Influenza (the flu) is a serious contagious respiratory illness caused by influenza viruses. Millions of people in the United States get the flu each year. Most people are sick for about a week. Some people (especially young children, pregnant women, older people, and people with chronic health problems) can get very sick and may die from the flu.

Google.org publishes Experimental Flu Trends for Mexico to help track swine flu, more....

To learn more about the research behind Google Flu Trends, please read Detecting influenza epidemics using search engine query data, published by Nature. To further explore the data behind Google Flu Trends you can download CSV spreadsheets containing Google Flu Trends estimates going back to 2003 for the United States and recent estimates for Mexico.