chickenpox

Definition

Chickenpox (also called varicella) is a common and extremely infectious childhood disease that also affects adults on occasion. It produces an itchy, blistery rash that typically lasts about a week and is sometimes accompanied by a fever or other symptoms. A single attack of chickenpox almost always confers lifelong immunity against the disease. Because the symptoms of chickenpox are easily recognized and in most cases merely unpleasant rather than dangerous, treatment can almost always be carried out at home. Severe complications can develop, however, and professional medical attention is essential in some circumstances.

Description

Before the varicella vaccine (Varivax) was released for use in 1995, virtually all of the four million children born each year in the United States contracted chickenpox, resulting in hospitalization in five of every 1,000 cases and 100 deaths. Chickenpox is caused by the varicella-zoster virus (a member of the herpes virus family), which is spread through the air or by direct contact with an infected person. Once someone has been infected with the virus, an incubation period of about 10–21 days passes before symptoms begin. The period during which infected people are able to spread the disease is believed to start one or two days before the rash breaks out and to continue until all the blisters have formed scabs, which usually happens fout to seven days after the rash breaks out but may be longer in adolescents and adults. For this reason, doctors recommend keeping children with chickenpox away from school for about a week. It is not necessary, however, to wait until all the scabs have fallen off.

Chickenpox has been a typical part of growing up for most children in the industrialized world (although this may change if the new varicella vaccine becomes more widely accepted). The disease can strike at any age, but by ages nine or 10 about 80–90% of American children have already been infected. U.S. children living in rural areas and many foreign-born children are less likely to be immune. Because almost every case of chickenpox, no matter how mild, leads to lifelong protection against further attacks, adults account for less than 5% of all cases in the United States. Study results reported by the Centers for Disease Control and Prevention (CDC) indicate that more than 90% of American adults are immune to the chickenpox virus. Adults, however, are much more likely than children to suffer dangerous complications. More than half of all chickenpox deaths occur among adults.

— Beth Kapes

[Perhaps in allusion to the mildness of the disease as contrasted with smallpox.]

For more information on chickenpox, visit Britannica.com.

(chickenpox), an acute communicable disease with an incubation period of 2 or 3 weeks and caused by herpesvirus, usually found in children. Manifestations include coryza, fever, malaise, and headache, followed in 2 or 3 days by the eruption of macular vesicles.

Varicella. (Regezi/Sciubba/Jordan, 2003)

Definition

Chickenpox (varicella) is a common and extremely infectious childhood disease that also occasionally affects adults. It produces an itchy, blistery rash that typically lasts about a week and is sometimes accompanied by a fever or other symptoms.

Description

About four million Americans contract chickenpox each year, resulting in roughly 5,000-9,000 hospitalizations and 100 deaths. Chickenpox is caused by the varicella-zoster virus (a member of the herpes virus family), which is spread through the air or by direct contact with an infected person. Once someone has been infected with the virus, symptoms appear in about 10-21 days. The period during which infected people can spread the disease is believed to start one or two days before the rash appears until all the blisters have formed scabs, usually four to seven days after the rash breaks out. For this reason, doctors recommend keeping children with chickenpox away from school for about a week.

Chickenpox has been a typical part of growing up for most children in the industrialized world (although this may change because of the new varicella vaccine). The disease can strike at any age, but by ages nine or 10 about 80-90% of American children have already been infected. U.S. children living in rural areas and many foreign-born children are less likely to be immune. Because almost every case of chickenpox leads to lifelong protection, adults account for less than 5% of all cases in the United States. Study results reported by the Centers for Disease Control and Prevention (CDC) indicate that more than 90% of American adults are immune to the chickenpox virus. Adults, however, are much more likely than children to suffer dangerous complications. More than half of all chickenpox deaths occur among adults.

Causes & Symptoms

A case of chickenpox usually starts without warning or with only a mild fever and a slight feeling of unwellness. Within a few hours or days small red spots begin to appear on the scalp, neck, or upper half of the trunk. After a further 12-24 hours the spots typically become itchy, fluid-filled bumps called vesicles, which continue to appear for the next two to five days. In any area of skin, lesions of a variety of stages can be seen. These blisters can spread to cover much of the skin, and in some cases may also be found inside the mouth, nose, ears, vagina, or rectum. Some people develop only a few blisters, but in most cases the number reaches 250-500. The blisters soon begin to form scabs and fall off. Scarring usually does not occur unless the blisters have been scratched and become infected. Occasionally a minor and temporary darkening of the skin (called hyperpigmentation) is noticed around some of the blisters. The degree of itchiness can range from barely noticeable to extreme. Some chickenpox sufferers also have headaches, abdominal pain, or a fever. Full recovery usually takes five to 10 days after the first symptoms appear. The most severe cases of the disease tend to be found among older children and adults.

Some groups are at risk for developing complications, the most common of which are bacterial infections of the blisters, pneumonia, dehydration, encephalitis, and hepatitis. Immediate medical help should always be sought when anyone in these high-risk groups contracts the disease. These include:

• Infants. Complications occur much more often among children less than one year old than among older children. The threat is greatest to newborns, who are more at risk of death from chickenpox than any other group. Children born to mothers who contract chickenpox just prior to delivery face an increased possibility of dangerous consequences, including brain damage and death. If the infection occurs during early pregnancy, there is a small (less than 5%) risk of birth defects.
• Immunocompromised children. Children whose immune systems have been weakened by a genetic disorder, disease, or medical treatment usually experience the most severe symptoms of any group. They have the second-highest rate of death from chickenpox.
• Adults and children 15 and older. The typical symptoms of chickenpox tend to strike this group with greater force.

