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Chicken Pox
Health Guide

What is chicken pox?

Chicken pox is a highly contagious but usually harmless infection that occurs mostly during childhood (90% of cases occur in children younger than 10 years of age)1, the most characteristic feature is a highly distinctive rash. Chicken pox results from infection with the Varicella-Zoster virus2 If the same virus is reactivated later in life it is called Herpes Zoster and causes Shingles. Shingles is an especially painful skin rash, which most commonly occurs after the age of 60.

What causes chicken pox?

Varicella Zoster Virus (VZV), a member of the herpes virus family is responsible for both primary (Varicella, Chickenpox) as well as reactivation (Zoster, Shingles) infections2. This virus is one of the most contagious of infectious diseases3 and is spread from person to person by direct contact with the skin rash or through the respiratory system from airborne droplets4. From the respiratory system the virus spreads to the lymph nodes then spleen and liver and finally the rest of the body via the bloodstream1. Humans are the only known carriers of Varicella- Zoster virus5. Patients with chicken pox are infectious from approximately 48hours before the rash develops until all the spots have crusted over5. The incubation period for chicken pox is between 10-21 days, usually between 14 to 17 days. This means children with chicken pox will begin to show symptoms approximately two weeks after they have been infected.  


In young children the illness usually begins abruptly with the simultaneous onset of rash, low-grade fever and general discomfort1. Occasionally this can be preceded by symptoms such as headache, nausea and vomiting in older children and adults. Temperatures range between 37.8-39.4C (100-103F)5 and this elevation lasts 3-5 days or as long as skin lesions continue to appear. This skin rash begins to appear within 24 hours, firstly on the trunk, face and scalp and rapidly spreading to involve other areas of the body, primarily the upper regions of the arms, with relatively sparing of the lower extremities1. The rash first appears as flat reddened spots with a diameter between 5-10mm. These progress over 12-14 hours to solid elevated lesions, then to small sacs containing fluid ("vesicles"), finally to dry crusts or scabs5. A characteristic feature of the rash is that different stages of the type of lesions described above can all be present, in different parts of the body, at the same time.

Almost universal is the symptom of severe itching associated with the skin rash. The severity varies form one individual to another. Some individuals have few lesions, others are covered extensively by the lesions. Younger children tend to have fewer spots than older individuals. Most scabs heal completely and patients are left with very few scars. Varicella infection in adults is usually more severe, with more skin lesions and more prominent and prolonged fever1. The most common complication is secondary bacterial infection of the skin2. This can result from rupture of skin lesions after scratching. In adults with chickenpox, one in 400 will develop Varicella pneumonia1, which is perhaps the most serious complication5.

Varicella infection of the newborn is associated with a high mortality rate when the mother develops the disease within five days before the delivery, or within two days after5. In pregnancy, Varicella infection can cause congenital defects in the first half of the pregnancy2. However, this is extremely uncommon. Adults or children with depressed immune function who contract Varicella will develop a severe illness with extensive rash and prolonged fever. They are also more likely to develop further co

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