Scientists Say Sex the Main Source of HIV in Africa

Although recent theories have speculated that the AIDS epidemic in some African countries arose from unsafe medical practices, scientists said Wednesday that the pattern of AIDS matches more closely with one primarily spread by unprotected sex.

In the April 17th issue of Nature (2003;422:679), UK investigators compared the changing HIV infection rate in sub-Saharan African countries to that of hepatitis C, which is spread mainly through contact with infected blood. Worldwide, more people are infected with hepatitis C than HIV. However, sub-Saharan African countries -- unlike other nations -- have a higher rate of HIV than hepatitis C. The authors note that a needle tainted with hepatitis C-infected blood is six times more likely to infect a person than is a needle tainted with HIV. And given that HIV is more common than hepatitis C in sub-Saharan Africa, a high prevalence of HIV must be attributed to factors other than the use of unsterile needles or tainted blood products, they concluded.

The researchers acknowledge that many Africans may have been infected with HIV as a result of unsafe medical practices, however it "is not the dominant contributor to the African HIV epidemic." "I think it's because of unsafe sex. This is clearly the key factor, although there are clearly a variety of socioeconomic factors which impact on this," said study author Dr. Edward C. Holmes of the University of Oxford. As a result, Holmes and colleagues said efforts aimed at preventing new infections should focus on safe sex messages.

A report from an international team of eight experts recently challenged the belief -- widely held by most scientists -- that heterosexual sex is the cause of HIV in 90 percent of new cases in adults in sub-Saharan Africa. The researchers claimed that only one-third of all adult cases in the region could be attributed to unsafe sex. Rather, a more significant factor of transmission rates may have been unsafe medical practices. They noted that HIV is more easily transmitted though unsafe injections and infected blood transfusions than through heterosexual sex.

Holmes and his team see quite a different picture by comparing rates of HIV and hepatitis C in the region. The authors noted that South Africa has the highest number of Africans with HIV, where the incidence of HIV increased from less than 1 percent in 1990 to almost 25 percent in 2000. They point out that the rate of hepatitis C in South Africa has remained steady and relatively low over the same time period. These divergent trends suggest "that current levels of HIV prevalence are not primarily the result of using unsterile medical equipment or contaminated blood products."

Back to other CDC news for April 18, 2003

Previous Updates