Shared breastfeeding identified as new risk factor for HIV

Breastfeeding of infants by multiple women may be contributing to the spread of HIV in Africa even when the child’s mother is not HIV-positive, according to research carried out in Gabon by German and Dutch researchers.

The researchers say that they observed children being breastfed by multiple women including the biological mother, and that the practice was distinct from wet nursing (feeding by a substitute for a mother who cannot breastfeed). Breastfeeding is taking place by carers or other family members, say the researchers, because mothers are unable to feed on demand owing to work or the need to buy food.

They interviewed 139 women taking part in a malaria prevention trial in Lambaréné, Gabon. Mothers of children aged four to seven months were interviewed; 90% were breastfeeding their children, although only 8 of 125 reported exclusive breastfeeding. Women had an average of 3.2 children, and the next youngest child averaged three years old.

Forty per cent reported breastfeeding up to four infants other than their own child since their most recent birth, and 40% of the infants born to mothers in the study had been breastfed by up to three other women. Twenty per cent of breastfed children and 20% of women who breastfed the respondent’s child were not family members, the interviewees reported.

The practice was more common among women from the Eshira ethnic group but the authors do not report if shared breastfeeding was practiced by all ethnic groups (at least five were represented in the study population). However, they do state that their findings could be relevant to a wide geographical area in Africa, and urge more research on the extent of the practice and its contribution to HIV transmission.

“In the context of the high rate of early mixed feeding in our sample population, a risk factor in and of itself for HIV transmission, the significance of even occasional shared breastfeeding is magnified,” say the researchers.

They argue that international recommendations on breastfeeding and HIV need to take the practice into account, and that training of health care workers and counsellors also needs to address shared breastfeeding.

Although epidemiological studies do not show a high level of unexplained HIV infection in infants whose mothers are HIV-negative, this does not prove that shared breastfeeding is unimportant.

Shared breastfeeding could increase the risk of HV transmission even where the child’s mother is HIV-positive because the infant may be exposed to breast milk from other women containing higher levels of HIV. Similarly, if the mother is receiving antiretroviral treatment shared breastfeeding could negate the effects of treatment on postpartum mother to child transmission. In both cases however epidemiological analysis would assume that the mother is the source of infection, which may explain why this potential route of transmission has not been identified previously.