Infection with the varicella zoster (var-uh-SEH-luh ZOS-ter) virus * (VZV), a member of the herpesvirus family * , causes the common childhood illness chickenpox (also called varicella). A vaccine * is available that prevents or ameliorates (reduces) the symptoms and prevents the spread of the virus.
Chickenpox is a highly contagious * disease caused by the initial or primary infection with VZV. It is characterized by the appearance of red, itchy spots on the skin. The spots progress to blisters (200 to 500 over the entire body) and eventually crust over.
With chickenpox there is a risk of serious, life-threatening complications especially for infants and for people with weakened immune systems. However, the virus is unpredictable and anyone can develop serious complications.
Most people cannot contract chickenpox a second time because the body's immune system * makes protective antibodies * . However VZV remains in the nerve tissues of the body in a dormant or inactive state. Years later—most often after a person is 50 years of age—VZV can be reactivated in the form of herpes zoster or shingles.
Chickenpox was once a disease experienced by nearly every child, causing an estimated 4 million illnesses, 11,000 hospitalizations, and 100 deaths each year in the United States. After the introduction of a varicella virus vaccine in 1995, the incidence * of chickenpox, especially in younger children, decreased dramatically. However, as of 2015, chickenpox remained relatively common among unvaccinated children and adults. In addition, 10 to 15 percent of vaccinated children also contract the disease.
Most people who have never had chickenpox or been vaccinated against it will contract varicella if they come in close contact with someone who has the illness. Anyone with chickenpox is contagious from one or two days before the rash first appears until the pox blisters have crusted over. VZV is spread in the air through the coughs or sneezes of an infected person. It can also be spread by contact with the fluid in pox blisters.
The symptoms and signs of chickenpox usually appear within two to three weeks after exposure to the virus and typically begin with fever, headache, and fatigue. The classic chickenpox rash starts as red spots on the face, chest, back, buttocks, and, less commonly, arms and legs. The spots quickly turn into blisters that break, ooze fluid, and then crust over. The pox often pop up in groups over a period of four or five days. The number of blisters varies from very few to hundreds. The rash ranges from mildly to severely itchy.
Doctors usually recognize chickenpox or shingles by their distinctive rashes. Laboratory tests on the fluid in blisters from either disease can diagnose VZV infection. Blood tests for antibodies against VZV can determine whether a person is immune to chickenpox.
In general, the goal of chickenpox treatment is to ease the discomfort caused by itchy blisters. Cool compresses or lukewarm baths in water sprinkled with uncooked oatmeal or baking soda can soothe the skin and relieve itching. Over-the-counter antihistamines * can also help control itching. Children with chickenpox should not be given aspirin for fever due to the risk of Reye's syndrome * . A non-aspirin fever reducer such as acetaminophen is recommended instead. A child's fingernails should be cut short, because scratching the blisters can lead to secondary skin infections caused by bacteria. Children usually recover from chickenpox within one to two weeks. Adults may take longer to recover. Adults and those with weakened immune systems are at greater risk for complications of chickenpox and may be treated with antiviral medications for a few days to control the infection.
The most common complication of chickenpox is cellulitis, a skin infection caused by bacteria such as streptococci (streptuh-KAH-kye) and staphylococci (stah-fih-lo-KAH-kye), which can invade the skin through repeated scratching of pox sores.
If a woman becomes infected with chickenpox during the first 20 weeks of pregnancy, there is a 2 percent risk that her baby will be born with congenital * varicella syndrome * , including multiple birth defects. Maternal infection during the final stages of pregnancy, before the mother has developed antibodies, can cause life-threatening varicella infection in her baby.
People with weakened immune systems, such as those with HIV * /AIDS * or cancer * or who are undergoing chemotherapy * , are at particular risk for widespread infection from either chickenpox or shingles. Varicella infection can spread to the lungs causing pneumonia * . Even in healthy people, pneumonia from varicella can be dangerous and potentially fatal. Newborn babies, teens, and adults are at greater risk than children. Adults are also more at risk for other serious—but rare—complications, including liver and kidney disease and encephalitis * .
The American Academy of Pediatrics recommends that all children be vaccinated against chickenpox before two years of age. A second dose of vaccine is recommended between the ages of 4 and 6. Two doses of the vaccine, at least 28 days between doses, are recommended for those individuals 13 years and older who were never immunized against chickenpox. Older children and teens who have not had chickenpox are usually vaccinated as part of routine health care. Women who have not had chickenpox or been previously vaccinated should be vaccinated before they become pregnant. Pregnant women cannot be vaccinated because the vaccine contains live virus that could harm the fetus * . However, vaccinations for family members and others in close contact with a pregnant woman can help protect her from infection. Some people who are vaccinated may still become infected with varicella though they usually have a milder case of chickenpox.
A single dose of varicella zoster immune globulin * (VZIG) can be administered intravenously * to protect a person with a weakened immune system who comes into contact with the virus. VZIG contains antibodies against VZV and, if it is given within three to four days of exposure, offers temporary protection. Exposure to varicella by a nonimmune pregnant woman can also be treated with VZIG to reduce the risk of transmitting the virus to her fetus.
