Chicken Pox: New Treatment for an Old Disease By Dr. Louis J. Tesoro The Pediatric Group, P.A.

Chicken pox (varicella) is one of the most common of the childhood viral exanthems (rashes). The infection is most common among children ages 5-10 years, though it may occur at any age. While varicella occurs year round, the peak periods occur in late autumn and in late winter/early spring.

In a normal child, varicella is most often a benign, though highly contagious illness caused by the varicella-zoster virus. Frequently, at the onset, there is a low-grade fever, runny nose, and mild malaise (fatigue) followed by the appearance of an itchy rash. The lesions occur in rapidly evolving crops that initially involve the trunk and scalp and then spread to the extremities. Each lesion begins as an erythematous papule (red pimple) that enlarges over several hours to form thin walled superficial vesicles (blisters) each surrounded by a red halo. As the lesion dries out over several days, the red halo fades and the vesicle develops a crust or scab. The presence of all three stages of the rash--pimples, blisters, and scabs--in the same region of the body is the hallmark of chicken pox. In most children, the scabs slough off in 10-14 days.

Chicken pox may occur on several body membranes as well including the eyes, mouth, external ear canal, vagina, and rectum. While skin lesions are generally itchy, these membranes lesions are sometimes painful. No additional treatment, however, is required for these lesions.

The symptoms of chicken pox generally begin ten to twenty-one days following exposure. An individual with chicken pox is contagious from one to two days before the appearance of the rash until the rash has been present for five days and the child is afebrile. Susceptible individuals exposed in a closed environment (for example, a home or schoolroom) to varicella are very likely (90%) to acquire the infection. Once infected, most individuals are immune for life. Like other viruses in the herpes virus family, chicken pox can become reactivated later in life, usually as zoster or shingles, a localized painful blistering rash. This can occur at any age, but is most common in elderly patients.

Varicella can be more serious in teenagers, adults, immunosuppressed individuals, and newborns whose mother developed the rash five days before to two days after delivery. The more serious complications of chicken pox, including pneumonia, hepatitis (liver inflammation), ITP (decrease platelet count), arthritis, encephalitis (brain inflammation), secondary bacterial infection and even death, are rare and occur most often in adults and immune compromised individuals. However, the most common complication of varicella for all children is impetigo--a secondary bacterial infection of chicken pox lesions.

Treatment of chicken pox is designed to relieve itching or pain and prevent impetigo. Young children's nails should be cleaned thoroughly and shortened. Benadryl® liquid, an oral antihistamine, and topical Calamine® lotion or clear Caladryl®, may be used to relieve itching. Three oatmeal based products by Aveeno® may be used to relieve itching as well--bath powder, cream and anti-itch lotion.

Aspirin must NOT be used in children with varicella because of its association with Reye Syndrome--a severe post-varicella neurologic condition. Some authorities also recommend avoiding ibuprofen since its association with Reye Syndrome is unknown. Acetaminophen may be used, if necessary, to relieve pain or irritability. (Check with your doctor regarding the appropriate dose for your child.) One study showed that the course of chicken pox may be prolonged by its regular use.

Recently, varicella vaccine became available to prevent chicken pox. The vaccine can be used in normal children twelve months of age and older who have not had chicken pox. Varicella vaccine is a live attenuated virus vaccine. Clinical trials, thus far, have shown the vaccine to be both safe and effective, and long term studies are ongoing. Following a single dose of vaccine in children less than thirteen years, or a pair of injections one month apart in older patients, protection against the severest form of disease is about 95 %. Against mild and moderate chicken pox, protection approximates 80%.

Side effects are usually minor and include local inflammation (20-30 %, zero to two days after vaccination), rash resembling mild chicken pox (1-5 %, 5-26 days after vaccination averaging about five lesions), and fever (10-15 %). A small number of close contacts of recipients of the vaccine (less than 1 %) may contract a very mild case of chicken pox.

The vaccine can not be given to individuals with a severe allergy to gelatin or neomycin. Varicella vaccine should not be used in patients who are pregnant or lactating, immune compromised, have malignancies or certain blood diseases, or who have an illness with fever. Vaccine recipients should avoid pregnancy and exposure to high risk individuals for three months, and salicylates (i.e., aspirin, Pepto-Bismol®) for six weeks. Reye Syndrome after varicella vaccine has not been reported. Ask your pediatrician if you have any question about the appropriateness of the vaccine for your child.

Recent data about vaccination against varicella suggests that protection is unlikely to wane over time. Furthermore, since more children are being immunized, the chance of acquiring the infection in preadolescence is diminishing. The Centers for Disease Control and the Committee on Infectious Diseases of the American Academy of Pediatrics recommend that all children receive vaccination against chicken pox at twelve months of age. Those older than twelve months may receive the vaccine if they have not yet had chicken pox. Patients ten years and older who have not yet had chicken pox should certainly be vaccinated.

Call your doctor with any questions you have.

All Rights Reserved 3/98 The Pediatric Group, P.A.

Dr. Tesoro has been member of the staff at The Pediatric Group since 1988. He is Chairman, Department of Pediatrics, Medical Center at Princeton and Attending Pediatrician, Medical Center at Princeton.