Traces of HIV drug in mother's milk

A drug used in the developing world to prevent HIV transmission from mother to child persists in breast milk, exposing their newborns to risk of developing drug-resistant strains of the virus. Researchers found that the drug nevirapine stays in the blood and breast milk of the infected mothers for at least two weeks.

During that time, the virus has ample opportunity to transform itself into drug-resistant strains of HIV that causes AIDS, which can be very difficult to treat.

"In the short term, nevirapine is better than nothing," said David Katzenstein, professor of infectious diseases and principal investigator of the study.

"But in the long term, I’m concerned about conferring resistance. If you’re talking about resistance on a broad scale, it could jeopardise future treatment for mothers and infants."

Last year, 420,000 babies were born HIV-positive, the large majority of them to HIV-infected mothers in sub-Saharan Africa, according to figures from the UN Joint Programme on HIV/AIDS.

The centre-piece of public health programmes in the developing world to stop mother-to-child transmission of HIV are both zidovudine (AZT) and nevirapine, which have been used as preventive tools in nearly 900,000 women and infants worldwide.

The drugs are relatively inexpensive and easy to administer, and nevirapine is typically given as a single pill as the mother goes into labour and as a liquid to the baby just after birth.

Use of the drug reduces the chance of HIV transmission by half, to about 13 per cent. However, not all HIV-infected women have access to one or both of these drugs, especially in sub-Saharan Africa.

In the latest study, the Stanford scientists set out to better understand this problem.

They looked at a group of 32 HIV-positive pregnant women in Zimbabwe, where Katzenstein and his colleagues have had ongoing research and clinical programs in HIV/AIDS for more than a decade.

The only drug they received was the single dose of nevirapine when they went into labour, largely for the sake of their babies.

The researchers found that the drug persisted in the body for weeks, with more than half of the women having detectable levels in their blood within two weeks after delivery. Two-thirds had measurable levels in their breast milk at two weeks, the researchers found.

Seble Kassaye, co-author of the study, presented the results Tuesday at the International AIDS Conference here.