Background: Varicella zoster virus (VZV) is recognized as one of the most common viral agents causing central nervous system (CNS) infections and comprises a wide spectrum of syndromes. Ameliorated diagnostic methods including real-time polymerase chain reaction (PCR) has facilitated the detection of virus in different body fluids and has also enabled quantification of the virus. Some data have been presented on viral load in the cerebrospinal fluid (CSF) of patients with VZV CNS infections, with diverging results, but so far no study has been published on the viral load in peripheral blood of these patients. Our aim was to investigate the viral load in peripheral blood in patients with acute neurological symptoms and detectable CSF VZV DNA by PCR and try to correlate the amount of VZV DNA to different clinical parameters.Methods: Seventy-two patients with VZV DNA detected in the CSF by PCR and contemporary neurological symptoms were included. The patients were diagnosed as encephalitis, meningitis, Ramsay-Hunt syndrome or "other neurological symptoms". The VZV CNS patients were compared to a control group of 36 patients hospitalized for herpes zoster but without neurological symptoms. VZV DNA concentrations in serum were measured by quantitative PCR and related to clinical manifestations and laboratory parameters.Results: The VZV CNS patients showed lower concentrations of VZV DNA in serum compared with the control group (p ≤ 0.001). In the VZV CNS patients, 40 patients had no detectable VZV DNA in serum compared to eight of the controls. When the subgroups were compared, the group of encephalitis showed higher viral amount in serum compared to both the group of meningitis and Ramsay-Hunt syndrome, respectively (p ≤ 0.01 and p ≤ 0.05). In only six VZV CNS patients with detectable VZV DNA in serum, rash was absent and there was a proportional correlation between absence of rash and negative VZV DNA PCR (p ≤ 0.001). The albumin ratio was positive in 47 of 63 patients. There was a tendency towards correlation between albumin ratio and VZV DNA concentrations in serum. There was no correlation between onset of neurological symptoms or time-point for initiation of i.v. treatment and viral load in serum.
Conclusions:The VZV viral load is lower in patients with VZV CNS infections compared to patients with herpes zoster and no neurological symptoms. The viremia in patients with VZV CNS infections seems associated with contemporary rash and possibly the degree of blood-brain barrier damage. http://dx.
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