Snapshot A 34-year-old man presents to a local urgent care after returning from a trip to Africa. He has endured multiple mosquito bites throughout his 2-week safari trip. He states that, like several members of his tour group, he has had a 3-day history of fever, non-itchy rash, and myalgias. One tour group member, however, developed seizures and confusion. This patient is scared that he may also develop severe symptoms like seizures. On physical exam, he has conjunctival injection and a papular rash on his trunk and legs. Given his age and current symptoms, his physician reassures him that it is highly unlikely but to watch out for any signs of meningoencephalitis. Introduction Classification West Nile virus an enveloped positive single-stranded RNA flavivirus transmission Culex mosquitoes Epidemiology demographics more severe in the elderly more common in the young risk factors mosquito bites Pathogenesis mosquito’s saliva transmits the virus to human blood virus then replicates in dendritic cells and spreads via lymphatics and bloodstream in some patients, the virus can invade the central nervous system and cause meningoencephalitis paralysis occurs when neurons are damaged in the anterior horn of the spinal cord Associated conditions West Nile fever meningoencephalitis Prognosis most infections are asymptomatic when symptomatic, the disease may progress to meningitis or encephalitis in < 1% of those infected Presentation Symptoms West Nile fever headache myalgias nausea and vomiting may develop a rash meningoencephalitis confusion coma acute headache photophobia nausea and vomiting Physical exam West Nile fever non-pruritic papular rash on trunk and extremities lymphadenopathy conjunctivitis meningoencephalitis acute flaccid paralysis myoclonus cerebellar ataxia seizures sensory is intact Imaging Magnetic resonance imaging (MRI) indication meningoencephalitis findings increased signal intensity in affected areas Studies Labs immunoglobulin M (IgM) enzyme-linked immunosorbent assay serum cerebrospinal fluid cerebrospinal fluid normal glucose ↑ or normal protein ↑ lymphocytes Making the diagnosis based on clinical presentation and laboratory studies Differential Dengue fever distinguishing factor characterized by mucosal bleeding, hemorrhage, and abdominal pain Treatment Management approach mainstay is supportive care Conservative supportive care indication all patients modalities fluids pain management mechanical ventilation Complications Rhabdomyolysis Guillain-Barré syndrome