Living World / Sex & Reproduction

The implications of the Northwestern studies are enormous. For one, they start to explain why Viagra doesn’t work for women, even though it stimulates blood flow to the genitals: The relationship between physiological arousal and sexual function is complicated. The results also offer important information to psychotherapists whose clients are struggling with sexual issues. “Because we have a male model of sexuality, women who don’t fit that model feel they’re different or weird,” says University of Utah psychologist Lisa Diamond. The new findings may help clinicians whose female patients are confused by their erotic reactions to the “wrong” sex, for example.

 The other research tier involves looking at networks of people rather than individuals. “Nothing occurs in a vacuum,” says Alan Leshner, head of the American Association for the Advancement of Science. “The more we learn about the context of risky behavior, the more we can develop strategies for dealing with its consequences.” Epidemiologists now talk about syndemics—sets of interlocking afflictions (such as AIDS, violence, and substance abuse) that affect entire communities. By studying the social forces that bind these ills together, “you can really push the boundaries of public health,” says Dale Stratford, a medical anthropologist at the Centers for Disease Control and Prevention in Atlanta.

NIH is funding researchers to look at risk behavior in many communities: Hispanic immigrant men who live thousands of miles from their wives, teens who cruise the Internet for pornography, Thai and Vietnamese women who work in San Francisco brothels. Each group presents specific health challenges. At the University of Washington, Karina Walters, an associate professor of social work, is studying American Indian “two-spirits,” who consider themselves a blend of male and female. (Many are gay or bisexual.) HIV is spreading through American Indian communities “on the scale of some small African countries,” she says, and men who have sex with other men are at particularly high risk. Walters has uncovered a syndemic of violence, substance abuse, and psychiatric problems among two-spirits and is now conducting extensive interviews to determine the underlying causes. She’s also exploring whether those with a stronger sense of their indigenous identities are less likely to participate in unprotected sex, drinking, and gangs.

Because much of this work involves interviews and observation rather than microscopes and petri dishes, it’s not always recognizable as hard science. It is science nonetheless. “Science is a way of obtaining knowledge through a systematic collection of data and testing of hypotheses,” says Christine Bachrach, chief of the demographics and behavioral sciences branch at the NIH’s National Institute of Child Health and Human Development. “In some studies, you draw blood and hook people up to machines. In other studies, you might need to map out the sexual ties that person A has with person B and that person B has with person C.”

Precisely this connect-the-dots method led to one of the most significant public-health breakthroughs of the past quarter century: In the early 1980s, epidemiologists studied the sexual and social connections among a group of gay men on both U.S. coasts who were developing fatal cases of Pneumocystis carinii pneumonia and Kaposi’s sarcoma. Their diagrams led them to realize that the cases were manifestations of an infectious disease spread by sexual contact—what we now call AIDS. Since then, network mapping has helped public-health officials control disease outbreaks throughout the United States. They learned, for instance, that tuberculosis was being spread in Kansas when crack cocaine users blew smoke (along with water droplets containing the TB bacterium) into one another’s mouths. This allowed TB-control experts to better identify people for screening and prevention. By identifying and targeting social networks, health researchers have also designed education campaigns that reduced needle sharing in Baltimore and unprotected anal sex in Louisiana and Mississippi and increased the use of modern contraceptives in Bangladesh.

“It’s not rocket science,” NIH’s Bachrach says. “It’s harder than rocket science, because what we see in the real world is the result of very complex forces. One of the challenges in observational science is sorting out what leads people to behave in the way they do.”

NIH officials were delighted when Apostolopoulos’s grant proposal arrived in January 2002. Except for a small project in the 1990s by Dale Stratford, little research had been done on American long-haul drivers and sexual health. “We knew from studies in Africa that truckers have played a role in the spread of HIV,” Bachrach says. “In the United States, the epidemic started on a different foot, so we never paid attention to the role of truckers. Yet truckers can bridge from one risk group to another, as well as bridging to the folks they’ve left at home.”

Apostolopoulos had come recently to health research. He earned his Ph.D. in sociology, studying the economic impact of tourism in his native Greece. That work spawned an interest in other mobile populations. Reviewing the literature, he discovered that few scientists had explored migration and health in any depth. This perplexed him. “Over a billion people are moving constantly in the world,” he says. “How can we study disease if we don’t study those people who are connecting high-prevalence and low-prevalence regions?”