Molecular Detection of Human Herpes Viruses 1, 2, 3 and 6 in the Cerebrospinal Fluid of Patients with Central Nervous System Infections

Abstract

Background: Infections of central nervous system (CNS), such as encephalitis, meningitis, and meningoencephalitis are potentially life-threatening syndromes. They are caused by a diverse array of infectious causes. Despite being relatively uncommon, the morbidity, mortality, and costs are substantial. Of major importance are the herpes simplex virus (HSV)-2 and varicella zoster virus (VZV) in meningitis, and HSV-1 in encephalitis. Human herpes virus 6 (HHV-6) infection can induce severe encephalitis cases, particularly in immunocompromised. Human herpes viruses (HHVs) can cause CNS disease following primary infection, reactivation or recurrence. Purpose: To estimate the frequency of four common neurotropic herpes viruses: HHV-1 (HSV-1), HHV-2 (HSV-2), HHV-3 (VZV) and HHV-6 as causative agents for viral encephalitis and aseptic meningitis. Patients and Methods: The study was conducted on sixty five (65) CSF samples selected from the CSF of patients clinically diagnosed with acute encephalitis or meningitis. The samples belonged to 39(60.0%) males and 26(40.0%) females. Their ages ranged from 12 days to 62 years old. All CSF samples included in the study were subjected to white cell count, estimation of the level of protein and glucose, direct macroscopic and microscopic examination and culture on blood, chocolate and MacConkey agar plates. All samples had a CSF leukocytic count ≥ 5 cells/ mm3 and all were negative for bacterial culture. Real time PCR for the following viruses: HHV-1 (HSV-1), HHV-2 (HSV-2), HHV-3 (VZV) and HHV-6 was done for each sample. Results: The results of the PCR showed that twenty six (40%) were positive: twenty two (34%) were positive for a single infection; HSV-1 was positive in seven (10.8%), HSV-2 in eight (12.3%), VZV in one (1.5%) and HHV-6 in six (9.2%) of the cases. Four (6.2%) samples showed co-infection with two viruses. VZV was common in all cases of co-infection, together with HSV-2 in two (3%), HSV-1 in one (1.5%) and HHV-6 in one (1.5%). Thirty nine cases (60.0%) were negative for the four viruses. Conclusion: The four herpes viruses (HSV-1, HSV-2, VZV and HHV-6) tested by PCR are causative agents in 40% of the tested cases of CNS infections. The most frequently detected virus by PCR was HSV-2 followed by HSV-1. In case of encephalitis, the most frequently detected virus was HSV-1, while HSV-2 was the most frequent in case of aseptic meningitis. VZV was common in all cases of co-infections.