Difference between revisions of "Chickenpox" - New World Encyclopedia

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'''Chickenpox''' (or '''chicken pox'''), also known as '''varicella''', is a common and very highly contagious viral disease caused by the varicella-zoster virus (VSZ). It is classically one of the childhood infectious diseases caught and survived by almost every child, although currently there is a vaccine.
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'''Chickenpox''' (or '''chicken pox'''), also known as '''varicella,''' is a common and very highly contagious viral disease caused by the varicella-zoster virus (VSZ). It is classically one of the childhood infectious diseases caught and survived by almost every child, although currently there is a vaccine.
  
Following primary infection, there is usually lifelong protective immunity from further episodes of chickenpox. Recurrent chickenpox, commonly known as [[shingles]], is fairly rare but more likely in people with compromised immune systems.
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Following primary infection, there is usually lifelong protective immunity from further episodes of chickenpox. Recurrent chickenpox, commonly known as [[shingles]], is fairly rare but more likely in people with compromised [[immune system]]s.
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{{toc}}
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As uncomfortable as chicken pox is—with [[fever]] and often hundreds of itchy blisters that proceed to open, but rarely scarring sores—there was a time that some mothers would deliberately expose their young daughters to chickenpox. This is because of the potential complications should a pregnant women get chickenpox, and the view that it is better to go through limited suffering for the sake of future benefit. Today, an easier course if available with the availability of a [[vaccine]] that is highly effective for preventing chickenpox, and especially for the most severe cases.  
  
 
==Overview==
 
==Overview==
 
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[[File:Chickenpox.png|thumb|300px|Chickenpox]]
===Varicell-zoster virus===
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===''Varicella-zoster'' virus===
 
Chickenpox is caused by the [[varicella-zoster virus]] (VZV), also known as human herpes virus 3 (HHV-3), one of the eight [[Herpesviridae|herpes viruses]] known to affect humans.  
 
Chickenpox is caused by the [[varicella-zoster virus]] (VZV), also known as human herpes virus 3 (HHV-3), one of the eight [[Herpesviridae|herpes viruses]] known to affect humans.  
  
The ''Varicella zoster'' virus (VZV), the causal agent of chickenpox, is one of the eight [[Herpesviridae|herpes viruses]] known to affect humans (and other vertebrates). Multiple names are used to refer to same virus, creating some confusion.  Varicella virus, zoster virus, human herpes 3 (HHV-3), and Varicella Zoster Virus (VZV) all refer to the same viral pathogen.  
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Multiple names are used to refer to same virus, creating some confusion.  Varicella virus, zoster virus, human herpes 3 (HHV-3), and Varicella Zoster Virus (VZV) all refer to the same viral pathogen.  
  
 
VZV is closely related to the [[herpes simplex virus]]es (HSV), sharing much [[genome]] homology. The known envelope glycoproteins (gB, gC, gE, gH, gI, gK, gL) correspond with those in HSV, however there is no equivalent of HSV gD. VZV virons are spherical and 150-200 nm in diameter. Their [[lipid]] envelope encloses the nucleocapsid of 162 capsomeres arranged in a [[hexagon]]al form. Its [[DNA]] is a single, linear, double-stranded molecule, 125,000 nt long.
 
VZV is closely related to the [[herpes simplex virus]]es (HSV), sharing much [[genome]] homology. The known envelope glycoproteins (gB, gC, gE, gH, gI, gK, gL) correspond with those in HSV, however there is no equivalent of HSV gD. VZV virons are spherical and 150-200 nm in diameter. Their [[lipid]] envelope encloses the nucleocapsid of 162 capsomeres arranged in a [[hexagon]]al form. Its [[DNA]] is a single, linear, double-stranded molecule, 125,000 nt long.
  
The virus is very susceptible to [[disinfectant]]s, notably [[sodium hypochlorite]]. Within the body it can be treated by a number of drugs and therapeutic agents including [[aciclovir]], [[zoster-immune globulin]] (ZIG), and [[vidarabine]].
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The virus is very susceptible to [[disinfectant]]s, notably [[sodium hypochlorite]]. Within the body it can be treated by a number of drugs and therapeutic agents, including [[aciclovir]], [[zoster-immune globulin]] (ZIG), and [[vidarabine]].
  
 
===Chickenpox and shingles===
 
===Chickenpox and shingles===
 
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{{readout||right|250px|The varicella-zoster virus which causes chickenpox can reactivate later in life causing the more painful [[shingles]]}}
 
The initial infection with the [[varicella-zoster virus]] (the primary VZV infection) results in chickenpox (varicella), which may rarely result in complications including VZV [[encephalitis]] or [[pneumonia]]. Even when clinical symptoms of varicella have resolved, VZV remains dormant in the [[nervous system]] of the host in the [[trigeminal nerve|trigeminal]] and [[dorsal root ganglion|dorsal root ganglia]].  
 
The initial infection with the [[varicella-zoster virus]] (the primary VZV infection) results in chickenpox (varicella), which may rarely result in complications including VZV [[encephalitis]] or [[pneumonia]]. Even when clinical symptoms of varicella have resolved, VZV remains dormant in the [[nervous system]] of the host in the [[trigeminal nerve|trigeminal]] and [[dorsal root ganglion|dorsal root ganglia]].  
  
In about 10-20% of cases, VZV reactivates later in life producing a disease known as [[shingles]], herpes zoster, or simply zoster. These localized eruptions occur particularly  in people with compromized [[immune system]]s, such as the elderly, and perhaps even those suffering sunburn. Serious complications of shingles include [[post-herpetic neuralgia]], zoster multiplex, myelitis, herpes ophthalmicus, or zoster sine herpete.   
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In about 10-20 percent of cases, VZV reactivates later in life, producing a disease known as [[shingles]], herpes zoster, or simply zoster. These localized eruptions occur particularly  in people with compromised [[immune system]]s, such as the elderly, and perhaps even those suffering sunburn. Serious complications of shingles include [[post-herpetic neuralgia]], zoster multiplex, myelitis, herpes ophthalmicus, or zoster sine herpete.   
  
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, including indirectly via an article of clothing with fresh fluid. The virus has a 10-121 day incubation period before symptoms appear. 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 (DermNet 2006; CDC 2001).  
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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, including indirectly via an article of clothing with fresh fluid. The virus has a 10-21 day incubation period before symptoms appear. 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 (NZDS 2016; CDC 2021).  
  
Before the 1995 introduction of the varicella vaccine, Varivax, virtually all children born each year in the [[United States]] contracted chickenpox, with a rate of only about five of every 1,000 needing hospitalization and about 100 deaths a year (Longe 2006). By ages nine or ten, about 80 to 90 percent of American children were infected, and adults counted for less than five percent of all cases, with about 90% immune to the virus (Longe 2005). However, adutls are more likely than children to suffer dangerous consequences, and about half of all deaths occur among adults (Knapp and Wilson 2005).  
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Before the 1995 introduction of the varicella vaccine, Varivax, virtually all children born each year in the [[United States]] contracted chickenpox, with a rate of only about five of every 1,000 needing hospitalization and about 100 deaths a year (Longe 2006). By ages nine or ten, about 80 to 90 percent of American children were infected, and adults counted for less than five percent of all cases, with about 90 percent immune to the virus (Longe 2005). However, adults are more likely than children to suffer dangerous consequences, and about half of all deaths occur among adults (Knapp and Wilson 2005).  
  
Although chickenpox is rarely fatal (usually from varicella [[pneumonia]]), pregnant women and those with a suppressed immune system are 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.
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Although chickenpox is rarely fatal (usually from varicella [[pneumonia]]), pregnant women and those with a suppressed immune system encounter greater risks. 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.
  
