to this retrovirus in Gabon. Our findings highlight the necessity to develop strategies to prevent and properly manage this infection.