Working modeler

One day in late 2004, television art director Karen Steward visited the penthouse floor of a glass office building in Los Angeles to sit down with UCLA epidemiologist Sally Blower and the half dozen members of Blower's Disease Modeling Group and talk about television. Steward was enlisting Blower's scientific expertise for the third episode of the CBS drama NUMB3RS, in which an FBI agent's brother uses mathematical models to determine the origin of a mysterious outbreak of Spanish flu. Presenting the multicolored script, "I asked her to show me graphics on her computer screen that show how to track a disease from one place to another. She just laughed at me," Steward recalls. Related Articles A New Dynamic New hope for HIV microbicide Implementing Change That's because the crux of tracking disease lies in relatively simple equations, which Blower drew out and explained for Steward on a large white board. Steward was "blown away" by Blower's thoroughness and enthusiasm. But the equations—which include parameters such as how long the infection lasts in one person and how many susceptible people that person contacts—were apparently too simple for Hollywood. "She wanted pretty math," Blower recalls. "So we ended up writing down equations for them that really didn't have anything to do with what they were saying." For the last two decades, Blower has applied her predictive models to a diverse array of disease scenarios, including a recent, controversial paper that suggested a vaginal microbicide against HIV could surprisingly benefit men more than women. That an increasing number of public health experts are starting to welcome the predictions of mathematical models "has been very satisfying," Blower says. But not all scientists side with Blower's models, arguing that reality (and not just TV) is significantly more complex than what she presents in her equations. Last July, Blower published a model showing that widespread use of vaginal microbicides—an antiretroviral therapy that was designed to help prevent HIV infection in women—could do more for men than women, and increase the risk of drug resistance in women who are already infected with the virus (PNAS, 105:9835-40, 2008). Microbicide experts took issue with the model's real-world relevance. "In some way, we felt like they slightly missed the point," says Lori Heise, director of the Global Campaign for Microbicides, in Washington, D.C, who published these concerns in a November letter to PNAS (105:E73, 2008). It's not clear whether the microbicides are absorbed in the bloodstream, where drug resistance would occur, Heise says. Plus, in order for men to benefit from the microbicide, it would have to protect them from an HIV-positive woman, she adds. "There's not much biological plausibility at this point to know that that would be the case," Heise says. (Blower and her co-authors argue that the model's conclusions hold even if antiviral microbicides do not protect men from infected women.) "I have not felt that there was a high degree of credibility [in some of Blower's work] mainly because some of the clinical and biological underpinnings or assumptions in her work just were not particularly realistic in my view," says Ron Gray, a reproductive epidemiologist and HIV specialist at the Johns Hopkins Bloomberg School of Public Health. Seventeen other international experts in infectious disease modeling declined to talk about Blower's research. Three cited specific unpleasant personal or professional interactions with her. (Some scientists did speak positively about her work.) In 2000, after circulating an email to several colleagues that accused the University of California, San Francisco (UCSF) of gender discrimination, Blower moved to the UCLA biomathematics department. Four years later, the heads of that department charged Blower with "verbal abuse, false statements, disparagement, and harassment of faculty," according to a news report in Science. Shortly after, Blower moved to UCLA's Semel Institute for Neuroscience and Human Behavior, and in 2006, the University and Blower settled the dispute. In a statement, Blower admitted her behavior was "at times inappropriate" and that her disparaging statements about the Department of Biomathematics and the University were "unwarranted," and all parties involved agreed to make no further public comments. "She's a controversial figure, but I've always thought that she was one of the smartest people that I've interacted with," says Philip Hopewell, a professor of medicine at UCSF who helped Blower determine realistic parameters for models of tuberculosis transmission. "I don't think her work is any more controversial than any other modeler's work. [Modeling] is intrinsically dependent on the assumptions used."

Working modeler

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