 
==Signs and symptoms==
 
==Signs and symptoms==
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[[File:Chickenpox blister.jpg|thumb|300px|A typical chickenpox blister shortly after appearance]]
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Chickenpox commonly starts without warning or with a mild fever and discomfort (Longe 2006). There may be [[conjunctival]] (membrane covering white of eye and inside eyelid) and [[catarrhal]] (runny nose) symptoms and then characteristic spots appearing in two or three waves. These small red spots appear on the scalp, neck, or upper half of the trunk, rather than the hands, and after 12 to 24 hours become itchy, raw, fluid-filled bumps ([[pox]], "pocks"), small open sores that heal mostly without scarring. They appear in crops for two to five days (Longe 2006).
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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.
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Although one lesion goes through this complete cycle in about 7 days, another hallmark of chickenpox is the fact that new lesions crop up every day for several days. One area of skin may have lesions of a variety of stages (Longe 2006). It may take about a week until new lesions stop appearing and existing lesions crust over. Children are not to be sent back to school until all lesions have crusted over at which point they are no longer considered contagious (Iannelli 2021).
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Some people only develop a few blisters, but in most cases the number reaches 250-500 (Knapp and Wilson 2005). The blisters may cover much of the skin and in some cases may appear inside the mouth, nose, ears, rectum, or vagina (Longe 2005). The blisters can itch very little or can be extremely itchy.
  
Chickenpox 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.
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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 immunization, low birth rates, and increased separation is that immunity has been reinforced by subclinical challenges and this is now less common.
  
The chickenpox lesions (blisters) start as a 2&ndash;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&ndash;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 the fact that new lesions crop up every day for several days. Therefore, it may take about a week until new lesions stop appearing and existing lesions crust over. Children are not to be sent back to school until all lesions have crusted over.<!--
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Shingles, a reactivation of chickenpox, may also be a source of the virus for susceptible children and adults.
  —><ref>{{cite web | author=Heather Brannon | title=Chicken Pox - Varicella Virus Infection | url=http://dermatology.about.com/cs/chickenpox/a/chickenpox.htm | date=December 25, 2005 | accessdate=2006-08-18}}</ref>
 
  
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.<!--
 
  —><ref>{{cite web | title=Definition of Chickenpox | url=http://www.medterms.com/script/main/art.asp?articlekey=2702 | publisher=MedicineNet.com | accessdate=2006-08-18}}</ref><!--Chickenpox is a rash caused by a virus. The chickenpox rash usually appears less than two weeks after exposure to the virus and begins as superficial spots. These spots quickly turn into small liquid-filled blisters that break open and crust over. New spots continue to appear for several days and may number in the hundreds. Itching may range from mild to intense.
 
 
The course of chickenpox will vary with each child, but a child generally will be sick with chickenpox for about 4-7 days.  New blisters usually stop appearing by the 5th day, most are crusted by the 6th day, and most scabs are gone within 20 days after the rash begins.  If complications set in, however, the recovery period may be even longer.
 
The course of chickenpox will vary with each child, but a child generally will be sick with chickenpox for about 4-7 days.  New blisters usually stop appearing by the 5th day, most are crusted by the 6th day, and most scabs are gone within 20 days after the rash begins.  If complications set in, however, the recovery period may be even longer.
  
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These are the most common symptoms of chicken pox:
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* Mild fever. The fever varies between 101°F to 105°F and returns to normal when the blisters have disappeared.
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* backache
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* headache
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* sore throat
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* a rash (red spots)
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* blisters filled with fluid
  
These are the most common symptoms of chicken pox:
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A doctor should be consulted if the child's fever goes above 102°F or takes more than four days to disappear, the blisters appear infected, or the child appears nervous, confused, unresponsive, unusually sleepy, complains of stiff neck or severe headache, shows poor balance, has trouble breathing, is vomiting repeatedly, finds bright lights hard to look at, or is having convulsions (Longe 2006).
o Mild fever. The fever varies between 101-o F to 105-o F and returns to normal when the blisters have disappeared.
 
