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Chickenpox, also known as varicella, is a highly contagious disease caused by the initial infection with varicella zoster virus (VZV).[1] The disease results in a characteristic skin rash that forms small, itchy blisters, which eventually scab over.[2] It usually starts on the chest, back, and face then spreads to the rest of the body.[2] Other symptoms may include fever, feeling tired, and headaches.[2] Symptoms usually last five to ten days.[2] Complications may occasionally include pneumonia, inflammation of the brain, or bacterial infections of the skin among others.[3] The disease is often more severe in adults than children.[4] Symptoms begin ten to twenty one days after exposure to the virus.[5]
Chickenpox is an airborne disease which spreads easily through the coughs and sneezes of an infected person.[5] It may be spread from one to two days before the rash appears until all lesions have crusted over.[5] It may also spread through contact with the blisters.[5] Those with shingles may spread chickenpox to those who are not immune through contact with the blisters.[5] The disease can usually be diagnosed based on the presenting symptom;[6]however, in unusual cases may be confirmed by polymerase chain reaction (PCR) testing of the blister fluid or scabs.[4] Testing for antibodies may be done to determine if a person is or is not immune.[4] People usually only get the disease once.[5]
The early (prodromal) symptoms in adolescents and adults are nausea, loss of appetite, aching muscles, and headache. This is followed by the characteristic rash or oral sores, malaise, and a low-grade fever that signal the presence of the disease. Oral manifestations of the disease (enanthem) not uncommonly may precede the external rash (exanthem). 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. 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 byumbilication and the formation of scabs.[13][14]
At the blister stage, intense itching is usually present. Blisters may also occur on the palms, soles, and genital area. 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. These symptoms of chickenpox appear 10 to 21 days after exposure to a contagious person. Adults may have a more widespread rash and longer fever, and they are more likely to experience complications, such as varicella pneumonia.[13]
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. 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 is a viral infection in which a person develops very itchy blisters all over the body. It was more common in the past. The illness is rare today because of the chickenpox vaccine.
Chickenpox is caused by the varicella-zoster virus. It is a member of the herpesvirus family. The same virus also causes shingles in adults.
Chickenpox can be spread very easily to others from 1 to 2 days before blisters appear until all the blisters have crusted over. You may get chickenpox:
Most cases of chickenpox occur in children younger than age 10. The disease is most often mild, although serious complications may occur. Adults and older children get sicker than younger children in most cases.
Children whose mothers have had chickenpox or have received the chickenpox vaccine are not very likely to catch it before they are 1 year old. If they do catch chickenpox, they often have mild cases. This is because antibodies from their mothers' blood help protect them. Children under 1 year old whose mothers have not had chickenpox or the vaccine can get severe chickenpox.
Severe chickenpox symptoms are more common in children whose immune system does not work well.
Most children with chickenpox have the following symptoms before the rash appears:
The chickenpox rash occurs about 10 to 21 days after coming into contact with someone who had the disease. In most cases, a child will develop 250 to 500 small, itchy, fluid-filled blisters over red spots on the skin.
Most pox will not leave scars unless they become infected with bacteria from scratching.
Some children who have had the vaccine will still develop a mild case of chickenpox. In most cases, they recover much more quickly and have only a few poxes (fewer than 30). These cases are often harder to diagnose. However, these children can still spread chickenpox to others.
Your health care provider can most often diagnose chickenpox by looking at the rash and asking questions about the person's medical history. Small blisters on the scalp confirm the diagnosis in most cases.
Lab tests can help confirm the diagnosis, if needed.
In most cases, a person recovers without complications.
Once you have had chickenpox, the virus often remains dormant or asleep in your body for your lifetime. About 1 in 10 adults will have shingles when the virus re-emerges during a period of stress.
Rarely, infection of the brain has occurred. Other problems may include:
Cerebellar ataxia may appear during the recovery phase or later. This involves a very unsteady walk.
Women who get chickenpox during pregnancy can pass the infection to the developing baby. Newborns are at risk for severe infection.
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 before the onset of the rash, to four days after the onset of the rash.[33] The chickenpox virus is susceptible to disinfectants, notably chlorine bleach (i.e., sodium hypochlorite). Like all enveloped viruses, it is sensitive to desiccation, heat and detergents.
It is part of the routine immunization schedule in the US.[36] Some European countries include it as part of universal vaccinations in children,[37] but not all countries provide the vaccine due to its cost.[8] In the UK as of 2014, the vaccine is only recommended in people who are particularly vulnerable to chickenpox.[38]
Treatment mainly consists of easing the symptoms. As a protective measure, people are usually required to stay at home while they are infectious to avoid spreading the disease to others. Cutting thenails short or wearing gloves may prevent scratching and minimize the risk of secondary infections.
