Viral meningoencephalitis: a focus on diagnostics.

PURPOSE OF REVIEW: This review provides an updated overview of diagnostic strategies for viral meningoencephalitis, with a focus on molecular techniques currently used in clinical practice and the emerging role of next-generation sequencing technologies.

RECENT FINDINGS: The clinical and laboratory presentation of viral meningoencephalitis is often nonspecific, making timely and accurate diagnosis challenging. While PCR and multiplex RT-PCR assays have become widely used, they have notable limitations, including reduced sensitivity in low-viral-load cases and the requirement for prior pathogen suspicion. Newer platforms like QIAstat-Dx allow interpretation through cycle threshold values, but false positives and false negatives remain concerns. mNGS offers a hypothesis-free approach with improved diagnostic yield - especially in immunocompromised hosts and atypical presentations - and has proven valuable for detecting rare, emerging, or unexpected pathogens. However, practical limitations such as cost, long turnaround times, and the need for expert interpretation currently restrict its routine use.

SUMMARY: The integration of mNGS into routine diagnostic workflows could significantly improve the diagnostic yield for viral meningoencephalitis, especially in cases with negative or inconclusive results from traditional methods. However, further studies are necessary to refine its clinical application, optimize cost-effectiveness, and establish guidelines for its use in the diagnostic management of meningoencephalitis.