WEDNESDAY, Sept. 15 (HealthDay News) -- Social networks may help health officials predict epidemics of flu and other infectious diseases, according to new research.

Before the start of the 2009 flu season, researchers contacted a random group of 319 Harvard University undergraduates who, in turn, named a total of 425 friends. The health of students in the two groups was monitored through self-reporting and data from Harvard University Health Services.

On average, the flu appeared in the friends' group about two weeks before the random group when the researchers used one method of detection, and 46 days before the epidemic peak when they used another method.

The study was published Sept. 15 in the journal PLoS One.

"We think this may have significant implications for public health," Nicholas Christakis, a professor of medicine, medical sociology and sociology at Harvard, said in a university news release. "Public health officials often track epidemics by following random samples of people or monitoring people after they get sick. But that approach only provides a snapshot of what's currently happening."

Tracking groups of friends might work better, he said.

"By simply asking members of the random group to name friends, and then tracking and comparing both groups, we can predict epidemics before they strike the population at large. This would allow an earlier, more vigorous, and more effective response," Christakis said.

This method could even be used to predict the spread of behaviors such as drug use or the distribution of ideas or fashion trends, according to the researchers.

More information

The U.S. National Institute of Allergy and Infectious Diseases has more about influenza.