A survey in Kenya has found fewer people may be infected with HIV than previously thought.
The Kenyan figures are regarded as being the most accurate yet
The study, carried out by the Kenyan government, suggests 6.7% of people have the disease.
Previous estimates had put the figure as high as 15% or 2.2m people.
Experts said the figures based on a sample of 8,561 households across the country are the most comprehensive to date.
The Kenya Demographic and Health Survey is carried out every five years and is used by ministers to plan health and social policies.
This latest survey was carried out in September last year. As part of the survey, people were asked if they would be tested for HIV. Some 70% of those asked agreed.
The tests were carried out by officials from the US Centers for Disease Prevention and Control. They found that 8.7% of women and 4.5% of men were HIV positive.
Infection rates ranged from less than 1% of those living in the country's North Eastern province to 14% in Nyanza.
Dr Kevin DeCock, the local director of the US Centers for Disease Control and Prevention, called the new figures the best HIV statistics in Kenya to date.
"The number of HIV infected people in Kenya ... is lower than previously estimated," he said.
Kenneth Chebet, director of Kenya's National AIDS and Sexually Transmitted Diseases Programme, said the findings suggested around 1.4m people had the disease.
"The average number of people infected with HIV/AIDS has dropped from about 2.5m people four years ago," he said.
"The average was about 1.4 million people and this is the closest and most accurate estimate ever in the country."
Similar population-based surveys in other African countries have also seen HIV prevalence rates downgraded.
A national survey in Mali, carried out in 2001, found 1.7% of people were HIV positive. Previous estimates had put the figure at 4%.
In Zambia, a survey suggested 21.%% of people had the disease. It had previously been at 27%.
Other countries in Africa are planning to carry out similar population based surveys to determine their true HIV infection rate.
Dr Catherine Hankins, the chief scientific adviser to UNAids, welcomed the Kenyan survey.
"We consider these health surveys extremely helpful," she said. "The more data we get, the better are the estimates."
Dr Hankins said the surveys were coming up with different figure to those produced by UNAids.
However, she said that did not mean that infection rates had been overestimated.
"We cannot say that we have overestimated HIV rates in Africa," she told BBC News Online. "All figures for HIV prevalence in Africa are estimates.
"The important thing to remember is that the epidemic is continuing. There is no evidence that globally things are levelling off."