Chickenpox Health Article

Definition

Chickenpox (also called varicella) is a common, extremely infectious, rash-producing childhood disease that also affects adults on occasion.

Description

Chickenpox is caused by the varicella-zoster virus (a member of the herpes virus family), which is spread through the air or by direct contact with an infected person. It produces an itchy, blistery rash that typically lasts about a week and is sometimes accompanied by a fever or other symptoms. A single attack of chickenpox almost always brings lifelong immunity against the disease. Because the symptoms of chickenpox are easily recognized and in most cases merely unpleasant rather than dangerous, treatment can almost always be carried out at home. Severe complications can develop, however, and professional medical attention is essential in some circumstances.

Once someone has been infected with the virus, an incubation period of about 10 to 21 days passes before symptoms begin. The period during which infected people are able to spread the disease is believed to start one or two days before the rash breaks out and to continue until all the blisters have formed scabs, which usually happens four to seven days after the rash breaks out but may be longer in adolescents and adults. For this reason, doctors recommend keeping children with chickenpox away from school for about a week. It is not necessary, however, to wait until all the scabs have fallen off.

Prior to the use of the varicella vaccine, chickenpox was a typical part of growing up for most children in the industrialized world. The disease can strike at any age, but throughout the twentieth century by ages nine or ten about 80 to 90 percent of American children had already been infected. U.S. children living in rural areas and many foreign-born children were less likely to be immune. Study results reported by the Centers for Disease Control and Prevention (CDC) indicate that more than 90 percent of American adults are immune to the chickenpox virus. Adults, however, are much more likely than children to suffer dangerous complications. More than half of all chickenpox deaths occur among adults.

Demographics

Before the varicella vaccine (Varivax) was released for use in 1995, nearly all of the 4 million children born each year in the United States contracted chickenpox, resulting in hospitalization in five of every 1,000 cases and 100 deaths. Because almost every case of chickenpox, no matter how mild, leads to lifelong protection against further attacks, adults account for less than 5 percent of all cases in the United States.

Causes and symptoms

A case of chickenpox usually starts without warning or with only a mild fever and a slight feeling of unwellness. Within a few hours or days small red spots begin to appear on the scalp, neck, or upper half of the trunk. After another 12 to 24 hours the spots typically become itchy, fluid-filled bumps called vesicles, which continue to appear in crops for the next two to five days. In any area of skin, lesions of a variety of stages can be seen. These blisters can spread to cover much of the skin, and in some cases also may be found inside the mouth, nose, ears, vagina, or rectum. Some people develop only a few blisters, but in most cases the number reaches 250 to 500. The blisters soon begin to form scabs and fall off. Scarring usually does not occur unless the blisters have been scratched and become infected. Occasionally a minor and temporary darkening of the skin (called hyperpigmentation) is noticed around some of the blisters. The degree of itchiness can range from barely noticeable to extreme. Some chickenpox sufferers also have headaches, abdominal pain, or a fever. Full recovery usually takes five to ten days after the first symptoms appear. Again, the most severe cases of the disease tend to be found among older children and adults.

Although for most people chickenpox is no more than a matter of a few days' discomfort, some groups are at risk for developing complications, the most common of which are bacterial infections of the blisters, pneumonia, dehydration, encephalitis, and hepatitis. Some of the groups at greater risk are:

• Infants: Complications occur much more often among children younger than one year old than among older children. The threat is greatest to newborns, who are more at risk of death from chickenpox than any other group. Under certain circumstances, children born to mothers who contract chickenpox just prior to delivery face an increased possibility of dangerous consequences, including brain damage and death. If the infection occurs during early pregnancy, there is a small (less than 5%) risk of congenital abnormalities.
• Immunocompromised children: Children whose immune systems have been weakened by a genetic disorder, disease, or medical treatment usually experience the most severe symptoms of any group. They have the second-highest rate of death from chickenpox.
• Adults and children 15 and older: Among this group, the typical symptoms of chickenpox tend to strike with greater force, and the risk of complications is much higher than among young children.

Immediate medical help should always be sought when anyone in these high-risk groups contracts the disease.