Scientists at Brigham Young University say posts on Twitter could be helpful to health officials looking for a head start on flu outbreaks.

In a study, published in the Journal of Medical Internet Research, the scientists sampled 24 million tweets from 10 million unique users. They determined that accurate location information is available for about 15 percent of tweets – gathered from user profiles and tweets that contain GPS data. That’s likely a critical mass for an early-warning system that could monitor terms like ‘fever,’ ‘flu’ and ‘coughing’ in a city or state.

“One of the things this paper shows is that the distribution of tweets is about the same as the distribution of the population so we get a good representation of the country. That’s another nice validity point especially if you’re going to look at things like diseases spreading,” said study co-author Prof Christophe Giraud-Carrier.

The team found surprisingly less data than they expected from Twitter’s feature that enables tweets to be tagged with a location. They found that just 2 percent of tweets contained the GPS info. That’s a much lower rate than what Twitter users report in surveys.

“There is this disconnect that’s well known between what you think you are doing and what you are actually doing,” Prof Giraud-Carrier said.

Location information can more often be found and parsed from user profiles. Of course some people use that location field for a joke, i.e. “Somewhere in my imagination” or “a cube world in Minecraft.” However, the researchers confirmed that this user-supplied data was accurate 88 percent of the time. Besides the jokes, a portion of the inaccuracies arise from people tweeting while they travel.

The net result is that public health officials could capture state-level info or better for 15 percent of tweets. That bodes well for the viability of a Twitter-based disease monitoring system to augment the confirmed data from sentinel clinics.

“The first step is to look for posts about symptoms tied to actual location indicators and start to plot points on a map,” said lead author Scott Burton. “You could also look to see if people are talking about actual diagnoses versus self-reported symptoms, such as “The doctor says I have the flu.”

Study co-author Prof Josh West said: “speed is the main advantage Twitter gives to health officials.”

“If people from a particular area are reporting similar symptoms on Twitter, public health officials could put out a warning to providers to gear up for something,” he added. “Under conditions like that, it could be very useful.”

_______

Bibliographic information: Burton SH et al. 2012. “Right Time, Right Place” Health Communication on Twitter: Value and Accuracy of Location Information. J Med Internet Res 14 (6): e156; doi: 10.2196/jmir.2121