CHICKENPOX

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Last Updated : 6/4/2007
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M R Lokeshwar
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What is chickenpox?
It is a viral disease caused by first exposure to the varicella zoster virus. The disease presents with fever and blistered rash. The virus then remains latent or dormant in the body.

How does chickenpox spread

?

The virus commonly spreads from person-to-person by air-borne droplets. This spread occurs when an infected person coughs or sneezes and causes dispersion of droplets of respiratory secretions in the surrounding air. It can also spread by direct contact with the chickenpox or herpes lesions as these contain infectious fluid.

When is chickenpox contagious?
Chickenpox is contagious from two days prior to appearance of the rash till all the lesions are covered by a scab, which occurs usually by 4-5 days of the rash. However, the transmission is most likely within first two days before the appearance of the rash.

Can chickenpox be prevented

?

Chickenpox is a highly contagious disease. Following a case of chickenpox, upto 90% of susceptible children and adults who come in close contact with the case can develop infection. Therefore, when one child develops chickenpox, many susceptible children in the school and persons in the child's house develop the disease.

Isolating the infected child and avoiding contact with him can prevent spread of infection. However, chickenpox is most infectious before the rash develops when there is no reason to suspect that he has chickenpox. Such a child, during this period, may continue to attend school, play with his playmates and therefore spread the disease.

Once a child has come in contact with a case of chickenpox, he can be immunized with antibodies (varicella zoster immunoglobulin) against the virus. However, for the immunization to be effective, it has to be given within 3-4 days of exposure. It is costly and offers protection only for a few weeks.Vaccination against chickenpox is now available and offers long-term protection against the disease.

Is chickenpox only a childhood disease?
Many people contract chickenpox during childhood or adolescence, but adults who have not been infected before are susceptible to infection and can develop chickenpox in adulthood if and when they come in contact with a case.

What are the

symptoms of chickenpox

?

Chickenpox presents with a characteristic rash. The rash first appears over the face, scalp or trunk. The rash initially consists of red / purple colored raised lesions (maculo-papular rash) which evolve into lesions filled with clear fluid. These lesions are called vesicular lesions. The fluid in these lesions then becomes hazy given the rash a characteristic blistered or pustular appearance. Most children have 200-300 lesions, which appear in successive crops and hence at a given time different types of lesions are present. The lesions then form a crust after 4-5 days of appearance. The crusts fall off after a week or two.

The rash is itchy and a young infant may get irritated due to the constant itch. Other common symptoms include fever, nausea and anorexia, bodyache, vomiting, listlessness, etc.

Is chickenpox a totally harmless disease in children?
In a vast majority of children chickenpox is not associated with any complications. Secondary bacterial infection affecting the skin lesions is the commonest complication that one encounters. In a minority of children, the virus could prove more aggressive and cause infection in the lungs leading to pneumonia and may affect the brain leading to swelling and infection of the brain (encephalitis). Such a child may develop unconsciousness and convulsions. These could prove fatal. Occasionally, virus may affect small brain (cerebellum) resulting in difficulty in walking. Many other complications are described. But these usually have a self-limited course. Most children get away with only a few scars that remain to the skin once the crusts fall of. At times, the scarring may be unsightly, which may cause cosmetic concerns later in life.

What happens if an adolescent or adult contracts chickenpox?
Chickenpox is more severe in adolescents and adults than in children. The fever is higher and continuous for much longer. The rash is much heavier. The likelihood of complications is greater, too. They are more likely to suffer from pneumonia. The risk of complications and death tend to be higher when chickenpox is contracted later in life.

Who are more likely to suffer from chickenpox?
Anyone who has not suffered from chickenpox previously is at risk of developing it.

If a mother has antibodies against chickenpox in her blood, she passes them on to her baby. These remain in the baby's blood for 9-12 months protecting him from chickenpox. After this period, the infant becomes susceptible to develop the infection.

As chickenpox usually affects infants and young children, those who spend a lot of time with children, like susceptible teachers and persons running the day-care centers have more chances of contracting the infection. In addition, health care providers (doctors, nurses, and hospital personnel) are at added risk of developing the infection since they may come in contact with a case during the course of their duty.

Is the course of chickenpox unusually severe in some children?
The disease is self-limited in most children as their immune system is well developed. If, however, a child whose immunity is low develops chickenpox, he is more likely to suffer from a severe course. Hence, children suffering from leukemia (blood cancer) or HIV infection or those on anti-cancer drugs may develop a severe variety of chickenpox. Adolescents may have an unusually severe course of chickenpox. Fever and constitutional symptoms are severe. Rash is heavier and confluent, complication rate higher and chances of fatality greater in them.

What are the consequences for a pregnant woman who comes
in contact with a case of chickenpox?

