Enlarge NICHOLAS KAMM/AFP/Getty Images

Two women check their cell phones as they hawk their wares on a bridge over the Artibonite river, whose waters are believed to be the source of Haiti's 2010 cholera outbreak.

NICHOLAS KAMM/AFP/Getty Images

Two women check their cell phones as they hawk their wares on a bridge over the Artibonite river, whose waters are believed to be the source of Haiti's 2010 cholera outbreak.

The year 2010 was a very bad one for Haiti. It started with an earthquake that killed over 300,000 people, mostly in the crowded capital of Port-au-Prince. After that, cholera originating in a U.N. camp broke out in a northern province and eventually spread to the city.

But public health researchers learned something useful from the tragedy: Cell phones can help stem an unfolding epidemic and funnel aid to the needy.

Shortly after the quake, Linus Bengtsson at Sweden's Karolinska Institute helped put together a team to capitalize on Haiti's cell phone system. "When people start to move around, as they often do after a natural disaster, it's very difficult to know where to deliver supplies," Bengtsson says.

 

But about a third of Haiti's population have cell phones. So Bengtsson and colleagues collaborated with the cell phone company Digicell to track calls by the SIM cards in the phones.

The phone owners remained anonymous, but their whereabouts showed that some 600,000 fled Port-au-Prince within three weeks of the quake. That relieved pressure on aid groups in the city, but not for long. Soon, the phone maps showed that most of those refugees returned because there was no food in the countryside.

While the quake experience was more a proof of principle for disaster relief, the team actually got results when they applied their tracking system to the cholera epidemic months later. The researchers describe their experiment in the journal PLoS Medicine.

Team member Richard Garfield of Columbia University says they tracked people leaving the epicenter of the epidemic, near the city of St. Marc. They wanted to alert medics to go where infected people might carry the disease. It worked, Garfield says.

"The second wave of cases did appear exactly in the areas where most of the population was moving to...out of the cholera zone," Garfield says.

In addition to trying to point health teams where the epidemic would spread, the cell phone trackers also sent health advice to Haitians via text or voice mailâ€"things like, wash your hands frequently, get oral rehydration if you get sick, and continue to breast feed infected babies.

People who track infectious diseases say the technique should work for other outbreaks. "I think it's incredibly beneficial," says Andrew Tatem, who studies malaria at the University of Florida. "I think we're seeing a glimpse into the future of gathering information for disaster management."