The spread of germs only gets worse as the winter goes on.

Public transit, schools, work environments, everywhere is teeming with bacteria from people who are suffering from a cold or flu.

But how long do you actually remain contagious for? Sometimes you think you're better, but then somehow someone in your family gets sick with the same thing you just had! How can that happen?

So how do you know when you've stopped being a germ-spreader? According to the Center For Disease Control, when you have a cold, you are contagious for 10 days. Though your risk of spreading your cold goes down as your symptoms go away, it still takes 10 days for the virus to completely leave your body.

The same goes with the flu. Expect to be contagious for 10 days. The flu is even more difficult to contain because it constantly evolves and makes it harder for your body to deal with it. This is why you can contract the flu every year. Normally, your body develops anti-bodies to fight the same virus, but the constant evolution doesn't let that happen.

So now you know how long to avoid your friends and family when someone is sick! No one wants to get the flu or a cold.