I thought this was an interesting post about colds and flu. There are more good links so go over if this interests you:
So, when are you most contagious? Most experts agree that adults with a cold or the flu start being contagious about a day before they start experiencing symptoms. For the flu, the contagious period then lasts five to seven days into the illness. For children, the contagious period for the flu can last up to two weeks after they start feeling sick, even if they start feeling better before that. The contagious period for a cold lasts about three to four days into the illness. As a general rule, people with a cold are most contagious about three days after their initial exposure to the virus.Also, you should know that the Chicken Pox Virus is contagious before you get a fever, it is airborne--which means all you need to do is breath the air, basically occupy the same space as a kid about to get sick and be exposed.
Hand washing and quarantine. Are you bored with me yet?