Chickenpox (Varicella)

Varicella (chickenpox) is a disease caused by infection with the varicella zoster virus, which causes fever and an itchy rash.

About Chickenpox

Chickenpox is an easily transmitted and common viral illness. Almost every adult in the United States has been infected. Until a vaccine became available in 1995, there were an estimated four million cases/year. Since the vaccine was licensed, the number of cases of chickenpox had fallen 83%-93% by 2004. Most people are immune to chickenpox after having the disease. However, although it is not common, second cases of chickenpox can occur, particularly in immunocompromised persons.

Many cases of chickenpox are mild, but deaths from this disease can occur. Before the development of a vaccine, about 100 people died every year in the United States from chickenpox. Most of these people were previously healthy. Chickenpox also accounted for about 11,000 hospitalizations each year. Even children with average cases of chickenpox are uncomfortable and need to be kept out of daycare or school for a week or more.


Symptoms, Spread, Diagnosis and Treatment

Symptoms of varicella include a skin rash of blister-like lesions, covering the body but usually more concentrated on the face, scalp, and trunk. Most, but not all, infected individuals have fever, which develops just before or when the rash appears. The rash usually forms 200-500 itchy blisters in several successive crops. The illness lasts about 5-10 days. It takes between 10-21 days to develop symptoms after being exposed to a person infected with chickenpox. If exposed, persons who have been vaccinated against the disease may get a milder illness, with less severe rash (sometimes involving only a few red bumps that look similar to insect bites) and mild or no fever. Other common symptoms include coughing, fussiness, headache and loss of appetite. 

Varicella is spread by coughing and sneezing (highly contagious), by direct contact, and by aerosolization of virus from skin lesions. Patients with chickenpox are contagious for 1-2 days before the rash appears and continue to be contagious through the first 4-5 days or until all the blisters are crusted over. It usually can be diagnosed by disease history and appearance alone. Adults who need to know if they've had chickenpox in the past can have this determined by a laboratory test.

Most cases of chickenpox in otherwise healthy children are treated with bed rest, fluids, and control of fever. Children with chickenpox should NOT receive aspirin because of possible subsequent risk of Reye's syndrome. Acetaminophen may be given for fever control. Chickenpox may be treated with an antiviral drug in serious cases, depending on the patient's age and health, the extent of the infection, and the timing of the treatment.

If You or Your Child Has Been Exposed

If your child is believe to have been exposed to someone with chickenpox, if the child has had chickenpox or has been vaccinated, nothing needs to be done. It is recommended that a susceptible person (one who has never had chickenpox) receive the chickenpox vaccine as soon as possible after being exposed to the virus.

There is evidence that the vaccine may prevent illness or reduce the seriousness of the disease, if given within 3 to 5 days following exposure. Even if the person was not infected with the chickenpox virus from the exposure, receiving the vaccination will prevent future disease.

Shingles and Other Complications

Both chickenpox and shingles are caused by the same virus. After a person has had chickenpox, the virus rests in the body permanently, but silently. About 20% of all people who have been infected with chickenpox later develop the disease known as herpes zoster, or shingles.

Symptoms of shingles are pain, itching, blisters, and loss of feeling along a nerve. Most cases occur in persons older than 50, and the risk of developing shingles increases with age. In May 2006, the FDA approved a zoster vaccine to prevent shingles. Currently, the vaccine is only licensed for persons age 60 years and older. 

The most common complication of the varicella virus is bacterial infection of the skin or other parts of the body including the bones, lungs, joints, and blood. The virus can also lead to pneumonia or infection of the brain. These complications are rare but serious. Complications are more common in infants, adults, and persons with weakened immune systems.

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If you're 60 years of age or older, there is a shingles vaccine for you. Talk to your doctor about whether you should get vaccinated against shingles.