Diagnosis of herpesvirus infections of the central nervous system

Human herpesviruses may cause infections of the central nervous system (CNS). The early diagnosis of herpesvirus-associated neurological diseases is of high importance.The objective of this paper is to summarize the experience gained with the diagnosis of herpesvirus infections of the CNS at our institute by polymerase chain reaction (PCR)-based assays within the past few years.A retrospective analysis of herpesvirus desoxy ribonucleic acid (DNA)-positive cerebrospinal fluid (CSF) samples was performed, with particular emphasis on data obtained by quantification of virus DNA in CSF by newly established real-time quantitative PCR assays.Herpesviruses were found in 26.6% of all virus-positive CSF samples detected at our institute between 1995 and 2001. The overall broad testing for different herpesviruses from CSF has led to an increase in the detection rate, especially in relation to varicella zoster virus (VZV)-associated CNS disease. The herpesvirus DNA load in CSF was investigated by TaqMan real-time PCR assays that were established for the individual herpesviruses. The amount of virus varied among the individual diseases, associated with herpes simplex virus type 1, herpes simplex virus type 2, VZV and cytomegalovirus, while for Epstein-Barr virus and human herpesvirus type 6 only low levels of virus were detectable in CSF.A generally broad testing for different herpesviruses in CSF samples is highly recommended. In addition, determination of the virus DNA level in CSF by quantitative assays seems to be of high importance for elucidating aspects concerning the prognosis of disease, the prediction of distinct CNS manifestations, and possibly the differentiation between specific virus-associated disease and unspecific presence of virus in CSF, especially in immunocompromised patients.