Mother-to-infant transmission of human immunodeficiency virus by breast milk: presumed innocent or presumed guilty?

This article reviews the virological and epidemiological data available on transmission of the human immunodeficiency virus type 1 (HIV-1) by breast milk. Colostrum and breast milk are considered major modes of transmission for many animal retroviruses as well as human T-cell leukemia virus, mainly as the consequence of ingestion of infected cells. Several cases that strongly suggest transmission of HIV-1 through breast-feeding have now been reported. In addition, recent evidence suggests that postpartum HIV-1 seroconversion of a mother may be associated with a high risk of postnatal transmission to offspring via breast milk. Preventive measures such as pasteurization of breast milk have not been fully examined. While the World Health Organization continues to promote breast-feeding in areas where no safe alternative exists, the Centers for Disease Control recommends that American women who are infected by HIV-1 not practice breast-feeding if a safe alternative is available. Large-scale, carefully controlled, prospective studies of the risk of HIV-1 infection associated with breast-feeding are of the utmost priority. Feasible and ethically acceptable feeding alternatives should be developed for countries where formula feeding has a strong negative effect on child morbidity and mortality.