Recent advances in flavivirus encephalitis.

PURPOSE OF REVIEW: Flaviviruses are an increasing public health concern, responsible for a broad spectrum of human disease ranging from asymptomatic or mild febrile illness to severe neuroinvasive infections such as encephalitis. Flavivirus encephalitis is associated with substantial mortality and long-term neurological sequelae, yet no specific antiviral therapy is currently available. Diagnosis remains challenging because of transient viremia and serological cross-reactivity, and preventive strategies are unevenly implemented. This review summarizes recent advances in the diagnosis, prognostic assessment, treatment, and prevention of flavivirus-associated encephalitis.

RECENT FINDINGS: Recent studies have reshaped diagnostic strategies through improved viral detection, including multimatrix molecular testing and metagenomic approaches, alongside better characterization of host-response markers in cerebrospinal fluid. Recent work has substantially refined understanding of host susceptibility, highlighting preexisting antitype I interferon autoantibodies as a major driver of severe disease across neurotropic flaviviruses, and identifying several biomarkers with potential prognostic value. Neuroimaging work has refined MRI pattern recognition across flaviviral encephalitis, with limited but evolving prognostic implications. While management remains largely supportive, the therapeutic pipeline is increasingly diverse, with growing interest in host-directed strategies.

SUMMARY: Flavivirus encephalitis represents a major clinical challenge driven by host vulnerability, diagnostic complexity, and the absence of validated therapies. Integrating recent advances in diagnostics, risk stratification, and prevention is essential, while ongoing therapeutic development offers cautious optimism for future management.