Retroviral Transmission and Breast-feeding

Transmission of animal retroviruses has been demonstrated both for oncogenic retroviruses and animal lentiviruses. In humans, breast-feeding is the major route for mother-to-child transmission of Human T-cell Leukemia/Lymphoma Virus type I (HTLV-I). HTLV-I transmission by breast milk is associated with ingestion of infected cells and can be prevented by formula-feeding. Breast-feeding transmission of the Human Immunodeficiency Virus type 1 (HIV-1) has only been recently recognized as responsible for one to two thirds of mother-to-child transmission in breast-fed populations. A primary HIV-1 infection acquired in mothers after the baby has begun breast-feeding is associated with a particularly high risk of transmission. Breast milk transmission appears to result from the coexistence of HIV-1 and an inadequate humoral response in milk. Due to the dramatic impact of formula-feeding on child morbidity and mortality, it is suggested that present recommendation continue to promote breast-feeding in women living in settings where infectious diseases and malnutrition are the primary causes of infant deaths, as in many developing countries. On the other hand, in settings where infectious diseases and malnutrition are not the primary causes of infant deaths, as in most of the developed world, mothers with a proven HIV-1 infection should be advised not to breast-feed their babies.