Childhood Diseases

Updated 11 March 2016

Diagnosing chickenpox

It is easy to identify the rash of blisters of chickenpox, so laboratory test are not necessary.


Chickenpox is usually an easily recognisable disease because of the distinctive rash of blisters. For this reason, laboratory tests are not often necessary.

If there is doubt, the virology laboratory can do rapid tests on fluid obtained from a vesicle with a tiny needle and syringe or on cellular material obtained by swabbing the raw base of a vesicle.

In situations of exposure to chickenpox, the knowledge that a person has definitely had chickenpox before is useful when deciding what measures, if any, need to be taken.

Often this information is not known or is incorrect, such as when adults try to recall whether they had chickenpox as a child.

In circumstances where an at-risk person has been exposed to chickenpox, a blood test can be done to show whether they have antibodies to the varicella-zoster virus.

The presence of antibodies means that they had had chickenpox in the past and that they are therefore wholly or only partially protected as with immune compromised people.

Read more: 

Risk factors for chickenpox 

Treating chickenpox       

Causes of chickenpox

Revised and reviewed by Prof Eugene Weinberg, paediatrician and Paediatric Allergist, Health24 expert, February 2015.