o backache
 
o headache
 
o sore throat
 
o a rash (red spots)
 
o blisters filled with fluid
 
  
  —><ref>{{cite web | author=American Academy of Pediatrics | title=Varicella Immunization | url=http://www.cispimmunize.org/fam/chpox/chpximm.html | publisher=CDCP | accessdate=2006-08-18}}</ref>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.  
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==Prognosis and treatment==
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Treatment usually takes place in the home, with a focus on reducing discomfort and [[fever]] (Longe 2006). Chickenpox infection tends to be milder the younger a child is and symptomatic treatment, with  a little [[sodium bicarbonate]] in baths or [[antihistamine]] medication to ease itching (Somekh et al. 2002), and [[paracetamol]] (acetaminophen) to reduce fever, are widely used. [[Ibuprofen]] can also be used on advice of a doctor. Aspirin should not be used because they can increase the probability of developing [[Reye's syndrome]]. Antibiotics are ineffective since it is viral in nature, rather than bacterial. There is no evidence to support the topical application of [[calamine lotion]], a topical barrier preparation containing zinc oxide in spite of its wide usage and excellent safety profile (Tebruegge et al. 2006).  
  
===Congenital defects in babies===
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It is important to maintain good hygiene and daily cleaning of skin with warm water to avoid secondary bacterial infection. Scratching the blisters can cause them to become infected and should be avoided. Mittens or socks on the hands of infants can help protect against scratching (Longe 2006).
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 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 reflex]]es, 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==
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[[Infection]] of the virus 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 United States, 55 percent of chickenpox deaths are in the over-20 age group.
Chickenpox infection tends to be milder the younger a child is and symptomatic treatment, with a little [[sodium bicarbonate]] in baths or [[antihistamine]] medication to ease itching,<ref>{{cite journal |author=Somekh E, Dalal I, Shohat T, Ginsberg''''' GM''''', Romano O |title=The burden of uncomplicated cases of chickenpox in Israel |journal=J. Infect. |volume=45 |issue=1 |pages=54-7 |year=2002 |pmid=12217733 |doi=}}</ref> and [[paracetamol]] (acetaminophen) to reduce fever, are widely used. Ibuprofen can also be used on advice of a doctor. There is no evidence to support the topical application of [[calamine lotion]], a topical barrier preparation containing zinc oxide in spite of its wide usage and excellent safety profile.<ref>{{cite journal |author=Tebruegge M, Kuruvilla M, Margarson I |title=Does the use of calamine or antihistamine provide symptomatic relief from pruritus in children with varicella zoster infection? |journal=Arch. Dis. Child. |volume=91 |issue=12 |pages=1035-6 |year=2006 |pmid=17119083 |doi=10.1136/adc.2006.105114 |url=http://adc.bmj.com/cgi/content/extract/91/12/1035 |format-Abstract}}</ref>.
 
  
It is important to maintain good hygiene and daily cleaning of skin with warm water to avoid secondary bacterial infection. [[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.
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==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 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 reflex]]es, anisocoria/[[Horner's syndrome]]
 +
* Damage to body: [[Hypoplasia]] of upper/lower extremities, anal and bladder [[sphincter]] dysfunction
 +
* Skin disorders: ([[Cicatricial]]) skin lesions, [[hypopigmentation]]
  
 
==Vaccination==
 
==Vaccination==
{{main|Varicella vaccine}}
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A [[varicella vaccine]] has been available since 1995, to inoculate against the disease.  Some countries and states in the United States 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 immunization (Chaves et al. 2007).
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 immunization.<!--
 
  —><ref>{{cite journal | author=Chaves SS, Gargiullo P, Zhang JX, ''et al.'' | title=Loss of vaccine-induced immunity to varicella over time | journal=N Engl J Med | year=2007 | volume=356 | issue=11 | pages=1121&ndash;9 | id=PMID 17360990}}</ref>
 
  
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 immunization against varicella is not otherwise practiced in the UK, because of lack of evidence of lasting efficacy or public health benefit.
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In the United Kingdom, varicella [[antibody|antibodies]] are measured as part of the routine of prenatal care, and by 2005, all NHS health care personnel had determined their immunity and been immunized if they were non-immune and have direct patient contact. Population-based immunization against varicella is not otherwise practiced in the UK, because of lack of evidence of lasting efficacy or public health benefit.
  
