Mondo Description La Crosse encephalitis (CE) is an acute arboviral infection caused by the La Crosse bunyavirus transmitted by an infected mosquito, usually observed in infants, children or adolescents (6 months to 16 years), and characterized by the onset of flulike symptoms such as fever, chills, nausea, vomiting, headache, and abdominal pain, followed by the onset of encephalitis characterized by somnolence, obtundation, and even seizures, focal neurologic signs (asymmetrical reflexes or Babinski signs), paralysis or even coma. CE can leave sequelae such as residual epilepsy and neurocognitive deficits.