Chickenpox

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For other uses, see Chickenpox (disambiguation). Chickenpox_sentence_0

"Varicella" redirects here. Chickenpox_sentence_1

For other uses, see Varicella (disambiguation). Chickenpox_sentence_2

Not to be confused with Fowlpox or Smallpox. Chickenpox_sentence_3

Chickenpox_table_infobox_0

ChickenpoxChickenpox_header_cell_0_0_0
Other namesChickenpox_header_cell_0_1_0 VaricellaChickenpox_cell_0_1_1
SpecialtyChickenpox_header_cell_0_2_0 Infectious diseaseChickenpox_cell_0_2_1
SymptomsChickenpox_header_cell_0_3_0 Small, itchy blisters, headache, loss of appetite, tiredness, feverChickenpox_cell_0_3_1
Usual onsetChickenpox_header_cell_0_4_0 10–21 days after exposureChickenpox_cell_0_4_1
DurationChickenpox_header_cell_0_5_0 5–10 daysChickenpox_cell_0_5_1
CausesChickenpox_header_cell_0_6_0 Varicella zoster virusChickenpox_cell_0_6_1
PreventionChickenpox_header_cell_0_7_0 Varicella vaccineChickenpox_cell_0_7_1
MedicationChickenpox_header_cell_0_8_0 Calamine lotion, paracetamol (acetaminophen), aciclovirChickenpox_cell_0_8_1
DeathsChickenpox_header_cell_0_9_0 6,400 per year (with shingles)Chickenpox_cell_0_9_1

Chickenpox, also known as varicella, is a highly contagious disease caused by the initial infection with varicella zoster virus (VZV). Chickenpox_sentence_4

The disease results in a characteristic skin rash that forms small, itchy blisters, which eventually scab over. Chickenpox_sentence_5

It usually starts on the chest, back, and face. Chickenpox_sentence_6

It then spreads to the rest of the body. Chickenpox_sentence_7

Other symptoms may include fever, tiredness, and headaches. Chickenpox_sentence_8

Symptoms usually last five to seven days. Chickenpox_sentence_9

Complications may occasionally include pneumonia, inflammation of the brain, and bacterial skin infections. Chickenpox_sentence_10

The disease is often more severe in adults than in children. Chickenpox_sentence_11

Symptoms begin 10 to 21 days after exposure to the virus. Chickenpox_sentence_12

Chickenpox is an airborne disease which spreads easily from one person to the next through the coughs and sneezes of an infected person. Chickenpox_sentence_13

It may be spread from one to two days before the rash appears until all lesions have crusted over. Chickenpox_sentence_14

It may also spread through contact with the blisters. Chickenpox_sentence_15

Those with shingles may spread chickenpox to those who are not immune through contact with the blisters. Chickenpox_sentence_16

The disease can usually be diagnosed based on the presenting symptom; however, in unusual cases it may be confirmed by polymerase chain reaction (PCR) testing of the blister fluid or scabs. Chickenpox_sentence_17

Testing for antibodies may be done to determine if a person is immune. Chickenpox_sentence_18

People usually only get chickenpox once. Chickenpox_sentence_19

Although reinfections by the virus occur, these reinfections usually do not cause any symptoms. Chickenpox_sentence_20

Since its introduction in 1995, the varicella vaccine has resulted in a decrease in the number of cases and complications from the disease. Chickenpox_sentence_21

It protects about 70 to 90 percent of people from disease with a greater benefit for severe disease. Chickenpox_sentence_22

Routine immunization of children is recommended in many countries. Chickenpox_sentence_23

Immunization within three days of exposure may improve outcomes in children. Chickenpox_sentence_24

Treatment of those infected may include calamine lotion to help with itching, keeping the fingernails short to decrease injury from scratching, and the use of paracetamol (acetaminophen) to help with fevers. Chickenpox_sentence_25

For those at increased risk of complications, antiviral medication such as aciclovir are recommended. Chickenpox_sentence_26

