AIDS Res Hum Retroviruses. 2022 Dec 26. doi: 10.1089/AID.2021.0230. Online ahead of print.
Background In 2012, the number of people infected with HTLV-1 was estimated to be 10 million worldwide. Prevalence varies according to geographic location, ethnic factors, sex, age, populations exposed to risk factors, income, and education, reaching countries with the worst socioeconomic scenarios. There is a need to determine the current global prevalence of HTLV-1 and examine its association with countries’ human development index (HDI) to provide data for global health policy. Methods Systematic review with meta-analysis according to PRISMA 2020 recommendations. It was registered at PROSPERO, CRD42021223146. Prevalence or cross-sectional studies of HTLV-1 infection with at least 100 participants, screening, and confirmatory serologic testing were included. Studies with incomplete or unavailable results or with duplicate information were excluded. Data were selected by two independent investigators and analyzed using R software, a metapackage that generated the forest plots (95% CI). Heterogeneity was assessed using the I² statistic, and funnel plot asymmetry was assessed using Egger’s test. Countries were compared using an HDI cutoff ≥ 0.8. Methodological quality was assessed using Joanna Briggs Institute criteria. Results The overall prevalence of HTLV-1 infection was 0.91% (95%CI: 0.80-1.02, p < 0.0001) and was higher in low HDI countries [1.18% (95%CI: 1.03-1.34)] than in high HDI countries [0.41% (95%CI: 0.27-0.57)]. Prevalence varied according to the populations studied: it was higher in the general population [1.65% (95%CI: 1.08-2.34)] compared to pregnant women [0.34% (95%CI: 0.17-0.57)] and blood donors [0.04% (95%CI: 0.01-0.08)]. Consistently, prevalence for each population group was higher in low HDI countries than in high HDI countries. Conclusion The worldwide prevalence of HTLV-1 infection is highly heterogeneous, with a global prevalence of 0.91%. In high HDI countries, the observed prevalence is approximately three times lower than in low HDI countries. In the general population, the observed prevalence is about five times higher than in pregnant women and forty-one times higher than in blood donors.