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.[39] It is important to maintain good hygiene and daily cleaning of skin with warm water to avoid secondary bacterial infection.[40] Scratching may also increase the risk of secondary infection.[41]
Paracetamol (acetaminophen) but not aspirin may be used to reduce fever. Aspirin use by someone with chickenpox may cause the serious, sometimes fatal disease of the liver and brain, Reye syndrome. 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.[42][43]
Antivirals are sometimes used.[44][45]
If oral acyclovir is started within 24 hours of rash onset, it decreases symptoms by one day but has no effect on complication rates.[46][47] Use of acyclovir therefore is not currently recommended for individuals with normal immune function. Children younger than 12 years old and older than one month are not meant to receive antiviral medication unless they have another medical condition which puts them at risk of developing complications.[48]
Treatment of chickenpox in children is aimed at symptoms while 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 scratch their blisters more deeply than adults.[49]
Aspirin is highly contraindicated in children younger than 16 years, as it has been related to Reye's syndrome.[50]
Infection in otherwise healthy adults tends to be more severe.[51] 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.[48] Remedies to ease the symptoms of chickenpox in adults are basically the same as those used for 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 advised to increase water intake to reduce dehydration and to relieve headaches. Painkillers such as paracetamol (acetaminophen) are recommended, as they are effective in relieving itching and other symptoms such as fever or pains. Antihistamines relieve itching and may be used in cases where the itching prevents sleep, because they also act as a 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.[52]
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.[53]
After recovering from chickenpox, it is recommended by doctors that adults take one injection of VZV immune globulin and one injection of varicella vaccine or herpes zoster vaccine.[citation needed]
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 infection is milder in young children, and symptomatic treatment, with sodium bicarbonate baths or antihistamine medication may ease itching. It is recommended to keep new infants from birth up to age 6 months away from an infected person for 10 to 21 days because their immune systems are not developed enough to handle the stress it can bring on.[54] 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.[55]
In adults, the disease is more severe,[56] though the incidence is much less common. Infection in adults is associated with greater morbidity and mortality due to pneumonia (either direct viral pneumoniaor secondary bacterial pneumonia),[57] bronchitis (either viral bronchitis or secondary bacterial bronchitis),[57] hepatitis,[58] and encephalitis.[59] 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.[24] Inflammation of the brain, or encephalitis, can occur in immunocompromised individuals, although the risk is higher with herpes zoster.[60] Necrotizing fasciitis is also a rare complication.[61]
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 of immunosuppressive therapies.[62]Varicella is a particular problem in hospitals, when there are patients with immune systems weakened by drugs (e.g., high-dose steroids) or HIV.[63]
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 include myocarditis,hepatitis, and glomerulonephritis.[64]
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 cause of these hemorrhagic chickenpox syndromes is not known.[64]Treatment involves keeping the person as comfortable as possible. Here are things to try:
Medicines that fight the chickenpox virus are available, but not given to everyone. To work well, the medicine should be started within the first 24 hours of the rash.
Do NOT give aspirin or ibuprofen to someone who may have chickenpox. Use of aspirin has been associated with a serious condition called Reyes syndrome. Ibuprofen has been associated with more severe secondary infections. Acetaminophen (Tylenol) may be used.
A child with chickenpox should not return to school or play with other children until all chickenpox sores have crusted over or dried out. Adults should follow this same rule while considering when to return to work or be around others.
In most cases, a person recovers without complications.
Once you have had chickenpox, the virus often remains dormant or asleep in your body for your lifetime. About 1 in 10 adults will have shingles when the virus re-emerges during a period of stress.
Rarely, infection of the brain has occurred. Other problems may include:
Cerebellar ataxia may appear during the recovery phase or later. This involves a very unsteady walk.
Women who get chickenpox during pregnancy can pass the infection to the developing baby. Newborns are at risk for severe infection.
Because chickenpox is airborne and spreads very easily even before the rash appears, it is hard to avoid.
A vaccine to prevent chickenpox is part of a child's routine vaccine schedule.
The vaccine often prevents the chickenpox disease completely or makes the illness very mild.
Most cases of chickenpox require little or no treatment beyond treating the symptoms.
The prescription antiviral drug aciclovir is effective for shortening the duration of chickenpox symptoms and may be recommended for certain people with chickenpox, such as pregnant women, those with a weakened immune system, and adults who seek medical advice within 24 hours of the rash appearing.
In addition, your doctor may recommend over-the-counter painkillers and anantihistamine to relieve pain, itching and swelling. Antibiotics are called for if a secondary bacterial skin infection arises or if the person with chickenpox develops bacterial pneumonia.
