Flu sufferers can be contagious the day before they start showing signs of the virus.
You're generally most infectious during the first two to three days of the illness.
Experts say you can head back to work or school when you've been fever-free for a full 24 hours.
Flu experts agree that this season is shaping up to be nasty in the US. In California alone, 27 people under the age of 65 have died from the flu, and 26 states (plus New York City) are now reporting high flu...