Chickenpox, also known as varicella, is an infectious disease that is more common in children under 12. It is a highly contagious, airborne disease which spreads easily through the coughs and sneezes of an infected person or by sharing food with them. It is usually more severe in adults than it is in children.

How does chickenpox evolve?

Chickenpox goes through three distinct stages:

• Incubation and prodromal stage. The incubation stage can last from 13 to 17 days, whereas the prodromal stage (that is, the moment when you start getting symptoms such as a high temperature, loss of appetite, coughing and generally feeling unwell) lasts about 48 hours;

• Exanthematous stage. This is marks the onset of spots. At the beginning they appear as red spots, but within a six to eight hours they start to fill with fluid. Within 24 hours the fluid inside the blisters will start looking clouded over. There can be several “waves” of spots and blisters, which can also cause an itching sensation. In case of complications, the pustules can become infected and become filled with pus.

• Remission stage. During this stage the blisters scab over. The crusts will dry out and fall on their own. This is a sign that the infection is over. This stage can last from one week to 20 days. You will only get scars if, when you feel itchy, you scratched the crusts before they had healed completely.

What causes chickenpox?

Chickenpox is caused by an infection of the varicella zoster virus (VZV). It only infects humans and it is spread by contact.

How can it be prevented?

Chickenpox is highly contagious. The only way of preventing the infection is to get the chickenpox vaccine. In the UK, chickenpox vaccines are not mandatory and are not offered as part of the childhood vaccination programme with the NHS. Chickenpox vaccines are only offered when there is a clinical need for them, such as in cases where a healthy child may come into contact with a person with a weakened immune system.

How can it be treated?

In the vast majority of cases, chickenpox goes away on its on within a couple of weeks. Complications may arise if your immune system is low, as a result of chemotherapy or of taking immunosuppressants or cortisone to treat HIV.

Which doctor should I talk to?

If a child or teenager has chickenpox, you should see a paediatrician.