Chickenpox is the common name for simple chickenpox, which is classically one of the childhood infectious diseases that most children contract and survive.
Chickenpox is caused by the varicella-zoster virus. It starts with a moderate fever and then characteristic spots that appear in two or three waves, mainly on the body and head, rather than the hands, and turn into raw pox (itching), small open sores that mostly heal without leaving scars.
This infectious disease has an incubation period of two weeks and is highly contagious by airborne transmission two days before symptoms appear. Therefore, it spreads rapidly through schools and other places of close contact.
Once someone has been infected with the disease, they generally develop lifelong protective immunity. It is quite rare to get chickenpox multiple times, but it is possible for people with irregular immune systems.
Since the disease is more serious if contracted by an adult, parents have been known to ensure that their children are infected before adulthood.
The disease can be fatal. Pregnant women and people with depressed immune systems are at higher risk. Death is usually due to chickenpox pneumonia. In the US, 55 percent of chickenpox deaths occurred in the age group over 20. Pregnant women who are not known to be immune and who come into contact with chickenpox should contact their doctor immediately, as the virus can cause serious problems to the fetus.
A vaccine has been available since 1995 and is now required in some countries for children to enter primary school. In addition, effective medications (eg, Acyclovir) are available to treat healthy and immunosuppressed people. Calamine lotion is often used to relieve itching and acetaminophen to reduce fever. Aspirin is not recommended in children, as it can cause Reye’s syndrome.
Chickenpox is an infection spread from person to person by direct contact or through the air when an infected person coughs or sneezes. Touching the fluid from a chickenpox blister can also spread the disease. A person is contagious 1-2 days before the rash appears and until all the blisters have crusted over. This can take 5-10 days. It takes 10 to 21 days after contact with an infected person for someone to develop the disease.
The blisters begin as a small red papule that develops an irregular rose petal-shaped outline. A thin-walled, clear vesicle (dewdrop) develops over the reddened area. This “dewdrop on a rose petal” lesion is very characteristic of chickenpox. After about 8-12 hours, the fluid in the gallbladder becomes cloudy and the gallbladder ruptures leaving a scab. The fluid is highly contagious, but once the lesion forms a scab, it is not considered contagious. The scab usually falls off after 7 days, sometimes leaving a crater-shaped scar.
Although an injury goes through this complete cycle in about 7 days, another hallmark of chickenpox is the fact that new injuries emerge every day for several days. Therefore, it may take about a week for new lesions to stop appearing and existing lesions to crust over.
Second infections occur in immunocompetent individuals, but are rare and rarely serious.
Japan was one of the first countries to be routinely vaccinated against chickenpox. Routine varicella zoster virus vaccination is also done in the United States, and the incidence of chickenpox has dropped dramatically from 4 million cases per year in the pre-vaccine era to approximately 400,000 cases per year in 2005.
The vaccine is extremely safe: approximately 5% of children who receive the vaccine develop a fever or rash, but as of May 2006 there have been no deaths attributable to the vaccine despite more than 40 million doses administered.
41 of the 50 US states require vaccination of children attending government-run schools. Vaccination is not routine in the UK. Debate continues in the UK as to when it will be desirable to adopt routine vaccination, and views are also expressed in the US that it should be abandoned, individually or in conjunction with all vaccines.
The CDC and relevant national organizations are carefully watching the failure rate, which can be high compared to other modern vaccines – there have been large outbreaks of chickenpox in schools that required their children to be vaccinated.
It has been thought that getting wild chickenpox in childhood often results in lifelong immunity. Parents have deliberately made sure of this in the past with parts of smallpox and similarly for some other diseases such as rubella.
Historically, the exposure of adults to contagious children has increased their immunity, reducing the risk of shingles.
Disclaimer: This article should not be a substitute for medical advice. Talk to a qualified professional to learn more about chickenpox.