Infectious encephalitis among adults: a prospective and population-based cohort study

Area of Science:

• Neurology
• Infectious Diseases
• Epidemiology

Background:

• Infectious encephalitis is a serious neurological condition with significant morbidity and mortality.
• Understanding its incidence, presentation, and prognosis is crucial for effective management.

Purpose of the Study:

• To determine the incidence, clinical characteristics, and outcomes of infectious encephalitis in adults in Denmark.
• To identify risk factors associated with severe disease and mortality.

Main Methods:

• A prospective, population-based cohort study was conducted using the Danish Study group for Infections of the Brain database (2015-2023).
• Cases were identified based on International Encephalitis Consortium criteria.
• Multivariable modified Poisson regression analyzed associations with ICU admission and 6-month mortality.

Main Results:

• The annual incidence was 1.18 per 100,000 population, with Herpes simplex virus type 1 (HSV-1) and Varicella zoster virus (VZV) being the most common etiologies (31% and 32%, respectively).
• Confusion, headache, and personality changes were common symptoms.
• Intensive care unit (ICU) admission was linked to low Glasgow Coma Scale (GCS) scores and seizures. Six-month mortality was 15%, with higher risks observed in immunocompromised patients, HSV-1 encephalitis cases, and those with GCS <12.

Conclusions:

• Infectious encephalitis, though rare, presents diagnostic challenges due to unspecific symptoms.
• Herpes simplex virus type 1 (HSV-1) and Varicella zoster virus (VZV) are leading causes.
• Prognosis remains poor, with increased mortality risk factors including immunocompromise, HSV-1, and low GCS at admission.