Google Flu Tracking System Suggests Flu Is Spreading

Google has released an experimental version of Google Flu Trends to track the spread of the swine flu in Mexico. Google on Monday said flu activity remained low, as seen by its flu tracking system, but the country-specific version published on Wednesday shows a spike in flu activity.

Google said that its system detected increases in flu-related queries in Mexico City and several other Mexican states during the April 19-25 time period.

At the same time, Google cautions that Experimental Flu Trends for Mexico is, as the name suggests, an experiment and that the data should be viewed as such.

"While we would prefer to validate this data and improve its accuracy, we decided to release an early version today so that it might help public health officials and concerned individuals get an up-to-date picture of the ongoing swine flu outbreak," explained Google engineers Jeremy Ginsberg and Matt Mohebbi in a blog post. "As with our existing Flu Trends system, estimates are provided across many of Mexico's states and updated every day."

Ginsberg and Mohebbi say that flu activity in the United States remains low, as might be expected given the relatively few cases reported in the country. But Google plans to continue its monitoring to look for rising infection.

Google introduced Google Flu Trends in November 2008 as a way to visualize the correlation between flu infections and flu-related search activity. Google maintains that searches provide an early warning about the spread of the flu because search data can be gathered and analyzed almost instantly, unlike traditional epidemiological reporting methods.

Ginsberg and Mohebbi explain that Google's "model tries to filter out search queries that are more likely associated with topical searches rather than searches by those who may be experiencing symptoms." Thus the spike shown in the graph on the Experimental Flu Trends for Mexico Web page should correlate with actual flu activity rather than searches prompted by worry.

As of 11 a.m. EDT, April 29, data from the Centers for Disease Control and Prevention indicates that 91 confirmed swine flu cases have been detected in the U.S. and that 1 person -- a child in Texas -- has died as a result of the outbreak.

Google planned to hold a media call at 11 a.m. PDT on Wednesday to field questions about its flu tracking project.