Tracking Disease on Twitter

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(CNN) — Haitians started dying of cholera just 10 months after the country’s devastating earthquake. Researchers say health ministries might have responded more quickly had they seen evidence of the unfolding epidemic in an unlikely place: Twitter.

Putting all publicly-available tweets with the word “cholera” and the hashtag “#cholera” on a timeline, researchers at Harvard Medical School were able to show a surge in cholera-related tweets early in the epidemic. The timeline correlates closely with later health-ministry tallies.

The researchers used tweets from around the world – 65,728 total with the word “cholera” – that were sent between October 20 and November 3, 2010, including those that came from aid organizations and/or media outlets in Haiti and elsewhere.

The goal is to someday harness the immediacy of social media and use it to make better decisions early on about where to deploy public health resources, said Professor John Brownstein of Children’s Hospital Boston and co-founder of HealthMap.org, which aggregates global information about infectious diseases.

“You don’t have a lot of data about what’s happening in the population early on — even in the best of situations, even in the U.S., but especially in Haiti. So the idea is what other health information can you draw on to make assessments of the impact of the disease?” said Brownstein.

“So in this case, what we were able to show — and this is retrospectively of course — is that utilizing this data that’s coming out from these news and social media we can begin to understand the impact. Depending on how transmissible the strain is, it impacts what types of prevention that you do.”

So far, there’s no replacement for the traditional chain-of-command structure of public health that tallies and reports case numbers in an epidemic, but social media could be another tool in the toolbox for decision makers.

The next step is figuring out how it could work in real-time, instead of in hindsight.

“We found that there was better correlation between the social media and the official case numbers early on,” said Rumi Chunara, a research fellow at HealthMap.

The tweets didn’t coincide uniformly to official health numbers, but there were periods of time when they corresponded best – such as the first incident of the outbreak and then a hurricane which passed by Haiti a few weeks after the cholera epidemic began.

Cholera brings about a painful death, as quickly as within two to three hours, because of the amount of fluid and electrolytes that are lost. Symptoms are watery diarrhea, dehydration, nausea and vomiting.

The bacterial disease spreads through contaminated water. While it has largely been eradicated in the West, it has been known to come back during war or natural disasters when people are forced to live in crowded places without proper sanitation and clean water.

As of mid-December 2011, cholera had killed 7,000 people and infected 520,000 in Haiti, according to the Pan American Health Organization.

Medical workers continue to encounter about 200 new cases everyday, said Dr. Jon Andrus, deputy director of PAHO, which is part of the World Health Organization.

The best way to prevent cholera is to get clean water and better sanitation. Immediate treatment for the disease is necessary through re-hydration, intravenous fluids, antibiotics and zinc supplements.

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