HTLV-1 Proviral DNA in Oral Aspirates of Newborns Born to Seropositive Mothers

To the Editor. —Milk-borne transmission of human T-lymphotropic virus type 1 (HTLV-1) has been well established both epidemiologically and experimentally. Switching from breastfeeding to bottle-feeding reduced the virus infection rate to approximately one tenth, but a few bottle-fed infants still became infected with HTLV-1 through an as yet unidentified route. 1 Transplacental or intrauterine transmission of HTLV-1 has been a controversial subject because detection of HTLV-1 antigen or proviral DNA in umbilical cord blood does not necessarily lead to seroconversion of the children. 2-4 We now report that perinatal infection of HTLV-1 may account for the rare cases of seroconversion not related to breast-feeding. We studied 17 HTLV-1 antibody—positive carrier mothers and their newborn infants: 10 of them were delivered by the vaginal route and the other seven by cesarean section at term. During pregnancy, the presence of HTLV-1 antibodies was checked by the particle agglutination method (titers 1:64 to