Chickenpox

 

The Basics

Chickenpox is a disease found throughout the world that causes an itchy rash and fever. It is most common in the winter and spring, and is caused by the varicella-zoster virus, or VZV, which is in the herpes family. This means VZV is related to the viruses that cause infectious mononucleosis (also known as mono), roseola, oral herpes, and genital herpes. When children without medical problems get chickenpox, the illness usually resolves on its own in about five to ten days. However, even some healthy children develop complications of the disease.

In the past, most children were exposed to chickenpox at a young age, and developed immune protection against getting it again. Today, children in several countries, including the United States, are vaccinated against the disease, so fewer cases of chickenpox occur than previously.

What are the signs and symptoms of chickenpox?

Chickenpox often starts with a low-grade fever, sore throat, and an ill or tired feeling. An itchy rash soon develops, with groups of blister-like lesions (called vesicles) appearing on the body over three to four days. The rash starts as spots, which become bumps, and then vesicles over a period of hours. It is often described as having the appearance of “dewdrops on rose petals”. Crops of lesions appear at different times, so at any given time there may be vesicles present in all different stages. There may be some lesions just beginning to show up when others are crusting over and resolving.

 The first spots of the rash often emerge near the hairline, followed by the trunk, arms and legs, and eventually may be present anywhere on the face, scalp, or body. There are usually more lesions on the face and trunk than on the arms and legs. One person may have several hundred vesicles on the body. Mucous membranes, such as the inside of the mouth, can also be involved. After the vesicles crust over, the scabs may take one to three weeks to fall off, and can occasionally leave behind scars. As chickenpox spreads through a household, it often becomes more severe, so a sibling may get a worse case than the child who was initially infected.

Child with chickenpox rash

                                                                                      From Public Health Image Library (http://phil.cdc.gov/phil/quicksearch.asp), image #6121

 

How is chickenpox spread?

Chickenpox is extremely contagious. More than 90% who have a household contact with the disease will get the disease if they have not been vaccinated or have not already had the disease.[1] It is spread by droplets released into the air when someone coughs, sneezes, or breaths. It can also spread when someone comes in contact with the fluid inside an infected person’s pox lesions. Chickenpox is only contagious from humans, not other animals.

 It usually takes about two weeks from the time a person becomes infected with chickenpox until the rash develops, but can take up to three weeks. Someone with chickenpox is contagious from approximately two days before the rash appears until five or six days after the development of the rash, when all of the lesions have crusted over. Patients with compromised immune systems often have new lesions appearing for a longer period of time, and a prolonged phase of contagiousness. 

 

How is chickenpox diagnosed?

 Most often, a diagnosis of chickenpox is made when the characteristic rash is recognized. If there is confusion about the diagnosis, fluid from a vesicle or a scab can be tested. Blood tests can show if a person has been infected with chickenpox in the past. Sometimes schools and jobs require these blood tests to show that people who have not been vaccinated against chickenpox had the infection as a child and are immune to it. These tests are also used to make sure that pregnant women are immune to the infection. 

 

What are the complications of chickenpox?

When children with normal immune systems get the chickenpox, they usually have an uncomplicated course. Nevertheless, even healthy children can have complications of the disease, most frequently bacterial infections of the vesicles. These infections may just involve the skin, or may cause problems beneath the skin, such as abscesses (collections of pus) or bone infections. Complications can involve almost any part of the body, ranging from the lungs to the brain. At times, they can be life-threatening. The most common complication among adults is pneumonia.

 Adults, older teenagers, infants under one year and people with compromised immune systems, such as those receiving steroids for asthma or chemotherapy for cancer are at greater risk for severe illness and complications of the infection. Pregnant women also have an increased chance of complications, not only for themselves, but if a pregnant woman gets the chickenpox, the fetus may develop birth defects. If a woman gets the chickenpox soon before or after delivering an infant, the baby is at risk of developing severe disease. This risk is greatest when the mother develops chickenpox in the period five days before delivery until two days after.

 Because some of the virus remains sleeping in the body after infection, about 10-15% of people who have had chickenpox will one day develop herpes zoster, otherwise known as shingles, a painful rash.

 

How is chickenpox treated?

 In uncomplicated cases, the goal of treatment of chickenpox is relief of symptoms. Acetaminophen (Tylenol) can be given for fever, and calamine lotion and oatmeal baths can help with itching. Aspirin should never be given because of an increased risk of Reye syndrome, a serious disease that can affect the liver and brain. Fingernails should be cut short to reduce the risk of scratching open lesions and causing a bacterial infection. It’s also important to keep people with chickenpox at home until all of the lesions have crusted over, since the infection is so contagious to others. People at risk of complications, such as young infants or individuals with a compromised immune system, may require further treatment, and should be seen by a doctor.

 

When should someone with chickenpox see the doctor?

