Chicken Pox
- Chicken Pox is a viral infection, caused by the Varicella Zoster Virus, which is a type of herpes virus.
- Children in Australia are routinely immunised against Chicken Pox at 18 months, as part of a 4 in 1 vaccine with the MMR (called the MMRV vaccine).
- The Chicken Pox vaccine does not give 100% protection, but prevents infection in around 85% of cases, and gives over 95% protection against severe infection- i.e. if you do get symptoms, they’ll tend to be a lot milder.
- The Chicken Pox rash consists of itchy water-filled blisters on the body. Other symptoms include fever, runny nose and cough.
How do you get Chicken Pox?
- Chicken Pox can be spread by coughs, sneezes or exposure to the fluid in the blisters
- It is highly contagious
- A person is infectious for 2-5 days before the rash appears until the lesions have all dried and crusted over, which may take a further 5 days or so.
- If you’ve never had Chicken Pox and have not been immunised against it, it’s possible to catch Chicken Pox from someone who has Shingles (as it’s caused by the same virus)
How long does it take to get symptoms following exposure?
- The incubation period (time between exposure and showing symptoms) varies.
- The rash tend to arise between 10 and 20 days after catching the virus.
What are the symptoms of Chicken Pox?
- Itchy water filled blisters- these usually start on the trunk and/or face
- Fever
- Runny nose
- Cough
- Aches & pains
How is Chicken Pox diagnosed?
- Usually it can be diagnosed by the typical appearance of the rash
- People who have had vaccination may get a milder form, which may not be diagnosed quite so easily
- Swabs of the skin lesions may be taken, if there is doubt about the diagnosis
What are the complications of Chicken Pox?
- Scarring can occur if lesions are very inflamed or are scratched a lot
- The blisters can become infected with bacteria- leading to weeping sores, crusts and/or cellulitis
- Viral pneumonia
- Viral encephalitis (infection of the brain)
- Bleeding disorders can rarely occur
- In rare cases, death can occur
Who should get the Chicken Pox Vaccine?
- The Chicken Pox vaccine is recommended for children as part of routine childhood vaccination
- If a child has missed the vaccine they can get it later, though after the age of 14 two shots (at least a month apart) are required to get an adequate immune response
- If you are not immune to Chicken Pox and someone in your household or close contacts is immunocompromised (a significantly suppressed immune system due to certain illnesses or treatments- see below)
- However, the Chicken Pox vaccine is not safe for everyone – see below
Who should not get the Chicken Pox Vaccine?
As the Chicken Pox Vaccine is “live”, it should not be given to certain people as it may cause harm/ severe infection
- Pregnant women and women who intend to become pregnant within the next month
- People who are immunocompromised (a weakened immune system)- for example, due to chemotherapy, immunosuppressant medication for organ transplant, some cancers, long term steroid treatment, radiation treatment, HIV infection etc. This should be discussed with your doctor, as the advice may vary depend on individual factors.
- Anaphylaxis (severe allergy) to any ingredients in the vaccine
- If unsure, seek medical advice
Is Chicken Pox in pregnancy dangerous?
- Most women who are exposed to Chicken Pox in pregnancy will not become infected – however, a small number of non-immune pregnant women may experience complications, including:
- Pneumonia
- Encephalitis (brain infection)
- Hepatitis (liver infection)
- Foetal abnormalities- if infection happens before 20 weeks of pregnancy, Congenital Varicella Syndrome may occur. The risk of damage after 20 weeks is lower.
- Pregnant women usually have a blood test at the start of pregnancy to check if they are immune. If not, they are advised to avoid anyone who may have Chicken Pox. If non-immune women are exposed to a case Chicken pox in pregnancy, they will usually be given special “immunoglobulin” treatment through a drip, to reduce the chances of the virus causing harm.
What is the treatment for Chicken Pox?
- General comfort measures include rest, fluids, and Paracetamol for fever
- Aspirin should NOT be given as it can cause serious complications (Reye’s Syndrome)
- Ibuprofen is often used to treat symptom of viral illness in children, but in Chicken Pox it may cause an increased risk of severe skin reactions. Until more research is done, it’s probably best to opt for Paracetamol instead.
- Calamine lotion is often applied to lesions to reduce the itch, and antihistamines may be used in older children.
- Cotton mittens may by worn by small children or babies to reduce scratching
- Antibiotics are not used for Chicken Pox as they don’t work against viruses- however, if a child gets a secondary bacterial infection of their Chicken Pox rash, antibiotics may be necessary.
- Less commonly, antiviral tablets may be prescribed if a person has a weakened immune system
When should you see a doctor?
- If you’re not sure about the diagnosis
- If the rash is severe or redness is spreading out from the lesions
- If symptoms of concern develop, such as drowsiness, headaches, dehydration or general unwellness
- If you are pregnant
Further Patient Resources:
Chickenpox (varicella) healthdirect.gov.au
Article Resources:
Cohen J, Breuer J. 2015. Chickenpox – treatment
Varicella Zoster Infection (Chickenpox and Shingles) health.qld.gov.au
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