All about chickenpox

Chickenpox is an infection that causes an itchy, blistering rash and is very contagious. It is caused by varicella-zoster virus (VZV), which enters the body through the mouth and nose after contact with an infected person.

A person with chickenpox can spread the disease to someone else from one day before the rash appears until all chickenpox blisters have crusted over. Once someone has had a chickenpox infection, he or she almost always develops a lifelong immunity, meaning that person usually does not get chickenpox a second time. The exception is a child who is infected at a very young age. Young children usually have milder cases and may not build up enough protection against the disease. Therefore, these children may develop the disease again later in life.

Because chickenpox is so contagious, 90% of a patient's family also will develop the illness if they live in the same house and are not already immune. In the past, chickenpox cases often occurred in groups (epidemics), usually during the late winter and early spring. However, the number of cases of chickenpox has dropped dramatically because of the chickenpox (varicella) vaccine, which was licensed in 1995 and is recommended for all children.

Chickenpox is an uncomfortable infection that, in most cases, goes away by itself. Chickenpox blisters form over a period of 3 to 5 days and then crust over during the next 7 to 10 days.

However, this disease has been associated with serious complications, including death. About one of every 100 children infected with chickenpox will develop a severe lung infection (pneumonia), an infection of the brain (encephalitis), or a problem with the liver. Dangerous skin infections also can occur. Before the introduction of the vaccine, about 100,000 people were hospitalized and 100 people in the United States died each year of chickenpox, most of them previously healthy children. Adolescents and adults who develop chickenpox are also at high risk of developing serious complications.

After a person has chickenpox, the virus (VZV) typically lives silently in the nervous system of the body for the rest of a person's life. The most common reason for the virus to reactivate is advancing age. Reactivation of the virus causes a condition called shingles, a painful blistering skin rash that typically occurs on the face, chest or back, in the same area where one or two of the body's sensory nerves travel.

Symptoms
Symptoms of chickenpox begin between 10 and 21 days after a person is exposed. The illness typically includes fever and a generally sick feeling. This is soon followed by itchy, red bumps that quickly become fluid-filled. These skin blisters are round, about 5 millimeters to 10 millimeters across (about the size of a pencil eraser), with a red base. Sometimes, they are described as a "dew drop on a rose petal." They appear in various stages over the next few days and eventually crust over. These blisters may appear anywhere there is skin, even inside the mouth, throat, or vagina. Some patients have only 50 blisters or fewer. Others have too many to count.

Treatment
Te antiviral medication acyclovir (Zovirax) to help minimize the symptoms of chickenpox in adults, but it is only effective if it is started within the first 24 hours after exposure. Any parent without a personal history of chickenpox whose child develops chickenpox should call his or her own doctor right away to see whether treatment is recommended. Healthy children who get chickenpox do not need acyclovir because the medicine is expensive and appears not to help much.

Most of the treatment for chickenpox focuses on relieving the annoying itch of chickenpox blisters and preventing broken blisters from getting infected from scratching. Oatmeal baths and calamine lotion can help to reduce the itchiness. Trim fingernails to decrease the risk of infection from scratching. If itchiness cannot be controlled with baths and lotion, oral (taken by mouth) antihistamines, such as diphenhydramine (Benadryl and other brand names) for children age 6 or older, may give some relief. Use a non-aspirin medication such as acetaminophen (Tylenol and other brand names) to lower your child's fever. Never give aspirin to a child with chickenpox because it can cause Reye's syndrome, a potentially fatal illness. Sometimes, chickenpox blisters can become infected with bacteria and require antibiotic treatment.

When to Call a Professional
Most cases of chickenpox do not require a visit to the doctor. Call your doctor if any child or adult in your family develops symptoms of chickenpox and:
•    You are unsure of the diagnosis
•    Someone in the household cannot fight infection well (for example takes steroids regularly or has cancer and is on chemotherapy)
•    Someone in the household, especially an adult, has not had chickenpox or the vaccine
•    Someone in the household is pregnant

Call your doctor for his or her recommendation if you or your child has been exposed to chickenpox and neither of you has had the disease or the vaccine before.
In people with confirmed chickenpox, call your doctor if any of the following symptoms develops:
•    Fever of 103°Fahrenheit or above
•    Itching that is not relieved by medication and baths
•    Blisters that are inflamed, painful, swollen or filled with pus
•    Blisters near the eyes
•    Signs of brain infection (encephalitis), including severe headache, sleepiness and vomiting
•    Signs of lung infection (pneumonia), including cough and difficulty breathing.

To decrease the spread of chickenpox, the person with chickenpox should avoid exposing people who have not had the disease, especially those who cannot fight infection well.
If you or your children (aged 1 and older) have never had chickenpox, ask your doctor about the chickenpox vaccine. If you are a woman who has never had chickenpox and you are considering becoming pregnant, speak with your doctor immediately about reducing your risk of chickenpox and other preventable infections before you become pregnant.

FamilyHealth Guide
To take advantage of the latest medical advances, and to deal with the often-confusing world of health care, you need information that is clear, accurate, easily understandable, and accessible. The HarvardMedical School Family Health Guide brings you the information you need to keep your and your family healthy and to cope with illness when it does strike. 170 faculty members of Harvard Medical School,physicians who care for patients every day, developed this comprehensive guide.

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