herpes zooster

[David Richard Harper]

I am a virologist working on this virus.  I hope what follows is helpful.

Acyclovir (Zovirax) inhibits active replication of the virus that causes 
zoster (varicella-zoster virus, VZV).  However, the virus will NOT be 
cleared from the body, with or without therapy.  It will remain, latent, 
in the spinal ganglia.  While it could in theory at least reactivate 
again and cause more zoster, most people only get one episode.  I do not 
know where you read of a zoster/cancer link, but I can only assume that 
this refers to the fact that zoster is a common disease in people with 
cancer because of their poor immune status (the same applies to other 
immunosuppressions).  Zoster is associated with lowering of immunity 
(which is why it is associated with ageing), but this lowering can be 
very slight, and can occur in otherwise healthy people.  Zoster itself 
can be nasty, particularly when it causes post-herpetic neuralgia/zoster 
associated pain (PHN/ZAP) or occurs in the eye, but once the zoster 
clears up there is no reason to suspect any ongoing effect other than the 
chance of another episode at a later date (and the continuing presence 
of latent virus).
I know of no direct causitive link between VZV and cancer, or of any link 
between acyclovir and cancer.  Acyclovir has been in worldwide use for 
many years and has an excellent safety record- rather better than many of 
the experimental drugs now in testing, in fact!  The only major side 
effect is due to poor solubility, when crystals of the drugs can cause 
some kidney damage if it is used at VERY high levels.

To sum up: no problem.

David Harper