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Nasty Infectious Diseases You Want To Avoid - Chicken Pox

Updated on November 30, 2008

 Chicken pox (varicella), is a common childhood infectious disease characterized by a rash and slight fever. It affects about 4 million children each year in the United States. About 90 percent of cases occur in children under age 10, primarily in winter and spring. Chicken pox is also known as varicella, after the virus that causes the disease (varicella zoster, or VZV). The name varicella dates back to the 1700s and is derived from the Latin term for "little pox."

Most people throughout the world have had the disease by age 10, and chicken pox is rare in adults. When it does occur after childhood, it is a far more serious illness.

Cause - VZV is a member of the family of herpesviruses similar to the herpes simplex virus (HSV); the same virus that causes chicken pox also causes shingles. Once a person has chicken pox, the virus stays in the body in a latent stage, hiding in the nerves of the lower spinal cord for the rest of the persons life. When reactivated (in old age or during times of stress), it can lead to shingles.

Symptoms - The VZV virus, which is spread by airborne droplets, is extremely contagious. The incubation period ranges from 10 to 23 days. One to three weeks after exposure, a rash appears on the torso, face, armpits, upper arms and legs, inside the mouth, and sometimes in the windpipe and bronchial tubes, causing a dry cough. The rash is made up of small red itchy spots that grow into fluid-filled blisters within a few hours. After several days, the blisters dry out and form scabs. New spots usually continue to form over four to seven days. Children usually have only a slight fever, but an adult may experience fever with severe pneumonia and breathing problems. Adults usually have higher fevers, more intense rash, and more complications than children. The average child will have between 250 and 500 blisters over about five days; the more blisters the child has, the harder the body has to fight to make enough antibodies to destroy the virus. The fight between the virus and the immune system causes fevers, fatigue, and poor appetite. Those who catch the disease from a sibling instead of a classmate usually have a more severe illness, from 300 to 5,000 blisters. This is because the close contact at home causes a much larger amount of virus to enter the system. The patient is infectious from five days before the rash erupts until all the blisters are completely healed, dried, and scabbed over. This can take from 6 to 10 days after the rash appears.

Complications - In children, these may include bacterial infection and, rarely, Reye's syndrome, or in even rarer cases, encephalitis. Immunocompromised patients who are susceptible to VZV are at high risk for having severe varicella infections with widespread lesions. Between 40 and 200 people die every year in the United States; half are previously healthy people and the other half are those with impaired immune systems.

Treatment - In most cases, rest is all that is needed for children, who usually recover within 10 days. Adult patients take longer to recover. Acetaminophen may reduce the fever, and calamine lotion, baking soda baths, and oral antihistamines ease the itch. Compresses can dry weeping lesions. Never give aspirin to a child who has flulike symptoms or has been exposed to (or has recently recovered from) chicken pox; aspirin in these cases has been linked to Reye's syndrome. The drug acyclovir may be prescribed for chicken pox patients who are not pregnant and who have any of the following: chronic skin or lung disorders, required regular administration of aspirin or steroids, overwhelming chicken pox, a compromised immune system (such as AIDS). Unlike the herpes-simplex viruses, VZV is relatively resistant to acyclovir, and doses required for treatment are much larger and must be administered intravenously. While the drug may shorten the length of the illness and lessen symptoms, its high cost and marginal effectiveness have prompted the American Academy of Pediatrics not to recommend it as a routine treatment.  Scratching should be avoided, as it may lead to secondary bacterial infection and increase the chance of scarring. If possible, don't bring a child with suspected chicken pox into the doctor's office where others will be exposed to the disease; it can be very dangerous to newborns or those with suppressed immune systems. The virus can be spread both through the air and by contact with an infected individual. Instead, call the physician on the phone and describe the symptoms, if you suspect it could be chicken pox.

Prevention - An infected child should not play with anyone at risk for serious disease from chicken pox, and should be kept away from infants younger than six weeks of age. They should also stay away from crowded public places where high-risk people might congregate.

Passive immunity that offers only temporary protection is available for high-risk susceptible patients via varicella-zoster immune globulin. This can abort or modify infection if administered within three days of exposure. Passive immunization is the administration of antibodies from donor's blood; since a person's blood is completely replaced every three months, the immunity lasts only that long. There is some disagreement about the value of giving passive immunity to susceptible pregnant women in the first trimester; some fear that while it may prevent symptoms, the virus may still be in the mother's blood and thereby infect the fetus. Vaccine Active immunization is provided by a vaccination that stimulates the immune system to make protective antibodies that last for life. The chicken pox vaccine is made from a live weakened virus that works by creating a mild infection similar to natural chicken pox, but without the related problems. The mild infection spurs the body to develop an immune response to the disease. These defenses are then ready when the body encounters the natural virus.

The development of a vaccine against the disease has been studied and used in clinical trials with children and adults in the United States since the early 1980s; it has been used in Japan for some time. It protects 70 to 90 percent of children, but it does not work well on adults. The U.S. Food and Drug Administration has licensed the vaccine for general use; the American Academy of Pediatrics has recommended the vaccine for all children and teenagers. Children younger than 12 require one dose; children 13 and over require two shots four to eight weeks apart. Not all physicians agree on the benefits of the vaccine for healthy children, however. While proponents of the vaccine point out that suffering children and parents' considerable lost work time are good reasons to use the vaccine, some researchers are uncertain about how long the vaccine confers immunity. Critics warn that if the vaccine wears off in later life, the adult could then be vulnerable to infection at an age when chicken pox can be serious. Other experts are concerned about possible side effects of the vaccine. Since the chicken pox virus belongs to the herpesvirus group, there are concerns that the vaccine might cause periodic reactivation of the varicella zoster virus, causing shingles.


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    • Hal Licino profile image

      Hal Licino 8 years ago from Toronto

      The acyclovir prophylaxis you've described usually has very minor beneficial results. There is no sure fire prophylactic post-exposure treatment at this time, whether pharmacological or immunological.

    • profile image

      danish 8 years ago

      i want to know the prophylactic measures for those who have recently exposed to chicken pox risk and is incubating the virus,if they are not previously been immunised.

      may be acyclovir 400mg 5 times a day for 7 days