Viruses

Viruses like influenza and those that cause the common cold (there are a

couple of hundred of them) have an incubation period once get into your body. The

virus gets into a group of healthy cells and then goes about requisitioning their

survival apparatus from the inside. During this incubation period, while the virus

is multiplying inside those infected cells, you have no symptoms – no sore throat,

no runny nose, no achy muscles – and no virus spreading like wildfire throughout

your body so that every drop of saliva or mucous you produce contains it. And

that’s how a virus spreads from one person to another; By a healthy person coming

into contact with the bodily fluids of an infected person, whether those fluids are

airborne (as from a sneeze) or left on a doorknob by a sick person who just wiped

his nose. So if you have no symptoms yet, it’s a lot less likely that you’re going

to spread the virus to another person.


Once the cells that have been taken over by the virus start to die, that’s

when all hell breaks loose. Here’s when you start having symptoms, and you start

spreading it to everyone you know if you are not careful. Some of those symptoms

are caused by the virus itself (runny nose and sore throat, for example), and

others are caused by your immune system (fever and exhaustion, for throughout your

body, your immune system recognizes that something is wrong and begins its

counterattack. All of this can take days to happen. With the flu in particular, the

time between exposure and the onset of symptoms is usually between one and four

days.


So, when are you contagious? Most experts agree that adults with a cold or the

flu start being contagious period then last five to seven days into the illness.

For children, the contagious period for the flu 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.