Chickenpox Health Article

Definition

Chickenpox (varicella) is a common and extremely infectious childhood disease that also occasionally affects adults. It produces an itchy, blistery rash that typically lasts about a week and is sometimes accompanied by a fever or other symptoms.

Description

About four million Americans contract chickenpox each year, resulting in roughly 5,000-9,000 hospitalizations and 100 deaths. 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. Once someone has been infected with the virus, symptoms appear in about 10-21 days. The period during which infected people can spread the disease is believed to start one or two days before the rash appears until all the blisters have formed scabs, usually four to seven days after the rash breaks out. For this reason, doctors recommend keeping children with chickenpox away from school for about a week.

Chickenpox has been a typical part of growing up for most children in the industrialized world (although this may change because of the new varicella vaccine). The disease can strike at any age, but by ages nine or 10 about 80-90% of American children have already been infected. U.S. children living in rural areas and many foreign-born children are less likely to be immune. Because almost every case of chickenpox leads to lifelong protection, adults account for less than 5% of all cases in the United States. Study results reported by the Centers for Disease Control and Prevention (CDC) indicate that more than 90% 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.

Causes & 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 a further 12-24 hours the spots typically become itchy, fluid-filled bumps called vesicles, which continue to appear 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 may also be found inside the mouth, nose, ears, vagina, or rectum. Some people develop only a few blisters, but in most cases the number reaches 250-500. 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 10 days after the first symptoms appear. The most severe cases of the disease tend to be found among older children and adults.

Some groups are at risk for developing complications, the most common of which are bacterial infections of the blisters, pneumonia, dehydration, encephalitis, and hepatitis. Immediate medical help should always be sought when anyone in these high-risk groups contracts the disease. These include:

• Infants. Complications occur much more often among children less 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. 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 birth defects.
• 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. The typical symptoms of chickenpox tend to strike this group with greater force.