Diagnosing herpes in CSF

The Virus

HERPES simplex virus (HSV) belongs to the α-herpesviridae subfamily of herpesviruses. 

There are two types of HSV: type 1 and type 2. HSV is an enveloped virus with an internal core (capsid) containing dsDNA. The genome of HSV-1 and HSV-2 share 50–70% homology.

Central nervous system (CNS) infections are serious complications of HSV disease, which can occur in children and adults. Immunocompromised patients and neonates experience severe symptoms with potential of disseminated infection and death. 

The viral load of HSV in cerebral spinal fluid (CSF) is low compared to other clinical specimens. Culture for HSV is therefore difficult, as this technique is not very sensitive. HSV PCR is now recognised as the reference standard, given its high sensitivity and specificity. The determination of HSV DNA in CSF has been markedly enhanced with the availability of commercial kits for real-time PCR