What is Chicken Pox?

Chickenpox is a common illness among kids, particularly those under age 12. An itchy rash of spots that look like blisters can appear all over the body and may be accompanied by flu-like symptoms. Symptoms usually go away without treatment, but because the infection is very contagious, an infected child should stay home and rest until the symptoms are gone.

Chickenpox is caused by the varicella-zoster virus (VZV). Kids can be protected from VZV by getting the chickenpox (varicella) vaccine, usually between the ages of 12 to 15 months. In 2006, the Centers for Disease Control and Prevention (CDC) recommended a booster shot at 4 to 6 years old for further protection. The CDC also recommends that people 13 years of age and older who have never had chickenpox or received chickenpox vaccine get two doses of the vaccine at least 28 days apart.

A person usually has only one episode of chickenpox, but VZV can lie dormant within the body and cause a different type of skin eruption later in life called shingles (or herpes zoster). Getting the chickenpox vaccine significantly lowers your child's chances of getting chickenpox, but he or she may still develop shingles later.

Symptoms of Chickenpox
Chickenpox causes a red, itchy rash on the skin that usually appears first on the abdomen or back and face, and then spreads to almost everywhere else on the body, including the scalp, mouth, nose, ears, and genitals.

The rash begins as multiple small, red bumps that look like pimples or insect bites. They develop into thin-walled blisters filled with clear fluid, which becomes cloudy. The blister wall breaks, leaving open sores, which finally crust over to become dry, brown scabs.

Chickenpox blisters are usually less than a quarter of an inch wide, have a reddish base, and appear in bouts over 2 to 4 days. The rash may be more extensive or severe in kids who have skin disorders such as eczema.

Some kids have a fever, abdominal pain, sore throat, headache, or a vague sick feeling a day or 2 before the rash appears. These symptoms may last for a few days, and fever stays in the range of 100°–102° Fahrenheit (37.7°–38.8° Celsius), though in rare cases may be higher. Younger kids often have milder symptoms and fewer blisters than older children or adults.

Typically, chickenpox is a mild illness, but can affect some infants, teens, adults, and people with weak immune systems more severely. Some people can develop serious bacterial infections involving the skin, lungs, bones, joints, and the brain (encephalitis). Even kids with normal immune systems can occasionally develop complications, most commonly a skin infection near the blisters.

Anyone who has had chickenpox (or the chickenpox vaccine) as a child is at risk for developing shingles later in life, and up to 20% do. After an infection, VZV can remain inactive in nerve cells near the spinal cord and reactivate later as shingles, which can cause tingling, itching, or pain followed by a rash with red bumps and blisters. Shingles is sometimes treated with antiviral drugs, steroids, and pain medications, and in May 2006 the Food and Drug Administration (FDA) approved a vaccine to prevent shingles in people 60 and older.

Contagiousness
Chickenpox is contagious from about 2 days before the rash appears and lasts until all the blisters are crusted over. A child with chickenpox should be kept out of school until all blisters have dried, usually about 1 week. If you're unsure about whether your child is ready to return to school, ask your doctor.

Chickenpox is very contagious — most kids with a sibling who's been infected will get it as well, showing symptoms about 2 weeks after the first child does. To help keep the virus from spreading, make sure your kids wash their hands frequently, particularly before eating and after using the bathroom. And keep a child with chickenpox away from unvaccinated siblings as much as possible.

People who haven't had chickenpox also can catch it from someone with shingles, but they cannot catch shingles itself. That's because shingles can only develop from a reactivation of VZV in someone who has previously had chickenpox.