This virus was asked about in Question 29.1 from the first paper of 2009. In that specific instance, the college had asked the candidates to recognise the rash of chicken pox from a photograph.
In Oh's Manual, Varicella doesn't even appear in the index. Though it appears around the book as a differential for various things (eg. viral encephalitis), it receives no attention beyond that.
For the CICM felloship candidates, this brief summary of what a CICM trainee is expected to know about VZV has been cobbled together from the following sources:
Risks factors for VZV pneumonia
These risk factors are also elaborated upon in this article. In addition to the above, one can mention "contact with an infected person" - in one case series, such contact was mentioned by 16 of the varicella pneumonia patients, and only by 10 of the non-pneumonia patients.
Complications associated with severe disseminated VZV infection:
Clinically: characteristic rash; this is usually unambigous.
Histologically: the Tzanck test: a scraping or smear of the base of an ulcer, which looks for giant multinucleated monocytes, swarming with the virus. This is a way of confirming that the rash is indeed VZV.
VZV PCR: this is the investigation of choice for CSF
This is of greatest relevance to the intensivist, because it is one fo the two major reasons the varicella patient might end up in the ICU. The other reason is VZV encephalitis, resulting in a decreased level of consciousness, requiring intubation.
From this article, I mined various factoids the ICU trainee should be aware of: