Background: Acute encephalitis syndrome (AES) is a significant public health issue in India, attributed to various etiologies. In eastern Uttar Pradesh, Japanese encephalitis (JE) was the leading cause of AES (10-14% of total AES) until scrub typhus (ST), caused by Orientia tsutsugamushi, was identified in cerebrospinal fluid and blood samples of AES patients contributing more than 60% of AES cases. This study investigates the prevalence of JE-ST coinfection and compares clinical outcomes among JE mono-infection, ST mono-infection, and JE-ST coinfection. Materials and

Methods: AES cases admitted to BRD Medical College, Gorakhpur, Uttar Pradesh, India, from January 1, 2017, to December 31, 2017, were included. JE and ST diagnosis was confirmed by serological (IgM) and molecular (PCR) tests. Statistical analysis was done to correlate clinical outcomes and infection group.

Results: Total 1180 cases were tested positive for JE and/or ST. The prevalence of JE-ST coinfection was 8.9% among AES cases. JE mono-infection showed a mortality rate of 34.5%, ST mono-infection 13.4%, and JE-ST coinfection 9.5%. JE-ST co-infected cases experienced less severe clinical outcomes compared to mono-infected cases.

Conclusion: JE-ST coinfection in AES cases is relatively common, with better clinical outcomes and lower mortality rates compared to JE or ST mono-infections.