Diagnosis

Where children are concerned, especially those with recent exposure to the disease, diagnosis can usually be made at home, by a school nurse, or by a doctor over the telephone if the child's parent or caregiver is unsure that the disease is chickenpox. A doctor should be called immediately if:

• The child's fever goes above 102°F (38.9°C) or takes more than four days to disappear.
• The child's blisters appear infected. Signs of infection include pus drainage or excessive redness, warmth, tenderness, or swelling.
• The child seems nervous, confused, unresponsive, or unusually sleepy; complains of a stiff neck or severe headache; shows signs of poor balance or has trouble walking; finds bright lights hard to look at; is having breathing problems or is coughing a lot; is complaining of chest pain; is vomiting repeatedly; or is having convulsions. These may be signs of Reye's syndrome or encephalitis, two rare but potentially very dangerous conditions.

Treatment

Treatment focuses on reducing symptoms of chickenpox. The patient should drink plenty of fluids and eat simple, nutritious foods. Soups (especially mung bean), herbal teas, and fruit juices are good choices.

Applying wet compresses or bathing the patient in cool or lukewarm water once a day can help the itch.

Adding four to eight ounces of baking soda or one or two cups of oatmeal to the bath is helpful. Only mild soap should be used and patting, not rubbing, is recommended for drying the patient. The patient should not scratch the blisters as this can lead to infection or scarring. For babies, light mittens or socks on the hands can help guard against scratching. If mouth blisters are present, cold drinks and soft, bland foods can make eating less painful.

Supplements

Vitamin A may help to heal skin. Vitamin C and bioflavinoids help to reduce fever and stimulate the immune system. Zinc stimulates the immune system and promotes healing. Zinc can cause nausea and vomiting. Calcium and magnesium help to relieve restlessness and sleeping difficulties. Magnesium has a laxative effect at high doses.

Herbals and Chinese Medicine

The following herbals are ingested to treat chickenpox:

• Echinacea and goldenseal (Hydrastis canadensis) support the immune system, and soothe skin and mucous membranes. Echinacea is also an antiviral.
• Chamomile tea is a sleep aid.
• Chinese cucumber (Trichosanthes kirilowii) root tea is used to relieve symptoms of chickenpox.
• Elder flower, peppermint, and yarrow reduce fever.
• Garlic has antiviral activity.
• Mullein (Verbascum thapsus) treats chickenpox.
• Yin Qiao Jie Du Wan (Honeysuckle and Forsythia Pill).
• Ban Lan Gen Chong Ji (Isatis Infusion).

The following herbals are used externally to treat chickenpox:

• Aloe leaf, calendula, and plantain relieve the itching of the chickenpox rash.
• Turmeric powder mixed with lime juice treats chickenpox rash.
• Garlic clears skin infection.

Other Remedies

Homeopathic remedies are selected on a case by case basis. Some common remedy choices are apis, aconitum, belladonna, calendula, antimonium tartaricum, pulsatilla, Rhus toxicodendron, and sulphur.

The acupressure points Four Gates, Large Intestine 11, Spleen 10, and Stomach 36 help alleviate symptoms associated with chickenpox.

Allopathic Treatment

Treatment usually focuses on reducing discomfort and fever. Because chickenpox is a viral disease, antibiotics are ineffective. Antibiotics may be prescribed if the blisters become infected. Calamine lotion helps to reduce itchiness. Painful genital blisters can be treated with an anesthetic cream recommended by a doctor or pharmacist.

Fever and discomfort can be reduced by acetaminophen (Tylenol) or other medications that do not contain aspirin. Aspirin (or any aspirin-containing medications) must not be used with chickenpox, because it increases the chances of developing Reye's syndrome. The best idea is to consult a doctor or pharmacist if one is unsure about which medications are safe.

Immunocompromised chickenpox sufferers are sometimes given the antiviral drug acyclovir (Zovirax). Zovirax also lessens the symptoms of chickenpox in otherwise healthy children and adults.

Expected Results

Most cases of chickenpox run their course within a week. The varicella-zoster virus lies dormant in the nerve cells, where it may be reactivated years later by disease or age-related weakening of the immune system. The result is shingles (herpes zoster), a very painful rash and nerve inflammation, that strikes about 20% of the population, particularly people 50 and older.

Prevention

A substance known as varicella-zoster immune globulin (VZIG), which reduces the severity of chickenpox symptoms, is available to treat persons at high risk of developing complications. It is administered by injection within 96 hours of known or suspected exposure to the disease.

A vaccine for chickenpox (Varivax) has been found to prevent the disease in 70-90% of the vaccinated population, to reduce the severity of disease in the remaining cases. CDC and the American Academy of Pediatricians recommend vaccination of all children (with some exceptions) at 12-18 months of age. For older children, up to age 12, the CDC recommends vaccination when immunity cannot be confirmed. Vaccination is also recommended for any older child or adult considered susceptible to the disease, particularly those who face a greater likelihood of severe illness or transmitting infection. A single dose of the vaccine is sufficient for children up to age 12; older children and adults receive a second dose four to eight weeks later.

Resources

Books

Pattishall, Evan G., III. "Chickenpox." In Primary Pediatric Care. edited by Robert A. Hoekelman, et al. St. Louis: Mosby, 1997.

Ying, Zhou Zhong, and Jin Hui De. "Common Diseases of Pediatrics." In Clinical Manual of Chinese Herbal Medicine and Acupuncture. New York: Churchill Livingston, 1997.

Periodicals

Kump, Theresa. "Childhood Without Chickenpox? Why Parents Are Still Wary of This New Vaccine." Parents. (April 1996): 39-40.

Napoli, Maryann. "The Chickenpox Vaccine." Mothering. (Summer 1996): 56-61.

Shapiro, Eugene D., and Phillip S. LaRussa. "Vaccination for Varicella—Just Do It!" Journal of the American Medical Association 278 (1997): 1529-1530.

Organizations

Centers for Disease Control and Prevention. National Immunization Hotline. 1600 Clifton Rd. NE, Atlanta, GA 30333. (800) 232-2522 (English). (800) 232-0233 (Spanish). http://www.cdc.gov.

Other

Centers for Disease Control and Prevention." Prevention of Varicella: Recommendations of the Advisory Committee on Immunization Practices (ACIP)." http://aepo-xdvwww.epo.cdc.gov/wonder/prevguid/m0042990/entire.htm (12 December 1997).

