Long-term follow-up study of HTLV-I infection in bottle-fed children born to seropositive mothers.

Human T-lymphotropic virus Type-I (HTLV-I) infects children via mother's milk. Infection of Human T-lymphotropic virus Type-I (HTLV-I) was investigated by long-term follow-up surveys of modified milk-fed children. Our observations of modified milk-fed infants revealed that: 1 of 154 (0.6%) at year 1, 5 of 129 (3.9%) at 1.5 years, and 5 of 108 (4.6%) at year 2 were anti-HTLV-I antibody-positive. No infants or children became newly antibody-positive thereafter. Modified milk feeding could prevent the HTLV-I infection of infants from mothers in many cases, however the infants who had became anti-HTLV-I antibody-positive due to established infection by the age 2 remained positive at age 11-12 with persistent infections. Modified milk-fed infants who had been born from HTLV-I seropositive mothers did not show that they had complete protection from HTLV-I infection, but a low infection rate was seen, showing that modified milk feeding is useful to protect from HTLV-I infection.