 
==History==
 
==History==
One history of medicine book credits [[Giovanni Filippo]] ([[1510]]&ndash;[[1580]]) of [[Palermo]] with the first description of varicella (chickenpox).  Subsequently in the [[1600s]], an [[United Kingdom|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.  
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One history of medicine book credits [[Giovanni Filippo]] (1510&ndash;1580) of [[Palermo]] with the first description of varicella (chickenpox).  Subsequently in the 1600s, an [[United Kingdom|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'':
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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;
+
* [[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 specks that appear looked as though the skin was pecked by chickens;
 
* the disease was named after [[Chickpea|chick pea]]s, from a supposed similarity in size of the seed to the lesions;
 
* the disease was named after [[Chickpea|chick pea]]s, 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''.
+
* 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.   
 
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 [[India|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.
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From ancient times, [[neem]] has been used by people in [[India]] to alleviate the external symptoms of itching and to minimize 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.
 
During the medieval era, [[oatmeal]] was discovered to soothe the sores, and oatmeal baths are today still commonly given to relieve itching.
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==References==
 
==References==
  
<!
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* Aronson, J. 2000. [http://www.bmj.com/cgi/content/full/321/7262/682 When I use a word...chickenpox]. ''BMJ'' 321(7262): 682. Retrieved March 9, 2022.
  ><ref name="DermNet NZ">{{cite web | author=New Zealand Dermatological Society | title=Chickenpox (varicella) | url=http://www.dermnetnz.org/viral/varicella.html | date=14 Jan 2006 | accessdate=2006-08-18}}</ref>
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* Iannelli, V. 2021. [https://www.verywellhealth.com/symptoms-of-chicken-pox-2634340 Symptoms of Chickenpox] ''Verywell health''. Retrieved March 9, 2022.
It takes from 10-21 days after contact with an infected person for someone to develop chickenpox.<!--
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* Centers for Disease Control and Prevention (CDC). 2021. [https://www.cdc.gov/chickenpox/about/transmission.html Chickenpox (Varicella): Transmission]. ''CDC''. Retrieved March 9, 2022.
  —><ref name="CDCP-diseaseFAQs">{{cite web | work=Varicella Disease (Chickenpox) | title=General questions about the disease | url=http://www.cdc.gov/nip/diseases/varicella/faqs-gen-disease.htm | date=December 2 2001 | publisher=CDCP | accessdate=2006-08-18}}</ref>
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* Centers for Disease Control and Prevention (CDC). 2005. [http://www.cdc.gov/mmwr/PDF/wk/mm5411.pdf Varicella-related deaths: United States, January 2003-June 2004]. ''MMWR Morb Mortal Wkly Rep'' 54(11): 272-274. Retrieved March 9, 2022.
 +
* Chaves, S. S., P. Gargiullo, J. X. Zhang, and et al. 2007. Loss of vaccine-induced immunity to varicella over time. ''N Engl J Med'' 356(11): 1121-1129.
 +
* Krapp, Kristine M., and Jeffrey Wilson. 2005. ''The Gale Encyclopedia of Children's Health: Infancy Through Adolescence.'' Detroit: Thomson Gale. ISBN 0787692417
 +
* Longe, J. L. 2005. ''The Gale Encyclopedia of Alternative Medicine.'' Farmington Hills, Mich: Thomson/Gale. ISBN 0787693960
 +
* Longe, J. L. 2006. ''The Gale Encyclopedia of Medicine.'' Detroit: Thomson Gale. ISBN 1414403682
 +
* New Zealand Dermatological Society (NZDS). 2016. [https://dermnetnz.org/topics/chickenpox Chickenpox (varicella)]. ''DermNet NZ''. Retrieved March 9, 2022.
 +
* Somekh, E., I. Dalal, T. Shohat, G. M. Ginsberg, and O. Romano. 2002. [https://pubmed.ncbi.nlm.nih.gov/12423610/ The burden of uncomplicated cases of chickenpox in Israel]. ''J. Infect.'' 45(1): 54-57. Retrieved March 9, 2022.
 +
* Tebruegge, M., M. Kuruvilla, and I. Margarson. 2006. [https://adc.bmj.com/content/91/12/1035 Does the use of calamine or antihistamine provide symptomatic relief from pruritus in children with varicella zoster infection?]. ''Arch. Dis. Child.'' 91(12): 1035-1036. Retrieved March 9, 2022.
 +
* Thomas, S. J., A. J. Wheeler, and A. Hall. 2002. [https://www.thelancet.com/pb-assets/Lancet/extras/01art6088web.pdf Contacts with varicella or with children and protection against herpes zoster in adults: A case-control study]. ''Lancet'' 360(9334): 678-682. Retrieved March 9, 2022.
  