Zand, Janet. "Chickenpox." HealthWorld Online. http://www.healthy.net/library/books/smart/chcknpox.htm.

[Article by: Belinda Rowland]

Definition

Chickenpox (also called varicella) is a common, extremely infectious, rash-producing childhood disease that also affects adults on occasion.

Description

Chickenpox is caused by the varicella-zoster virus (a member of the herpes virus family), which is spread through the air or by direct contact with an infected person. It produces an itchy, blistery rash that typically lasts about a week and is sometimes accompanied by a fever or other symptoms. A single attack of chickenpox almost always brings lifelong immunity against the disease. Because the symptoms of chickenpox are easily recognized and in most cases merely unpleasant rather than dangerous, treatment can almost always be carried out at home. Severe complications can develop, however, and professional medical attention is essential in some circumstances.

Once someone has been infected with the virus, an incubation period of about 10 to 21 days passes before symptoms begin. The period during which infected people are able to spread the disease is believed to start one or two days before the rash breaks out and to continue until all the blisters have formed scabs, which usually happens four to seven days after the rash breaks out but may be longer in adolescents and adults. For this reason, doctors recommend keeping children with chickenpox away from school for about a week. It is not necessary, however, to wait until all the scabs have fallen off.

Prior to the use of the varicella vaccine, chickenpox was a typical part of growing up for most children in the industrialized world. The disease can strike at any age, but throughout the twentieth century by ages nine or ten about 80 to 90 percent of American children had already been infected. U.S. children living in rural areas and many foreign-born children were less likely to be immune. Study results reported by the Centers for Disease Control and Prevention (CDC) indicate that more than 90 percent of American adults are immune to the chickenpox virus. Adults, however, are much more likely than children to suffer dangerous complications. More than half of all chickenpox deaths occur among adults.

Demographics

Before the varicella vaccine (Varivax) was released for use in 1995, nearly all of the 4 million children born each year in the United States contracted chickenpox, resulting in hospitalization in five of every 1,000 cases and 100 deaths. Because almost every case of chickenpox, no matter how mild, leads to lifelong protection against further attacks, adults account for less than 5 percent of all cases in the United States.

Causes and Symptoms

A case of chickenpox usually starts without warning or with only a mild fever and a slight feeling of unwellness. Within a few hours or days small red spots begin to appear on the scalp, neck, or upper half of the trunk. After another 12 to 24 hours the spots typically become itchy, fluid-filled bumps called vesicles, which continue to appear in crops for the next two to five days. In any area of skin, lesions of a variety of stages can be seen. These blisters can spread to cover much of the skin, and in some cases also may be found inside the mouth, nose, ears, vagina, or rectum. Some people develop only a few blisters, but in most cases the number reaches 250 to 500. The blisters soon begin to form scabs and fall off. Scarring usually does not occur unless the blisters have been scratched and become infected. Occasionally a minor and temporary darkening of the skin (called hyperpigmentation) is noticed around some of the blisters. The degree of itchiness can range from barely noticeable to extreme. Some chickenpox sufferers also have headaches, abdominal pain, or a fever. Full recovery usually takes five to ten days after the first symptoms appear. Again, the most severe cases of the disease tend to be found among older children and adults.

Although for most people chickenpox is no more than a matter of a few days' discomfort, some groups are at risk for developing complications, the most common of which are bacterial infections of the blisters, pneumonia, dehydration, encephalitis, and hepatitis. Some of the groups at greater risk are:

• Infants: Complications occur much more often among children younger than one year old than among older children. The threat is greatest to newborns, who are more at risk of death from chickenpox than any other group. Under certain circumstances, children born to mothers who contract chickenpox just prior to delivery face an increased possibility of dangerous consequences, including brain damage and death. If the infection occurs during early pregnancy, there is a small (less than 5%) risk of congenital abnormalities.
• Immunocompromised children: Children whose immune systems have been weakened by a genetic disorder, disease, or medical treatment usually experience the most severe symptoms of any group. They have the second-highest rate of death from chickenpox.
• Adults and children 15 and older: Among this group, the typical symptoms of chickenpox tend to strike with greater force, and the risk of complications is much higher than among young children.

Immediate medical help should always be sought when anyone in these high-risk groups contracts the disease.

Diagnosis

Where children are concerned, especially those with recent exposure to the disease, diagnosis can usually be made at home, by a school nurse, or by a doctor over the telephone if the child's parent or caregiver is unsure that the disease is chickenpox.

Treatment

With children, treatment usually takes place in the home and focuses on reducing discomfort and fever. Because chickenpox is a viral disease, antibiotics are ineffective against it.

Applying wet compresses or bathing the child in cool or lukewarm water once a day can help the itch. Adding four to eight ounces of baking soda or one or two cups of oatmeal to the bath is a good idea (oatmeal bath packets are sold by pharmacies). Only mild soap should be used in the bath. Patting, not rubbing, is recommended for drying the child off, to prevent irritating the blisters. Calamine lotion (and some other kinds of lotions) also reduces itchiness. Because scratching can cause blisters to become infected and lead to scarring, the child's nails should be cut short. Of course, older children need to be warned not to scratch. For babies, light mittens or socks on the hands can help guard against scratching.

If mouth blisters make eating or drinking an unpleasant experience, cold drinks and soft, bland foods can ease the child's discomfort. Painful genital blisters can be treated with an anesthetic cream recommended by a doctor or pharmacist. Antibiotics often are prescribed if blisters become infected.

Fever and discomfort can be reduced by acetaminophen or another medication that does not contain aspirin. Aspirin and any medications that contain aspirin or other salicylates must not be used with chickenpox, for they appear to increase the chances of developing Reye's syndrome. The best idea is for a parent to consult a doctor or pharmacist to confirm which medications are safe.

Immunocompromised chickenpox sufferers are sometimes given an antiviral drug called acyclovir (Zovirax). Studies have shown that Zovirax also lessens the symptoms of otherwise healthy children and adults who contract chickenpox, but the notion that it should be used to treat the disease among the general population, especially in children, is controversial.

