Prevention of Human T-Cell Leukemia Virus Type 1 (HTLV-1) Mother-to-Child Transmission

Abstract

Human T-cell leukemia virus type 1 (HTLV-1) is the etiologic human retrovirus of adult T-cell leukemia/lymphoma (ATL). The estimated risk for an HTLV-1 carrier to develop ATL is approximately 5%. However, to date, medical treatments for ATL are not effective, and therefore the prognosis for this disease is poor. The vertical transmission of HTLV-1 occurs predominantly through breastfeeding. Therefore, for the prevention of mother-to-child transmission, bottle-feeding is the most effective method to prevent the endemic cycle of HTLV-1. When vertical transmission of HTLV-1 is prevented, the incidence of ATL is significantly reduced in the next generation. In Nagasaki prefecture, which is one of the endemic areas for HTLV-1 in Japan, prefecture-wide screening of pregnant women and advice to refrain from breastfeeding by carrier mothers have been implemented since 1987. HTLV-1-positive women are provided with counseling about methods of feeding, i.e., bottle-feeding, short-term breastfeeding, and freeze-thawing of breast milk, to reduce the risk of HTLV-1 mother-to-child transmission. A recent study of HTLV-1 carriers in Japan showed that the estimated number of HTLV-1 carriers in 2007 was one million and that HTLV-1 carriers have spread to other geographical areas in Japan (prevalence has decreased in endemic areas but increased in metropolitan areas). Therefore, in Japan, since 2011, the nationwide screening of pregnant women for HTLV-1 infection has been recommended to prevent breast milk-borne transmission of HTLV-1. In this chapter, critical points regarding the prevention program for mother-to-child transmission of HTLV-1 are discussed.