Herpes simplex virus infection in Bulgarian patients with neurological diseases

Background: Herpes simplex virus (HSV) seroprevalence in Bulgaria is higher than that in other countries but there is no information concerning involvement of these viruses in neuropathology. The aim of the present study was to determine the frequency of HSV DNA detection in cerebrospinal fluid (CSF) of patients with neurological diseases. Methods: This study is a retrospective survey of test results obtained from January 2015 to October 2019. During this period 617 CSF specimens were tested for the presence of HSV-1 and/or HSV-2 DNA by PCR. Results: Of all 612 CSF samples tested for HSV-1, 16.5% were positive. Of 547 CSF samples tested for HSV-2, 6.2% were positive. Co-infection with HSV-1 and HSV-2 was detected in 1.3% of tested 543 CSF samples. The difference of HSV-1 and/or HSV-2 prevalence in CSF of patients according to the gender and age was not statistically significant. The highest HSV-1 prevalence (25%) was detected in CSF from patients with multiple sclerosis (MS), followed by patients with encephalitis (20.6%). The highest HSV-2 prevalence (22.2%) was detected in CSF from patients with myelitis, followed by patients with encephalopathies (7.5%). Conclusion: Our results show a considerable prevalence of HSV-1 and HSV-2 in CSF of patients with neurological diseases indicating the important role of these viruses in neuropathology in Bulgaria. HSV-1 is with predominant role in development of both encephalitis and meningitis in different age groups. Testing of CSF for HSV should be indispensable part of diagnostic algoritm of these diseases.