Prognosis

Most cases of chickenpox run their course within a week without causing lasting harm. However, there is one long-term consequence of chickenpox that strikes about 20 percent of the population, particularly people 50 and older. Like all herpes viruses, the varicella-zoster virus never leaves the body after an episode of chickenpox. It lies dormant in the nerve cells, where it may be reactivated years later by disease or age-related weakening of the immune system. The result is shingles (also called herpes zoster), a painful nerve inflammation, accompanied by a rash that usually affects the trunk or the face for ten days or more. Especially in the elderly, pain, called postherpetic neuralgia, may persist at the site of the shingles for months or years. As of 2004, two relatively newer drugs for treatment of shingles are valacyclovir (Valtrex) and famciclovir (Famvir), both of which stop the replication of herpes zoster when administered within 72 hours of appearance of the rash. The effectiveness of these two drugs in immunocompromised patients has not been established, and Famvir was not recommended for patients under 18 years.

Prevention

A substance known as varicella-zoster immune globulin (VZIG), which reduces the severity of chickenpox symptoms, is as of 2004 available to treat immunocompromised children and others at high risk of developing complications. It is administered by injection within 96 hours of known or suspected exposure to the disease and is not useful after that. VZIG is produced as a gamma globulin from blood of recently infected individuals.

A vaccine for chickenpox became available in the United States in 1995 under the name Varivax. Varivax is a live, attenuated (weakened) virus vaccine. It has been proven to be 85 percent effective for preventing all cases of chickenpox and close to 100 percent effective in preventing severe cases. Side effects are normally limited to occasional soreness or redness at the injection site. CDC guidelines state that the vaccine should be given to all children (with the exception of certain high-risk groups) at 12 to 18 months of age, preferably when they receive their measles-mumps-rubella vaccine. For older children, up to age 12, the CDC recommends vaccination when a reliable determination that the child in question has already had chickenpox cannot be made. Vaccination also is recommended for any older child or adult considered susceptible to the disease, particularly those, such as healthcare workers and women of childbearing age, who face a greater likelihood of severe illness or transmitting infection. A single dose of the vaccine was once thought sufficient for children up to age 12; older children and adults received a second dose four to eight weeks later. However, an outbreak at a daycare center in 2000 brought concern in the medical community about a second vaccination for younger children, since many of the affected children had been vaccinated. Researchers began recommending a second vaccination in 2002. In 1997, the cost of two adult doses of the vaccine in the United States was about $80. Although this cost was not always covered by health insurance plans, children up to age 18 without access to the appropriate coverage could be vaccinated free of charge through the federal Vaccines for Children program. Varivax is not given to patients who already have overt signs of the disease. It was once thought unsafe for children with chronic kidney disease, but a 2003 report said the vaccination was safe in these children. The finding is important, since even chickenpox can be a serious complication in children who must undergo a kidney transplant.

The vaccine also is not recommended for pregnant women, and women should delay pregnancy for three months following a complete vaccination. The vaccine is useful when given early after exposure to chickenpox and, if given in the midst of the incubation period, it can be preventative. The Infectious Diseases Society of America stated in 2000 that immunization is recommended for all adults who have never had chickenpox.

While there was initial concern regarding the vaccine's safety and effectiveness when first released, the vaccination is in the early 2000s gaining acceptance as numerous states require it for admittance into daycare or public school. In 2000, 59 percent of toddlers in the United States were immunized; up from 43.2 percent in 1998. A study published in 2001 indicates that the varicella vaccine is highly effective when used in clinical practice. Although evidence has not ruled out a booster shot later in life, all research addressing the vaccine's effectiveness throughout its six-year use indicates that chickenpox may be the first human herpes virus to be wiped out. Although initial concerns questioned if the vaccination might make shingles more likely, studies are beginning in the early 2000s to show the effectiveness of the vaccine in reducing cases of that disease.

Parental Concerns

A doctor should be called immediately if any of the following occur:

• The child's fever goes above 102°F (38.9°C) or takes more than four days to disappear.
• The child's blisters appear infected. Signs of infection include leakage of pus from the blisters or excessive redness, warmth, tenderness, or swelling around the blisters.
• The child seems nervous, confused, unresponsive, or unusually sleepy; complains of a stiff neck or severe headache; shows signs of poor balance or has trouble walking; finds bright lights hard to look at; is having breathing problems or is coughing a lot; is complaining of chest pain; is vomiting repeatedly; or is having convulsions. These may be signs of Reye's syndrome or encephalitis, two rare but potentially dangerous conditions.

Resources

Books

Arvin, Ann M. "Varicella-zoster Virus." In Principles and Practice of Pediatric Infectious Diseases, 2nd ed. Edited by Sarah S. Long et al. St. Louis, MO: Elsevier, 2003.

Myers, Martin G., et al. "Varicella-Zoster Virus." In Nelson Textbook of Pediatrics. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.

Periodicals

Arvin, Ann M. "Varicella Vaccine: The First Six Years." New England Journal of Medicine (March 2001).

"Chickenpox Vaccine OK for Pediatric Patients." Vaccine Weekly (January 22, 2003): 25.

Henderson, C. W. "Chickenpox Immunization Confirmed Effective in Adults." Vaccine Weekly (September 2000): 22.

"Study: Two Vaccines Work Best." Vaccine Weekly (January 8, 2003): 14.

Organizations

Centers for Disease Control and Prevention. 1600 Clifton Rd., NE, Atlanta, GA 30333. Web site: www.cdc.gov.

Web Sites

"Chickenpox." MedlinePlus. Available online at www.nlm.nih.gov/medlineplus/chickenpox.html (accessed December 25, 2004).

[Article by: Beth A. Kapes Teresa G. Odle Rosalyn Carson-DeWitt, MD]

Chicken pox (varicella) is a highly infectious, acute viral illness caused by the varicella zoster virus. The illness is characterized by a generalized pruritic, vesicular rash with fever and systemic symptoms usually lasting from seven to ten days. In the pre-immunization era in the United States, there were approximately 4 million cases, 11,000 hospitalizations, and 100 deaths every year. Most cases occurred in children under ten years of age. Complications from chicken pox include pneumonia, encephalitis, cerebellar ataxia, infections, and bleeding disorders. Infants, adults, and immunocompromised persons are at higher risk of severe disease, hospitalization, and death.