Chickenpox occurs in all parts of the world. Chickenpox_sentence_27

In 2013 there were 140 million cases of chickenpox and herpes zoster worldwide. Chickenpox_sentence_28

Before routine immunization the number of cases occurring each year was similar to the number of people born. Chickenpox_sentence_29

Since immunization the number of infections in the United States has decreased nearly 90%. Chickenpox_sentence_30

In 2015 chickenpox resulted in 6,400 deaths globally – down from 8,900 in 1990. Chickenpox_sentence_31

Death occurs in about 1 per 60,000 cases. Chickenpox_sentence_32

Chickenpox was not separated from smallpox until the late 19th century. Chickenpox_sentence_33

In 1888 its connection to shingles was determined. Chickenpox_sentence_34

The first documented use of the term chicken pox was in 1658. Chickenpox_sentence_35

Various explanations have been suggested for the use of "chicken" in the name, one being the relative mildness of the disease. Chickenpox_sentence_36

Signs and symptoms Chickenpox_section_0

The early (prodromal) symptoms in adolescents and adults are nausea, loss of appetite, aching muscles, and headache. Chickenpox_sentence_37

This is followed by the characteristic rash or oral sores, malaise, and a low-grade fever that signal the presence of the disease. Chickenpox_sentence_38

Oral manifestations of the disease (enanthem) not uncommonly may precede the external rash (exanthem). Chickenpox_sentence_39

In children the illness is not usually preceded by prodromal symptoms, and the first sign is the rash or the spots in the oral cavity. Chickenpox_sentence_40

The rash begins as small red dots on the face, scalp, torso, upper arms and legs; progressing over 10–12 hours to small bumps, blisters and pustules; followed by umbilication and the formation of scabs. Chickenpox_sentence_41

At the blister stage, intense itching is usually present. Chickenpox_sentence_42

Blisters may also occur on the palms, soles, and genital area. Chickenpox_sentence_43

Commonly, visible evidence of the disease develops in the oral cavity and tonsil areas in the form of small ulcers which can be painful or itchy or both; this enanthem (internal rash) can precede the exanthem (external rash) by 1 to 3 days or can be concurrent. Chickenpox_sentence_44

These symptoms of chickenpox appear 10 to 21 days after exposure to a contagious person. Chickenpox_sentence_45

Adults may have a more widespread rash and longer fever, and they are more likely to experience complications, such as varicella pneumonia. Chickenpox_sentence_46

Because watery nasal discharge containing live virus usually precedes both exanthem (external rash) and enanthem (oral ulcers) by 1 to 2 days, the infected person actually becomes contagious one to two days before recognition of the disease. Chickenpox_sentence_47

Contagiousness persists until all vesicular lesions have become dry crusts (scabs), which usually entails four or five days, by which time nasal shedding of live virus ceases. Chickenpox_sentence_48

The condition usually resolves by itself within a week or two. Chickenpox_sentence_49

The rash may, however, last for up to one month. Chickenpox_sentence_50

Chickenpox is rarely fatal, although it is generally more severe in adult men than in women or children. Chickenpox_sentence_51

Non-immune pregnant women and those with a suppressed immune system are at highest risk of serious complications. Chickenpox_sentence_52

Arterial ischemic stroke (AIS) associated with chickenpox in the previous year accounts for nearly one third of childhood AIS. Chickenpox_sentence_53

The most common late complication of chickenpox is shingles (herpes zoster), caused by reactivation of the varicella zoster virus decades after the initial, often childhood, chickenpox infection. Chickenpox_sentence_54

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Pregnancy and neonates Chickenpox_section_1

During pregnancy the dangers to the fetus associated with a primary VZV infection are greater in the first six months. Chickenpox_sentence_55

In the third trimester, the mother is more likely to have severe symptoms. Chickenpox_sentence_56

