The Place of Viral Etiology in Encephalitis and Meningoencephalitis

Abstract

Introduction : Encephalitis and meningoencephalitis are inflammatory disorders of the brain tissue responsible for neurological dysfunction, sometimes of infectious or non-infectious origin. They may follow an acute, subacute or chronic course. Infectious encephalitis is more frequent in young children, individuals over 65 years of age and immunocompromised patients. The objective of this study was to describe the Algerian epidemiology by demonstrating the frequency of viral etiologies.
Materials and methods: A prospective study was conducted using a broad testing approach. We used a case definition compatible with those employed in previous studies, namely acute cerebral dysfunction and signs of inflammation, including patients who also had meningeal inflammation with an encephalic component (meningoencephalitis). Patients were recruited from three departments (intensive care, infectious diseases and paediatrics); data were collected according to the case definition using a standardised form. We sought to identify etiological pathogens using a standardised procedure based on SPILF recommendations, while describing the epidemiological, clinical, biological and etiological characteristics. Risk factors associated with in-hospital death were evaluated by multivariate logistic regression.
Results: A total of 141 patients with acute infectious encephalitis were included in the study. A viral etiology was determined in 73/141 (51.8%); it was confirmed for 29 (39.7%) patients, considered probable for 42 (57.3%) and possible for 2 (2.7%). Epstein–Barr virus (EBV) 14 (19.2), herpes simplex virus (HSV) 14 (9.9%), cytomegalovirus (CMV) 11 (15.1%), adenovirus 6 (4.3%) and coronavirus 12 (16.4%) were the most frequently identified pathogens.
Twenty-three patients (16.3%) (69% of whom were older than 16 years) died. Risk factors associated with death were: admission to intensive care (p < 10⁻³), age ≥ 65 years (p = 0.005), initial level of consciousness (p = 0.04), Glasgow Coma Scale score < 8 (p < 10⁻³), status epilepticus (p = 0.022), hydrocephalus (p = 0.024), involvement of the parietal lobe (p = 0.046), length of hospital stay < 5 days (p = 0.006), rhinovirus infection (p = 0.032), CMV infection (p = 0.013) and coronavirus infection (p = 0.013).
Conclusion: This study highlights a “cocktail” of numerous pathogens, most of which were potentially preventable. We observed a high proportion of EBV, which could probably be explained by the high prevalence of nasopharyngeal cancer in our setting.