Chickenpox
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For other uses, see Chickenpox (disambiguation).
"Varicella" redirects here. For other uses, see Varicella (disambiguation).
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) is a highly contagious illness caused by primary infection with
varicella zoster virus (VZV).[1] It usually starts with vesicular skin rash mainly on the body and
head rather than at the periphery and becomes itchy, raw pockmarks, which mostly heal without
scarring. On examination, the observer typically finds lesions at various stages of healing.
Chickenpox is an airborne disease spread easily through coughing or sneezing of ill individuals
or through direct contact with secretions from the rash. A person with chickenpox is infectious
one to two days before the rash appears.[2] They remain contagious until all lesions have crusted
over (this takes approximately six days)[3]. Immunocompromised patients are contagious during
the entire period as new lesions keep appearing. Crusted lesions are not contagious.[4]
Chickenpox has been observed in other primates, including chimpanzees[5] and gorillas.[6]
Contents
[hide]
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1 Signs and symptoms
2 Diagnosis
3 Epidemiology
4 Pathophysiology
o 4.1 Infection in pregnancy and neonates
o 4.2 Shingles
5 Prevention
o 5.1 Hygiene measures
o 5.2 Vaccine
6 Treatment
o 6.1 Children
o 6.2 Adults
7 Prognosis
8 See also
9 References
10 External links
[edit] Signs and symptoms
It takes from 10 to 21 days after initial infection for the disease to develop.
The onset of illness with chickenpox is often characterized by symptoms including myalgia,
itching, nausea, fever, headache, sore throat, pain in both ears, complaints of pressure in head or
swollen face, and malaise in adolescents and adults. In children, the first symptom is usually the
development of a papular rash, which begins on the trunk and then spreads to the face and limbs.
[7]
This is then followed by development of malaise, fever (a body temperature of 38 °C (100 °F),
but may be as high as 42 °C (108 °F) in rare cases), sometimes severe back pains to the lower
back, and loss of appetite. Typically, the disease is more severe in adults.[8] Chickenpox is rarely
fatal, although it is generally more severe in adult males than in adult females or children. Nonimmune pregnant women and those with a suppressed immune system are at highest risk of
serious complications. Chickenpox is believed to be the cause of one third of stroke cases in
children.[9] The most common late complication of chickenpox is shingles (herpes zoster), caused
by reactivation of the varicella zoster virus decades after the initial episode of chickenpox.
[edit] Diagnosis
The diagnosis of varicella is primarily clinical, with typical early "prodromal" symptoms, and
then the characteristic rash. Confirmation of the diagnosis can be sought through either
examination of the fluid within the vesicles of the rash, 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).[10]
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 fetal varicella
syndrome.[11]
[edit] Epidemiology
Primary varicella is a disease that is endemic to all countries worldwide. Varicella has a
prevalence that is stable from generation to generation.[12]
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. It 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. In temperate countries, most people become infected before adulthood but
10% of young adults remain susceptible.
In the tropics, chickenpox often occurs in older people and may cause more serious disease.[13] In
adults the pock marks are darker and the scars more prominent than in children.[14]
[edit] Pathophysiology
A single blister, typical during the early stages of the rash
The back of a 30-year-old male, on day 5 of the rash
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), postherpetic neuralgia, and
sometimes Ramsay Hunt syndrome type II.[citation needed]
[edit] 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.[15] 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.[16]
Varicella infection in pregnant women could 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).[17] Effects on the fetus
can range in severity from underdeveloped toes and fingers to severe anal and bladder
malformation. Possible problems include:
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Damage to brain: encephalitis,[18] 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
Infection late in gestation or immediately following birth is referred to as "neonatal varicella".[19]
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.[11]
[edit] Shingles
Main article: Herpes zoster
After a chickenpox infection, the virus remains dormant in the body's nerve tissues. The immune
system keeps the virus at bay, but later in life, usually as an adult, it can be reactivated and cause
a different form of the viral infection called shingles (scientifically known as herpes zoster).[20]
Many adults who have had chicken pox as children are susceptible to shingles as adults, often
with the accompanying condition postherpetic neuralgia, a painful condition that makes it
difficult to sleep. Even after the shingles rash has gone away, there can be night pain in the area
affected by the rash.[21]
Shingles affect one in three adults, especially those who are immune suppressed, particularly
from cancer, HIV, or other conditions. However, stress can bring on shingles as well, although
scientists are still researching the connection.[22]
A shingles vaccine is available for adults over 50 for both adults who had childhood chickenpox
or who previously had shingles.[23] The vaccine for shingles lessens the impact of shingles and its
side effects.
[edit] Prevention
[edit] Hygiene measures
The spread of chickenpox can be prevented by isolating affected individuals. Contagion is by
exposure to respiratory droplets, or direct contact with lesions, within a period lasting from three
days prior to the onset of the rash, to four days after the onset of the rash.[24] The chickenpox
virus (VZV) is susceptible to disinfectants, notably chlorine bleach (i.e., sodium hypochlorite).
