Summer 2017

Hot Spot Hunting

To target hepatitis C prevention efforts, researchers had to find areas where transmission risk was the highest.

By Genevieve Rajewski

The opioid crisis shows few signs of slowing, with unintentional overdose deaths quintupling between 2000 and 2016 in Massachusetts alone. Meanwhile, as people who are addicted increasingly turn toward injectable street drugs—heroin now kills more Americans than prescription painkillers —two infections linked to the sharing of dirty needles have also reached epidemic levels: hepatitis C, a potentially fatal liver disease, and bacterial endocarditis, a once-rare and life-threatening heart infection.

An estimated 3.2 million Americans have hepatitis C, which can lead to cirrhosis and liver cancer and costs tens of thousands of dollars per patient to treat. The scope of the problem is vast, but public-health funding to solve it is not. That’s why Thomas Stopka, an assistant professor of public health and community medicine at Tufts School of Medicine, recently led an innovative study to identify locations in Massachusetts where targeted efforts to combat hepatitis C might have an outsized impact.

Stopka’s team, including colleagues from the School of Medicine, the Massachusetts Department of Public Health and Brown University, compared three separate kinds of data: more than 84,000 reports of hepatitis C infection between 2002 to 2013, sociodemographic data from 1,464 census tracts and hyperlocal information, such as whether communities had programs that supply clean syringes.  After geostatistical cluster analyses, the team could map not just hot spot areas with the highest number of hepatitis C cases—and the highest rates of infection—but also places where the chances of passing on the disease were higher than average.  “Our analyses allow us to assess the geospatial relationships, patterns and trends that actually reveal where there’s truly a larger burden of disease,” Stopka explained. “And potentially more risk for transmission.”

The study, published in BMC Infectious Disease, found that census tracts around Boston, New Bedford and Springfield had the most significant rates of infection per 100,000 people. (At the time of the study, New Bedford and Springfield both lacked syringe-exchange programs; New Bedford recently authorized one.) The researchers also found high densities of disease in the smaller cities of Lawrence, Holyoke and Fitchburg, where results showed between 477 and 1,070 hepatitis C cases per square mile.

The researchers hope that their novel analysis of existing data will inform efforts to target public-health spending in the places where it can have the greatest impact. Fast-acting drugs that treat hepatitis C have been available since 2013—“They have amazing cure rates,” Stopka said, “greater than 95 percent in most populations”—yet they’re extremely expensive. Knowing the location of hepatitis C hot spots may help secure funding for treatment and prevention campaigns in those areas, treating people before they can infect others.

He has been working with communities affected by substance abuse for almost 20 years, ever since Stopka coordinated a government-funded study that put him in contact with people at risk of contracting HIV and hepatitis C through injection drug use. “Doing this work, you get to know people who are infected and affected by the virus,” he said. “And it’s hard to turn your back once you do.”

Genevieve Rajewski can be reached at 

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