Giving a single dose of the anti-retroviral drug, nevirapine, to HIV-infected mothers to prevent them infecting their babies at birth can cause drug resistance in about one-fifth of women, a new study suggests.
Anti-retroviral drugs stop the maternal transmission of HIV, and ideally pregnant women with HIV should get full-time therapy with several drugs, as this prevents the virus becoming resistant to any one drug. But where women cannot afford this, clinics give a one-off treatment with the powerful drug nevirapine. Previous studies suggested that drug-resistant HIV 鈥渇ades鈥� or disappears from the mothers soon after.
But when Sarah Palmer and colleagues at the National Institutes of 91色情片 in Maryland, US, looked more carefully for specific nevirapine-resistance mutations in the HIV in 22 women given the treatment in Soweto, South Africa, they found that at least 23% of women were likely to have some drug-resistant HIV one year later.
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The problem is that viral infections consist of a swarm of mutant strains. But standard tests for drug resistance do not detect mutants that make up less than 30% of the swarm, Palmer told New Scientist, and the drug-resistant strains detected in her study were just such a minority.
So if the woman takes nevirapine again, to treat her own disease or protect another child, it may not work 鈥� and such drug failures may already be happening in women treated years earlier. 鈥淏ut if that鈥檚 the woman鈥檚 only option, what can you do?鈥� says Palmer. 鈥淲e need more effective interventions that are available to everyone.鈥�
Journal reference: Proceedings of the National Academy of Sciences (DOI: 10.1073_pnas.0602033103)