 In some states, chickenpox is a reportable disease, which means the government keeps track of all cases to watch for trends and epidemics. Because of this – and to make sure that they are not at risk of complications – patients should always let their doctor know about possible cases of chickenpox. It is especially important that the following people with the chickenpox see their doctor immediately:

• infants, adolescents, and adults
• pregnant women
• those who have problems with the immune system
• those who are taking any medications that might affect the immune system, such as steroids or chemotherapy
• people with chronic medical problems
• anyone having trouble breathing or coughing
• anyone with confusion, drowsiness, bad headaches or trouble walking
• those with any redness, tenderness, warmth, or drainage of pus from the skin
• people with high or persistent fevers
• anyone who feels worse after getting better
• anyone with worsening or persistent symptoms

Finally, patients who may have the chickenpox should always let the doctor’s office know in advance; because the infection is so contagious, those who have it may need to use a separate waiting area.

 

What can be done to prevent chickenpox?

A vaccine for chickenpox was developed in Japan, and has been approved for use in the US since 1995. The vaccine is made from a weakened, live virus, and prevents severe disease in more than 95% of people who receive it[2]. Initially, it was given as one shot between the ages of 12 and 15 months. Children now also receive a booster shot of the vaccine between the ages of four and six years to strengthen their immune response against chickenpox. Older individuals who have not been vaccinated and have not had the chickenpox should also receive two doses of the vaccine. Sometimes the vaccine is given as a combination shot with the one for measles, mumps, and rubella (MMR).

Before the varicella vaccine was introduced, there were about 4 million cases of chickenpox in the United States each year. While most of these cases were well tolerated, there were 10,000 people hospitalized and 100 people who died each year.[3] Some kids who are vaccinated still get the chickenpox, but they usually have a very mild case. With vaccination, we have the ability to drastically reduce the number of people severely affected, as well as the number of days of school and work missed by children and their parents as a result of the illness.

Additionally, hand washing and staying away from those who are sick can help avoid the spread of chickenpox. If someone who is unvaccinated is exposed to chickenpox, the vaccine can be given as soon as possible within 72 hours. This may prevent or decrease the severity of the illness.

 

Who should be vaccinated against chickenpox?

All healthy children should be given the chickenpox vaccine, with the first dose between 12 and 15 months of age and a second dose between four and six years of age. (Consider that even healthy children who do not have risk factors for severe disease can develop complications of chickenpox – and that an uncomplicated case still causes discomfort, as well as several days of missed school and work.) Older individuals who have not been vaccinated and have not had the chickenpox should also receive two doses of the vaccine.

Because the vaccine is made from a live virus, certain people should not receive it, such as pregnant women, people with some immune problems, and some people with cancer. Anyone who has had an allergic reaction to a previous dose of the vaccine or a component of it also should not receive it. Check with the doctor to see if you or your children should receive the chickenpox vaccine.

 

More information

            KidsHealth.org

            The Centers for Disease Control (CDC)

            Mayo Clinic

 

References

Albrecht, Mary A. “Clinical features of varicella-zoster virus infection: Chickenpox.” UpToDate 13 April 2007, accessed 16 January 2008. [Requires a subscription to access] http://utdol.com/utd/content/topic.do?topicKey=viral_in/13883&selectedTitle=3~150&source=search_result>

 

Albrecht, Mary A. “Treatment and prevention of chickenpox.” UpToDate  9 September 2007, accessed 16 January 2008. [Requires a subscription to access]

http://utdol.com/utd/content/topic.do?topicKey=viral_in/11333&selectedTitle=2~150&source=search_result>

 

Behrman, Richard E, Robert M. Kliegman, and Hal B. Jenson, eds. Nelson Textbook of Pediatrics. Philadelphia: Saunders, 2004.

 

“Chickenpox.” KidsHealth.org. August 2006, accessed 16 January 2008. http://www.kidshealth.org/parent/infections/skin/chicken_pox.html

 

“Chickenpox.” MayoClinic.com. 16 March 2007, accessed 17 January 2008.

http://www.mayoclinic.com/health/chickenpox/DS00053/DSECTION=1

 

Kane, Kay Shou-Mei et al. Color Atlas & Synopsis of Pediatric Dermatology. New York: McGraw-Hill, 2002.

 

McMillan, Julia A et al., eds. Oski’s Pediatrics: Principles and Practice. New York: Lippincott Williams & Wilkins, 1999.

 

Meyer, George Keith and Patricia A. DeLaMora. Last Minute Pediatrics: A Concise Review for the Specialty Boards. New York: McGraw-Hill, 2004.

 

Pickering, Larry K, Carol J.Baker, Sarah S. Long, Julia A. McMillan, eds. Red Book: 2006 Report of the Committee on Infectious Diseases. Elk Grove Village, IL: American Academy of Pediatrics, 2006.

 

Riley, Laura E. “Varicella-zoster virus infection in pregnancy.” UpToDate 20 September 2007, accessed 17 January 2008. [Requires a subscription to access] http://utdol.com/utd/content/topic.do?topicKey=viral_in/4765&selectedTitle=1~150&source=search_result>

 

“Varicella (Chickenpox) Vaccination.” Centers for Disease Control and Prevention. 12 June 2007, accessed 17 January 2008.

http://www.cdc.gov/vaccines/vpd-vac/varicella/default.htm

 

“Varicella Vaccine.” World Health Organization. May 2003, accessed 17 January 2008.

http://www.who.int/vaccines/en/varicella.shtml

 

Zitelli, Basil J and Holly W. Davis, eds. Atlas of Pediatric Physical Diagnosis. Philadelphia: Mosby, 2002.