Viral etiology and clinico-epidemiological profile of clinically suspected acute viral encephalitis

Abstract

Background: Acute viral encephalitis is a medical emergency which could lead to considerable morbidity and mortality. The spectrum of brain involvement, with varying severity, and the outcome of the disease depend on the causative virus. Geography is a major determinant for encephalitis caused by vector-borne viruses. This retrospective study will focus on Flaviviral etiology, diagnosis, geography and clinical profile of acute viral encephalitis in Sri Lanka. Methods & Materials: This study included 381clinically Japanese Encephalitis(JE) suspected acute encephalitis patients’ samples from December 2016 through February 2017. The CSF samples received from both children and adults across the country were first tested for JE using JE IgM Capture Enzyme Linked Immunosorbent (ELISA) assay (NIV Pune). The positive samples for JE IgM were tested with the Anti Dengue Ig M capture ELISA (SD Korea) assay and to rule-out dengue, with the dengue real time typing PCR assay. Patients were diagnosed with dengue if they were positive for dengue RNA. Only detectable JE IgM was judged to have JE infection, while detectable JE IgM and dengue IgM, but not dengue RNA were identified as having Flavivirus infection. The clinico-epidemiological profiles sent along with the samples were analyzed on diagnosed cases. Results: A total of 381 CSF samples were tested and 23(6%) were positive for JE IgM. Of the JE positives, 08(35%) were positive for dengue IgM and only 04(17%) positive for dengue RNA. JE only was positive in 11(48%) patients. Dengue and JE serology both positive in 8(35%) while 4(17%) were confirmed with dengue RNA. All cases experienced fever. Altered consciousness and seizures observed in 91%(21/23) of patients. It was noted that 63%(7/11) of JE was reported from the Sabaragamuwa Province and young adults and elderly were affected most. Conclusion: JE and dengue were identified as contributing viral etiology for acute viral encephalitis. Even though dengue is not primarily neurotropic, the study convinced the importance of considering dengue encephalitis in appropriate situations. Findings appreciated common clinical profile of acute encephalitis to intervene timely. Data explained the geography of high JE activity and the most affected age group, to strengthen the preventive/control measures.