Passing on immunity -
How breastmilk protects babies
A nursing, infected mother develops a viraemia (virus in the blood) long before she becomes symptomatic. Some of that virus can get into her milk in small numbers. Since viral infection is a numbers game, this small number of virus in breastmilk usually provides enough exposure to develop immunity, but as a rule, is not enough for the baby to become ill. In addition, the milk's anti-infective properties further protect the baby. By the time the mother actually has symptoms, she has already developed specific immunity that she passes on to her nursling.
If by a remote chance the baby does get sick, the baby is less likely to be seriously ill than if it were not breastfeeding.
The only known exception to this is HIV. Because of the faltering immunity of the mother, there are often periods of viraemia unlike those one sees with other acute infections. However, recent information from South Africa suggests that the exclusively breastfed baby does not have a higher risk of getting infected than the exclusively formula fed baby.
Spring 2003 Newsletters Contents