Chickenpox

Definition

Chickenpox is a highly contagious viral infection. It produces a widespread itchy rash. It can cause serious complications. Chickenpox is more dangerous for adults, newborns, or people with suppressed immune systems.

Chickenpox

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Causes

Chickenpox is caused by the varicella zoster virus (VZV). It spreads from person to person via:

  • Airborne droplets of moisture containing the VZV virus
  • Direct contact with fluid from a chickenpox rash

Chickenpox is contagious 1-2 days before the rash erupts. It remains so until all of the blisters have crusted. It is most contagious just after the rash has broken out.

Risk Factors

Factors that increase your chance of getting chickenpox include:

  • Close contact with an infected person (unless you've been vaccinated or have already had chickenpox)
  • Age: less than three years old with peak incidence between 5-9 years old
  • Immune deficient state (eg, leukemia, organ transplantation)
  • Time of year (late winter, early spring)

Symptoms

Adults have more severe symptoms than children. Symptoms usually break out 10-21 days after contact.

Initial symptoms include mild headache, moderate fever, and a general feeling of malaise.

Within 1-2 days after the initial symptoms, a rash develops. The rash consists of small, flat, red spots. The spots become raised and form a round, itchy, fluid-filled blister. The blisters develop in clusters, with new clusters forming over 5-6 days.

The rash usually develops on the skin above the waist, including the scalp. The rash may also appear on the eyelids, in the mouth, upper airway, voice box, or on the genitals. The rash typically crusts over by day six or seven and disappears within three weeks.

Diagnosis

The doctor will ask about your symptoms and medical history. A physical exam will be done. Diagnosis is usually made on the basis of age and the rash. Blood and laboratory tests to identify the VZV virus are rarely necessary.

Treatment

In most people, chickenpox is mild and will naturally run its course. In these cases, treatment focuses on relieving the symptoms.

To Reduce Itching

  • Wet compresses on the skin
  • Nonprescription anti-itch creams or lotions
  • Oatmeal baths
  • Oral antihistamines

Note:Aspirin should not be given to children, adolescents, and young adults with chickenpox. It can increase the risk of Reye's syndrome.

Antibiotics

Since a virus causes chickenpox, antibiotics are not curative. They may be prescribed, however, if the rash becomes infected with bacteria.

Antiviral Medication

  • Acyclovir
  • Valacyclovir
  • Famciclovir

May shorten the course and reduce the severity of infection. They are often used in:

  • Adolescents, adults, and individuals with compromised immune systems
  • Individuals with chronic skin or lung diseases and those taking aspirin or steroids

Special Needs

Varicella-zoster immune globulin is often given immediately after exposure. It is reserved for newborns and people with weak immune systems.

Prevention

Avoid contact with anyone who has the condition. This is more important if you have not had chickenpox and have never been vaccinated.

The varicella vaccine is recommended for virtually all children 12-18 months of age. The second dose is administered between age 4-6 years.

For those who have not been vaccinated, the Centers for Disease Control and Prevention (CDC ) recommend the following schedule:

  • Up to age 13 years—2 doses, with an interval of 3 months between the first and second dose (minimum age of 12 months for the first dose)
  • 13 years and above—2 doses, with a minimum interval of 4 weeks between the first and second dose *

It is recommended that the following people not be vaccinated:

  • Those with a history of severe allergic reaction to vaccines
  • Anyone who is immunosuppressed, or receiving immunosuppressive drugs or therapies
  • Pregnant women

RESOURCES:

American Academy of Family Physicians
http://www.aafp.org/

American Academy of Pediatrics
http://www.aap.org/

National Immunization Program
Centers for Disease Control and Prevention
http://www.cdc.gov/vaccines/

CANADIAN RESOURCES:

AboutKidsHealth
http://www.aboutkidshealth.ca/

Canadian Family Physician
http://www.cfpc.ca/cfp/

References:

Berkow R. The Merck Manual of Medical Information. 17th ed. Newy York, NY:Simon and Schuster, Inc; 2000.

Skull SA, Wang EE. Varicella vaccination: a critical review of the evidence. Arch Dis Child. 2001;85:83-90.

Varicella (chickenpox). National Centers for Infectious Diseases website. Available at: http://www.cdc.gov/vaccines/vpd-vac/varicella/in-short-adult.htm. Accessed July 11, 2008.

Vaccine and Immunizations. Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov/vaccines/vpd-vac/varicella/default.htm. Accessed July 11, 2008.

Vazquez M, LaRussa PS, Gershon AA, et al. Effectiveness over time of varicella vaccine. JAMA. 2004;291:851-855.

*Updated Who Should Get Vaccinated and When section on 1/31/2008 according to the following study, as cited by DynaMed's Systematic Literature Surveillance http://www.ebscohost.com/dynamed/what.php: Centers for Disease Control and Prevention. Recommended immunization schedules for persons aged 0-18 years—United States, 2008. MMWR. 2008;57;Q1-Q4. Centers for Disease Control and Prevention, MMWR website. Available at: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5701a8.htm. Updated January 10, 2008. Accessed January 28, 2008.



Last reviewed February 2008 by David Horn, MD, FACP

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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