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Malawi and Tanzania Research Shows Promise in Preventing HIV and Sexually-Transmitted Infections

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  • HIV Prevalence 60% Lower among Girls Receiving Cash Payments in Malawi Experiment. 
  • STI Prevalence 25% Lower among Adults Eligible for a $60 Reward In Tanzania Study. 
  • Studies Suggest Cash Transfers Should be Explored on larger Scale for HIV/STI Prevention.

July 18, 2010—For years, the global community has zeroed in on behavior change as a key to fighting the global HIV epidemic. But so far, the approach has brought only limited success in reducing HIV infections in developing countries.

The frustrations are especially evident in sub-Saharan Africa, which has two-thirds of the world’s HIV infections and an equally alarming share of new infections among adults. Women and girls, in particular, are at greater risk, partly because of the biological, social and economic challenges they face.

Economists at the World Bank’s Development Research Group are trying to change that. Already, two large randomized trials involving cash incentives are showing promise in reducing sexually-transmitted infections in Tanzania and Malawi. The innovative studies, if proven to be equally effective on a larger scale, could help make a dent in reversing the HIV epidemic.

“The two studies look ‘outside the box’, while at the same time relying on rigorous experimental evaluation methods,” says Adam Wagstaff, research manager of human development at the Development Research Group. “They’re using cash incentives to persuade people to change their behavior in a way that benefits them in the medium term. The first results are promising and suggest that the idea of using incentives as a tool for HIV prevention should be further explored and tested."

The Malawi Study

The studies are modeled on “conditional cash transfer” programs, which use cash payments to encourage good behaviors, such as attending schools or getting basic health care. For example, studies show that one such program in Mexico, Oportunidades, which is being funded in part by the World Bank, led to better education and health care among poor families receiving monthly payments.

Similarly, the Malawi program gave girls ages 13 to 22 and their parents as much as $15 each month if the girls attended school regularly. A control group, however, didn’t get any cash reward for schooling. In total, the study enrolled 3,796 never-married schoolgirls in Zomba, a district in southern Malawi. A year later, as in the Mexican program, more schoolgirls receiving cash (95%) stayed in school than the control group (89%).

But there’s a surprise finding: 18 months after the program began in January 2008, biomarker data show that HIV infection rates among girls who received cash was 1.2% versus the control group’s 3%. This translates to 60% lower prevalence. Girls in the cash group also had a lower infection rate of herpes simplex virus type 2, the common cause of genital herpes (0.7% vs. 3%).
Those findings hold even for a third group of girls who got cash without any schooling or other strings attached.

How did it happen? The key seems to be an “income effect” on the sexual behaviors of young women receiving cash payments. A year after the program started, girls who received payments not only had less sex, but when they did, they tended to choose safer partners, says Berk Özler, a senior economist at the Development Research Group who conducted the study with Sarah Baird of George Washington University and Craig McIntosh at the University of California, San Diego. In fact, the infection rate among those partners is estimated to be half of that of partners of the control group.

The cash transfers may have led to a drop in the so-called “transactional sex.” At the beginning of the study, a quarter of sexually-active participants said they started relationships because they “needed his assistance” or “wanted gifts/money.” Meanwhile, among the sexually-active schoolgirls in the control group, 90% said they received an average of US$6.50 a month in gifts or cash from their partners. Such “gifts” are significant, given the country’s GDP per capita was $287.5 in 2008.

After a year, schoolgirls receiving payments from the cash-transfer program seemed to avoid older men, who tend to be wealthier and are much more likely to be HIV positive than schoolboys. The sexual partners were two years older on average than the girls, compared with three years for the control group.

“The program immediately boosted income for many poor girls and their families as well as invested in their health and education,” Özler says. “Such programs could become an important part of effective HIV-prevention strategies.”

The two-year program, which has cost about $2 million so far, is funded by the Global Development Network, the Bill and Melinda Gates Foundation, World Bank funds such as the Knowledge for Change Program, the Spanish Impact Evaluation Fund, the Bank’s Research Support Budget, and others.

The Tanzania Study

The Tanzania study was designed to directly expand conditional transfers to encourage the prevention of sexually-transmitted diseases. But it differs from traditional transfer programs in two aspects. First, the participants weren’t youth, but adults. Second, it didn’t pay participants to do something, but paid them not to do something: unsafe sex.

Specifically, the $1.8 million randomized controlled trial only gave payments to those tested negative for a group of common, sexually-transmitted diseases. The cash, up to $60 per person over 12 months, made a difference in many households. The country’s gross national income per capita was $496.4 in 2008, and on average, the annual earnings of study participants were half of that amount.

And it worked. A year later, among the 2,399 young enrollees from southwestern Tanzania, 9% of participants eligible for the $60 award tested positive for the infections. By comparison, the rate was 12% for a control group who didn’t receive payments.

That 25% reduction could make it worthwhile to expand the program elsewhere and on a larger scale, says Damien de Walque, a senior economist at the World Bank’s Development Research Group. He conducted the study with Will Dow of the University of California in Berkeley and Rose Nathan at the Ifakara Health Institute in Tanzania.

To better record the program’s impact, researchers chose half a dozen curable sexually-transmitted diseases as proxy for risky sexual behavior. That includes chlamydia, gonorrhea, trichomonas, mycoplasma genitalium and syphilis. Like HIV, these diseases are spread by risky sex.
The researchers didn’t link HIV status to cash payments because of ethical concerns. In addition, the study area has a new infection rate of 0.6% every year, which could make it hard to record statistical differences.

The project was funded by the World Bank, its Spanish Trust Fund for Impact Evaluation and, through the nonprofit Population Reference Bureau, the William and Flora Hewlett Foundation. The cash payments ended in May, and the researchers will test participants again next year to see if the cash group’s infection rate would hold without cash incentives.

Researchers chose Tanzania’s Kilombero/Ulanga districts because its infection rates are about average for Africa. Residents in the district are aware of HIV/AIDS, partly because it’s close to a major highway, where migration and mobility have made it a major pathway for HIV transmission in Tanzania and East Africa.

The researchers partnered with the Ifakara Health Institute, which manages a health and demographic surveillance system and other interventions in the area. The institute helped enroll 2,399 people from 10 villages in the districts, most of them 18 to 30 years old, a group considered at high risk for sexually-transmitted infections.

Medical teams were sent to each village every four months, about one week at a time. One group introduced the participants to the project, obtained consent, took samples and conducted interviews, and the other gave out the lab results two weeks later in private, face-to-face interviews. All samples and results were marked with bar codes, instead of names, to protect privacy.

All participants received free treatment, such as antibiotics, and counseling. But only those tested negative in the cash group received payments. Those who tested positive first, but negative after four months, also received cash payments.

There’s a twist: half of the cash group were eligible for $30 a year and the other half $60. The study found that the $30 group still had the same infection rate as the control group that received no payments. And not surprisingly, the program is more effective for people from poorer and rural areas.

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