AIDS Declines in Zimbabwe, Linked to Behavior Changes

Richard A. Lovett
for National Geographic News
February 3, 2006
The southern African nation of Zimbabwe has one of the highest HIV
infection rates in the world. But efforts to control the epidemic may
finally be bearing fruit.

An international team of AIDS researchers has found that HIV infection rates in the eastern province of Manicaland declined from 23 percent in 1998 to 20.5 percent in 2003, a reduction of nearly 11 percent.

The decline appears to be linked to increasing levels of safe sex, says study author Simon Gregson of Imperial College London.

Most important, researchers say, is the substantial decrease in casual sex partners reported by Manicaland residents.

This, combined with increased abstinence by teenagers, may be contributing to the region's HIV decline.

The study appears in today's issue of the journal Science.

Hopeful Tidings

According to the Centers for Disease Control, sub-Saharan Africa is home to about 62 percent of the estimated 10 million people age 15 to 24 living with HIV worldwide. Zimbabwe alone has about 1.8 million infected individuals.

Between 1998 and 2000 Gregson's team contacted nearly 10,000 people in Zimbabwe. The researchers administered HIV tests and asked about sexual behaviors.

Three years later the team repeated the survey, contacting as many of the original participants as they could locate.

Not only had the overall rate of infection come down, they found, but the biggest drop occurred in the youngest age groups.

The researchers say that's important with a disease like AIDS, because there is no cure. Positive changes will first show up when the current cadre of young people, just moving into their sexually active years, show lower infection rates than their predecessors.

"It's in the youngest age groups that you can see things happening soonest," Gregson said.

Declining AIDS rates in Zimbabwe could herald similar changes in other parts of Africa.

Zimbabwe may be a bellwether, Gregson says, because it has a high literacy rate, particularly among young people. That may have given its citizens a head start on AIDS awareness compared to neighboring countries.

"People shouldn't give up hope in other countries," he said. "Hopefully, in three or four years we'll start to see similar declines in other places."

Richard Hayes, of the London School of Hygiene and Tropical Medicine at the University of London, agrees. The Zimbabwe findings, he said, are "very significant."

Hayes is co-author of a commentary that accompanies the Science study.

"It is the first really clear evidence that we are beginning to see some [HIV] reductions in southern Africa," he said. "And [Gregson] has strong evidence not only of a reduction, but also of behavior change. That's really good news."

Hayes cautions, however, against applying the results too broadly.

"We tend to think of Africa as one homogeneous region and the epidemic as the same everywhere," he said. "That is very much not the case."


A few years ago, Hayes was part of a team that carried out its own study of factors influencing HIV infection rates in four African cities.

The researchers expected that the cities where residents practiced the riskiest sexual behaviors would have the highest infection rates. But that wasn't the case.

"That was quite a surprise," Hayes said.

What the study instead found was that circumcised men appear to be less likely to catch the disease than uncircumcised men. (Read a related news article.)

People with other sexually transmitted diseases, particularly herpes, are also more likely to become infected with HIV.

Currently, Hayes says, three studies are looking more closely at circumcision as an HIV prevention measure. One study in South Africa found a two-thirds reduction in the infection rate of recently circumcised men compared to uncircumcised men.

"These studies emphasize that sexual behavior is only one of the factors driving AIDS epidemics in Africa," Hayes said. "Although [behavior] seems to have played a key role in the HIV decrease in Zimbabwe."

Keeping Our Eyes on the Ball

Hayes warns that there is a risk that hopeful findings can cause people to lapse into complacency.

"The temptation is to say that things are looking up a bit," he said. "That would be a dangerous message."

Complacency can lead to a resurgence of risky behavior, he says. For example, the ready availability of AIDS drugs in the U.S. and Europe may be lulling people into thinking they can take more risk.

Furthermore, as the same drugs become prevalent in Africa and the life spans of infected people increase, there will be an increase in AIDS-related medical costs.

"Unless we can turn off the tap of new infections, it will be increasingly difficult to sustain treatment programs," Hayes cautioned.

John Stover, a policy analyst based in Glastonbury, Connecticut, agrees.

Stover works for the Futures Group, a consulting firm that specializes in creating public health programs for developing nations. In a study published this week in the online journal Science Express, his team compares the cost of preventing HIV infections to that of treating them.

Some prevention programs are easy and inexpensive, he says, such as focused intervention programs in settings with a high occurrence of HIV. But others can be costly.

Nevertheless, Stover's team concluded that a comprehensive package of prevention programs—even including the most expensive plans—would cost up to U.S. $800 less per case than treatment.

That's an important message, Stover says, because treatment programs tend to hog media attention.

"We want to remind people that prevention is important and affordable as well," he said.

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