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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.
