Viral aetiologies of acute encephalitis in a hospital-based population in Sri Lanka

Abstract

Attached

Background: The aetiological spectrum of acute encephalitis in Sri Lanka remains unknown. We aimed to identify the viruses which are known to be a major cause of infectious encephalitis Methods & Materials: A cross-sectional study was conducted among 99 patients with encephalitis/meningoencephalitis admitted to two tertiary care hospitals in Colombo. CSF and serum were tested for conventional viruses and emerging viruses that can cause encephalitis. Specific nucleic acid amplification assays and antibody assays were used to identify viruses. Plaque reduction neutralization test (PRNT) was done to confirm the diagnosis of West Nile virus (WNV). Results: Patients’ age ranged from 1 month to 73 years (mean=24.91; SD=21.33) with male: female ratio of 1.75:1. A viral aetiology was identified in only 27.3%. These included Dengue virus (40.7%), Japanese encephalitis virus (25.9%), Varicella zoster virus, Epstein Barr virus and WNV (11.1% each). None of the patients were positive for Herpes simplex virus 1 or 2, Cytomegalovirus, Nipah or Chandipura viruses. Screening for bacterial aetiologies was negative for all patients. There were no distinguishable clinical or routine laboratory features between the different viral aetiologies. Conclusion: A viral aetiology was identified in only about a quarter of patients with encephalitis. Dengue virus accounted for the majority. HSV accounted for none. This is the first identification of human WNV in Sri Lanka.