Most youngsters infected with HIV still catch the virus from their mothers despite the existence of simple and effective ways to reduce transmission during birth.

Anti-retroviral medicines can give AIDS' youngest sufferers a chance to grow up healthy, but doctors and activists say most are being left behind in the drive to scale up treatment on the world's most infected continent.

An estimated 2.2 million children globally are infected with HIV, the virus that causes AIDS, according to the United Nations, which launched a campaign to fight the disease in children ahead of World AIDS Day on Dec. 1.

Anti-retroviral therapy has allowed many of those infected in wealthy nations to reach adulthood and in some cases start families of their own. But treatment remains out of reach for the overwhelming majority in sub-Saharan Africa -- home to more than 85 percent of all children under 15 living with the disease.

Less than 1 percent of infected children globally are receiving the life-prolonging drugs. Without them, most will die before their fifth birthday.

'Children Also Deserve the Best'

Botswana, the first African nation to pledge to give free AIDS medicine to all who need it, is one of the few treating children through the public health system.

It boasts the continent's first center devoted to pediatric AIDS, operated by the Houston, Texas-based Baylor College of Medicine and funded by pharmaceutical giant Bristol-Myers Squibb.

The Botswana-Baylor Children's Clinical Center of Excellence -- a bright, modern facility whose walls are filled with cheery high school art -- offers some 1,400 African children the same care available in the United States.

"This center is a political statement that children also deserve the best," said pediatrics professor Gabriel Anabwani, who heads the facility.

Jennifer, whose infected mother withheld their last name because of the stigma still associated with HIV, is one of its star patients. Her immune cells have soared and her viral load is undetectable.

"Every time 7 o'clock comes, she tells me: 'Mama, it's time for my medicine,'" Refilwe said proudly.

But even in Botswana, where some 5,000 youngsters are on treatment, government officials concede there are more options for adults. So far, only five of the 32 sites dispensing free anti-retrovirals around the country will treat children.

Clinical Obstacles

Most youngsters still catch the virus from their mothers despite the existence of simple and effective ways to reduce transmission during birth.

A single dose of nevirapine given to an infected mother at onset of labor and to her newborn can reduce transmission by about 50 percent. In the United States, nevirapine is used in combination with other drugs to reduce transmission to less than 2 percent. But only 10 percent of pregnant women globally have access to such services.

Too many children then go undiagnosed until it is too late to save them, Anabwani said. In countries like Botswana, where HIV has infected more than a third of adults, children living with the virus have often lost one or both parents leaving no one to ensure they are tested and treated in time.

There are also clinical obstacles to diagnosing the youngest patients. The most common way of identifying HIV in adults is to test for antibodies. But even HIV-free infants can have antibodies from their mothers, making the test ineffective before 15-18 months. By that time, many infected babies will have suffered life-threatening opportunistic infections.

The Baylor center tests for the virus itself, but this is expensive and requires specialized laboratories not readily available in poorer settings.

Most physicians at public hospitals are not familiar with pediatric AIDS and can be reluctant to take on cases, said Anabwani, whose center helps train health workers across the country.

There has also been little research on treating children, so the options are more limited and dosing guidelines less precise than for adults, he said. The youngest children cannot swallow pills and need liquid formulations, which are not always available.

Children's Medicines

Of the 20 drugs developed so far, just 12 are labeled for pediatric use and seven for children under 2, according to the US-based Elizabeth Glaser Pediatric AIDS foundation. While prices have dropped significantly for adult medicines, children's formulations remain up to eight times more expensive, the foundation said in a recent report.

Some countries cannot afford to include children's medicines in their programs. In Malawi, clinicians grind up adult pills to approximate a child-sized dose, Anabwani said.

Fixed-dose combinations, which include several drugs in one pill, are making it simpler and cheaper to treat adults. But none of those on the market here have been formulated or tested for children.

Pilang Letsebe struggled to cope with the complex regimen for her great-granddaughter, Mary, after the child's parents died of AIDS complications. The 9-year-old missed doses, sickened and developed resistance to the drugs she was taking.

In Botswana, there are alternatives. But in other countries, children get one chance at treatment. With the help of a young aunt, Letsebe is now determined that Mary should receive all her drugs on time.

"I want Mary to grow like any other child," she said, waiting patiently to collect the girl's monthly supply of medicine.