Chickenpox Facts

Chickenpox is one of the most common childhood illnesses. Before the vaccine was approved in March, 1995, there were 4 million cases of it appearing in the United States every year. In fact, 95 percent of adults in America today had chickenpox before the age of 18. It occurs most often in the late winter/early spring and in children between the ages of 6 and 10.

Chickenpox is caused by Varicella zoster virus and is highly contagious. About 90 percent of people who never had chickenpox (or the vaccine) will catch it if a family member has it. A person with chickenpox is contagious from one to two days before the rash starts until about five days after the rash appears. It can be spread by direct contact (through lesions or sores) or through the air. Children with chickenpox have to stay home from childcare or school until they are no longer contagious.

A child who catches chickenpox may not show symptoms for 10 to 21 days after being exposed to the virus. At that point, the characteristic symptom usually appears -- an itchy rash, which usually develops first on a child's scalp and body, and then spreads to his face, arms, and legs over the next three to four days. In total, a child with chickenpox will have 250 to 500 itchy blisters that dry up into scabs two to four days later.

While the rash is the most well-known symptom of chickenpox, it's not the only one. Here are some other symptoms that often accompany chickenpox:

• A mild fever for one or two days before the rash appears
• General malaise
• Coughing
• Fussiness
• Lack of appetite

Once someone has had chickenpox, the virus stays in her body permanently. This is usually a form of immunity -- she will probably never suffer from chickenpox again. But in about 10 to 20 percent of the population, the virus will reappear later in life (usually over the age of 50) and cause shingles. Shingles typically causes numbness and itching or severe pain in various areas of the skin. Within three to four days, clusters of blister-like sores develop and last for two to three weeks.