Detection of encephalitis-causing viruses reveals predominance of chikungunya virus in the state of Bahia, Brazil

Objectives: Encephalitis is a severe neurological syndrome for which herpesvirus and enteroviruses are the most common etiological agents. Arboviruses, a wildly diverse group of pathogens, are also critical epidemiological agents associated with encephalitis. In Brazil, little is known about the causative agents of encephalitis. Methods: We conducted a hospital surveillance for encephalitis between 2020 and 2022. Molecular (RTPCR and qPCR) and serological (virus-specific IgM and viral antigens) techniques were performed in cerebrospinal fluid and serum samples obtained from study participants. Results: In the 43 participants evaluated, the etiologic agent or the presence of IgM was detected in 16 (37.2%). Nine (20.9%) cases were positive for chikungunya virus (CHIKV), three (7.0%) for dengue virus, two (4.7%) for human adenovirus, one (2.3%) for varicella-zoster virus, and one (2.3%) for enterovirus. Whole-genome sequencing revealed that the CHIKV identified belongs to the East/Central/South African lineage. Conclusion: Herein, CHIKV is a common pathogen identified in encephalitis cases. Our results reinforce previous evidence that chikungunya represents a significant cause of encephalitis during CHIKV outbreaks and epidemics and add to existing information on the epidemiology of encephalitis in Brazil. (c) 2024 Published by Elsevier Ltd on behalf of International Society for Infectious Diseases. This is an open access article under the CC BY-NC-ND IGO license ( http://creativecommons.org/licenses/by-nc-nd/3.0/igo/ )