HIV/Aids is twice as common in the war-torn north of Uganda as in the rest of the country, an aid agency says.
Uganda began campaigning on Aids in the late 1980s
Uganda has been widely praised for its fight against Aids but the conflict in the north is threatening its success, says World Vision International.
The Lord's Resistance Army rebels often abduct boys to become fighters and girls as sex slaves.
About half the girls who escape from the rebels are found to be HIV positive, doctors say.
"If these girls make it back from the bush, they are sometimes rejected and abandoned by their families," said World Vision.
"Some resort to survival sex, engaging in high risk behaviours that increase the spread of the disease."
Pawns of politics
The aid agency said that health care facilities in the north had virtually collapsed.
"National prevalence rates for Uganda are estimated at 6.2% and declining, but rates in war-affected areas are almost double that of the national average, at 11.9%," its report said.
In Gulu district, epicentre of the rebellion, researchers found HIV/Aids was the leading cause of death in 69% of fatalities - three times higher than the number of people killed in fighting.
In the early 1990s, some 30% of Ugandans were HIV positive.
The World Vision report, Pawns of Politics: Children, Conflict and Peace in Northern Uganda, says that some 1.6 million people have fled their homes in northern Uganda - more than in Sudan's Darfur region, which has received far more international help and attention.
Some 80% of the population in the north are living rough, the report says.