Arboviral Encephalitis

Arboviruses can produce a spectrum from clinically inapparent infection or nonspecific febrile illness to meningitis, encephalitis, and death. Neuroinvasive disease should enter the differential for acute febrile neurologic illness during vector season, after relevant mosquito or tick exposure, in an area with known circulation, or after travel to an endemic region. CDC+1CDCGuidelines for West Nile Virus Surveillance and Control | West Nile Virus | CDCCDCArboviral Diseases, Neuroinvasive and Non-neuroinvasive 2014 Case Definition | CDC

In the United States, West Nile virus is the most commonly diagnosed arboviral disease and a leading consideration in seasonal neuroinvasive illness; however, regional alternatives matter. California serogroup viruses, including La Crosse virus, are important causes of pediatric arboviral encephalitis, particularly in Midwest and Appalachian regions. CDC+1CDCNeutralizing Antibodies against California Serogroup Orthobunyaviruses in Human Serum Samples, Montana, USA - Volume 31, Number 4—April 2025 - Emerging Infectious Diseases journal - CDCCDCUse of Testing for West Nile Virus and Other Arboviruses - Volume 22, Number 9—September 2016 - Emerging Infectious Diseases journal - CDC

Do not anchor on arbovirus. The differential for arboviral CNS disease includes other viral, bacterial, mycoplasmal, protozoal, fungal, toxic, metabolic, and postinfectious conditions. Parallel evaluation for alternative, potentially treatable etiologies is necessary. CDCCDCGuidelines for West Nile Virus Surveillance and Control | West Nile Virus | CDC

Patients can deteriorate rapidly from impaired consciousness, seizures, autonomic dysfunction, cerebral edema, or respiratory failure. ICU admission is appropriate when airway protection, ventilatory support, circulatory support, or close neurologic monitoring is required. NEJM+2NEJMEastern Equine Encephalitis Virus — Another Emergent ...ScienceDirectIntensive care management of patients with viral encephalitisScienceDirectAllergic Encephalitis - an overview

Start acyclovir in all patients with suspected encephalitis while diagnostic studies are pending. This recommendation is directed at empiric coverage of herpes simplex virus and should not be interpreted as evidence of activity against arboviruses. Oxford AcademicOxford AcademicManagement of Encephalitis: Clinical Practice Guidelines by ...

Once arboviral encephalitis is the working diagnosis, treatment is supportive. The supplied evidence does not establish a specific antiviral, immunotherapy, or corticosteroid regimen that improves arboviral encephalitis outcomes. NEJM+2NEJMEastern Equine Encephalitis Virus — Another Emergent ...ScienceDirectLa Crosse Encephalitis - an overviewCDCNeutralizing Antibodies against California Serogroup Orthobunyaviruses in Human Serum Samples, Montana, USA - Volume 31, Number 4—April 2025 - Emerging Infectious Diseases journal - CDC

Definitive arboviral diagnosis requires laboratory testing with specific reagents. Test selection should account for age, immune status, vaccination history, timing of infection, pathogens in the differential, and the capabilities of initial and confirmatory laboratories. CDCCDCGuidelines for West Nile Virus Surveillance and Control | West Nile Virus | CDC

Send serum and CSF as appropriate for arboviral testing and involve the hospital laboratory, state health department, or public health laboratory early when a neuroinvasive arboviral syndrome is suspected. Specimens submitted for West Nile virus testing should also be assessed for other arboviruses known to be active or present in the relevant area or travel region. CDCCDCGuidelines for West Nile Virus Surveillance and Control | West Nile Virus | CDC

Flavivirus serology has a major interpretive limitation: IgM and IgG assays may cross-react among West Nile, St. Louis encephalitis, dengue, yellow fever, Powassan, and other flaviviruses. Treat initial flavivirus antibody results as screening results and pursue plaque-reduction neutralization testing for species differentiation when confirmation is clinically or epidemiologically important. CDCCDCGuidelines for West Nile Virus Surveillance and Control | West Nile Virus | CDC

B-cell depletion changes both risk and diagnostic reasoning. CDC describes severe neuroinvasive arboviral disease among patients receiving rituximab and related agents, with a reported case-series mortality of 4 of 5 patients diagnosed with arboviral neuroinvasive disease; survivors often had long-term cognitive or motor disability. A negative or delayed antibody response may be a concern in this population, warranting early specialist and public-health laboratory coordination. CDC+1CDCClinical Guidance for Vector-Borne Viral Diseases in People Who Are Immunocompromised | Vector-Borne Diseases | CDCCDCSevere Arboviral Neuroinvasive Disease in Patients on Rituximab Therapy: A Review

Timely diagnosis and reporting can clarify exposure source, prevent unnecessary antimicrobial treatment, and allow public health authorities to detect and respond to additional cases. CDCCDCClinical Guidance for Vector-Borne Viral Diseases in People Who Are Immunocompromised | Vector-Borne Diseases | CDC

Counsel patients, particularly those who are immunocompromised, on seasonal and geographic risk and on personal measures to prevent mosquito and tick bites. CDCCDCClinical Guidance for Vector-Borne Viral Diseases in People Who Are Immunocompromised | Vector-Borne Diseases | CDC There is no routine human vaccine strategy for the major endemic U.S. arboviral encephalitides described in the supplied sources; prevention therefore relies primarily on vector-exposure reduction and public-health surveillance.