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==External links==
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All links retrieved December 10, 2023.
 +
*[https://my.clevelandclinic.org/health/diseases/4017-chickenpox Chickenpox] ''Cleveland Clinic''.
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*[https://www.mayoclinic.org/diseases-conditions/chickenpox/symptoms-causes/syc-20351282 Chickenpox] ''Mayo Clinic''.
  
* Krapp, Kristine M., and Jeffrey Wilson. 2005. The Gale encyclopedia of children's health: infancy through adolescence. Detroit: Thomson Gale. ISBN 0787692417.
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* Longe, J. L. 2005. ''The Gale Encyclopedia of Alternative Medicine''. Farmington Hills, Mich: Thomson/Gale. ISBN 0787693960.
 
 
 
* Longe, J. L. 2006. ''The Gale Encyclopedia of Medicine''. Detroit: Thomson Gale. ISBN 1414403682.
 
 
 
 
 
* {{cite web | author=Bernstein, Henry | url=http://www.familyeducation.com/experts/advice/0,1183,25-26758,00.html | title=Who Discovered Chickenpox? | work=Pediatrics Questions and Answers | publisher=Family Education Network | accessdate=2005-10-16}}
 
* {{cite web | title=Chickenpox (Varicella) Vaccine | url=http://www.vaccineinformation.org/varicel/qandavax.asp | month=October | year=2005 | publisher=Immunization Action Coalition | accessdate=2006-06-12}}
 
* {{cite web | author= U.S. Census Bureau | authorlink=United States Census Bureau | title=Countries Ranked by Popn: 2006 | url=http://www.census.gov/cgi-bin/ipc/idbrank.pl | work = International Data Base | accessdate=2005-10-16}}
 
* {{cite journal | author=Centers for Disease Control and Prevention (CDC) | authorlink=Centers for Disease Control and Prevention  | title=Varicella-related deaths—United States, January 2003-June 2004. | journal=MMWR Morb Mortal Wkly Rep | volume=54 | issue=11 | pages=272-4 | year=2005 | id=PMID 15788992 | url=http://www.cdc.gov/mmwr/PDF/wk/mm5411.pdf | format=PDF}}
 
* {{cite journal | author=Thomas S, Wheeler J, Hall A | title=Contacts with varicella or with children and protection against herpes zoster in adults: a case-control study. | journal=Lancet | volume=360 | issue=9334 | pages=678-82 | year=2002 | id=PMID 12241874 | url=http://image.thelancet.com/extras/01art6088web.pdf | format=PDF}}
 
* {{cite journal | author=Jeff Aronson | title=When I Use a Word...Chickenpox | journal=BMJ | volume=321 | issue=7262 | page=682 | year=2000 |  url=http://www.bmj.com/cgi/content/full/321/7262/682 | format=web}}
 
 
 
==Notes==
 
<div class="references-small"><references/></div>
 
  
==External links==
 
{{commonscat|Chickenpox}}
 
* {{cite web | title=Varicella Disease (Chickenpox): Varicella, although a common disease, can be dangerous and even deadly. | url=http://www.cdc.gov/vaccines/vpd-vac/varicella/default.htm | date=May 26, 2005 | publisher=[[Centers for Disease Control and Prevention|CDC]]}}
 
