What are the signs of chickenpox, and how long is my child contagious?

Q: How long is a child contagious after breaking out with chickenpox? When is it safe for them to be around others?

What are the signs of chickenpox, and how long is my child contagious?
What are the signs of chickenpox, and how long is my child contagious?

A: Nancy Snyderman, M.D., F.A.C.SO: Chickenpox is contagious until all the sores have crusted over. That is usually about four or five days from the first appearance of the rash. The child should stay home and away from other children during that time. It is also a good idea to keep the sick child away from any adults, especially pregnant women, who have never had chickenpox.

Considered highly contagious, chickenpox spreads very easily through close contact. Anyone who has not had it before can get it by direct contact with the bumps, called vesicles. You can also get it just from being near an infected person who coughs or sneezes, spreading the germs into the air in invisible droplets.

Three to four million people in the United States get chickenpox every year, most of them children. In the evolutionary sense, viruses have to be pretty cagey to survive and to become as prevalent as chickenpox, the varicella-zoster virus. The spread of this disease would probably be reduced if it were only contagious aft! ! er the rash broke out, because then you could just steer clear of anyone with visible symptoms. But chickenpox is contagious for about two days before the rash appears.

The total infectious period can be as much as a week — two days before and five days after the rash begins. For families with two or more children who have never had chickenpox, there can be a protracted cycle of illness. That is because there is an incubation period of 10 to 21 days between the time that you catch the virus and the time that you get sick. So just as one child is recovering, the siblings may be just starting to get ill. It can add up to quite a bit of missed work for some parents.

There is a vaccine, but the chickenpox vaccine is not 100 percent effective. Sometimes children who have been immunized against it will come down with chickenpox during a local epidemic. But when they do, it is usually a very mild case.