Chickenpox is very contagious and is one of the most common childhood infectious diseases.
Chickenpox occurs worldwide as a childhood disease, which lasts four to five days. It presents with fever and a widespread rash of small blisters (vesicles), which are usually distributed on the chest, back, face and the arms and legs.
Sometimes the disease can be more severe, affecting internal organs such as the lungs and liver.
A person will only have one episode of chickenpox in their lifetime. Once that person has recovered, he or she has life-long immunity to chickenpox.
Importantly, the virus that causes chickenpox (varicella-zoster virus) belongs to the herpes virus family.
It usually takes about 14 days from the time people are exposed to the chickenpox virus, to the time when symptoms start to occur. Sometimes this period can be as short as 10 days or as long as 21 days.
The preliminary symptoms of fever and headache usually begin 24 to 36 hours before the rash appears. The fever subsides a few days after the rash appears and the rash usually lasts for 5 or 6 days. The last dried-up crusts fall off by 10 days.
Like other members of this virus family following recovery from the initial infection, the virus never really leaves the host.
Instead, it remains hidden in certain nerve cells, without causing any obvious illness. This hidden or "latent” virus may be reactivated later on by a variety of causes such as stress, malnutrition and in the elderly.
The reactivated virus will cause an illness called shingles. Shingles is a band of painful blisters, usually involving the skin on the side of the chest or abdomen, but may involve the face.
Risk factors for chickenpox
Symptoms of chickenpox
Revised and reviewed by Prof Eugene Weinberg, Paediatrician and Paediatric Allergist, Health24 expert, February 2015.