Ukrainian priorities for herpesvirus infections that affect the central nervous system

Introduction: Herpesviruses (HVs) are ubiquitous pathogens that infect humans usually during childhood, followed by a life-long persistence in a latent state in many sites of a body including the nerve cells. After reactivation HVs can affect the Central Nervous System (CNS) becoming a major cause of morbidity and mortality worldwide as well as long-term neurological sequelae. Despite being an important public health problem very few population-based studies were conducted so far in the world and none in Ukraine. The aim: to explore the clinical features and etiology of herpesvirus encephalitis (HVE) in a prospective single center study from January 2014 to January 2017.

Materials and methods: 107 adult patients with confirmed herpesvirus infection and symptoms of possible encephalitis (CNS lesion) were analyzed in the study. CSF and blood contents, antibody for HVs M and G classes, and MRI scans have been studied, but the crucial diagnostic sign was the presence of specific viral DNA in the CSF or blood.

Results: 74 (69.3%) out of 107 patients were females, the male to female ratio was 1:2.2. The median age of patients was 36.9 years (range 20-65 years). Most common clinical features were fever, meningism (stiff neck), and focal neurological signs. The genome of HVs was detected in CSF samples obtained from all patients as follows: Herpes simplex virus 1 and 2 - 13 (12.1 %), Varicella zoster virus - 2 (1.8), Cytomegalovirus - 14 (13 %), Epstein Barr virus - 22 (20.5 %), Human herpesvirus 6 - 5 (4.7 %), Human herpesvirus 7 - 13 (12.1 %). Co-infection (≥ 2 HVs) was observed in 38 patients (35.5 %). CSF of 27 patients contained two viral DNA, and 11 - three one in various combination. Human herpesvirus 8 was not found.

Conclusions: The most frequently diagnosed infections in hospital based study were Human herpesvirus 5 (EBV), followed by HSV-1/2, CMV, and HHV-7. Significant part of patients (35.5 %) were co-infected with two or three HVs. Predisposing factor for Ukrainian population is sex.