For pregnant women, antibodies produced as a result of immunization or previous infection are transferred via the placenta to the fetus. Chickenpox_sentence_57

Varicella infection in pregnant women could lead to spread via the placenta and infection of the fetus. Chickenpox_sentence_58

If infection occurs during the first 28 weeks of gestation, this can lead to fetal varicella syndrome (also known as congenital varicella syndrome). Chickenpox_sentence_59

Effects on the fetus can range in severity from underdeveloped toes and fingers to severe anal and bladder malformation. Chickenpox_sentence_60

Possible problems include: Chickenpox_sentence_61

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Infection late in gestation or immediately following birth is referred to as "neonatal varicella". Chickenpox_sentence_62

Maternal infection is associated with premature delivery. Chickenpox_sentence_63

The risk of the baby developing the disease is greatest following exposure to infection in the period 7 days before delivery and up to 8 days following the birth. Chickenpox_sentence_64

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. Chickenpox_sentence_65

Newborns who develop symptoms are at a high risk of pneumonia and other serious complications of the disease. Chickenpox_sentence_66

Pathophysiology Chickenpox_section_2

Main article: Varicella zoster virus Chickenpox_sentence_67

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. Chickenpox_sentence_68

Cell-mediated immune responses are also important in limiting the scope and the duration of primary varicella infection. Chickenpox_sentence_69

After primary infection, VZV is hypothesized to spread from mucosal and epidermal lesions to local sensory nerves. Chickenpox_sentence_70

VZV then remains latent in the dorsal ganglion cells of the sensory nerves. Chickenpox_sentence_71

Reactivation of VZV results in the clinically distinct syndrome of herpes zoster (i.e., shingles), postherpetic neuralgia, and sometimes Ramsay Hunt syndrome type II. Chickenpox_sentence_72

Varicella zoster can affect the arteries in the neck and head, producing stroke, either during childhood, or after a latency period of many years. Chickenpox_sentence_73

Shingles Chickenpox_section_3

Main article: Herpes zoster Chickenpox_sentence_74

After a chickenpox infection, the virus remains dormant in the body's nerve tissues. Chickenpox_sentence_75

The immune system keeps the virus at bay, but later in life, usually in an adult, it can be reactivated and cause a different form of the viral infection called shingles (also known as herpes zoster). Chickenpox_sentence_76

The United States Advisory Committee on Immunization Practices (ACIP) suggests that every adult over the age of 50 years get the herpes zoster vaccine. Chickenpox_sentence_77

Shingles affects one in five adults infected with chickenpox as children, especially those who are immune-suppressed, particularly from cancer, HIV, or other conditions. Chickenpox_sentence_78

Stress can bring on shingles as well, although scientists are still researching the connection. Chickenpox_sentence_79

Shingles is most commonly found in adults over the age of 60 who were diagnosed with chickenpox when they were under the age of 1. Chickenpox_sentence_80

Diagnosis Chickenpox_section_4

The diagnosis of chickenpox is primarily based on the signs and symptoms, with typical early symptoms followed by a characteristic rash. Chickenpox_sentence_81

Confirmation of the diagnosis is by examination of the fluid within the vesicles of the rash, or by testing blood for evidence of an acute immunologic response. Chickenpox_sentence_82

Vesicular fluid can be examined with a Tzanck smear, or by testing for direct fluorescent antibody. Chickenpox_sentence_83

The fluid can also be "cultured", whereby attempts are made to grow the virus from a fluid sample. Chickenpox_sentence_84

Blood tests can be used to identify a response to acute infection (IgM) or previous infection and subsequent immunity (IgG). Chickenpox_sentence_85

Prenatal diagnosis of fetal varicella infection can be performed using ultrasound, though a delay of 5 weeks following primary maternal infection is advised. Chickenpox_sentence_86

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's developing fetal varicella syndrome. Chickenpox_sentence_87

Prevention Chickenpox_section_5

Hygiene measures Chickenpox_section_6

The spread of chickenpox can be prevented by isolating affected individuals. Chickenpox_sentence_88