*[http://www.assortedinformation.com/chickenpox How to tell you Have Chickenpox]
 
 
{{Viral diseases}}
 
{{Viral diseases}}
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{{credit|Chickenpox|146373449|Varicella_zoster_virus|152686465}}
 
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[[Category:Diseases]]

Latest revision as of 15:24, 10 December 2023

Chickenpox
Child with chickenpox.jpg

Child with varicella disease
ICD-10 B01
ICD-O:
ICD-9 052
OMIM [1]
MedlinePlus 001592
eMedicine ped/2385
DiseasesDB 29118

Chickenpox (or chicken pox), also known as varicella, is a common and very highly contagious viral disease caused by the varicella-zoster virus (VSZ). It is classically one of the childhood infectious diseases caught and survived by almost every child, although currently there is a vaccine.

Following primary infection, there is usually lifelong protective immunity from further episodes of chickenpox. Recurrent chickenpox, commonly known as shingles, is fairly rare but more likely in people with compromised immune systems.

As uncomfortable as chicken pox is—with fever and often hundreds of itchy blisters that proceed to open, but rarely scarring sores—there was a time that some mothers would deliberately expose their young daughters to chickenpox. This is because of the potential complications should a pregnant women get chickenpox, and the view that it is better to go through limited suffering for the sake of future benefit. Today, an easier course if available with the availability of a vaccine that is highly effective for preventing chickenpox, and especially for the most severe cases.

Overview

Chickenpox

Varicella-zoster virus

Chickenpox is caused by the varicella-zoster virus (VZV), also known as human herpes virus 3 (HHV-3), one of the eight herpes viruses known to affect humans.

Multiple names are used to refer to same virus, creating some confusion. Varicella virus, zoster virus, human herpes 3 (HHV-3), and Varicella Zoster Virus (VZV) all refer to the same viral pathogen.

VZV is closely related to the herpes simplex viruses (HSV), sharing much genome homology. The known envelope glycoproteins (gB, gC, gE, gH, gI, gK, gL) correspond with those in HSV, however there is no equivalent of HSV gD. VZV virons are spherical and 150-200 nm in diameter. Their lipid envelope encloses the nucleocapsid of 162 capsomeres arranged in a hexagonal form. Its DNA is a single, linear, double-stranded molecule, 125,000 nt long.

The virus is very susceptible to disinfectants, notably sodium hypochlorite. Within the body it can be treated by a number of drugs and therapeutic agents, including aciclovir, zoster-immune globulin (ZIG), and vidarabine.

Chickenpox and shingles

Did you know?
The varicella-zoster virus which causes chickenpox can reactivate later in life causing the more painful shingles

The initial infection with the varicella-zoster virus (the primary VZV infection) results in chickenpox (varicella), which may rarely result in complications including VZV encephalitis or pneumonia. Even when clinical symptoms of varicella have resolved, VZV remains dormant in the nervous system of the host in the trigeminal and dorsal root ganglia.

In about 10-20 percent of cases, VZV reactivates later in life, producing a disease known as shingles, herpes zoster, or simply zoster. These localized eruptions occur particularly in people with compromised immune systems, such as the elderly, and perhaps even those suffering sunburn. Serious complications of shingles include post-herpetic neuralgia, zoster multiplex, myelitis, herpes ophthalmicus, or zoster sine herpete.

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, including indirectly via an article of clothing with fresh fluid. The virus has a 10-21 day incubation period before symptoms appear. 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 (NZDS 2016; CDC 2021).

Before the 1995 introduction of the varicella vaccine, Varivax, virtually all children born each year in the United States contracted chickenpox, with a rate of only about five of every 1,000 needing hospitalization and about 100 deaths a year (Longe 2006). By ages nine or ten, about 80 to 90 percent of American children were infected, and adults counted for less than five percent of all cases, with about 90 percent immune to the virus (Longe 2005). However, adults are more likely than children to suffer dangerous consequences, and about half of all deaths occur among adults (Knapp and Wilson 2005).

