Detection of dengue virus encephalitis in central part of Sri Lanka.

Background: In tropical Asia, arbovirus-induced encephalitis continues to be a serious public health issue. Encephalitis is caused by wide range of neurotropic pathogens, and flaviviruses are one of the main causative agents in the area. Sri Lanka reports a considerable number of central nervous system infections annually. Both dengue and Japanese encephalitis are endemic, and cases of Zika and West Nile virus infections were reported occasionally in Sri Lanka. Although reported number of Japanese encephalitis cases has reduced in the past, aetiological diagnosis in majority of encephalitis cases is still unknown.

Aim: To detect dengue virus (DENV) infections in individuals in the central region of Sri Lanka who were clinically suspected of having encephalitis.

Methods: A retrospective observational analysis was conducted on 99 cerebrospinal fluid samples received to a virology laboratory from patients in the central part of Sri Lanka who were clinically suspected of having encephalitis. Samples were analyzed using reverse transcriptase polymerase chain reaction (RT-PCR) with universal flavivirus primers to detect flaviviral RNA followed by DENV serotyping real-time RT-PCR, and an immunoglobulin M (IgM) detection enzyme-linked immunosorbent assay to detect IgM antibodies indicative of a possible recent DENV infection.

Results: DENV aetiology was detected in 6 (6.06%) cerebrospinal fluid samples, and all were confirmed as DENV infections. A single positive result (1.01%) was yielded through RT-PCR and was identified as DENV serotype 3. Serology testing detected 05 (5.05%) anti-dengue IgM positives and further investigation indicated probable DENV aetiology. Among positives 02 (33.33%) were children (aged less than 14 years), and rest were adults.

Conclusion: These findings underscore the presence of DENV-associated central nervous system infections and highlight the need for broader surveillance and more advanced diagnostic approaches in the future.