Chickenpox

Chickenpox, also spelled chicken pox, is the commonly known name for varicella disease, frequently but not exclusively contracted in childhood.

Chickenpox is caused by the varicella-zoster virus (VZV), also known as human herpes virus 3 (HHV-3), one of the eight herpes viruses known to affect humans. It is characterized by a fever, followed by itchy raw pox or open sores which heal without scarring.

Contents
1 Effects
2 History
3 Vaccination
4 Controversy
Effects
 
Child with varicella disease.Chickenpox has a two-week incubation period and is highly contagious by air transmission two days before symptoms appear. Therefore, chickenpox spreads quickly through schools and other places of close contact. Once someone has been infected with the disease, they usually develop protective immunity for life, and cannot get it again. As the disease is more severe if contracted by an adult, parents have been known to ensure their children become infected before adulthood.

The disease is rarely fatal: if it is involved in a fatality, the actual death is usually from opportunistic varicella pneumonia, and occurs more frequently in pregnant women. In the US, 55 percent of chickenpox deaths were in the over-20 age group, which is indeed at risk from the virus. Doctors advise pregnant women who come into contact with chickenpox should contact their doctor immediately, as the virus can cause serious problems for the foetus.

Later in life, viruses remaining in the nerves can develop into the painful disease, shingles, particularly in people with compromised immune systems, such as the elderly, and perhaps even those suffering sunburn. Some of these will develop zoster-associated pain or post-herpetic neuralgia, described usually as horrible or "excruciating". A chickenpox vaccine has been available since 1995, and is now required in some countries for children to be admitted into elementary school. In addition, effective medications (e.g., acyclovir) are available to treat chickenpox in healthy and immunocompromised persons. Symptomatic treatment: calamine lotion to ease itching and paracetamol to reduce fever, is widely used. It is contraindicated to use aspirin in children with chickenpox, as it can lead to Reye's syndrome.

History
One history of medicine book claims Giovanni Filippo (1510–1580) of Palermo gave the first description of varicella (chickenpox). Subsequently in the 1600s, an English physician named Richard Morton described what he thought was a mild form of smallpox as "chicken pox." Later, in 1767, a physician named William Heberden, also from England, was the first physician to clearly demonstrate that chickenpox was different from smallpox. However, it is believed the name chickenpox was commonly used in earlier centuries before doctors identified the disease.

There are many explanations offered for the origin of the name chickenpox:

the specks that appear looked as though the skin was picked by chickens,
the disease was named after chick peas, from a supposed resemblance of the seed to the lesions
Samuel Johnson suggested that the disease was "no very great danger," thus a "chicken" version of the pox
the term reflects a corruption of the Old English word, "giccin", which meant "itching"
As "pox" also means curse, in medieval times some believed it was a plague brought on to curse children by the use of black magic.

During the medieval era, oatmeal was discovered to soothe the sores, and oatmeal baths are today still commonly given to relieve itching.

Vaccination
Routine vaccination against varicella zoster virus is performed mainly in the United States, and the incidence of chickenpox has been dramatically reduced there (from 4 million cases per year in the pre-vaccine era to approximately 400,000 cases per year as of 2005). In Europe most countries do not currently vaccinate against varicella, though the vaccine is gaining wider acceptance. Australia, Canada, and other countries have now adopted recommendations for routine immunization of children and susceptible adults against chickenpox. Other countries, such as Germany and The United Kingdom have targeted recommendations for the vaccine, e.g. for susceptible health care workers at risk of varicella exposure.

Chickenpox is most often a mild disease -- especially for children. Prior to the introduction of vaccine, there were around 4,000,000 cases per year in the US, mostly children, yet typically 100 or fewer people died. Though mostly children caught it, the majority of deaths (by as much as 80%) were among adults. Additionally, chickenpox involved the hospitalization of about 10,000 people each year. During 2003 and the first half of 2004, the CDC reported eight deaths from varicella, six of whom were children or adolescents. These deaths and hospitalizations have substantially declined in the US due to vaccination, though the rate of shingles infection has increased for the same reason. The vaccine has more recently been determined to be effective at preventing shingles (zoster) in persons 60 years of age and older, if administered regularly.

The long-term duration of protection from varicella vaccine is unknown, but there are now persons vaccinated more than thirty years ago with no evidence of waning immunity, while others have become vulnerable in as few as 6 years. Assessments of duration of immunity are complicated in an environment where natural disease is still common, which typically leads to an overestimation of effectiveness, and we are only now entering an era in the US where the long-term efficacy of varicella vaccine can be accurately gauged (Goldman, 2005).

Controversy
Although mortality due to primary varicella has declined significantly in the United States with increasing use of the varicella vaccine, as one might expect (given that zoster occurs decades after varicella), use of the varicella vaccine has had no discernible effect on zoster incidence in multiple studies, but several have suggested the incidence of dangerous adult versions like shingles may be increasing since the introduction of the varicella vaccine (Yih, et al., 2005). [1].

Although, vaccination is common in the US, with 41 of the 50 states in the US require parents to immunize their children; some people question the necessity of chickenpox vaccination. Children vaccinated have been found, in some cases, to lose their protective antibody in as little as five to eight years. The officially expected span is only 20 years. These factors are seen by critics as likely to leave children vulnerable to the disease as adults, when instead of being among the least dangerous of diseases, it bears very high risk factors.

Catching chickenpox as a child through conventional means tends to result in lifelong immunity, and exposure of adults to children so infected protects adults from other varicella-related diseases, like shingles[2] . Second episodes of chickenpox are rare, but do occur, in both vaccine and naturally acquired immunity, but far more often from the vaccine; in one study, 30% of children had lost the antibody after five years, and 8% had already caught "wild" chickenpox in that five year period[3]. The mortality rate in immunocompromised patients with disseminated herpes zoster is 5-15%, with most deaths from pneumonia. The vaccine, unfortunately, is less effective among these high-risk patients, as well as being more dangerous because it is an attenuated live virus (see last footnote).

Some parents opposed for various medical, philosophical, or religious reasons to vaccination have thrown "chickenpox parties", where their children are invited to play with an infected child who has chickenpox, in the hopes that all of them will therefore gain permanant immunity before adulthood. There have also been parties for other diseases, such as rubella. The majority of doctors would suggest that such high-risk behaviour does little protect children later in life but rather increases the risk to society as a whole.

Yet another issue under direct investigation from the CDC is the possibility that the vaccine has a high failure rate from the outset. Large outbreaks of chickenpox have occurred at schools which required their children to be vaccinated.