Computer scientists at Johns Hopkins University determined that Twitter posts reveal key patterns and trends related to health, from which ailments are on the rise in certain areas of the country to which medicines are actually working.

Researchers fed 2 billion public tweets posted between May 2009 and October 2010 into computers and used software to filter out the 1.5 million messages that referred to health matters.

"Our goal was to find out whether Twitter posts could be a useful source of public health information and we determined that indeed they could," said computer scientist Mark Drezde. "In some cases, we probably learned things that even the tweeters' doctors were not aware of, such as which over-the-counter medicines the posters were using to treat their symptoms at home."

By sorting these health-related tweets into electronic "piles," patterns were uncovered about allergies, flu cases, insomnia, cancer, obesity, depression, pain and other ailments.

Although there have been some studies about how to use Twitter posts to track certain ailments such as the flu, using tweets to look at many health issues is new territory, the researchers said.

The researchers also discovered that some tweets even pointed to misuse of medicine.

"We found that some people tweeted that they were taking antibiotics for the flu," said computer scientist Michael J. Paul. "But antibiotics don't work on the flu, which is a virus, and this practice could contribute to the growing antibiotic resistance problems. So these tweets showed us that some serious medical misperceptions exist out there."

In about 200,000 of the health-related tweets, the researchers were able to draw on user-provided public information to identify the state from which the message was sent. That allowed them to track some trends by time and place, such as when the allergy and flu seasons peaked in various parts of the country.

"We were able to see from the tweets that the allergy season started earlier in the warmer states and later in the Midwest and the Northeast," Dredze said.

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