Erick Gong earned his doctorate in economics from University of California, Berkeley.

MIDDLEBURY, Vt. – Assistant Professor of Economics Erick Gong presented findings from six years of studying the HIV/AIDS epidemic in sub-Saharan Africa—and reflected on ways to reduce the number of new infections in the region—during a lecture at Middlebury College on October 25.

Gong, who describes himself as a “development economist,” showed how the number of new HIV infections is affected by two factors: an individual’s knowledge of his or her HIV status (which he termed “information”) and an individual’s economic status (which he termed “income”). Before delving into his research, Gong defined the scope of the HIV/AIDS epidemic like this:

- There are 36 million people living with HIV in the world;

- 25.5 million of those people live in sub-Saharan Africa;

- 19.5 million people in the world are receiving antiretroviral treatment (ART); and

- there are 1.8 million newly infected individuals each year.

Gong’s talk in the Hillcrest Environmental Center focused on the change in the number of new infections per year, and his findings were derived from research he has published (along with other social scientists) in the Economic Journal, the Journal of Health Economics, and the journals AIDS and Behavior and BMJ Open.

To discern whether information gleaned from AIDS testing affects the sexual behavior of individuals and their likelihood of contracting HIV, Gong studied 1,000 sub-Saharan Africans and divided them into two categories —high-risk types and low-risk types—based on their marital status and other factors. He learned that for the people whose tests came back as HIV-negative, the high-risk types felt as though they had “dodged a bullet,” while the low-risk types received confirmation of something they already knew (or suspected). And for the people who tested HIV-positive, the high-risk types received confirmation of something they already knew (or suspected), while the low-risk types received “shocking” news.

Based upon that study, Gong developed a hypothesis that the two groups that received new or surprising information—the high-risk types who tested negative and the low-risk types who tested positive—would change their behaviors. “It was a nice theory,” Gong said, “but I am an empiricist, so I had to go and see” if it would prove true.

Next, he conducted a study of 2,900 urban dwellers in East Africa. This time the participants were divided into low-risk types and high-risk types, and their self-reported behavior and test results for sexually transmitted infections were recorded over a six-month period.

The Middlebury economist learned that the high-risk group that tested negative for HIV/AIDS showed a dramatic decrease in their rate of unprotected sex. This group, which was now taking steps to protect their health and the health of others, signaled “good news from a public health perspective … a win,” said Gong.

Gong, however, received “disturbing” results from the other group that had received new information: the people in the low-risk group who had tested positive for HIV. This group showed a “dramatic increase in having unprotected sex”—a “negative externality … that could lead to additional HIV infections,” he said. Does this finding, which suggests that testing leads to an increase in HIV infections, mean that we should stop testing? he asked. “No,” Gong answered, but the key is to test and treat with antiretroviral (ART) drugs.

“The World Health Organization encourages a test-and-treat program,” he stated, and research has shown that a person taking ART drugs for HIV who engages in unprotected sex experiences a 90 percent decrease in their rate of transmission. The message, Gong said, is don’t stop testing, but always test and treat. “The problem is that not everyone who is infected has access to ART drugs,” he said.

Gong also looked closely at how an individual’s income affects their sexual behavior. “There is a positive relationship around the world between income and health. People in wealthier countries tend to have better health,” Gong said, “and this association holds in Africa as well.”

“But the mystery is that when we look at HIV, we don’t see this pattern,” and the issue, he believes, is income volatility. He cited a study of 1,000 women in Tanzania over a one-year period that showed that negative income shocks (such as loss of a job or being hospitalized) led to a greater rate of transactional sex and, consequently, higher rates of HIV. He cited a second study of 1,800 men in Tanzania over the same period and learned that men who experienced positive income shocks (such as winning a cash prize) displayed increased sexual activity and greater vulnerability to contracting HIV.

Gong explained a third study of 200,000 people in 8,000 locations across Africa that took into account monthly precipitation data and crop-planting seasons to see if there was a direct link between the income shock of a severe drought and new cases of HIV.

In the rural sample where people were likely to be reliant upon agriculture for income, he found a 20 percent increase in HIV among individuals in areas that experienced drought. “My coauthors and I conclude that it is not income levels that drive new HIV infections; it is income fluctuations. The countries that experience more drought and more income shocks have higher rates of HIV.”

Gong discussed the implications of his research and likened it to unraveling a big ball of yarn, which was the final image he displayed in his PowerPoint presentation.

“When I started out,” Gong said, “I thought we should really expand testing because more information has to be better. Then I started pulling on the ball of yarn … and found out that certain groups do not act altruistically. When some people found out they were HIV positive, they engaged in more risky sexual behavior” and not less, as might be expected.

Similarly, conventional thinking about income—that greater income leads to better health outcomes—does not tell the whole story. After individuals experience income volatility, allowing them access to “social safety nets” such as insurance, credit, and savings “might” result in a reduction of new HIV infections, he concluded.

For More Information

Prof. Gong’s publications