Also, like all enveloped viruses, VZV is sensitive to desiccation, heat and detergents. Therefore
these viruses are relatively easy to kill.[citation needed]
[edit] Vaccine
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 US since 1995 to inoculate against the disease. Some countries
require the varicella vaccination or an exemption before entering elementary school. Protection
from one dose is not lifelong and a second dose is necessary five years after the initial
immunization,[25] which is currently part of the routine immunization schedule in the US.[26] The
chickenpox vaccine is not part of the routine childhood vaccination schedule in the UK. In the
UK, the vaccine is currently only offered to people who are particularly vulnerable to
chickenpox. A person who already took the vaccine is more likely to have only a few
chickenpox.[27]
[edit] Treatment
Varicella treatment mainly consists of easing the symptoms as there is no actual cure of the
condition. Some treatments are however available for relieving the symptoms while the immune
system clears the virus from the body. As a protective measure, patients are usually required to
stay at home while they are infectious to avoid spreading the disease to others. Also, sufferers are
frequently asked to cut their nails short or to wear gloves to prevent scratching and to minimize
the risk of secondary infections.
The condition resolves by itself within a couple of weeks but meanwhile patients must pay
attention to their personal hygiene.[28] The rash caused by varicella zoster virus may however last
for up to one month, although the infectious stage does not take longer than a week or two.[29]
Also, staying in a cold surrounding can help in easing the itching as heat and sweat makes it
worse.
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.[30] It is important to
maintain good hygiene and daily cleaning of skin with warm water to avoid secondary bacterial
infection.[31] Scratching may also increase the risk of secondary infection.[32]
To relieve the symptoms of chickenpox, people commonly use anti-itching creams and lotions.
These lotions are not to be used on the face or close to the eyes. Neem leaves can be made into
paste form and can be applied on the rashes. Warm water bath with neem leaves may be helpful.
Water bath may be done at least seven days from the onset of the vesicles. It should be done so
because the vesicles contain the virus and may splash while bathing and it may cause the vesicles
to appear on subsequent regions. An oatmeal bath also might help ease discomfort.[33]
[edit] 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 on immunosuppressive medication). Children younger than 12 years old and older than one
month are not meant to receive antiviral medication if they are not suffering from another
medical condition which would put them at risk of developing complications.[34]
Treatment of chickenpox in children is aimed at symptoms whilst the immune system deals with
the virus. With children younger than 12 years cutting nails and keeping them clean is an
important part of treatment as they are more likely to deep scratch their blisters.[35]
Aspirin is highly contraindicated in children younger than 16 years as it has been related with a
potentially fatal condition known as Reye's syndrome.[36]
Some parents believe that it is better for children to contract chickenpox than to get the vaccine.
They even go to the extent of exposing their children to others who have the disease – even by
taking them to "chickenpox parties." Doctors counter that children are safer getting the vaccine,
which is a weakened form of the virus, than by getting the disease, which can be fatal.[37]
[edit] Adults
Infection in otherwise healthy adults tends to be more severe and may be fatal. Treatment with
antiviral drugs (e.g. acyclovir or valacyclovir) is generally advised, as long as it is started within
24–48 hours from rash onset.[34] Remedies to ease the symptoms of chickenpox in adults are
basically the same as those used on children. Adults are more often prescribed antiviral
medication as it is effective in reducing the severity of the condition and the likelihood of
developing complications. Antiviral medicines do not kill the virus, but stop it from multiplying.
Adults are also advised to increase water intake to reduce dehydration and to relieve headaches.
Painkillers such as paracetamol (acetaminophen) are also recommended as they are effective in
relieving itching and other symptoms such as fever or pains. Antihistamines relieve itch and may
be used in cases where the itch prevents sleep, because they are also sedative. As with children,
antiviral medication is considered more useful for those adults who are more prone to develop
complications. These include pregnant women or people who have a weakened immune
system.[38]
Sorivudine, a nucleoside analogue 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.[39]
[edit] 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.[40] Paracetamol (acetaminophen)
is widely used to reduce fever. Aspirin, or products containing aspirin, should not be given to
children with chickenpox as it can cause Reye's Syndrome.[41]
In adults, the disease is more severe,[42] though the incidence is much less common. Infection in
adults is associated with greater morbidity and mortality due to pneumonia,[43] hepatitis, and
encephalitis.[citation needed] 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.[11] Inflammation of the brain, or encephalitis, can
occur in immunocompromised individuals, although the risk is higher with herpes zoster.[44]
Necrotizing fasciitis is also a rare complication.[45]
Varicella can be lethal to adults with impaired immunity. The number of people in this high-risk
group has increased, due to the HIV epidemic and the increased use immunosuppressive
therapies.[46] Varicella is a particular problem in hospitals, especially when there are patients
with immune systems weakened by drugs (e.g., high-dose steroids) or HIV.[47]
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 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.[48]
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.[48]
[edit] See also
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List of cutaneous conditions
Pox party
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[edit] External links