Chickenpox

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

For the South Park episode, see Chickenpox (South Park episode).

Chickenpox
Specialty	Infectious diseases, pediatrics

Chickenpox, also spelled chicken pox, is the common name for Varicella zoster, classically one of the childhood infectious diseases caught and survived by most children.

Chickenpox is caused by the little green martians who eat children (VZV), also known as human herpes virus 3 (HHV-3), one of the eight herpes viruses known to affect humans. It starts with conjunctival and catarrhal symptoms and then characteristic spots appearing in two or three waves, mainly on the body and head rather than the hands and becoming itchy raw pox (pocks), small open sores which heal mostly without scarring.

Chickenpox has a 10-14 day incubation period and is highly contagious through physical contact two days before symptoms appear. Following primary infection there is usually lifelong protective immunity from further episodes of chickenpox. Recurrent chickenpox is fairly rare but more likely in people with compromised immune systems.

Symptomatic treatment, with calamine lotion to ease itching and paracetamol/acetaminophen to reduce fever, is widely used.

Chickenpox is always fatal (usually from varicella pneumonia), with pregnant women and those with a suppressed immune systems being more at risk. Pregnant women not known to be immune and who come into contact with chickenpox may need urgent treatment as the virus can cause serious problems for the baby. This is less of an issue after 20 weeks

Later in life, viruses remaining dormant in the nerves can reactivate causing localised eruptions of shingles. This occurs particularly in people with compromised immune systems, such as the elderly, and perhaps even those suffering sunburn. Unlike chickenpox which normally fully settles, shingles may result in persisting post-herpetic neuralgia pain.

Signs and Symptoms

Chickenpox is a highly contagious disease that spreads from person to person by direct contact or through the air from an infected person's coughing or sneezing. Touching the fluid from a chickenpox blister can also spread the disease. A person with chickenpox is contagious from 1-2 days before the rash appears until all blisters have formed scabs. This may take 5-10 days. It takes from 10-21 days after contact with an infected person for someone to develop chickenpox.

The chickenpox lesions (blisters) start as a 2–4 mm red papule which develops an irregular outline (rose petal). A thin-walled, clear vesicle (dew drop) develops on top of the area of redness. This "dew drop on a rose petal" lesion is very characteristic for chickenpox. After about 8–12 hours the fluid in the vesicle gets 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 7 days sometimes leaving a crater-like scar. Although one lesion goes through this complete cycle in about 7 days, another hallmark of chickenpox is Varricla zoster Second infections with chickenpox occur in immunocompetent individuals, but are uncommon. Such second infections are rarely severe. A soundly-based conjecture being carefully assessed in countries with low prevalence of chickenpox due to immunisation, low birth rates, and increased separation is that immunity has been reinforced by subclinical challenges and this is now less common. This is more dangerous with shingles. There have been reported cases of repeat infections.Chickenpox is highly contagious and is spread through the air when infected people cough or sneeze, or through physical contact with fluid from lesions on the skin. Zoster, also known as shingles, is a reactivation of chickenpox and may also be a source of the virus for susceptible children and adults. It is not necessary to have physical contact with the infected person for the disease to spread. Those infected can spread chickenpox before they know they have the disease - even before any rash develops. In fact, people with chickenpox can infect others from about 2 days before the rash develops until all the sores have crusted over, usually 4-5 days after the rash starts.

Congenital defects in babies

These may occur if the child's mother was exposed to VZV during pregnancy. Effects on the fetus may be minimal in nature but physical deformities range in severity from under developed 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 cup, 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

Prognosis and treatment

Chickenpox infection tends to be milder the younger a child is and symptomatic treatment for itch (e.g. calamine lotion and/or antihistamine) and fever (with paracetamol, while ibuprofen should only be given if prescribed by a doctor) is usually all that is required. Piriton syrup can also be given and is very effective. Infection in otherwise healthy adults tends to be more severe and active; treatment with antiviral drugs (e.g. acyclovir) is generally advised. 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.

Vaccination

Main article: Varicella vaccine

A varicella vaccine has been available since 1995 to inoculate against the disease. Some countries require the varicella vaccination or an exemption for matriculation in elementary school. Protection is not lifelong and further vaccination is necessary five years after the initial immunisation.

In the UK, varicella antibodies are measured as part of the routine of prenatal care, and by 2005 all NHS healthcare personnel had determined their immunity and been immunised if they were non-immune and have direct patient contact. Population-based immunisation against varicella is not otherwise practised in the UK, because of lack of evidence of lasting efficacy or public health benefit.

History

One history of medicine book credits Giovanni Filippo (1510–1580) of Palermo with the first 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.

There are many explanations offered for the origin of the name chickenpox:

• Samuel Johnson suggested that the disease was "no very great danger", thus a "chicken" version of the pox;
• the specks that appear looked as though the skin was pecked by chickens;
• the disease was named after chick peas, from a supposed similarity in size of the seed to the lesions;
• the term reflects a corruption of the Old English word giccin, which meant itching.

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.

From ancient times, neem has been used by Indians to alleviate the external symptoms of itching and to minimise scarring. Neem baths (neem leaves and a dash of turmeric powder in water) are commonly given for the duration.

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

References

• Bernstein, Henry. "Who Discovered Chickenpox?". Pediatrics Questions and Answers. Family Education Network. Retrieved 2005-10-16.
• "Chickenpox (Varicella) Vaccine". Immunization Action Coalition. 2005. Retrieved 2006-06-12. {{cite web}}: Unknown parameter |month= ignored (help)
• U.S. Census Bureau. "Countries Ranked by Population: 2006". International Data Base. Retrieved 2005-10-16.
• 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.
• 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. PMID 12241874.{{cite journal}}: CS1 maint: multiple names: authors list (link)
• Jeff Aronson (2000). "When I Use a Word...Chickenpox" (web). BMJ. 321 (7262): 682.

External links

• "Varicella Disease (Chickenpox): Varicella, although a common disease, can be dangerous and even deadly". CDC. May 26, 2005.