A Review of the Prevention of Mother-to-Child Transmission of Human T-Cell Lymphotrophic Virus Type 1 (HTLV-1) With a Proposed Management Algorithm

Abstract

Human T cell lymphotropic virus type 1 (HTLV-1) is a human retrovirus that is endemic in a number of regions across the world. There are an estimated 5–10 million people infected worldwide. Japan is currently the only country with a national antenatal screening programme in place. HTLV-1 is primarily transmitted sexually in adulthood, however it can be transmitted from mother-to-child perinatally. This can occur transplacentally, during the birth process or via breastmilk. If HTLV-1 is transmitted perinatally then the lifetime risk of adult T cell leukemia/lymphoma rises from 5 to 20%, therefore prevention of mother-to-child transmission of HTLV-1 is a public health priority. There are reliable immunological and molecular tests available for HTLV-1 diagnosis during pregnancy and screening should be considered on a country by country basis. Further research on best management is needed particularly for pregnancies in women with high HTLV-1 viral load. A first step would be to establish an international registry of cases and to monitor outcomes for neonates and mothers. We have summarized key risk factors for mother-to-child transmission of HTLV-1 and subsequently propose a pragmatic guideline for management of mothers and infants in pregnancy and the perinatal period to reduce the risk of transmission. This is clinically relevant in order to reduce mother-to-child transmission of HTLV-1 and it's complications.

The slowdown of new infections by human retroviruses has reached a plateau in Spain

“…The results of HTLV-1 testing of pregnant women in Spain during 2022 showed that prevalence rate has remained stable for two decades. 48,49 However, among Latin American pregnant women was 0.4%, a rate higher than that observed for other infections such as HIV (0.1%−0.26%) 50 or syphilis (0.11%), 51 almost fully stopped avoiding breastfeeding, 53 universal HTLV screening of pregnant women in Spain seems to be justified.…”

“…Finally, around 25% of pregnant women attended in Spain during the last 5 years are foreigners and 80% come from endemic countries for HTLV‐1. Given that vertical transmission is almost fully stopped avoiding breastfeeding, 53 universal HTLV screening of pregnant women in Spain seems to be justified.…”

Milk Transmission of Mammalian Retroviruses

“…To make matters worse, only a few countries screen pregnant women for HTLV antenatally. Finally, if HTLV-1 is transmitted via MTCT, the lifetime risk of developing ATLL rises from 5 to 20% [ 179 ]. Thus, there is a need for further research in HTLV-1 MTCT, which is also highlighted by the recent technical report of the WHO on HTLV-1 [ 180 ].…”

Current Interventions to Prevent HTLV-1 Mother-to-Child Transmission and Their Effectiveness: A Systematic Review and Meta-Analysis

“…The following interventions were identified in the literature: exclusive formula feeding, shortening the duration of breastfeeding, use of freeze and thaw milk [11][12][13][14][15][16][17], pasteurization of milk [18,19], use of milk bank [13], antiretroviral treatment (maternal and infant) [20][21][22], caesarean section [23], early clamping of umbilical cord [24], screening of milk donors [25,26] and avoidance of wet nursing. Multidisciplinary support for mothers living with HTLV-1 and training of healthcare professionals were also identified as important strategies for the effectiveness of any policy [27].…”

“…There is a paucity of data on the risk of HTLV-1 transmission with short-term breastfeeding outside Japan, especially in women considered to have high risk of HTLV-1 transmission, such as those with HTLV-1 associated diseases, those co-infected by Strongyloides, those with high HTLV-1 proviral load and those who already have a child with an HTLV-1 infection [21,60]. Remark 3.…”