Nipah Virus Encephalitis and the Medico Legal Brain: Neuropathology, Neurobehavioural Sequelae, Capacity, and One Health Forensics

Abstract

Background: Nipah virus encephalitis is a highly lethal zoonotic infection capable of producing acute cerebral dysfunction, delayed neurological disease, and persistent neurobehavioural impairment; however, its implications for legal capacity, forensic pathology, and One Health investigation remain poorly integrated.A scoping review was conducted according to JBI methodology and reported it in accordance with PRISMA ScR. MEDLINE, Embase, Scopus, Web of Science, APA PsycINFO, CINAHL, Global Health, CAB Abstracts, WHO Global Index Medicus, the Cochrane Library, and relevant grey literature sources were searched from inception through July 2026. Of 624 records identified, 146 duplicates were removed, 478 titles and abstracts were screened, 77 full texts were assessed, and 15 primary studies were included. Methodological quality was evaluated with design specific JBI instruments, the SYRCLE tool for animal studies, and AMSTAR 2 for systematic reviews. The evidence showed that Nipah virus encephalitis involves a combined neurovascular and neurotropic process characterized by endothelial infection, necrotizing vasculitis, thrombosis, microinfarction, parenchymal necrosis, and direct neuronal involvement. Acute disease was associated with altered consciousness, seizures, focal deficits, brainstem dysfunction, and high mortality. Survivors exhibited persistent fatigue, memory and attentional deficits, depression, personality change, behavioural disturbance, impaired mobility, and reduced functional independence; relapsed or late onset encephalitis was documented after apparent recovery. Outbreak investigations further demonstrated occupational, household, caregiving, and health care associated transmission, emphasizing the forensic importance of exposure reconstruction, molecular confirmation, infection control, and evidentiary continuity. No included study directly assessed decisional, testamentary, financial, or criminal capacity. The evidence was limited by small and overlapping cohorts, retrospective designs, inconsistent neuropsychological assessment, incomplete premorbid data, and sparse lesion specific behavioural correlation. Nipah virus may injure neural systems governing memory, judgement, behaviour, and autonomy; nevertheless, neuropathology establishes a biological substrate, not a legal conclusion. Medico legal attribution must remain individual, time specific, function specific, and supported by convergent clinical, cognitive, imaging, pathological, and collateral evidence.