Breaking the Chain

Martina Morris ’80 looks at sexual concurrency and HIV.

By Geoff Koch | March 1, 2012

The defining moment in Martina Morris’s professional career took place in Uganda in 1993. Fresh out of grad school, she was giving a talk to a small group of African academics and public health workers on her dissertation, which explored how age differences between sexual partners might be related to the spread of the HIV virus.

As she described the mathematical model she used in her research, a man in the audience abruptly stood up.

“Can your model handle people having more than one partner at a time?” he asked. 

No, Morris said, it couldn’t. In fact, she added, there was no mathematical model for overlapping partnerships, partly because it was difficult, but mostly because epidemiologists had never considered the issue relevant. Her answer evoked a startling reaction.

“He got up and walked out of the room,” she says. “This wasn’t a big lecture hall. Everybody saw it. So there was a long silence after he left, and then I just stumbled my way through the rest of my talk.” 

Afterwards, the field manager for the project Morris was working on pulled her aside. Many in Uganda were coming to believe that the practice of having concurrent sexual partners might be related to spread of the disease, the manager said.

At first, Morris was skeptical. It was well established that the spread of HIV was related to the number of sexual partners a person had over a given period of time. But who cared, epidemiologically speaking, if those partnerships overlapped? The issue seemed to have more to do with morality than with medicine. As she considered the question more deeply, however, she reached the startling conclusion that the issue of concurrency was fundamentally different from the number of partners—and that it might play a dramatic role in the spread of HIV.

The awkward experience left its mark on Morris, who is now a professor of both sociology and statistics at the University of Washington. Today there is a robust model describing the risks of concurrent sexual partnerships. Morris herself developed it. In a series of papers dating back to the mid-1990s, she has explained the model in great detail, along the way stirring up a surprising controversy.

Few dispute the basic facts on the ground about HIV in eastern and southern Africa, where more than 22 million people were living with HIV in 2009. Heterosexual sex remains the dominant mode of HIV transmission. The overall prevalence of HIV, though generally stable or falling, remains astonishingly high, at least by American standards: the prevalence in Uganda is estimated at 6.5%, in South Africa at 18%, and in Swaziland more than 25%. And these are figures for the general population. Specific groups, such as urban men aged 15–49, often show much higher prevalence, thousands of times the rate seen in developed nations. This vast difference cannot be explained by what’s generally seen as high-risk behavior: having lots of sexual partners, starting to have sex at an early age, and failing to use condoms. Survey after survey indicates that these behaviors aren’t all that more common in Africa than elsewhere in the world.

The issue is multifaceted for sure. In recent years, much attention has been paid to male circumcision, which does reduce the risk of HIV transmission and is not commonly practiced in Africa. Yet neither is the practice widespread in much of Europe, Asia, or Latin America, where prevalence of HIV is much lower.   

So what’s different?

One cultural norm that does seem to vary is the practice of having a small number of overlapping sexual partners. There are many scenarios, but the classic example is the husband who also keeps a mistress, or a “side dish,” as it’s known in Uganda. 

Data from a 2011 paper by Morris and colleagues in the journal PLoS ONE drive the point home. Among various groups of men surveyed in Uganda, anywhere from 27 to 32% admit to overlapping partnerships at some point in the last three years, the researchers report. In contrast, concurrency rates among men in the United States typically range from 9 to 23%, depending on race and ethnicity.

That may not sound like a big difference, but Morris’s research suggests that minor variations in sexual concurrence can lead to vast increases in overall transmission of HIV. The reasons are twofold. First, HIV is much more virulent in the early stages of infection, so the chance of transmitting the virus is higher in overlapping partnerships because the interval between sexual contact with different partners is considerably reduced. (No courtship or chocolates to slow things down.)

Second, in an overlapping partnership, you go back to your previous partner, exposing her or him to whatever you picked up in the meantime. Concurrence is not so much a risk to individuals (it has the same effect as multiple partners) as it is to their partners, who are unwittingly exposed to infection without ever engaging in risky behavior.

Take a theoretical group of people where the concurrency rate is 55% (not as unusual as you might like to believe). On any given day, roughly 2% of this group is sexually connected to a larger network, exposing them to infection. Now nudge the concurrency rate up to 63%. Suddenly, the vulnerable population jumps to 41%. Push concurrency to 65%, and the vulnerable population vaults to 64%. Minor changes in concurrency, in other words, have profound implications for the spread of the virus.

In sub-Saharan Africa, Morris believes, the elevated rates of concurrency create what amounts to an HIV superhighway, exposing vast numbers of people to infection.

“In a sense, what you have is a system like the interstate highways in the United States,” says journalist and public health consultant Helen Epstein, who coauthored the 2011 paper with Morris. “Each town isn’t connected to very many other towns, but you can get anywhere across the continent on that system.”

Perhaps the most significant aspect of Morris’s work is its corollary. If concurrency is the key to understanding the spread of HIV, concurrency is also the key to reducing it.

