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An electron micrograph of the varicella virus, which causes chickenpox. Image courtesy of the CDC.
What is Varicella (Chickenpox)?
Chickenpox is an infectious disease caused by the varicella-zoster virus which results in a blister-like rash, itching, tiredness and fever.
The rash appears first on the trunk and face, but can spread over the entire body causing between 250 to 500 itchy blisters. Most cases of chickenpox occur in persons less than 15 years old. Prior to the use of varicella vaccine, the disease had annual cycles, peaking in the spring of each year.
Chickenpox is highly infectious and spreads from person to person by direct contact or through the air from an infected person’s coughing or sneezing. A persons with chickenpox is contagious 1-2 days before the rash appears and until all blisters have formed scabs. It takes from 10-21 days after contact with an infected person for someone to develop chickenpox.
An adolescent with chickenpox. Image courtesy of the CDC.
In children, chickenpox most commonly causes an illness that lasts about 5-10 days. Children usually miss 5 or 6 days of school or childcare due to their chickenpox. About half of all children with chickenpox visit a health care provider due to symptoms of their illness such as high fever, severe itching, an uncomfortable rash, dehydration or headache. In addition, about 1 child in 10 has a complication from chickenpox serious enough to visit a health care provider including infected skin lesions, other infections, dehydration from vomiting or diarrhea, exacerbation of asthma or more serious complications such as pneumonia.
Certain groups of persons are more likely to have more serious illness with complications. These include adults, infants, adolescents and people with weak immune systems from either illnesses or from medications such a long-term steroids.
Serious complications from chickenpox include bacterial infections which can involve many sites of the body including the skin, tissues under the skin, bone, lungs (pneumonia), joints and the blood. Other serious complications are due directly to the virus infection and include viral pneumonia, bleeding problems and infection of the brain (encephalitis). Many people are not aware that, before a vaccine was available, there were approximately 11,000 hospitalizations and 100 deaths from chickenpox in the U.S. every year . One child and one adult died each week. (More information can be found here.)
Chickenpox can now be prevented by vaccination.
Can a healthy person with varicella die from the disease?
Yes, many of the deaths and complications from chickenpox occur in previously healthy children and adults. From 1990 to 1994, before there was a vaccine available, there were about 50 chickenpox deaths in children and 50 chickenpox deaths in adults every year; most of these persons were healthy or did not have a medical illness (such as cancer) that placed them at higher risk of getting severe chickenpox. Since 1999, states have been encouraged to report chickenpox deaths to CDC. In 1999 and 2000, CDC received reports that showed that deaths from chickenpox continue to occur in healthy, unvaccinated children and adults. Most of the healthy adults who died from chickenpox contracted the disease from their unvaccinated children.
Can you get chickenpox more than once?
Yes, but it is uncommon to do so. For most people, one infection is thought to confer lifelong immunity.
Chickenpox in children is usually not serious, so why not let them catch it?
It is never possible to predict who will have a mild case of chickenpox and who will have a serious or even deadly case of disease. Now that there is a safe and effective vaccine available, it is not worth taking this chance.
Source: Centers for Disease Control and Prevention
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