Mother-to-child transmission of human T-cell lymphotropic virus type I associated with prolonged breast-feeding.

OBJECTIVES: We assessed the risk of transmitting human T-cell lymphotropic virus type I (HTLV-I) through breast-feeding.

STUDY DESIGN/METHODS: To assess the risk of mother-to-child transmission of HTLV-I, 212 HTLV-I-seropositive women and 145 HTLV-I-seronegative women were enrolled in a prospective cohort study conducted in Kingston, Jamaica. Their offspring were examined at regular intervals, and HTLV-I serostatus was determined at each visit.

RESULTS: Twenty-eight of the 181 children with at least one postnatal visit born to HTLV-I-seropositive women (and none of the children born to HTLV-I-seronegative women) were persistently seropositive and were considered HTLV-I infected (Kaplan-Meier estimated cumulative incidence, 18%; 95% CI, 12%-24%). Among children observed for at least 24 months, 19 (32%) of 60 children breast fed for 12 months or longer were HTLV-I seropositive, compared with only 8 (9%) of 86 children breast-fed for less than 12 months (relative risk, 3.4; 95% CI, 1.7-6.9). Compared with children weaned at younger ages, transmission of HTLV-I was associated with continued breast-feeding of children who were 12 to 18 months of age (relative hazard, 6.4; 95% CI, 2.1-180.2) and older than 18 months (relative hazard, 18.1; 95% CI, 1.4-29.5). Transmission was also associated with higher maternal antibody titer (a possible marker of virus load), prolonged duration of ruptured membranes during childbirth, and lower maternal income.

CONCLUSIONS: These results suggest that limiting the duration of breast-feeding to less than 12 months for children born to HTLV-I-seropositive mothers may significantly reduce mother-to-child transmission of HTLV-I.