Although chickenpox is rarely fatal (usually from varicella pneumonia), pregnant women and those with a suppressed immune system encounter greater risks. 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.

Signs and symptoms

A typical chickenpox blister shortly after appearance

Chickenpox commonly starts without warning or with a mild fever and discomfort (Longe 2006). There may be conjunctival (membrane covering white of eye and inside eyelid) and catarrhal (runny nose) symptoms and then characteristic spots appearing in two or three waves. These small red spots appear on the scalp, neck, or upper half of the trunk, rather than the hands, and after 12 to 24 hours become itchy, raw, fluid-filled bumps (pox, "pocks"), small open sores that heal mostly without scarring. They appear in crops for two to five days (Longe 2006).

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 the fact that new lesions crop up every day for several days. One area of skin may have lesions of a variety of stages (Longe 2006). It may take about a week until new lesions stop appearing and existing lesions crust over. Children are not to be sent back to school until all lesions have crusted over at which point they are no longer considered contagious (Iannelli 2021).

Some people only develop a few blisters, but in most cases the number reaches 250-500 (Knapp and Wilson 2005). The blisters may cover much of the skin and in some cases may appear inside the mouth, nose, ears, rectum, or vagina (Longe 2005). The blisters can itch very little or can be extremely itchy.

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 immunization, low birth rates, and increased separation is that immunity has been reinforced by subclinical challenges and this is now less common.

Shingles, a reactivation of chickenpox, may also be a source of the virus for susceptible children and adults.

The course of chickenpox will vary with each child, but a child generally will be sick with chickenpox for about 4-7 days. New blisters usually stop appearing by the 5th day, most are crusted by the 6th day, and most scabs are gone within 20 days after the rash begins. If complications set in, however, the recovery period may be even longer.

These are the most common symptoms of chicken pox:

  • Mild fever. The fever varies between 101°F to 105°F and returns to normal when the blisters have disappeared.
  • backache
  • headache
  • sore throat
  • a rash (red spots)
  • blisters filled with fluid

A doctor should be consulted if the child's fever goes above 102°F or takes more than four days to disappear, the blisters appear infected, or the child appears nervous, confused, unresponsive, unusually sleepy, complains of stiff neck or severe headache, shows poor balance, has trouble breathing, is vomiting repeatedly, finds bright lights hard to look at, or is having convulsions (Longe 2006).

Prognosis and treatment

Treatment usually takes place in the home, with a focus on reducing discomfort and fever (Longe 2006). Chickenpox infection tends to be milder the younger a child is and symptomatic treatment, with a little sodium bicarbonate in baths or antihistamine medication to ease itching (Somekh et al. 2002), and paracetamol (acetaminophen) to reduce fever, are widely used. Ibuprofen can also be used on advice of a doctor. Aspirin should not be used because they can increase the probability of developing Reye's syndrome. Antibiotics are ineffective since it is viral in nature, rather than bacterial. There is no evidence to support the topical application of calamine lotion, a topical barrier preparation containing zinc oxide in spite of its wide usage and excellent safety profile (Tebruegge et al. 2006).

It is important to maintain good hygiene and daily cleaning of skin with warm water to avoid secondary bacterial infection. Scratching the blisters can cause them to become infected and should be avoided. Mittens or socks on the hands of infants can help protect against scratching (Longe 2006).

Infection of the virus 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 United States, 55 percent of chickenpox deaths are in the over-20 age group.

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 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

Vaccination

A varicella vaccine has been available since 1995, to inoculate against the disease. Some countries and states in the United States 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 immunization (Chaves et al. 2007).

In the United Kingdom, varicella antibodies are measured as part of the routine of prenatal care, and by 2005, all NHS health care personnel had determined their immunity and been immunized if they were non-immune and have direct patient contact. Population-based immunization against varicella is not otherwise practiced 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 people in India to alleviate the external symptoms of itching and to minimize 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
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External links

All links retrieved December 10, 2023.



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