Long-term Follow up Study of Vertical HTLV-I Infection in Children Breast-fed by Seropositive Mothers

Abstract Infection of Human T-ymphotropic virus type-I (HTLV-I) was investigated by long-term follow up surveys of mother's milk-fed infants. HTLV-I infections of infants via seropositive mother's milk, that is, anti-HTLV-I antibody-positive infants, increased in number up to the age 2, but no infants became antibody-positive thereafter. Infants who had became antibody positive by age 2 remained so at age 11–12. HTLV-I infection via feeding with mother's milk was established by the age 2. While in epidemiologic surveys an increase of the anti-HTLV-I antibody-positive rate has been reported, this survey revealed that after acquisition of HTLV-I from breast feeding, there was no further horizontal transmission prior to puberty.