Snapshot A 67-year-old male presented to the ED this past summer with a three day history of fever, chills, lower limb weakness, and increasing confusion. His spouse reports that two weeks ago the patient had gone hiking in upstate New York. He is a known hypertensive diabetic. Temperature is 102.9°F (39.4°C), BP is 140/90 mmHg, and pulse is 90/min. Physical exam reveals the patient is disoriented and has bilateral lower limb weakness. CSF analysis reveals a pleocytosis with 81% neutrophils, protein 68 mg/dL, glucose 63 mg/dL, and negative Gram stain. Blood and CSF cultures are negative. CT scan of the head was normal. Patient was admitted and treated empirically for both bacterial and viral meningitis. CSF IgM for WNV was initially negative, but a repeat test was carried out on day seven of admission. Introduction Classification linear, enveloped, icosahedral (+) ssRNA flavivirus West Nile virus (WNV) Arthopod borne virus that causes a severe encephalitis, meningitis, or meningoencephalitis mosquitos are the prime vector birds are the prime reservoir host approximately 80% of WNV infections are subclinical and asymptomatic < 1 % affect the CNS Epidemiology incidence first case in the US was in 1999 in NYC in 2012, WNV killed 286 people in the US risk factors suppressed immune system history of organ transplantation > 50 years of age male HTN DM mutated CCR5 gene (protects against HIV infection) location found in temperate and tropical regions Transmission via female mosquitos (only females feed on blood) to birds the virus amplifies in the bird and then are transmited to other biting mosquitos mosquitos innoculate their saliva into the skin while feeding once in a human, the virus can be transmitted by blood transfusions organ transplants intrauterine exposure breast feeding Presentation History places and dates of recent travel (possible endemic areas) recent "bug bites" Symptoms incubation period of 2-15 days headache fever meningitis encephalitis meningoencephalitis Evaluation Labs CSF clear increased protein reference glucose levels lymphocytic pleocytosis particularly neutrophilia no RBCs Definitive diagnosis virus specific IgM and neutralizing antibodies ELISA WNV IgM kits Differential Etiology of bacterial meningitis viral meningitis viral encephalitis Treatment Supportive care no specific treatments have been developed for WNV infections hospitalization IVF respiratory support prevention of secondary infections Prognosis, Prevention, and Complications Prognosis worse in neuroinvasive disease older patients immunosuppression organ transplant Prevention no available vaccines vector control insect repellant protective clothing report dead birds to local authorities Complications persistent symptoms can last for years fatigue memory problems weakness in extremities depression