Contagion is by exposure to respiratory droplets, or direct contact with lesions, within a period lasting from three days before the onset of the rash, to four days after the onset of the rash. Chickenpox_sentence_89

The chickenpox virus is susceptible to disinfectants, notably chlorine bleach (i.e., sodium hypochlorite). Chickenpox_sentence_90

Like all enveloped viruses, it is sensitive to drying, heat and detergents. Chickenpox_sentence_91

Vaccine Chickenpox_section_7

Main article: Varicella vaccine Chickenpox_sentence_92

The varicella vaccine is recommended in many countries. Chickenpox_sentence_93

Some countries require the varicella vaccination or an exemption before entering elementary school. Chickenpox_sentence_94

A second dose is recommended five years after the initial immunization. Chickenpox_sentence_95

A vaccinated person is likely to have a milder case of chickenpox if they become infected. Chickenpox_sentence_96

Immunization within three days following household contact reduces infection rates and severity in children. Chickenpox_sentence_97

Being exposed to chickenpox as an adult (for example, through contact with infected children) boosts immunity to shingles. Chickenpox_sentence_98

When children are vaccinated against chickenpox, then they lose this natural boosting, so immunity in adults will drop and more shingles cases will occur. Chickenpox_sentence_99

It is part of the routine immunization schedule in the US. Chickenpox_sentence_100

Some European countries include it as part of universal vaccinations in children, but not all countries provide the vaccine. Chickenpox_sentence_101

In the UK as of 2014, the vaccine is only recommended in people who are particularly vulnerable to chickenpox. Chickenpox_sentence_102

This is to keep the virus in circulation thereby exposing the population to the virus at an early age, when it is less harmful, and to reduce the occurrence of shingles in those who have already had chickenpox by repeated exposure to the virus later in life. Chickenpox_sentence_103

In populations that have not been immunized or if immunity is questionable, a clinician may order an enzyme immunoassay. Chickenpox_sentence_104

An immunoassay measures the levels of antibodies against the virus that give immunity to a person. Chickenpox_sentence_105

If the levels of antibodies are low (low titer) or questionable, reimmunization may be done. Chickenpox_sentence_106

Treatment Chickenpox_section_8

Treatment mainly consists of easing the symptoms. Chickenpox_sentence_107

As a protective measure, people are usually required to stay at home while they are infectious to avoid spreading the disease to others. Chickenpox_sentence_108

Cutting the nails short or wearing gloves may prevent scratching and minimize the risk of secondary infections. Chickenpox_sentence_109

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. Chickenpox_sentence_110

It is important to maintain good hygiene and daily cleaning of skin with warm water to avoid secondary bacterial infection. Chickenpox_sentence_111

Scratching may also increase the risk of secondary infection. Chickenpox_sentence_112

Paracetamol (acetaminophen) but not aspirin may be used to reduce fever. Chickenpox_sentence_113

Aspirin use by someone with chickenpox may cause serious, sometimes fatal disease of the liver and brain, Reye syndrome. Chickenpox_sentence_114

People at risk of developing severe complications who have had significant exposure to the virus may be given intra-muscular varicella zoster immune globulin (VZIG), a preparation containing high titres of antibodies to varicella zoster virus, to ward off the disease. Chickenpox_sentence_115

Antivirals are sometimes used. Chickenpox_sentence_116

Children Chickenpox_section_9

If aciclovir by mouth is started within 24 hours of rash onset, it decreases symptoms by one day but has no effect on complication rates. Chickenpox_sentence_117

Use of aciclovir therefore is not currently recommended for individuals with normal immune function. Chickenpox_sentence_118

Children younger than 12 years old and older than one month are not meant to receive antiviral drugs unless they have another medical condition which puts them at risk of developing complications. Chickenpox_sentence_119