Nearly 2,500 miles, much of which can be traversed on Interstates 84 and 80, separate Portland from Cleveland, Ohio, where Morris grew up. Her first exposure to Reed came in the 10th grade when she visited her high school library and pulled the massive College Board catalog of all U.S. colleges and universities from the shelf.

Reed caught her eye for two central and somewhat contradictory elements of its reputation, both of which are still celebrated today. The college gave its students vast amounts of freedom—in loco parentis was apparently not in the vocabulary, despite the college’s longstanding tradition in classics. At the same time, Reed maintained a highly demanding academic environment.

“Well, actually there were three reasons, I guess,” says Morris. “It was about as far away from home as I could get.” 

Cleveland in the 1960s and ’70s was defined by social unrest and environmental disaster, including the infamous 1969 Cuyahoga River fire. The unfortunate “Mistake by the Lake” moniker seems to date to that era. This is perhaps why Morris was drawn to campuses known for their rigor and their beautiful settings. She considered Stanford and University of California, Santa Cruz, before deciding on Reed.

Morris proceeded to have what she says was a typical Reed experience in the 1970s. She dropped out twice, traveled to prerevolutionary Iran, hitchhiked through Europe, and studied dance in New York. More important, she was profoundly influenced by the notoriously demanding professor John Pock [sociology 1955–98]. She still remembers sitting in Sociology 210 and taking furious notes during his lectures.

“I was hooked, basically, from then on,” she says. “He is the reason I am where I am now... the things that he showed me remain important to me, to this day.”

Pock has vivid memories of his former student. “She was the kind of student that the founders of Reed were thinking about when they set up the college,” he says. “She never took the easy answer. She investigated. She wanted to find out how things worked instead of just writing down a pat response. I’m proud of her.”

Morris felt Pock’s pull even in New York during her encore as a dropout. She’d traveled east to study dance, but on a whim wound up taking a course at Columbia from Robert Merton, among the country’s most eminent sociologists.

“As soon as I got in his class, it was, like, ‘Oh, my God, of course this is what I want to do.’” she says.

At a Chock Full o’Nuts coffee shop at 116th and Broadway in Manhattan, across the street from Columbia, Morris figured out the topic of her Reed thesis, which she would eventually finish, under Pock’s guidance, in 1980. Why, she wondered, did all the leftist organizations from the 1960s, particularly the Students for a Democratic Society (SDS), eventually implode?

Her conclusion, relevant to the Occupy Wall Street movement today, was that the participatory democracy espoused by SDS is not a viable form of political organization. The only way it works, she found, is if individuals completely submit to the collective will, which of course is exactly the opposite of the reason people join such groups in the first place.

Morris, subject to withering attacks by colleagues in recent years, is not one to submit easily. Maybe studying the tumultuous activist movements of the ’60s inoculated her to this sort of criticism—or maybe it was defending her thesis before John Pock.

Both the tone and substance of the conflict were on full display on October 7, 2010. That was the day of a World Bank–sponsored debate on this simple proposition: concurrent sexual partnerships have been and remain a key driver of HIV epidemics in southern and eastern Africa, and interventions to this effect should receive the majority of prevention resources.

That proposition is the central focus of Morris’s recent professional life, so it was perhaps only natural that she spoke first. At the end of her opening statement, Morris calmly looked into the camera and summarized her reasoning: “Concurrency can have a dramatic impact on network connectivity and offers the possibility of large prevention impact.”

The debate was structured as a three-on-three format, and as other presenters stood to make their case or rebut others, it soon became clear that real passion and quite likely even personal animosity simmer just beneath the surface.  

Speaking via video conference from Johannesburg, South Africa, Brown University epidemiologist Mark Lurie all but accused Morris and other advocates of the concurrency hypothesis of shoddy work or even of outright lying, urging those in the audience to be wary of tricks and sleight of hand.

“You might believe that empirical evidence for concurrency is as rock solid as Mount Everest,” said Lurie. “In fact, rather than a mountain of evidence, the hypothesis rests on a very thin layer of ice.”

Lurie’s remarks are consistent with the stridency of the debate, which has been hashed out in academic journals in recent years. Stripped to its essentials, the criticism of the concurrency hypothesis is that there is little field evidence to support it: areas with high HIV prevalence do not always show high rates of concurrency, and areas with high rates of concurrency do not always have high HIV prevalence.

One big problem is that collecting reliable scientific data about sexual behavior is extremely difficult, especially in Africa, where levels of trust in the government are low. Surveys of sexual behavior are usually designed to be conducted in private. Respondents are supposed to be given assurances that their answers will be recorded anonymously. Epstein, Morris’s collaborator, who has seen several such surveys administered in Africa, says that in practice these guidelines are almost never followed.  

“Think about it,” Epstein says. “Someone comes to you with a questionnaire and says, ‘I’m from the government. I’d like to know how many sexual partners you have and when you’ve had them.’ People might be tempted not to answer honestly. I know I would.”  

