Blocking HTLV-1/2 silent transmission in Brazil: Current public health policies and proposal for additional strategies

Abstract

Human T-cell lymphotropic viruses 1 and 2 (HTLV-1/2) are relatively common in Brazil but remain silent and neglected infections. HTLV-1 is associated with a range of diseases with high morbidity and mortality. There is no curative treatment for this lifelong infection, so measures to prevent transmission are essential. This narrative review discusses HTLV-1/2 transmission routes and measures to prevent its continuous dissemination. The public health policies that are currently implemented in Brazil to avoid HTLV-1/2 transmission are addressed, and further strategies are proposed.

Development and Validation of Multiplex Quantitative Real-Time PCR Assays for Simultaneous Detection and Differentiation of HTLV-1 and HTLV-2, Using Different PCR Platforms and Reagent Brands

“…Molecular confirmatory assays, mostly qPCR, are important tools for HTLV-1/2 diagnosis, for avoiding vertical transmission in children born to HTLV-1/2-infected mothers, and for monitoring HTLV-1/2 PVLs and disease development ( Rosadas et al, 2021b ). Serological confirmatory assays for HTLV-1 and HTLV-2 (WB and LIA) are expensive and prone to delivering inconclusive results (indeterminate or HTLV untyped results) ( Campos et al, 2020 ; Caterino-de-Araujo et al, 2021 ).…”

“…Thus, it is important to perform confirmatory and discriminatory diagnosis of HTLV-1/2 infections. There is no curative treatment available for these infections, therefore preventive measures, which include correct diagnosis, are the only means to eliminate HTLV transmission ( Rosadas et al, 2021b ).…”

Milk Transmission of HTLV-1 and the Need for Innovative Prevention Strategies

“…Routine screening of milk banks originating from donors of endemic regions should be advisable. Brazil has been recommending HTLV-1/2 infected mothers to avoid breastfeeding in 2019 ( 3 ), a strategy that proved successful in Japan earlier: Abstinence from breastfeeding by PHTLV mothers reduced the prevalence of HTLV carriers from 20–25% to 4% in the Nagasaki population in Japan ( 8 ). In Japan, HTLV-1 infected mothers are advised not to breastfeed or to do so only for less than 3 months ( 7 ).…”

“…Endemic regions are located in Japan, Melanesia, Central Australia, Sub-Saharan Africa, parts of South America (e.g., Brazil), the Caribbean, and the Middle East ( 2 ). A high frequency of people infected with HTLV-1 (PHTLV) worldwide lives in resource-limited settings or belongs to social or ethnic minorities ( 2 , 3 ). Problematically, many of the PHTLV are unaware of their infection since HTLV-1 is not screened routinely in every endemic country ( 1 ).…”

“…In endemic areas of HTLV-1-infection, such as southwestern Japan, MTCT has been demonstrated to be the primary mode of transmission ( 7 ), while the main route of transmission for other countries like Brazil (ca. 0.8–2.5 million PHTLV) or Central Australia is still a matter of discussion ( 3 , 8 , 9 ). Although intra-uterine transmission of HTLV-1 has been described and perinatal transmission cannot be fully excluded ( 10 , 11 ), the majority of HTLV-1 MTCT occurs via breastfeeding since the level of infection among babies that are exclusively formula fed is low ( 6 , 7 ).…”