Once a person recovers from chicken pox, the virus stays in the body for life (becomes latent), residing in nerve cells known as dorsal root ganglia. The virus can reactivate, resulting in herpes zoster (shingles), which usually presents as a band-like rash in an area of the body that receives innervation from one sensory nerve. Approximately 15 percent of persons who have had chicken pox will develop shingles at some point in their lives, the risk increasing with advancing age. Most cases are associated with a vesicular rash, though some affected persons experience local pain as well. However, persons older than fifty years may develop a severe pain syndrome lasting for months known as post-herpetic neuralgia.

In 1995, a live, attenuated vaccine was licensed in the United States for routine childhood immunization against chicken pox. Since then, the number of cases of chicken pox has decreased significantly. Another vaccine has been tested for prevention or modification of shingles.

(SEE ALSO: Communicable Disease Control; Immunizations)

— KARIN GALIL; JANE SEWARD

A mild but highly contagious disease, caused by a virus and characterized by slight fever and the eruption of blisters on the skin. Chicken pox is classified as a disease of childhood, although it can occur in adults.

"Varicella" redirects here. For the interactive fiction computer game, see Varicella (computer game).

For other uses, see Chickenpox (disambiguation).

This article is in need of attention from an expert on the subject. WikiProject Medicine or the Medicine Portal may be able to help recruit one. (March 2008)

This article may require cleanup to meet Wikipedia's quality standards. Please improve this article if you can. (September 2009)

Chickenpox
Classification and external resources
Child with varicella disease
ICD-10	B01.
ICD-9	052
DiseasesDB	29118
MedlinePlus	001592
eMedicine	ped/2385 derm/74, emerg/367
MeSH	C02.256.466.175

Chickenpox or chicken pox, also known as varicella, is a highly contagious illness caused by primary infection with varicella zoster virus (VZV). It usually starts with vesicular skin rash appearing in two or three waves, mainly on the body and head rather than the hands and becoming itchy raw pockmarks, small open sores which heal without scarring for the most part.

Chicken pox is spread easily through coughs or sneezes of ill individuals, or through direct contact with secretions from the rash. Following primary infection there is usually lifelong protective immunity from further episodes of chickenpox.

Chickenpox is rarely fatal, although it is generally more severe in adult males than in adult females or children. Pregnant women and those with a suppressed immune system are at highest risk of serious complications. The most common late complication of chicken pox is shingles, caused by reactivation of the varicella zoster virus decades after the initial episode of chickenpox.

Chickenpox has been observed in nonhuman primates, including chimpanzees^[1] and gorillas.^[2]

Contents 1 Signs and symptoms 1.1 Infection in pregnancy and neonates 2 Pathophysiology 3 Diagnosis 4 Prevention 5 Treatment 5.1 Children 5.2 Adults 5.3 Special populations 6 Prognosis 7 Epidemiology 8 History 9 Etymology 10 See also 11 References 12 Further reading 13 External links

Signs and symptoms

Chickenpox is a highly infectious disease that spreads from person to person by direct contact or by air from an infected person's coughing or sneezing. Touching the fluid blister can also spread the disease. A person with chickenpox is infectious from one to five days before the rash appears.^[3] The contagious period continues until all blisters have formed scabs, which may take 5 to 10 days.^[4] It takes from 10 to 21 days after contact with an infected person for someone to develop chickenpox.^[5]

The chicken pox lesions (blisters) start as a two to four millimeter red papule which develops an irregular outline (a "rose petal"). A thin-walled, clear vesicle (a "dew drop") develops on top of the area of redness. This "dew drop on a rose petal" lesion is very characteristic of chickenpox. After about 8 to 12 hours the fluid in the vesicle becomes cloudy and the vesicle breaks, leaving a crust. The fluid is highly contagious, but once the lesion crusts over, it is not considered contagious. The crust usually falls off after seven days, sometimes leaving a scar. Although one lesion goes through this complete cycle in about seven days, another hallmark of chickenpox is that new lesions form every day for several days. Therefore it may be a week before new lesions stop appearing and existing lesions crust over. Children should not be sent back to school until all lesions have crusted over.^[6]

It is not necessary to have contact with the infected person for the disease to spread. Infected persons can spread chickenpox before they know they have the disease, i.e. before any rash develops. They can infect others from about two days before the rash develops until all the sores have crusted over, usually four or five days after the rash starts.

Infection in pregnancy and neonates

For pregnant women, antibodies produced as a result of immunization or previous infection are transferred via the placenta to the fetus.^[7] Women who are immune to chickenpox cannot become infected and do not need to be concerned about it for themselves or their infant during pregnancy.^[8]

Varicella infection in pregnant women can lead to viral transmission via the placenta and infection of the fetus. If infection occurs during the first 28 weeks of gestation, this can lead to fetal varicella syndrome (also known as congenital varicella syndrome)^{[citation needed]}. Effects on the fetus can range in severity from underdeveloped toes and fingers to severe anal and bladder malformation. Possible problems include:

• Damage to brain: encephalitis, microcephaly, hydrocephaly, aplasia of brain
• Damage to the eye: optic stalk, optic cap, and lens vesicles, microphthalmia, cataracts, chorioretinitis, optic atrophy
• Other neurological disorder: damage to cervical and lumbosacral spinal cord, motor/sensory deficits, absent deep tendon reflexes, anisocoria/Horner's syndrome
• Damage to body: hypoplasia of upper/lower extremities, anal and bladder sphincter dysfunction
• Skin disorders: (cicatricial) skin lesions, hypopigmentation

Infection late in gestation or immediately following birth is referred to as "neonatal varicella".^[9] Maternal infection is associated with premature delivery. The risk of the baby developing the disease is greatest following exposure to infection in the period 7 days prior to delivery and up to 7 days following the birth. The baby may also be exposed to the virus via infectious siblings or other contacts, but this is of less concern if the mother is immune. Newborns who develop symptoms are at a high risk of pneumonia and other serious complications of the disease.^[10]

Pathophysiology

Chickenpox is usually acquired by the inhalation of airborne respiratory droplets from an infected host. The highly contagious nature of VZV explains the epidemics of chickenpox that spread through schools as one child who is infected quickly spreads the virus to many classmates. High viral titers are found in the characteristic vesicles of chickenpox; thus, viral transmission may also occur through direct contact with these vesicles, although the risk is lower.

