Chickenpox

(Varicella)

by Rick Alan

---

Definition | Causes | Risk Factors | Symptoms | Diagnosis | Treatment | Prevention

---

 

Definition

Chickenpox is a viral infection. It is highly contagious. It creates a widespread itchy rash. In some, the infection can also cause serious complications. The infection is more dangerous for adults and newborns. It is also a danger for people with suppressed immune systems.

 

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

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

A pregnant mother can transmit virus to fetus.

 

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, high-dose steroid, HIV)
• Cancer
• Pregnancy
• Time of year (late winter, early spring)

 

Symptoms

Symptoms break out about 10-21 days after contact. They are more severe in adults than they are in children.

Initial symptoms include:

• Mild headache
• Moderate fever
• Cough
• Sore throat
• Severe itch
• Lack of appetite
• General feeling of malaise
• Some children complain of abdominal pain

The rash appears within 1-2 days after the first symptoms. The rash will:

• At first consists of small, flat, red spots
  • Spots become raised and form a round, intensely itchy, fluid-filled blister
  • Blisters develop in clusters, with new clusters forming over 5-6 days
• Usually develop into crops on the skin above the waist, including the scalp
• May also appear on the eyelids, in the mouth, upper airway, voice box, or on the genitals
• 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 lab tests to identify the virus are rarely needed.

 

Treatment

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

 

Prevention

Avoid contact with anyone who has the condition. This is very important if you have not had the chickenpox or the vaccine.

The varicella vaccine is

• Recommended for nearly all children 12-18 months of age
  • Second dose is given between age 4-6 years

For those who have not been vaccinated the recommended schedule is as follows:

• 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

If your child has not been vaccinated but has been exposed to chickenpox:

• A vaccination within three days can help lessen or prevent the virus

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

Varicella-zoster immune globulin (VZIG):

• Given to high risk individuals after exposure to the virus to prevent illness
• Should be given right after exposure (it can either prevent or lessen the severity of chickenpox)

VZIG is recommended for the following individuals:

• Immunosuppressed individuals who is unsure if he/she has previously had chickenpox
• Pregnant women
• On immunosuppressing drugs (eg, steroids)
• Individuals with HIV, AIDS or any other immunodeficiency disorders
• Children with lymphoma or leukemia not vaccinated and without history of chickenpox
• Newborn babies whose mothers are exposed five days before to two days after delivery

 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:

A New Product (VariZIG) for Postexposure Prophylaxis of Varicalla Available under an Investigational New Drug Application Expanded Access Protocol. MMWR 2006;55: 209-210.

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

Gales SA, Sweet A, Beninger P et al: The safety profile of varicella vaccine: a 10-year review. J Infect Dis 2008;197(Suppl2):S165-9).

Marin M, Meissner HC, Seward JF: Varicella prevention in the United States: a review of successes and challenges. Pediatrics 2008;122: e744-51.

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.

¹1/31/2008 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.

²10/14/2008 DynaMed's Systematic Literature Surveillance http://www.ebscohost.com/dynamed/what.php : Macartney K, McIntryre P. Vaccines for post-exposure prophylaxis against varicella (chickenpox) in children and adults. Cochrane Database Syst Rev. 2008;(3):CD001833.

---

Last reviewed October 2009 by David L. Horn, MD, FACP
Last Updated: 10/20/09