It seems logical that in areas where people are suffering from the flu that more search terms about the flu would roll into Google Search. So Google Trends has taken data from search inquiries related to the flu and made a map.
Of course, not every person who searches for "flu" is actually sick, but a pattern emerges when all the flu-related search queries from each state and region are added together. We compared our query counts with data from a surveillance system managed by the U.S. Centers for Disease Control and Prevention (CDC) and discovered that some search queries tend to be popular exactly when flu season is happening. By counting how often we see these search queries, we can estimate how much flu is circulating in various regions of the United States.
At the site you can mouseover a state and see how active flu searches are. Kentucky is labeled as moderate, so I'd better get my flu shot! Link -Thanks, Jefffss!