Varicella zoster virus: an under-recognised cause of central nervous system infections?

Background Varicella zoster virus (VZV) causes infections of the central nervous system (CNS) manifesting as meningitis or encephalitis. It is not commonly tested in CNS infections when compared with enterovirus (EV) and herpes simplex virus 1 (HSV-1) and 2 (HSV-2). Cerebrospinal fluid (CSF) findings of viral CNS infections are thought to be comparable. Aims To describe the manifestations of VZV CNS infections and ascertain if there is a predominant syndrome. To compare CSF parameters of VZV with EV, HSV-1 and HSV-2. Methods Retrospective study at two hospitals in Brisbane, reviewing medical notes and laboratory information system for results between January 2001 and 2019. The following parameters were recorded - disease classification, presence of rash, duration of symptoms prior to hospitalisation, length of admission, duration of antiviral treatment and 30-day mortality. CSF biochemistry, cell count (differential), PCR for VZV, EV, HSV-1 and HSV-2 were recorded. Statistical analysis of CSF parameters included Student's t-test and linear regression. Results Incidence of meningitis was comparable to encephalitis (44 vs 39%) in 52 cases. CSF protein in VZV was significantly elevated compared with EV (median 1121 vs 569 mg/L; P < 0.001) as was CSF monocytosis (96% vs 61%; P < 0.001). CSF parameters between VZV, HSV-1 and HSV-2 were similar. VZV had a higher incidence than HSV-1 or 2, while it was tested one-third as often. Conclusions VZV CNS infection cannot be predicted by syndrome. CSF findings are markedly different from EV but like HSV-1 and 2. VZV should be routinely tested with HSV-1 and 2 when viral CNS infection is suspected.