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Chickenpox
Chickenpox is an infection caused by the Varicella zoster virus. It is a highly
contagious illness and occurs most commonly in late winter or early spring.Incubation Period
2 - 3 weeks (commonly 14 - 16 days).Signs and Symptoms
2 days before onset of rash:
- Low grade fever
- Loss of appetite
- Decreased activity
Rash:
- Itchy. Small red spots that start on the scalp, face and trunk and then
spread to the arms and legs (may also occur in the mouth and genitalia).
- Spots then become blisters with clear and then cloudy fluid, and then become
open sores and finally crust over within about twenty-four hours.
- The child will
continue to get new spots for about four more days. By the time the spots have
stopped forming and are dried over and the temperature has fallen back to
normal, the child is no longer infectious. Usually this takes about a week,
until then they should remain off playgroup or school.
Complications (rare):
- Pneumonia (viral & bacteria)
- Secondary bacterial infections
- Haemorrhagic complications
- Encephalitis
Treatment
There is no effective treatment for children who develop uncomplicated
chickenpox. Many people find that calamine lotion helps to soothe the itch, and
paracetamol liquid helps to ease any aches and pains and also keep down the
temperature.Chickenpox During Pregnancy
- The pregnant mother should immediately inform her obstetrician if she develops
chickenpox or comes into contact with a case to discuss the necessary treatment.
Risk to the unborn child depends on the stage of pregnancy.
- Varicella infection during the first trimester of pregnancy can cause
spontaneous abortion but, overall, the risk is not significantly increased.
- During the third trimester, maternal chickenpox can lead to premature onset of
labour.
- Maternal chickenpox within five days prior to delivery and up to 48 hours
postpartum is associated with a high mortality rate. Newborn death is around
30%.
Control and Prevention
Exclude children from school, medical offices, emergency rooms or public places
until the spots become dry. Exclude infected adults from the workplace and avoid
contact with susceptibles. In the hospital, strict isolation is appropriate
because of the risk of serious varicella in susceptible immunocompromised
patients.Chickenpox Vaccine
The chickenpox vaccine is a live attenuated vaccine. It should be stored at 2
– 8oC.
- Children: 1 – 12 years: single dose. It can be given at same time as MMR but
at different sites. If given separately, should be separated by at least 30
days. It offers 90% protection.
- Adults: More than 13 years old: two doses: second dose repeated after 4 – 8
weeks. It offers 75% protection.
- 5% of children and 10% of adults develop vaccine-related rash within 1 month
of immunisation. The risk of transmitting the vaccine virus from vaccinated
people to others is very low.
Varicella Immunoglobulin
The varicella immunoglobulin is recommended for:
- Varicella zoster antibody negative pregnant mothers who come in contact with a
case of chicken pox at any stage of pregnancy (within 10 days of initial
exposure)
- Neonates:
- Whose mother had chickenpox 7 days prior to delivery up to 7 days after,
- Who come into contact with a case of chickenpox (but 48 hrs have not elapsed
since first exposure) and:
- Are less than 7 days old OR
- Premature (less than 28 weeks) OR
- Less than 1 kg birth weight OR
- Received repeated blood sampling OR
- On SCBU
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