Treatment of chickenpox in children is aimed at symptoms while the immune system deals with the virus. Chickenpox_sentence_120

With children younger than 12 years, cutting nails and keeping them clean is an important part of treatment as they are more likely to scratch their blisters more deeply than adults. Chickenpox_sentence_121

Aspirin is highly contraindicated in children younger than 16 years, as it has been related to Reye syndrome. Chickenpox_sentence_122

Adults Chickenpox_section_10

Infection in otherwise healthy adults tends to be more severe. Chickenpox_sentence_123

Treatment with antiviral drugs (e.g. aciclovir or valaciclovir) is generally advised, as long as it is started within 24–48 hours from rash onset. Chickenpox_sentence_124

Remedies to ease the symptoms of chickenpox in adults are basically the same as those used for children. Chickenpox_sentence_125

Adults are more often prescribed antiviral medication, as it is effective in reducing the severity of the condition and the likelihood of developing complications. Chickenpox_sentence_126

Adults are advised to increase water intake to reduce dehydration and to relieve headaches. Chickenpox_sentence_127

Painkillers such as paracetamol (acetaminophen) are recommended, as they are effective in relieving itching and other symptoms such as fever or pains. Chickenpox_sentence_128

Antihistamines relieve itching and may be used in cases where the itching prevents sleep, because they also act as a sedative. Chickenpox_sentence_129

As with children, antiviral medication is considered more useful for those adults who are more prone to develop complications. Chickenpox_sentence_130

These include pregnant women or people who have a weakened immune system. Chickenpox_sentence_131

Prognosis Chickenpox_section_11

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 fifth day. Chickenpox_sentence_132

Chickenpox infection is milder in young children, and symptomatic treatment, with sodium bicarbonate baths or antihistamine medication may ease itching. Chickenpox_sentence_133

Paracetamol (acetaminophen) is widely used to reduce fever. Chickenpox_sentence_134

Aspirin, or products containing aspirin, should not be given to children under 16 with chickenpox, as this is linked to Reye syndrome. Chickenpox_sentence_135

In adults, the disease is more severe, though the incidence is much less common. Chickenpox_sentence_136

Infection in adults is associated with greater morbidity and mortality due to pneumonia (either direct viral pneumonia or secondary bacterial pneumonia), bronchitis (either viral bronchitis or secondary bacterial bronchitis), hepatitis, and encephalitis. Chickenpox_sentence_137

In particular, up to 10% of pregnant women with chickenpox develop pneumonia, the severity of which increases with onset later in gestation. Chickenpox_sentence_138

In England and Wales, 75% of deaths due to chickenpox are in adults. Chickenpox_sentence_139

Inflammation of the brain, or encephalitis, can occur in immunocompromised individuals, although the risk is higher with herpes zoster. Chickenpox_sentence_140

Necrotizing fasciitis is also a rare complication. Chickenpox_sentence_141

Varicella can be lethal to individuals with impaired immunity. Chickenpox_sentence_142

The number of people in this high-risk group has increased, due to the HIV epidemic and the increased use of immunosuppressive therapies. Chickenpox_sentence_143

Varicella is a particular problem in hospitals, when there are patients with immune systems weakened by drugs (e.g., high-dose steroids) or HIV. Chickenpox_sentence_144

Secondary bacterial infection of skin lesions, manifesting as impetigo, cellulitis, and erysipelas, is the most common complication in healthy children. Chickenpox_sentence_145

Disseminated primary varicella infection usually seen in the immunocompromised may have high morbidity. Chickenpox_sentence_146

Ninety percent of cases of varicella pneumonia occur in the adult population. Chickenpox_sentence_147

Rarer complications of disseminated chickenpox include myocarditis, hepatitis, and glomerulonephritis. Chickenpox_sentence_148

Hemorrhagic complications are more common in the immunocompromised or immunosuppressed populations, although healthy children and adults have been affected. Chickenpox_sentence_149

