Nearly 7 percent of South African children between 2 and 9 years old are infected with HIV, a survey said Wednesday, offering grim new data for a country struggling with the world’s worst AIDS epidemic.

The Human Sciences Research Council said parentless children were at highest risk, with an estimated 12.7 percent of orphans under 18 years old infected with the AIDS virus.

“The risk of HIV/AIDS among children has received little attention in South Africa…it appears that children run a much greater risk of contracting the disease than previously thought,” Olive Shisana, executive director of the state-subsidized council, said at a meeting of African AIDS experts in Cape Town.

Until now no research has been done on prevalence rates among children, many of whom lack adequate medical care.

An estimated 5.3 million of South Africa’s 45 million population are infected with HIV, making the country the hardest hit by the epidemic.

The South African government, accused by activists of reacting far too slowly to the crisis, this year launched its first public program to distribute life-prolonging antiretroviral drugs.

The survey, based on a study of 3,988 youths, found that an estimated 5.4 percent of children between 2 and 18 years old were HIV positive, with the highest prevalence-6.7 percent-among ages 2 to 9.

An estimated 4.7 percent of children 10 to 14 years old were infected. Young girls in that age group were most at risk with 5.9 percent infected compared to 3.5 percent for boys.

Shisana said one of the possible causes of high HIV prevalence among children was a lack of care and supervision, partly a result of parents dying of AIDS.

“The risk of being HIV-positive is much higher for children whose mother and father have died,” she said.

The percentage of child-headed households had increased marginally from statistics in the state’s 1999 household survey, she said.

The research found “0.6 percent of households claim to be headed by children aged between 14 and 18, up from 0.25 percent. It is an increase but not as high as one would have expected given the HIV epidemic,” Shisana said.