On average, 5 percent to 20 percent of Americans will contract the flu this winter. Since it looks like many of us will be unable to get hold of a flu vaccine this year, it is crucial to recognize early symptoms of this viral respiratory infection and understand when to seek treatment.

The flu causes a whole host of unpleasant symptoms: fever, headache, extreme tiredness, dry cough, sore throat, runny or stuffy nose and muscle aches. Children may also experience gastrointestinal symptoms, although this is uncommon in adults.

The peak season for flu is late December through March, and it is important to be especially vigilant during this time. Toward this end, the Centers for Disease Control and Prevention has pulled together various fact sheets and patient and provider information at its Web site [url=http://www.cdc.gov/flu]http://www.cdc.gov/flu[/url]

Look and feel: The CDC’s flu site follows the same format as all government sites: exceptionally well-organized and a cinch to navigate. A search function is provided to quickly find your way to the content, and a vertical sidebar neatly outlines the key sections of information. English and Spanish versions of the content are available (as are seven other languages), and a toll-free number enables visitors to reach a representative from the CDC.

A quick tour: Visitors will find on the home page a list of the main sections of content, including direct links. For a quick overview of influenza, head to the area that focuses on key facts and other critical information. A Q&A portion gives answers to frequently asked questions, such as how to distinguish the flu from the common cold or other respiratory illnesses.

It’s also helpful to keep track of the impact of the current flu season, and the CDC site offers numerous tools in this regard. There is a weekly flu activity report tracking when, where and what types of influenza are circulating in the United States, and a weekly report on flu-related deaths in the United States.

Health care professionals will also find useful information on the site to aid in diagnosis and treatment of the flu. Tips on lab diagnosis, the biology of the illness, and medical references and resources are available, as are guides on how to help prevent influenza infection among health care workers.