Varicella-zoster virus

What is varicella (chickenpox)?
Chickenpox is a very contagious disease caused by the varicella-zoster virus (VZV). It causes a blister-like rash, itching, tiredness, and fever. Chickenpox can be serious, especially in babies, adults, and people with weakened immune systems. It spreads easily from infected people to others who have never had chickenpox or received the chickenpox vaccine. Chickenpox spreads in the air through coughing or sneezing. It can also be spread by touching or breathing in the virus particles that come from chickenpox blisters.

The best way to prevent chickenpox is to get the chickenpox vaccine. Before the vaccine, about 4 million people would get chickenpox each year in the United States. Also, about 10,600 people were hospitalized and 100 to 150 died each year as a result of chickenpox.

Signs and symptoms
Anyone who hasn’t had chickenpox or received the chickenpox vaccine can get the disease. Chickenpox most commonly causes an illness that lasts about 5-10 days.

The classic symptom of chickenpox is a rash that turns into itchy, fluid-filled blisters that eventually turn into scabs. The rash may first show up on the face, chest, and back then spread to the rest of the body, including inside the mouth, eyelids, or genital area. It usually takes about one week for all the blisters to become scabs.

Other typical symptoms that may begin to appear 1 to 2 days before rash include:
• high fever
• tiredness
• loss of appetite
• headache

Children usually miss 5 to 6 days of school or childcare due to their chickenpox.

Vaccinated persons: Some people who have been vaccinated against chickenpox can still get the disease. However, the symptoms are usually milder with fewer blisters and mild or no fever. About 25% to 30% of vaccinated people who get chickenpox will develop illness as serious as chickenpox in unvaccinated persons.

People at risk for severe chickenpox: Some people who get chickenpox may have more severe symptoms and may be at higher risk for complications

Complications
Complications from chickenpox can occur, but they are not as common in otherwise healthy people who get the disease.

People who may have more severe symptoms and may be at high risk for complications include
• Infants
• Adolescents
• Adults
• Pregnant women
• People with weakened immune systems because of illness or medications; for example,
-- People with HIV/AIDS or cancer
-- Patients who have had transplants, and
-- People on chemotherapy, immunosuppressive medications, or long-term use of steroids.

For more information, see People at High Risk for Varicella Complications.

Serious complications from chickenpox include:
• dehydration
• pneumonia
• bleeding problems
• infection or inflammation of the brain (encephalitis, cerebellar ataxia)
• bacterial infections of the skin and soft tissues in children including Group A streptococcal infections
• blood stream infections (sepsis)
• toxic shock syndrome
• bone infections
• joint infections

Some people with serious complications from chickenpox can become so sick that they need to be hospitalized. Chickenpox can also cause death.

Some deaths from chickenpox continue to occur in healthy, unvaccinated children and adults. Many of the healthy adults who died from chickenpox contracted the disease from their unvaccinated children.

Transmission
Chickenpox is a very contagious disease caused by the varicella-zoster virus. The virus spreads easily from people with chickenpox to others who have never had the disease or received the chickenpox vaccine. The virus spreads in the air when an infected person coughs or sneezes. It can also be spread by touching or breathing in the virus particles that come from chickenpox blisters.

Chickenpox can also be spread from people with shingles. Varicella-zoster virus also causes shingles. A person with shingles can spread the virus to others who have never had chickenpox or received the chickenpox vaccine. In these cases, the exposed person might develop chickenpox.

When is a person contagious?
A person with chickenpox can spread the disease from 1 to 2 days before they get the rash until all their chickenpox blisters have formed scabs.

It takes from 10 to 21 days after exposure to a person with chickenpox or shingles for someone to develop chickenpox.

If a person vaccinated for chickenpox gets the disease, they can still spread it to others.

For most people, getting chickenpox once provides immunity for life. However, for a few people, they can get chickenpox more than once, although this is not common.

Prevention
The best way to prevent chickenpox is to get the chickenpox vaccine. Children, adolescents, and adults should have two doses of chickenpox vaccine.

Chickenpox vaccine is very safe and effective at preventing the disease. Most people who get the vaccine will not get chickenpox. If a vaccinated person does get chickenpox, it is usually mild—with fewer blisters and mild or no fever. The chickenpox vaccine prevents almost all cases of severe disease.

For more information about chickenpox vaccine, see Vaccination.

For people exposed to chickenpox, call a health care provider if the person:
• has never had chickenpox disease and is not vaccinated with the chickenpox vaccine
• has a weakened immune system caused by disease or medication; for example,
-- People with HIV/AIDS or cancer
-- Patients who have had transplants, and
-- People on chemotherapy, immunosuppressive medications, or long-term use of steroids
• is pregnant

Treatments at home for people with chickenpox
There are several things that can be done at home to help relieve the symptoms and prevent skin infections. Calamine lotion and colloidal oatmeal baths may help relieve some of the itching. Keeping fingernails trimmed short may help prevent skin infections caused by scratching blisters.

Over-the-counter medications: Use non-aspirin medications, such as acetaminophen, to relieve fever from chickenpox.

Do not use aspirin or aspirin-containing products to relieve fever from chickenpox. The use of aspirin in children with chickenpox has been associated with Reye’s syndrome, a severe disease that affects the liver and brain and can cause death.

When to call the health care provider: For people with chickenpox at risk of serious complications, call a health care provider if the person

• is older than 12 years of age
• has a weakened immune system
• is pregnant
• develops any of the following:
-- fever that lasts longer than 4 days
-- fever that rises above 102°F (38.9°C)
-- any areas of the rash or any part of the body becomes very red, warm, or tender, or begins leaking pus (thick, discolored fluid), since these symptoms may indicate a bacterial infection
-- extreme illness
-- difficult waking up or confused demeanor
-- difficulty walking
-- stiff neck
-- frequent vomiting
-- difficulty breathing
-- severe cough

Treatments prescribed by your doctor for people with chickenpox
Your health care provider can advise you on treatment options. Antiviral medications are recommended for people with chickenpox who are more likely to develop serious disease including:
• otherwise healthy people older than 12 years of age
• people with chronic skin or lung disease
• people receiving steroid therapy
• some groups of pregnant women

Acyclovir, an antiviral medication, is licensed for treatment of chickenpox. Other antiviral medications that may also work against chickenpox include valacyclovir and famciclovir.

This information was developed by the Centers for Disease Control and Prevention, Scientific Resources Program.

Centers for Disease Control and Prevention, Office of Communication, National Center for Infectious Diseases (NCID), Scientific Resources Program. What is Varicella? Available at: https://www.cdc.gov/chickenpox/about/index.html. Accessed January 24, 2014.

The information in this document is for general educational purposes only. It is not intended to substitute for personalized professional advice. Although the information was obtained from sources believed to be reliable, MedLink Corporation, its representatives, and the providers of the information do not guarantee its accuracy and disclaim responsibility for adverse consequences resulting from its use. For further information, consult a physician and the organization referred to herein.