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by Dr. Mas Suhaila

What is chickenpox?

Chickenpox is a highly contagious infection caused by the varicella-zoster virus (VZV) that can lead to fever and an itchy rash of blisters.


Symptoms of chickenpox

The blister-like rash appears 10 to 21 days after exposure to the virus, first on the chest, back, face and then spreads over the entire body, causing up to 250 and 500 itchy blisters which eventually turn into scabs. It usually takes about a week for all the blisters to become scabs and children would miss school or childcare during this time.


These may begin 1-2 days before the rash : fever, tiredness, loss of appetite, headache


For most people, getting chickenpox once provides immunity for life. However, it is possible to get chickenpox more than once; although this is not common.



Doctors generally diagnose chickenpox based on the appearance of the rash.

If there is any doubt about the diagnosis, chickenpox can be confirmed with laboratory tests, including blood tests or a swab of the blister fluid.


Who is at risk?

Anyone who has not had chickenpox or gotten the vaccine can get the disease. People who may get a serious case of chickenpox or suffer complications include babies, adolescents, adults, pregnant women, and people with a weakened immune system. 



Chickenpox is generally mild in healthy children but the itching can be very uncomfortable.


Serious complications from chickenpox that can require hospitalisation and even be life-threatening include :

Bacterial infections of the skin, soft tissues, bones, joints or bloodstream (sepsis)

Infection of the lungs (pneumonia)

Swelling of the brain (encephalitis)

Bleeding problems 

Loss of body fluids (dehydration)

Toxic shock syndrome

Reye's syndrome in those who take aspirin during chickenpox


Deaths are very rare now but some continue to occur in healthy, unvaccinated children and adults. 


How does chickenpox spread?

It spreads easily when a person touches or breathes in the virus particles that come from chickenpox.  It can also spread through tiny droplets that get into the air when someone who has chickenpox breathes or talks. 


Chickenpox can spread 1 to 2 days before the infected person gets a rash until all the blisters have formed scabs. 


The varicella-zoster virus also causes shingles. Chickenpox can also be spread through close contact from someone who has shingles.


Vaccinated people who get chickenpox may develop lesions that do not crust. These people are considered contagious until no new lesions have appeared for 24 hours.


When to see a doctor:

If you have been exposed to chickenpox and :

  • never had chickenpox and are not vaccinated with the chickenpox vaccine

  • less than 1 year old or older than 12 years old

  • are pregnant

  • have a weakened immune system 

  • have a household member who is a newborn, pregnant or weakened immune system


Or, if you are infected and develop any of the following symptoms :

  • Fever that lasts longer than 4 days or above 38.9°c 

  • The rash or any part of the body becomes red, warm, tender, or begins leaking pus 

  • Difficult waking up, confused behaviour, difficulty walking or stiff neck

  • Frequent vomiting

  • Worsening cough or difficulty breathing

  • Severe abdominal pain

  • Rash with bleeding or bruising 


To avoid infecting others in the clinic waiting area, call ahead for an appointment and mention that you think your child may have chickenpox.



In otherwise healthy children, chickenpox typically needs no medical treatment. Your doctor may prescribe an antihistamine or lotions like calamine to relieve itching and paracetamol for fever. Mostly, the disease is allowed to run its course.


To help ease the symptoms of an uncomplicated case of chickenpox, this may help :

  • Cool baths and calamine lotion help soothe the itch

  • Minimize scratching by keeping fingernails short


Do not use aspirin or aspirin-containing products to relieve fever. The use of aspirin in children with chickenpox has been associated with Reye’s syndrome, a severe disease that affects the liver and brain and can cause death. 


Avoid ibuprofen as well, if possible, as there may be an association with life-threatening bacterial skin infections.


Antiviral medications work best if it is given as early as possible, preferably within the first 24 hours after the rash starts. 

It is recommended for people who are more likely to develop serious illness, including:

  • Otherwise healthy people older than 12 years of age

  • People with chronic skin or lung disease

  • People receiving long-term salicylate therapy (eg. aspirin) or steroid therapy

  • Pregnant women

  • People with a weakened immune system


In some instances, your doctor may recommend getting the chickenpox vaccine after you have been exposed to the virus. This can prevent the disease or lessen its severity. 


Another medication called Varicella Immunoglobulin (a type of antibody) is sometimes given to people with weakened immune system (including newborns whose mothers do not have immunity) after being exposed to chickenpox.


Prevention/ Vaccination

The best way to prevent chickenpox is to get the vaccine. This protects your child from chickenpox, which can be potentially serious and even deadly. It keeps you and your child from missing work, school or childcare.


The vaccine is very safe and effective at protecting against chickenpox. Vaccines, like a medicine, can have side effects. Side effects like redness, soreness, swelling and small bumps at the site of the injection, fever, pain and stiffness in the joints are usually mild and temporary.


Two doses of the chickenpox vaccines are recommended for children. In Singapore, it will be part of the routine national immunisation schedule administered at 12 and 15 months of age.


Why not let my child get chickenpox naturally?

Previously,  some parents bring their children to “chickenpox parties” to intentionally expose their unvaccinated children to a child with chickenpox in the hope that they would get the disease and obtain natural immunity.  Chickenpox is a mild disease for many children, but not all. There is no way to know how severe your child’s symptoms will be. 


"Chickenpox Parties"—Don't Take the Chance.

The vaccine will provide your child with the immunity from chickenpox but without the risk of serious complications of the disease.


Chickenpox and Shingles

If you have had chickenpox before, you are at risk of developing a later complication called shingles. This is because the virus remains in your nerve cells after the skin infection has healed. Many years later, the virus can become active again and resurface as shingles which is a condition causing a painful cluster of blister-like rash. It is more common in older adults and those with weakened immune systems. The pain after having shingles can persist long after the rash disappear and can be severe. Your risk for shingles would be extremely low if you have received the chickenpox vaccine and didn’t develop chickenpox.


Chickenpox and pregnancy

Low birth weight and limb abnormalities are more common among babies born to women who are infected with chickenpox early in their pregnancy.


When a mother is infected with chickenpox in the week before birth or within a couple of days after giving birth, her baby has a higher risk of developing a serious, life-threatening infection. If you are pregnant and not immune to chickenpox, talk to your doctor about the risks to you and your unborn child.



References :

Centers for Disease Control and Prevention, USA

Red book, 2018 edition

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