Article updated and reviewed by Daniel A. Rauch, MD, FAAP, Associate Professor of Clinical Pediatrics, Associate Residency Program Director and Director of Pediatric Hospitalist Service, New York University on May 11, 2005.
Chicken pox is a generalized infection caused by the varicella zoster virus, a member of the herpes virus family . It is characterized by a blistery rash, poetically described as a “dew drop on a rose petal base.” It occurs most frequently in children, between the ages of five and eight. Less than 20 percent of all cases in the U.S. affect people over the age of 15. Chicken pox is highly contagious to non-immune individuals (up to 90%), although the disease severity can range from asymptomatic to serious illness with complications. Having the disease usually creates life-long immunity, although it is possible to get chicken pox again, particularly when the first case happened at less than one year old or if the person becomes immunocompromised. Anyone who has had chicken pox may later develop Shingles, which is a local recurrence of the rash, often quite painful. Shingles comes from the initial infection and not from being exposed again.
Certain children are at risk for more severe disease. These include newborns, any children with an underlying immunodeficiency, such as children undergoing treatment for cancer, and children on steroids. Additionally, because the virus can be spread to a developing fetus, non-immune pregnant women who have been exposed and any pregnant woman who develops the rash should seek medical care.
Chicken pox is contracted by touching an infected person's blisters or anything that has been contaminated by contact with them. The virus is also airborne since it may be spread by an infected person by coughing and sneezing even before the rash develops. Another way to get chicken pox is by direct contact to shingles, a localized rash caused by the same virus. People with shingles are not infectious by the respiratory route.
The incubation period (time between exposure to the illness and the appearance of symptoms) of chicken pox is 10 to 21 days. It is contagious from one to two days prior to the rash until all of the blisters have crusted, typically about a week.
Typically, the younger the patient, the less severe the disease, and some people get infected without ever showing any signs of illness. Variations of the disease course, although rare, can be very severe, particularly in at risk patients, and can include disseminated disease, hemorrhagic disease, and secondary bacterial infection.
Because of the current efforts to vaccinate children and prevent the disease, as well as the potential risks from the disease, the old practice of having “Chicken Pox parties” to ensure that children did get the disease while young is discouraged.
There are usually no symptoms before the rash occurs but occasionally there is fatigue and some fever in the 24 hours before the rash is noticed. The typical rash goes through a number of stages:
1. First it appears as flat red splotches
2. They become raised and may resemble small pimples
3. They develop into small blisters, called vesicles, which are very fragile
4. They may look like drops of water on a red base
5. As the vesicles break, the sores become pustular and form a crust - the crust is made of dried serum, and not true pus. Itching is severe in the pustular stage.
The vesicles tend to appear in crops within two to six days. (This is an important difference from small pox, where the lesions can look similar to chicken pox, but they are all in the same stage.) All stages may be present in the same area. They often appear on the scalp and in the mouth, and then spread to the rest of the body, but they may begin anywhere. They are most numerous over shoulders, chest and back. There may be only a few sores, or there may be hundreds. In patients with pre-existing eczema, the lesions may first appear in the eczema patches.
The doctor should be called if the rash involves an eye, if fever is higher than 103, if there is much vomiting, or if there are signs of bacterial infection (such as a green or yellow discharge from the blisters, or any blisters with red streaks radiating outwards). Go to the emergency room if there is difficulty breathing, indicating a possible pneumonia, or if the person is confused, disoriented, ataxic (unsteady), has seizures, or shows any other neurologic signs. When seeking medical attention, remember to let health care providers know that the child might have chicken pox so that proper isolation policies can be instituted to prevent additional exposures.
The major problem in dealing with chicken pox is control of the intense itching and reduction of the fever. Warm baths containing baking soda or oatmeal can help; sometimes cool compresses or cool baths will calm itching. Anti-itching medication such as diphenhydramine (Benadryl) and hydroxyzine (Atarax) can also be helpful. Topical lotions may also help, but care should be exercised that children are not overdosed with diphenhydramine by accidentally giving it by mouth and lotion. Steroid containing anti-itch creams should never be used.
Aspirin should not be used for children or adolescents with chicken pox because of the associated risk of Reye's syndrome, a rare but life-threatening condition. Fever can be treated with acetaminophen. Ibuprofen should be avoided because of the association of its use and more severe disease.
Cut the fingernails or use gloves to prevent skin damage from intense scratching. When lesions occur in the mouth, gargling with salt water may provide comfort. Drink cold fluids, and avoid hot, spicy, and acidic foods (e.g., orange juice).
Hands should be washed frequently and all of the skin should be kept clean in order to prevent a complicating bacterial infection. If a bacterial infection is suspected or becomes severe and results in the return of a fever, see a physician. Again, please remember to announce that the child has chicken pox so that others may be appropriately protected.
Scratching and infection can result in permanent scars. A visit to the physician may not be necessary, unless a complication seems possible.
Acyclovir (Zovirax), an antiviral drug, can be used if started in the first day of the rash. It is usually not necessary in previously well children, but is recommended for immunocompromised patients.
Because chickenpox is extremely contagious, keep children home from daycare or school until the blisters are all crusted over.
Is someone contagious 24 hours prior to having a fever?
At what age is the greatest risk of complications?
Do you recommend calamine lotion to help the itching?
Do you recommend any medications to decrease the severity of this virus?
What are the side effects?
Are showers less likely to spread the disease verses baths?
Can you get chicken pox a second time?
Does having a mild case or a severe case affect your chances of acquiring the virus?
As a parent, what can I do to avoid acquiring chicken pox for the first time or as a repeat?
Does chicken pox increase the chances of developing shingles?
What are some of the complications?
What are the signs and symptoms that should be reported to the doctor?
Are there any measures that can help prevent scarring, such as vitamin E?
Editorial review provided by VeriMed Healthcare Network.
Chicken pox can be prevented through vaccination (now recommended by almost all major national health and public health groups). Recommendations are:
- Children and Adolescents: Healthy children can be vaccinated, optimally at age 12 to 18 months or anytime through age 12, if they have no history of chicken pox. Adolescents 13 years and older who have no history of chicken pox, should receive two doses of vaccine four to eight weeks apart. Duration of immunity after vaccination is not completely known. Re-vaccination with a booster dose to sustain immunity through adulthood is currently being considered.
- Adults: Two doses of varicella vaccine four to eight weeks apart are recommended for healthy adults with no history of chicken pox or previous vaccination. Health care workers, daycare workers, employees of colleges or residential facilities, family members of immunocompromised individuals, and others who live or work in environments in which transmission may be easy are particularly encouraged to receive vaccination.
Most adults who do not know their immune status are, in fact, immune. However, whenever there is a need to know, blood tests are available to check a person’s immune status.
The vaccine is designed to prevent serious disease and it is highly effective for this purpose. It is still possible to get a mild form of chicken pox, even after receiving the vaccine. Sometimes, the vaccine itself can produce a few chicken pox lesions.
The vaccine may also be used as part of post-exposure prophylaxis to prevent disease in someone who has had a known exposure. It should be given within three days of the exposure and would count the same as routine immunization. Additionally, within the first four days, exposed individuals may get VZIG, a special anti-varicella immunoglobulin that protects against infection, but does give any lasting protection, so that the person should be immunized at a later time.