South African researchers are calling for their government to take immediate action to prevent mother-to-child transmission of HIV, the virus that causes AIDS. Writing in the British medical journal The Lancet, they say it is the ethical and moral thing to do. University of Natal professor Salim Abdool Karim is the lead author of The Lancet commentary. He said with more than five-million people in South Africa infected with HIV, "the few opportunities to control the spread of the disease need to be maximized."

For professor Abdool Karim one of those opportunities is using drugs such as Nevirapine and AZT to protect newborns. "The government's own estimate of 75,000 children born with HIV infection in the year 2000 is a reasonable estimate to work with. And if we use anti-retroviral therapies, like Nevirapine and AZT, we estimate that we can close to halve that infection rate," he said.

South African President Thabo Mbeki has questioned the safety of the drugs and says he is awaiting further research. The government is also appealing a court order that it come up with a national plan to prevent mother-to-child transmission of HIV.

But a number of South African provinces have taken it upon themselves to administer the anti-retrovirals. Professor Abdool Karim says the drugs are proven to be relatively safe.

"We have looked at the available data and we see no reason to be concerned and no reason to hold back on Nevirapine based on concerns about toxicity and drug resistance," he said.

He also rejects government arguments that breastfeeding will reduce the effectiveness of the drugs, since it is a known means of HIV transmission. He says a study done in Uganda shows breastfeeding had little impact.

"Those children who received Nevirapine and the mothers who received Nevirapine, those children are not at increased risk of breastfeeding transmission," he noted.

As for the cost of the drugs, the University of Natal researcher has said that is no longer a factor. "I think there is no question about affording the drugs since the drugs are now being offered for free by the manufacturers. The issue is can we afford the infrastructure in terms of counseling and testing and the formula feeds and so on," he said .

He said three separate studies show the benefits far outweigh the cost.

The 22 scientists who signed The Lancet commentary say it is their "moral and ethical duty to act in the best interests of their patients." And they say there is no scientific argument to prevent them from doing so.