Epstein, who earned a PhD in molecular biology from Cambridge before turning to journalism, prominently featured Morris in her 2007 book The Invisible Cure, which chronicled the catastrophic failure to reverse the AIDS epidemic in Africa. Convinced the concurrency hypothesis is correct and can save lives, Epstein has gone on to publish academic articles with Morris and speak on the topic to audien-
ces around the world years after the publication of her book, which the New York Times Book Review described as a “bolt of clarity from the blue.”     

“I guess I feel very strongly that she was right and that she’s been right for a long time,” says Epstein. “Until the rest of the world begins to really understand this and appreciate the meaning of this, and implement the right sorts of programs that I think really have a chance at success, I don’t think I can quite let it go.”

Morris, measured throughout her interview with Reed and in the World Bank debate, becomes animated when asked about the resistance to her work among American and European academics.   

“In some ways it’s a crime at this point that people are arguing that we shouldn’t even make this information available to people through a public health campaign,” she says.   

Reasons behind the vehemence of the attacks are difficult to pinpoint. One possibility, both Morris and Epstein suggest, is the rise of quantitative purists in the social and health sciences who insist on unrealistically precise data to plug into their increasingly powerful computer models. Another is concerns about moralizing to African audiences, sensitive after a long history of racial stereotyping dating back to the colonial-era missionaries. Still another is the self-serving behavior of Western scientists and aid agencies to find and trumpet data supporting work that’s most likely to be funded, including intervention programs focused on abstinence and condom usage.

Even while arguments continue among PhDs in the West, African governments and nonprofits have for years embraced the idea that concurrent partnerships pose real risk. And they’re trying to do something about it.

Reducing concurrent partnerships was identified as the number one priority for prevention at a 2006 meeting of the South African Development Community, which encompasses 15 member countries. Since then, various Africa-based public health information campaigns, relying on everything from traveling skits and billboards to Facebook and YouTube, have been making waves across the continent.

One example comes from the Uganda Health Marketing Group. Staffed by Ugandan public relations professionals and supported by the U.S. Agency for International Development, the organization won a series of awards in 2010 for its campaign titled “One Love—Get off the Sexual Network.” The goal: increase serial monogamy among the population by 5% by warning about the dangers of “side dishes” in relationships.

The campaign is blunt. In a January 2010 column for the Observer, an independent weekly newspaper based in Kampala, journalist Simon Kasyate wrote, “[T]his ‘sexual network’ campaign is really sending heavier jabs below the belt than initially anticipated. ‘Man, they have skits you don’t want to listen to when driving with your wife,’ a colleague said recently. ‘The guilt of the realism in the message makes you almost break down in confession.’”

Morris didn’t advise the campaign but says that in general she has been “remarkably impressed” by the locally planned and managed interventions focused on concurrency that have sprung up around sub-Saharan Africa, where the AIDS crisis remains widespread.  

In Kenya, where Morris is currently working on a small intervention and research project, AIDS deaths still number close to 100,000 per year, according to UNAIDS. In contrast, AIDS deaths in the United States, which has a population more than seven times that of Kenya’s, number less than 25,000.

Despite the staggering nature of numbers like these, and the difficulty of working halfway around the globe, Morris says there’s a strong sense of hope for the continent’s future among local Africans with whom she works. So, several times a year, she makes the arduous 24-hour flight from Seattle through Amsterdam to a major African city. In January 2012, that city was Nairobi, Kenya, home of one of her current collaborators, Kawango Agot.

“Martina is out in the field with us,” says Agot, director of Impact Research and Development Organization, a Kenyan NGO that develops public health programs aimed at the country’s vulnerable populations. “She spends the day drinking tea with women in villages, eating boiled maize, helping us push our vehicle when it gets stuck in the mud, and walking long distances when the roads become impassable. Then, when we get back to the office at night, she pulls out her laptop and works on these complex statistics.”

Those statistics seem likely to be a bone of contention among Western scientists for years to come. But perhaps not among everyday Africans. Evidence of this came on a recent Kenyan trip, when Morris had another memorable exchange with a local man with strong opinions about her work. 

During a focus group to plan an intervention campaign, Morris was attempting to explain the risks of concurrency by having people stand in a circle and hold hands. Each person, she noted, is linked to just two people, but the entire room is connected. (See right.)

In the middle of her explanation, one of the older men in the community stood up and asked to speak.

“This is the medicine we’ve been waiting for,” he said.

Geoff Koch is a writer in Portland. He wrote the cover story, “Growing the Curriculum,” in the December 2010 issue of Reed.


“Timing Is Everything: International Variations in Historical Sexual Partnership Concurrency and HIV Prevalence.” M. Morris, H. Epstein and M. Wawer. PLoS One. Nov. 24, 2010

Watch an animated simulation of how concurrency accelerates HIV.

Get Off the Sexual Network. AIDS prevention ad for Uganda TV.

The Side Dish Issue. P. Bakibinga. BBC World Service. Apr. 30, 2011.

“Sexual network ad grating on nerves,” by S. Kasyate. The Observer. Jan. 24, 2010. 

Tags: Alumni, Health/Wellness, Research