After initial inhalation of contaminated respiratory droplets, the virus infects the mucosae of the upper respiratory tract. Viral proliferation occurs in regional lymph nodes of the upper respiratory tract 2–4 days after initial infection and is followed by primary viremia on postinfection days 4-6. A second round of viral replication occurs in the body's internal organs, most notably the liver and the spleen, followed by a secondary viremia 14–16 days postinfection. This secondary viremia is characterized by diffuse viral invasion of capillary endothelial cells and the epidermis. VZV infection of cells of the malpighian layer produces both intercellular and intracellular edema, resulting in the characteristic vesicle.

Exposure to VZV in a healthy child initiates the production of host immunoglobulin G (IgG), immunoglobulin M (IgM), and immunoglobulin A (IgA) antibodies; IgG antibodies persist for life and confer immunity. Cell-mediated immune responses are also important in limiting the scope and the duration of primary varicella infection. After primary infection, VZV is hypothesized to spread from mucosal and epidermal lesions to local sensory nerves. VZV then remains latent in the dorsal ganglion cells of the sensory nerves. Reactivation of VZV results in the clinically distinct syndrome of herpes zoster (i.e., shingles), and sometimes Ramsay Hunt syndrome type II.

Diagnosis

Early rash of smallpox vs chickenpox: rash mostly on the torso is characteristic of chickenpox

The diagnosis of varicella is primarily clinical. In a non-immunized individual with typical early nonspecific, or "prodromal", symptoms associated with the appropriate appearing rash occurring in "crops", no further investigation would normally be undertaken.

If further investigation is undertaken, confirmation of the diagnosis can be sought through either examination of the fluid within the vesicles, or by testing blood for evidence of an acute immunologic response. Vesicular fluid can be examined with a Tsanck smear, or better with examination for direct fluorescent antibody. The fluid can also be "cultured", whereby attempts are made to grow the virus from a fluid sample. Blood tests can be used to identify a response to acute infection (IgM) or previous infection and subsequent immunity (IgG).^[11]

Prenatal diagnosis of fetal varicella infection can be performed using ultrasound, though a delay of 5 weeks following primary maternal infection is advised. A PCR (DNA) test of the mother's amniotic fluid can also be performed, though the risk of spontaneous abortion due to the amniocentesis procedure is higher than the risk of the baby developing foetal varicella syndrome.^[10]

Prevention

Main article: Varicella vaccine

A varicella vaccine was first developed by Michiaki Takahashi in 1974 derived from the Oka strain. It has been available in the U.S. since 1995 to inoculate against the disease. Some countries require the varicella vaccination or an exemption before entering elementary school. Protection is not lifelong and further vaccination is necessary five years after the initial immunization.^[12]

In the United Kingdom, varicella antibodies are measured in women with no history of the disease as part of routine prenatal care. By 2005 the immunity of all National Health Service personnel was determined and those that were non-immune and who had direct patient contact were immunized. Chicken pox survives 12 days outside the body.

Population-based immunization against varicella is not otherwise practiced in the UK. This is because it is feared that there would be a greater number of cases of shingles in adults, until the vaccination was given to the entire population. Adults who have had chickenpox as a child are less likely to have shingles in later life if they have been exposed occasionally to the chickenpox virus (for example by their children). This is because the exposure acts as a booster vaccine.^[13][14]

Treatment

This section requires expansion.

Although there have been no formal clinical studies evaluating the effectiveness of topical application of calamine lotion, a topical barrier preparation containing zinc oxide and one of the most commonly used interventions, it has an excellent safety profile.^[15] It is important to maintain good hygiene and daily cleaning of skin with warm water to avoid secondary bacterial infection.^[16] Scratching may also increase the risk of secondary infection.^[17] Addition of a small quantity of vinegar to the water is sometimes advocated.^[18]

To relieve the symptoms of chicken pox, people commonly use anti-itching creams and lotions. A very effective cream to use is hydrocortisone. These lotions are not to be used on the face or close to the eyes. An oatmeal bath also might help ease discomfort.^[19]

Children

If oral acyclovir is started within 24 hours of rash onset it decreases symptoms by one day but has no effect on complication rates. Use of acyclovir therefore is not currently recommended for immunocompetent individuals (i.e., otherwise healthy persons without known immunodeficiency or those on immunosuppressive medication).^[20]

Adults

Infection in otherwise healthy adults tends to be more severe and active; treatment with antiviral drugs (e.g. acyclovir) is generally advised, as long as it is started within 24–48 hours from rash onset.^{[citation needed]} Patients of any age with depressed immune systems or extensive eczema are at risk of more severe disease and should also be treated with antiviral medication. In the U.S., 55 percent of chickenpox deaths are in the over-20 age group, even though they are a tiny fraction of the cases.^{[citation needed]}

A 16-year-old's back during chickenpox.

