Chickenpox, also known as varicella, is a highly contagious and self-limited infection that most commonly affects children between 5-10 years of age. The disease has a worldwide distribution and is reported throughout the year in regions of temperate climate. Lifelong immunity for chickenpox generally follows the disease. If the patient’s immune system does not totally clear the body of the virus, it may retreat to skin sensory nerve cell bodies where it is protected from the patient’s immune system. The disease shingles (also known as “zoster”) represents release of these viruses down the length of the skin nerve fiber and produces a characteristic painful rash. Shingles is most commonly a disease of adults.
The Varicella-zoster virus (VZV) causes chickenpox. The disease is highly contagious — over 90% of nonimmune individuals will develop chickenpox following exposure. VZV is communicable by both direct skin-to-skin contact and via respiratory droplets (for example, coughing, sneezing) from the infected individual. While the average incubation period from viral exposure to onset of symptoms is 12-14 days.
Healthy children generally experience one to two days of fever, sore throat, and malaise approximately two weeks following exposure to VZV. Within 24 hours of these symptoms, a characteristic rash develops initially on the torso and then spreads over the next seven to 10 days outward to the head, arms, and legs. The rash progresses through a predictable evolution from a red papule (“bug bite”) appearance to blister (“vesicle”) to pustule and then scabs over. The vesicle and pustular fluids are highly concentrated with infectious virus particles. New lesions characteristically come in “waves” over the skin surface. The patient may thus have newly formed papules, middle-aged vesicles and pustules, and crusted lesions all at the same time. At the peak of the disease, a patient may have over 300 skin lesions at one time. Once all lesions are scabbed over, the person is no longer contagious. The lesions rarely cause permanent scarring, unless secondary infection develops (see below). Lesions may commonly be found in the mouth and may also involve the genitalia.
When to Seek Medical Care
Although most cases of chickenpox heal without complications, sometimes medical attention is required. Call the doctor if any of the following conditions develop:
- Fever higher than 103°F
- A rash involving an eye; eye pain (especially unusual sensitivity to light)
- Dehydration, vomiting, or decreased fluid intake
- Uncertainty of diagnosis or what medication to give
- Secondary skin infections
- Signs of bacterial infection include the following:
- Blisters leaking a thick yellow or green fluid
- Areas around a blister are red, increasingly painful, or swollen, or have red streaking extending from the site
- Signs of bacterial infection include the following:
Exams and Tests
A doctor usually bases a diagnosis of chickenpox on the clinical history and physical findings. However, laboratory exams can be useful. Your doctor can test blister fluid if there is a concern about secondary skin infection by Staphylococcus or Streptococcus. If the blisters are infected with bacteria, such a bacterial culture can help determine which antibiotics may be needed.
Self-Care at Home
Most cases of chickenpox can be managed at home. Chickenpox rash tends to be extremely itchy. Several treatments can be used at home to help a child feel better.
- Cool compresses applied to blisters may give relief, as may calamine lotion.
- You can give cool-water baths every three to four hours, adding baking soda to the water to calm itching.
- Trimming fingernails can help prevent infection from scratching the blisters. If you have a small infant with chickenpox, cover the child’s hands with mittens to minimize scratching.
- Antihistamines also can relieve itching. These medicines are available over the counter.
- Treat fever with acetaminophen (for example, Tylenol) or ibuprofen (for example, Advil, Motrin, Excedrin, Nuprin, and Pamprin are common brand names). Never give aspirin to a child because aspirin has been associated with Reye syndrome.
- Occasionally a child will develop blisters in the mouth, making eating or drinking painful. A person should be encouraged to drink fluids to prevent dehydration. To alleviate pain, provide cold fluids (ice pops, milk shakes, and smoothies) and soft bland foods. Avoid any foods that are spicy, hot, or acidic (for instance, orange juice).
- Keep children at home from school and daycare until all blisters have crusted. A child with chickenpox is extremely contagious until the last crop of blisters has crusted.
- If you take your child to a doctor’s office, call ahead to let the staff know that you think your child has chickenpox. They may usher you to a special waiting or treatment room to avoid exposing other children.
- For people who have severe infections, an antiviral agent called acyclovir (Zovirax) has been shown to shorten the duration and severity of symptoms if given soon after the onset of the rash. Acyclovir may be given by mouth or by IV to help people at risk for severe infection.
Varivax, a two-dose vaccine for chickenpox, is highly recommended for healthy children, adolescents, and adults. Set up an immunization schedule for your child with your doctor.
When fully immunized, the vaccine has been shown to be 95% effective in preventing childhood cases of chickenpox. A small percentage of newly immunized people will develop a mild rash. Pregnant women and infants younger than 1 year of age should not be vaccinated.