In Box

The Changing Face of AIDS

The people most at risk today are not always who you'd expect.

South African President Thabo Mbeki famously asserted that poverty -- not HIV -- causes AIDS. Mbeki's claim may have been dangerous pseudoscience (one Harvard University study blamed his government's AIDS policies for at least 330,000 deaths), but he was right that socioeconomic factors play a major role in the transmission of the virus. Poverty does affect the spread of HIV, but in a more complicated way than was previously thought.

A recent study by Ashley M. Fox of the Mount Sinai School of Medicine compares rates of HIV infection across 170 regions in 16 sub-Saharan African countries. Surprisingly, she found that in the poorest regions, it was richer people who were more likely to be infected with HIV, while in wealthier regions, the poor were more at risk.

The reason, she argues, is that AIDS acts more like a chronic condition, such as obesity, than the infectious disease it is. In Ethiopia, for example, the wealthy are more likely to be overweight, a result of more affluent lifestyles and a greater array of food choices. In the United States, however, the poor are less educated about nutrition and eat lower-quality food, increasing their obesity risk. AIDS, says Fox, works in a similar way. Wealthy people in developing countries tend to have more sexual partners and are also more likely to be mobile, traveling to cities for work and coming into contact with the virus. The effect, however, tends to even out once the disease becomes more common, as the wealthy adopt safer habits -- while poorer people, with less education and access to condoms, are more vulnerable.

Fox's research focused only on developing countries, but it might hold true in richer countries as well. In the 1980s, AIDS in the United States was often described as a uniquely "democratic" disease, affecting all social classes, but today it's considered a disease of the poor. In low-income urban communities, Americans living below the poverty line are twice as likely to be infected, according to a recent Centers for Disease Control and Prevention report.

In the three decades since it was identified, AIDS has gone through a remarkable socioeconomic mutation, from a condition closely identified with gay men in urban areas of the United States to one synonymous with poverty in the developing world. Fox's data suggest that despite more than 30 million deaths over the past 30-odd years, it's still a disease we don't understand very well.

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In Box

Lean Times

Do people live longer during recessions?

No one enjoys being short of cash, stressed about finding a job, or worried about the future. And you might think that cutting back on things like regular doctor visits, leisure activities, and nutritious food would make people less healthy. It turns out, however, that people are actually more likely to live longer during hard times.

In a 2000 paper published in the Quarterly Journal of Economics, economist Christopher Ruhm found that in the United States, a 1 percentage point increase in a state's unemployment rate brings a 0.5 to 0.6 percent decrease in its mortality rate. The largest impact was on 20- to 44-year-olds -- who saw a 2 percent decrease -- while the elderly saw a slight decrease as well.

For young people, the main factors driving the decrease are reductions in motor vehicle accidents, suicide, and homicide. According to Ruhm's research, people tend to smoke less and lose weight during economic downturns (those cigarettes and foie gras are expensive) and get more physical activity and sleep (more walking, less partying).

Some evidence suggests the trend holds internationally too. In a 2006 study Ruhm found that across OECD countries -- the world's most developed -- mortality increases 0.4 percent when unemployment decreases 1 percentage point. And in a paper published this year, economists Hideki Ariizumi and Tammy Schirle of Ontario's Wilfrid Laurier University compared the U.S. data to trends in Canada. Similar to findings for the United States, they discovered a 0.53 percent reduction in mortality rates for every 1 percentage point increase in unemployment, largely due to big drops in mortality among 20- to 44-year-olds, indicating the trend holds despite differences in health-care systems.

So maybe there's a bright side for all those job seekers: Life may be hard right now, but you'll probably have more time to live it.

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