Five major clinical syndromes have been described: febrile purpura, malignant chickenpox with purpura, postinfectious purpura, purpura fulminans, and anaphylactoid purpura. Chickenpox_sentence_150

These syndromes have variable courses, with febrile purpura being the most benign of the syndromes and having an uncomplicated outcome. Chickenpox_sentence_151

In contrast, malignant chickenpox with purpura is a grave clinical condition that has a mortality rate of greater than 70%. Chickenpox_sentence_152

The cause of these hemorrhagic chickenpox syndromes is not known. Chickenpox_sentence_153

Epidemiology Chickenpox_section_12

Primary varicella occurs in all countries worldwide. Chickenpox_sentence_154

In 2015 chickenpox resulted in 6,400 deaths globally – down from 8,900 in 1990. Chickenpox_sentence_155

There were 7,000 deaths in 2013. Chickenpox_sentence_156

In temperate countries, chickenpox is primarily a disease of children, with most cases occurring during the winter and spring, most likely due to school contact. Chickenpox_sentence_157

It is one of the classic diseases of childhood, with most cases occurring in children up to age 15. Chickenpox_sentence_158

Like rubella, it is uncommon in preschool children. Chickenpox_sentence_159

Varicella is highly communicable, with an infection rate of 90% in close contacts. Chickenpox_sentence_160

In temperate countries, most people become infected before adulthood, and 10% of young adults remain susceptible. Chickenpox_sentence_161

In the tropics, chickenpox often occurs in older people and may cause more serious disease. Chickenpox_sentence_162

In adults, the pock marks are darker and the scars more prominent than in children. Chickenpox_sentence_163

In the United States, the Centers for Disease Control and Prevention (CDC) does not require state health departments to report infections of chickenpox, and only 31 states currently volunteer this information. Chickenpox_sentence_164

However, in a 2013 study conducted by the social media disease surveillance tool called Sickweather, anecdotal reports of chickenpox infections on Facebook and Twitter were used to measure and rank states with the most infections per capita, with Maryland, Tennessee and Illinois in the top three. Chickenpox_sentence_165

Society and culture Chickenpox_section_13

Etymology Chickenpox_section_14

How the term chickenpox originated is not clear but it may be due to it being a relatively mild disease. Chickenpox_sentence_166

It has been said to be derived from chickpeas, based on resemblance of the vesicles to chickpeas, or to come from the rash resembling chicken pecks. Chickenpox_sentence_167

Other suggestions include the designation chicken for a child (i.e., literally 'child pox'), a corruption of itching-pox, or the idea that the disease may have originated in chickens. Chickenpox_sentence_168

Samuel Johnson explained the designation as "from its being of no very great danger". Chickenpox_sentence_169

Intentional exposure Chickenpox_section_15

Because chickenpox is usually more severe in adults than it is in children, some parents deliberately expose their children to the virus, for example by taking them to "chickenpox parties". Chickenpox_sentence_170

Doctors counter that children are safer getting the vaccine, which is a weakened form of the virus, rather than getting the disease, which can be fatal. Chickenpox_sentence_171

Repeated exposure to chickenpox may protect against zoster. Chickenpox_sentence_172

Other animals Chickenpox_section_16

Humans are the only known species that the disease affects naturally. Chickenpox_sentence_173

However, chickenpox has been caused in other primates, including chimpanzees and gorillas. Chickenpox_sentence_174

Research Chickenpox_section_17

Sorivudine, a nucleoside analog, has been reported to be effective in the treatment of primary varicella in healthy adults (case reports only), but large-scale clinical trials are still needed to demonstrate its efficacy. Chickenpox_sentence_175

There has also been speculation that continuous dosing of aciclovir by mouth for a period of time can eradicate VZV from the host, although further trials remain to discern whether eradication is actually viable. Chickenpox_sentence_176


Credits to the contents of this page go to the authors of the corresponding Wikipedia page: en.wikipedia.org/wiki/Chickenpox.