See also Congenital Infections • Fever • Herpes Simplex Virus Infections • Immune Deficiencies • Shingles (Herpes Zoster) • Skin and Soft Tissue Infections • Staphylococcal Infections • Streptococcal Infections • Vaccines and Immunizations • Viral Infections
Dator, James. “The Royals Have a Very Serious Chickenpox Problem in Their Clubhouse.” SB Nation. September 2, 2015. Also available online at http://www.sbnation.com/lookit/2015/9/2/9247263/kansas-city-royals-chickenpox-outbreak-mlb-alex-rios-kelvin-herrera (accessed March 19, 2016).
Offit, Paul A. Deadly Choices: How the Anti-Vaccine Movement Threatens Us All. New York: Basic Books, 2015.
Perry, Susan. “Study Finds Dramatic Drop in Chickenpox Cases and Complications.” MinnPost. August 18, 2015. Also available online at https://www.minnpost.com/second-opinion/2015/08/study-findsdramatic-drop-chickenpox-cases-and-complications (accessed March 19, 2016.
Sears, Robert W. The Vaccine Book: Making the Right Decision for Your Child. New York: Little, Brown and Company, 2011.
MedlinePlus. “Chickenpox.” U.S. National Library of Medicine https://www.nlm.nih.gov/medlineplus/chickenpox.html. Https://www.nlm.nih.gov/medlineplus/ency/article/001592.htm (accessed March 19, 2016).
American Academy of Pediatrics. 141 Northwest Point Blvd., Elk Grove Village, IL 60007-1098. Telephone: 847-434-4000. Website: http://www.aap.org (accessed March 19, 2016).
Immunization Action Coalition (IAC). 2550 University Ave. W, Suite 415 North, Saint Paul, MN, 55114.Telephone: 651-647-9009. Website: http://www.vaccineinformation.org/chickenpox (accessed March 19, 2016).
March of Dimes. 1275 Mamaroneck Ave., White Plains, NY 10605. Telephone: 914-997-4488. Website: http://www.marchofdimes.org/chickenpox-during-pregnancy.aspx (accessed March 19, 2016).
* virus (VY-rus) is a tiny infectious agent that can cause infectious diseases. A virus can only reproduce within the cells it infects.
* herpesvirus family (her-peez-VYrus) is a group of viruses that can store themselves permanently in the body. The family includes varicella zoster virus, Epstein-Barr virus, and herpes simplex virus.
* vaccines (vak-SEENS) are preparations of killed or weakened germs, or a part of a germ or product it produces, given to prevent or lessen the severity of the disease that can result if a person is exposed to the germ itself. Use of vaccines for this purpose is called immunization.
* contagious (kon-TAY-jus) means transmittable from one person to another, usually referring to an infection.
* immune system (im-YOON SIStem) is the system of the body composed of specialized cells and the substances they produce that helps protect the body against disease-causing germs.
* antibodies (AN-tih-bah-deez) are protein molecules produced by the body's immune system to help fight specific infections caused by microorganisms, such as bacteria and viruses.
* incidence means rate of occurrence.
* antihistamines (an-tie-HIS-tuhmeens) are drugs used to combat allergic reactions and relieve itching.
* Reye's syndrome (RYES SINdrome) is a rare condition that involves inflammation of the liver and brain, and sometimes appears after illnesses such as chickenpox or influenza. It has also been associated with taking aspirin during certain viral infections especially when aspirin or aspirin-containing products are given to children under the age of 12 years.
* congenital (kon-JEH-nih-tul) means present at birth.
* syndrome is a group or pattern of symptoms or signs that occur together.
* HIV or human immunodeficiency virus (HYOO-mun ih-myoono-dih-FIH-shen-see) is the virus that causes AIDS (acquired immunodeficiency syndrome).
* AIDS or acquired immunodeficiency (ih-myoo-no-dih-FIH-shensee) syndrome is an infection that severely weakens the immune system; it is caused by the human immunodeficiency virus (HIV).
* cancer is a condition characterized by abnormal overgrowth of certain cells, which may be fatal.
* chemotherapy (KEE-mo-THER-apee) is the treatment of cancer with powerful drugs that kill cancer cells.
* pneumonia (nu-MO-nyah) is inflammation of the lungs.
* encephalitis (en-seh-fuh-LYEtis) is an inflammation of the brain, usually caused by a viral infection.
* fetus (FEE-tus) is the term for an unborn human after it is an embryo, from nine weeks after fertilization until childbirth.
* immune globulin (ih-MYOON GLAH-byoo-lin), also called gamma globulin, is the protein material that contains antibodies.
* intravenous (in-tra-VEE-nus) or IV, means within or through a vein. For example, medications, fluid, or other substances can be given through a needle or soft tube inserted through the skin's surface directly into a vein.