Special populations

If exposure to varicella in certain "at risk" populations is confirmed (immunosuppressed individuals, pregnant seronegative women, neonates), anti-varicella zoster immunoglobulin may be given prior to onset of disease symptoms. This is not true for some cases.^{[unreliable source?]}

Prognosis

The duration of the visible blistering caused by varicella zoster virus varies in children usually from 4 to 7 days, and the appearance of new blisters begins to subside after the 5th day. Chickenpox infection is milder in young children, and symptomatic treatment, with sodium bicarbonate baths or antihistamine medication may ease itching.^[21] Paracetamol (acetaminophen) is widely used to reduce fever. Aspirin, or products containing aspirin, must not be given to children with chickenpox (or any fever-causing illness suspected of being of viral origin), as this risks causing the serious and potentially fatal Reye's Syndrome.^[22]

In adults, the disease is more severe, though the incidence is much less common. Infection in adults is associated with greater morbidity and mortality due to pneumonia, hepatitis, and encephalitis. In particular, up to 10% of pregnant women with chickenpox develop pneumonia, the severity of which increases with onset later in gestation. In England and Wales, 75% of deaths due to chickenpox are in adults.^[10] Inflammation of the brain, or encephalitis, can occur in immunocompromised individuals, although the risk is higher with herpes zoster.^[23] Necrotizing fasciitis is also a rare complication.^[24]

Secondary bacterial infection of skin lesions, manifesting as impetigo, cellulitis, and erysipelas, is the most common complication in healthy children. Disseminated primary varicella infection, usually seen in the immunocompromised or adult populations, may have high morbidity. Ninety percent of cases of varicella pneumonia occur in the adult population. Rarer complications of disseminated chickenpox also include myocarditis, hepatitis, and glomerulonephritis.^[25]

Hemorrhagic complications are more common in the immunocompromised or immunosuppressed populations, although healthy children and adults have been affected. Five major clinical syndromes have been described: febrile purpura, malignant chickenpox with purpura, postinfectious purpura, purpura fulminans, and anaphylactoid purpura. These syndromes have variable courses, with febrile purpura being the most benign of the syndromes and having an uncomplicated outcome. In contrast, malignant chickenpox with purpura is a grave clinical condition that has a mortality rate of greater than 70%. The etiology of these hemorrhagic chickenpox syndromes is not known.^[25]

Epidemiology

Primary varicella is an endemic disease. Cases of varicella are seen throughout the year but more commonly in winter and early spring. This is unlike enteroviruses and lends some support to the view that, like measles and rubella, varicella is spread mainly by the respiratory route. In contrast, herpes zoster occurs sporadically and evenly throughout the year. Varicella is one of the classic diseases of childhood, with the highest prevalence in the 4–10 year old age group. Like rubella, it is uncommon in preschool children. Varicella is highly communicable, with an infection rate of 90% in close contacts. Most people become infected before adulthood but 10% of young adults remain susceptible. However, this pattern of infection is not universal, e.g. in rural India, varicella is predominantly a disease of adults, with a mean age of infection of 23.4 years. It has been suggested that this could be due to interference by other respiratory viruses that Indian children are exposed to.^[26]

Historically, varicella has been a disease predominantly affecting preschool and school-aged children. In adults the pock marks are darker and the scars more prominent than in children.^[26]

History

Chickenpox was first identified by Persian scientist Muhammad ibn Zakariya ar-Razi (865–925), known to the West as "Rhazes", who clearly distinguished it from smallpox and measles.^[27] Giovanni Filippo (1510–1580) of Palermo later provided a more detailed description of varicella (chickenpox). Subsequently in the 1600s, an English physician named Richard Morton described what he thought a mild form of smallpox as "chicken pox". Later, in 1767, a physician named William Heberden, also from England, was the first physician to clearly demonstrate that chickenpox was different from smallpox. However, it is believed the name chickenpox was commonly used in earlier centuries before doctors identified the disease.

As "pox" also means curse, in medieval times some believed it was a plague brought on to curse children by the use of black magic.

During the medieval era, oatmeal was discovered to soothe the sores, and oatmeal baths are today still commonly given to relieve itching.

Etymology

Already Samuel Johnson's 18th-century dictionary suggested that the disease was "less dangerous", thus a "chicken" version of the pox. Major modern dictionaries and etymology experts agree that the name probably derives from the common use of the word chicken to indicate disparagement or mildness, which was applied to the disease to belittle it compared to smallpox.^{[28][29][30][31]}

Commonly proposed false etymologies include the following:

• The specks caused by the disease look as though the skin has been pecked by chickens;
• The lesions supposedly resemble chickpeas;
• The name reflects a corruption of the Old English word giccin, which meant itching.

