10: Herpes simplex and varicella-zoster virus infections.

Any new patient with suspected genital herpes should have diagnostic testing with virus identification. Type-specific serological tests that distinguish between antibodies for type 1 and type 2 herpes simplex virus (HSV) may be useful to determine previous exposure but cannot be used to diagnose recurrences of genital herpes. Initial episodes of genital herpes usually require antiviral therapy, while recurrences may be treated with continuous antiviral suppression (if frequent) or episodic therapy; patient counselling and education (including how to recognise lesions) are essential. Topical or systemic therapy is available for initial and recurrent non-genital herpes simplex. Primary varicella infection (chickenpox) and herpes zoster (shingles) are usually diagnosed clinically, but can be confirmed by detection of varicella-zoster virus antigens or nucleic acid from swabs of lesions or by antibody tests. Antiviral therapy should be considered in chickenpox if disease is complicated or the patient is immunocompromised. In herpes zoster, antiviral therapy should be given within 72 hours of onset to patients aged over 50 years or with severe pain or neurological abnormalities to reduce the likelihood and duration of postherpetic neuralgia. The availability of effective antiviral therapy makes early diagnosis vital