If a pregnant woman has previously suffered from chickenpox and has immunity against it, she is at no risk of developing chickenpox. If not, she may contract the infection which may have a severe course with higher likelihood of complications like pneumonia and may even succumb to the disease. There could be effects on her unborn fetus too.

What are the effects on fetus, if a pregnant woman develops chickenpox?
The effects depend on timing of the infection. If a mother develops infection during early pregnancy (e.g. first three months of pregnancy), the growth of various fetal organs may get affected and baby may be born with skin scarring, abnormalities of limb development and cataract. These babies may be mentally retarded, and may develop heart defect too. There is a possibility that abortion may occur in the pregnant woman. If the infection occurs later in pregnancy but not too close to delivery, the baby will be normally born but there is a possibility that she will develop herpes zoster (shingles) during infancy.

If mother develops chickenpox within 5 days prior to the delivery or in 2 days after the delivery, the baby receives the virus but not the ready-made maternal antibodies. Given her immature immune system, such a baby is in a weaker position to combat varicella infection and may develop severe manifestation of the disease. Newborn babies are more likely to develop serious complications like pneumonia and are at an enhanced risk of death from infection.

How is shingles related to chickenpox?
Both these conditions are caused by varicella zoster virus. First exposure to the varicella zoster virus results in chickenpox, which is followed by immunity against the infection, which usually lasts life-long. The virus, however, hides in certain nerve roots and remains dormant. The virus may get reactivated many years later leading to shingles (Herpes Zoster).

How does shingles present?
Shingles usually afflicts adults' especially old people. The rash, in shingles is vesicular and is limited to one or two segments on one side of the body. However, the rash is extremely painful. This pain is notorious for not getting easily controlled by routinely used analgesics or painkillers. If the rash affects the eye, it is a potentially sight-threatening complication.

Shingle may be followed by neuralgia and pain may persist for several months and years. Immunocompromised individuals like those suffering from leukemia / cancer or AIDS or patients on immunosuppressive therapy like steroids, anti-cancer therapy or radiation, may develop shingles which may involve many segments of the body and can have complications which are potentially fatal.

Does childhood chickenpox have a social impact?
Yes. The full impact of childhood chickenpox on patients and their families is often not appreciated. Physically, varicella is very uncomfortable for patients because they have to endure discomfort from symptoms such as the rash and the associated itching, fever anorexia and other constitutional symptoms. Patients often need to be isolated and kept at home. Thus, a school-going child may miss her school for a few days upto month (which is ideally not needed). Child may develop chickenpox during the examination period, which is usually held during March-April, which is also peak period for developing chickenpox (in winter). The rash may leave behind a permanent scar, which, for cosmetic reasons, may cause concern during adolescence or adulthood.

What are economic costs for a family when a child suffers from chickenpox?
The economic costs can be divided into direct costs and indirect costs. The cost of medications to control fever, relieve itching can be considered as direct costs. Occasionally, the child may have to be hospitalized or rarely suffer a severe complication. These add to direct costs. In addition, there are indirect expenses that the family has to incur. E.g. when a child has chickenpox, he cannot attend school and cannot be cared for in a day-care center, for the fear of spreading infection. This compels one of the adult household members, usually a parent to abstain from work and be at home to take care of the sick child. This may mean missing important appointments, rescheduling assignments or even loss of wages.

How does one treat chickenpox
?

As stated earlier, chickenpox presents with fever, other constitutional symptoms and rash. In most children, it has a self-limited course. Paracetamol can be given to control fever. Use of aspirin should be avoided, as it is feared to give rise to certain complications. Itching can be controlled by application of calamine lotion or oral antihistaminic drugs after consulting your doctor. The fingernails should bathed daily (contrary to general belief) so as to decrease the possibility of secondary infection.

Anti-viral drugs effective against vericella are known but are usually not required for otherwise healthy children and for uncomplicated cases of chickenpox. They may, however, be required when complications such as varicella pneumonia occur or when an immunocompromised child suffers from chickenpox.

What vaccines are available against chickenpox?
A vaccine containing a live attenuated strain of varicella is available. This strain is capable of stimulating the body's immune system to produce immunity against varicella virus without causing the disease. The vaccine is administered subcutaneously and is effective in providing protection for over 90% of vaccinees. Children below the age of 12 years require only one dose while older children; adolescents and adults require two doses at an interval of 6-10 weeks. The vaccine is usually well tolerated and side effects are generally mild and transient. These include local pain, mild rash and fever. Thus chickenpox is now preventable through vaccination. Please consult your doctor.



Contributor Information and Disclosures M R Lokeshwar
Consultant Pediatrician, Hinduja Hospital, Mumbai, India


First Created : 2/4/2002
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