People can work more when their ailments are treated. And HIV is no exception. Adults who tested positive for HIV in Uganda but had a less severe infection were able to work more hours per week, and their kids were more likely to be in school, according to findings presented July 26 at the 2012 International AIDS Conference in Washington, D.C.

If this correlation holds up in further research, more widespread testing and earlier treatment could mean greater earning potential for individuals—and, especially for some countries in Africa where HIV infection rates top 15 percent of the adult population, a better economic outlook for entire regions.

Earlier research suggested that people who take antiretroviral therapy (ART) to manage their HIV feel better and are able to work more. But Harsha Thirumurthy, a health economist at University of North Carolina at Chapel Hill's Gillings School of Global Public Health, wanted to know more specifically if an individual's CD4 (helper T immune cell) counts correlate with how much that person is able to work. If people miss a lot more work not just when they have full-blown AIDS, but even when their counts are only moderately low, it would be more reason to test people more widely—and start them on medication sooner.

Thirumurthy's group launched a weeklong public health campaign in a rural Uganda town of about 3,000 people. Most residents worked on farms. The labor is physically demanding, and illness often prevents a farmer from tending the fields. Not only does that directly impact a family's livelihood, it has an effect on children. When adults are not healthy enough to work, they often recruit any household children between the ages of 12 and 18, who then miss school.

Of the people who were tested, about 7.8 percent were HIV positive, and their CD4 status had a surprisingly large impact on how much they were able to work. Uninfected adults typically have CD4 counts from 500 to more than 1,000 (per cubic millimeter). This number falls during an HIV infection; the lower the value, generally, the worse a person's health. HIV-positive adults in the study with CD4 counts below 350 (the threshold for receiving antiviral treatment in Uganda), had "a big drop off" in hours worked each week, Thirumurthy says. Those who had CD4 counts below 200 worked, on average, 5.8 fewer days a month—the equivalent of more than a full workweek—than those with CD4 counts above 500. "The difference between those with high and low counts is bigger than we thought," Thirumurthy says.

Teenage children living in households where an adult had a CD4 count below 350 were 15 percent less likely to go to school. Missing these crucial years of education could lead, in turn, to reduced earning potential for them in the future. The research was funded by the National Institute of Allergy and Infectious Diseases (at the National Institutes of Health) and was part of the larger Sustainable East Africa Research on Community Health (SEARCH) Collaboration.

The study did not ascertain exactly why some people were less able to work, but the most likely culprits are other infections that sicken those with HIV-weakened immune systems more easily. Other factors might include mental and emotional strain and general malaise.

Other studies also have found that ARTs can improve a person's ability to make a living. Earlier this month, Sydney Rosen of Boston University's School of Public Health and her colleagues presented their research on how people on ARTs in South Africa seem to be doing both physically and economically over time. After five years of therapy, the proportion employed increased from 39 percent to 56 percent (compared to three months before starting therapy). The proportion who reported that their illness impaired their daily activities decreased from 42 percent to 4 percent.

The novelty of the Uganda study was the use of CD4 counts. But there is a caveat: the data come from a single point in time, rather than from following the individuals over a period. And that, Rosen says, introduces the possibility that confounding factors skewed the results. For instance, someone who is proactive in getting tested and obtaining treatment might be a  person who is likely to work more hours a week, anyway.

Even the choice of testing site might make the findings less applicable to other areas, Thirumurthy says. His team sampled a rural population where most adults had access to work through farming. In a large urban setting, such as Johannesburg or Kampala, where unemployment is high across the board, HIV status and CD4 counts might have a weaker correlation with how much a person is able to work.

Nevertheless, Rosen says, all of the recent studies "point to the same conclusion: that treatment is associated with better employment outcomes."

Thirumurthy and his colleagues are currently planning a five-year controlled trial to follow up and study this correlation over time. The trial will study multiple communities, some of which will continue receiving standard care (with treatment starting when CD4 counts dip below 350) and others of which will receive earlier treatment. They will then be able to track whether changes in an individual's CD4 status impacts economic status. These longer studies, Rosen notes, will check whether "starting treatment will forestall some of the negative impacts of [low] CD4 counts on employment." With more detailed data, the researchers should be able to provide more information about long-term health and economic gains of people living longer and potentially working more to measure against the cost of treatment.

A secondary lesson of the work by Thirumurthy and his colleagues was the impressive community response. During the weeklong campaign, 74 percent of the area's adults participated in testing. The program included testing and treatment for HIV as well as other infectious and noninfectious diseases. Nearly half of the people who tested positive for HIV had not previously been diagnosed. With such a large turnout rate, too, Thirumurthy and his colleagues also "were able to learn something about the entire population of HIV-infected adults" in an area, rather than just a subset as in other studies.

"There's so much interest in identifying people early—and possibly implementing early treatment, which is not the national policy yet" in Uganda, Thirumurthy says. Along with recent research showing that treatment can limit the infection's spread, the reasons to start therapy early seem to be growing.