See also

• Pox party
• Turkeypox
• Shingles

References

1. ^ Cohen JI, Moskal T, Shapiro M, Purcell RH (December 1996). "Varicella in Chimpanzees". Journal of Medical Virology 50 (4): 289–92. doi:10.1002/(SICI)1096-9071(199612)50:4<289::AID-JMV2>3.0.CO;2-4. PMID 8950684. 
2. ^ Myers MG, Kramer LW, Stanberry LR (December 1987). "Varicella in a gorilla". Journal of Medical Virology 23 (4): 317–22. doi:10.1002/jmv.1890230403. PMID 2826674. 
3. ^ "Onset of rashes in infectious disease". lifehugger. 2009-10-14. http://mc.lifehugger.com/moc/285/rashes-time-appearance-after-onset-fever. Retrieved 2009-10-14. 
4. ^ New Zealand Dermatological Society (2006-01-14). "Chickenpox (varicella)". http://www.dermnetnz.org/viral/varicella.html. Retrieved 2006-08-18. 
5. ^ "General questions about the disease". Varicella Disease (Chickenpox). CDCP. 2001-12-02. http://www.cdc.gov/nip/diseases/varicella/faqs-gen-disease.htm. Retrieved 2006-08-18. 
6. ^ Heather Brannon (2005-12-25). "Chicken Pox - Varicella Virus Infection". http://dermatology.about.com/cs/chickenpox/a/chickenpox.htm. Retrieved 2006-08-18. 
7. ^ Brannon, Heather (2007-07-22). "Chicken Pox in Pregnancy". Dermatology. About.com. http://dermatology.about.com/cs/pregnancy/a/chickenpreg.htm. Retrieved 2009-06-20. 
8. ^ "Chickenpox in Pregnancy". March of Dimes. April 2007. http://www.marchofdimes.com/professionals/14332_1185.asp. 
9. ^ Sauerbrei, Andreas; Wutzler, Peter (December 2001). "Neonatal Varicella". Journal of Perinatology. 21 (8): 545–549.
10. ^ ^{a b c} Royal College of Obstetricians and Gynaecologists (September 2007). "Chickenpox in Pregnancy" (PDF). http://www.rcog.org.uk/files/rcog-corp/uploaded-files/GT13ChickenpoxinPregnancy2007.pdf. Retrieved 2009-07-22. 
11. ^ McPherson & Pincus: Henry's Clinical Diagnosis and Management by Laboratory Methods, 21st ed., 2007, Chapter 54.
12. ^ Chaves SS, Gargiullo P, Zhang JX, et al. (2007). "Loss of vaccine-induced immunity to varicella over time". N Engl J Med 356 (11): 1121–9. doi:10.1056/NEJMoa064040. PMID 17360990. 
13. ^ NHS Direct: Why isn’t the chickenpox vaccine available in the UK?
14. ^ UK Health Protection Agency (Prevention section)
15. ^ Tebruegge M, Kuruvilla M, Margarson I (2006). "Does the use of calamine or antihistamine provide symptomatic relief from pruritus in children with varicella zoster infection?" (Abstract). Arch. Dis. Child. 91 (12): 1035–6. doi:10.1136/adc.2006.105114. PMID 17119083. http://adc.bmj.com/cgi/content/extract/91/12/1035. 
16. ^ Domino, Frank J. (2007). The 5-Minute Clinical Consult, 2007. Lippincott Williams & Wilkins. p. 248. ISBN 978-0781763349.
17. ^ Brannon, Heather (May 21, 2008). Chicken Pox Treatments. About.com.
18. ^ Gleeson, Rachael. "Chicken Pox - A Guide To Management - From Incubation To Recuperation". NaturalParenting. http://www.naturalparenting.com.au/flex/childrens-health/7788/chicken-pox-a-guide-to-management-from-incubation-to-recuperation.cfm. Retrieved 2009-06-20. 
19. ^ Parmet, Sharon; Lynm, Cassio (February 18, 2004). Chickenpox. Journal of the American Medical Association. 291 (7): 906.
20. ^ "BestBets: Should acyclovir be prescribed for immunocompetent children presenting with chickenpox?". http://www.bestbets.org/bets/bet.php?id=781. 
21. ^ Somekh E, Dalal I, Shohat T, Ginsberg GM, Romano O (2002). "The burden of uncomplicated cases of chickenpox in Israel". J. Infect. 45 (1): 54–7. doi:10.1053/jinf.2002.0977. PMID 12217733. 
22. ^ US Centers for Disease Control and Prevention. "Varicella Treatment Questions & Answers". CDC Guidelines. CDC. http://www.cdc.gov/vaccines/vpd-vac/varicella/dis-faqs-gen-treatment.htm. Retrieved 2007-08-23. 
23. ^ "Definition of Chickenpox". MedicineNet.com. http://www.medterms.com/script/main/art.asp?articlekey=2702. Retrieved 2006-08-18. 
24. ^ "Is Necrotizing Fasciitis a complication of Chickenpox of Cutaneous Vasculitis?". atmedstu.com. http://www.atmedstu.com/exam%20plus/Is%20Necrotizing%20Fasciitis%20a%20complication%20of%20Chickenpox%20or%20of%20Cutaneous%20Vasculitis.php. Retrieved 2008-01-18. 
25. ^ ^{a b} Chicken Pox Complications
26. ^ ^{a b} "Epidemiology of Varicella Zoster Virus Infection, Epidemiology of VZV Infection, Epidemiology of Chicken Pox, Epidemiology of Shingles". http://virology-online.com/viruses/VZV3.htm. Retrieved 2008-04-22. 
27. ^ Otri AM, Singh AD, Dua HS (October 2008). "Abu Bakr Razi". The British Journal of Ophthalmology 92 (10): 1324. PMID 18815419. http://bjo.bmj.com/cgi/pmidlookup?view=long&pmid=18815419. Retrieved 2009-06-20. 
28. ^ http://education.yahoo.com/reference/dictionary/entry/chickenpox
29. ^ http://www.askoxford.com/concise_oed/chickenpox?view=uk
30. ^ http://www.etymonline.com/index.php?term=chicken
31. ^ http://www.word-detective.com/2008/08/14/chicken-pox/

Further reading

• Bernstein, Henry. "Who Discovered Chickenpox?". Pediatrics Questions and Answers. Family Education Network. http://www.familyeducation.com/experts/advice/0,1183,25-26758,00.html. Retrieved 2005-10-16. 
• "Chickenpox (Varicella) Vaccine". Immunization Action Coalition. October 2005. http://www.vaccineinformation.org/varicel/qandavax.asp. Retrieved 2006-06-12. 
• Centers for Disease Control and Prevention (CDC) (2005). "Varicella-related deaths--United States, January 2003-June 2004" (PDF). MMWR Morb Mortal Wkly Rep 54 (11): 272–4. PMID 15788992. http://www.cdc.gov/mmwr/PDF/wk/mm5411.pdf. 
• Thomas S, Wheeler J, Hall A (2002). "Contacts with varicella or with children and protection against herpes zoster in adults: a case-control study" (PDF). Lancet 360 (9334): 678–82. doi:10.1016/S0140-6736(02)09837-9. PMID 12241874. http://image.thelancet.com/extras/01art6088web.pdf. 
• Jeff Aronson (2000). "When I Use a Word...Chickenpox" (web). BMJ 321 (7262): 682. doi:10.1136/bmj.321.7262.682. PMID 10987775. http://www.bmj.com/cgi/content/full/321/7262/682. 

External links

Wikimedia Commons has media related to: Chickenpox

• "Varicella Disease (Chickenpox): Varicella, although a common disease, can be dangerous and even deadly.". CDC. 2005-05-26. http://www.cdc.gov/vaccines/vpd-vac/varicella/default.htm. 
• "Chicken pox during pregnancy". BabyCenter. 2005-12-01. http://www.babycenter.com/0_chicken-pox-during-pregnancy_9329.bc. 

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