BACKGROUND: In this retrospective study, our objective was to review the 
epidemiology of viral meningitis and to compare clinical features associated 
with enterovirus, herpes simplex virus (HSV), and varicella zoster virus (VZV) 
infections in immunocompetent adults.
METHODS: Data on cerebrospinal fluid (CSF) samples submitted to the Trust 
Virology Laboratory (Sheffield, UK) from April 2004 through April 2007 were 
reviewed. Notes on immunocompetent adults who were polymerase chain reaction 
(PCR) positive for enterovirus, HSV type 2, or VZV and who had presented to 
local clinical departments were scrutinized (4 patients were positive for HSV 
type 1 and did not meet the inclusion criteria).
RESULTS: A total of 2045 samples were analyzed for viral pathogens during the 
3-year period. Of the 109 PCR-positive samples, 38 (35%) were from 
immunocompetent adults, of whom 22 were infected with enterovirus, 8 were 
infected with HSV type 2, and 8 were infected with VZV. The median ages were 32 
years (range, 16-39 years), 39 years (range, 22-53 years), and 47.5 years 
(range, 26-80 years), respectively. Rash occurred after the meningitis symptoms 
in 5 patients infected with VZV (median time from meningitis symptoms to rash, 6 
days). Protein levels were significantly higher in CSF samples from patients 
infected with HSV type 2 (median, 1205 mg/L) and in samples from those infected 
with VZV (median, 974 mg/L) than in samples from those infected with enterovirus 
(median, 640 mg/L; P = .001 and P = .01, respectively). White blood cell counts 
were significantly higher in CSF samples from patients infected with HSV type 2 
(median, 240 x 10(6) cells/L) than in samples from those infected with 
enterovirus (median, 51 x 10(6) cells/L; P = .01).
CONCLUSIONS: Enterovirus infection was the most common cause of viral meningitis 
in immunocompetent adults in this study. White blood cell counts and protein 
levels were significantly higher in CSF samples from patients infected with HSV 
type 2 than in samples from patients with enterovirus infection. Zoster rash 
often occurs after meningitis. PCR testing provides a rapid and specific 
etiological diagnosis.