Western Equine Encephalitis

Excerpt

Western Equine encephalitis is one of many mosquito-transmitted viral infections that may progress to acute inflammation of the brain parenchyma and meninges. It is caused by an Alphavirus, which is spread primarily by the bite of the Culex and Aedes species of mosquito, or possibly by small, wild mammals. Birds are a reservoir but not a primary vector for the virus. Infections most frequently occur in the summertime in the western United States. Most infections are subclinical but may present with a nonspecific viral syndrome consisting of fever, chills, malaise, and myalgias. While most patients recover spontaneously, some will progress to develop encephalitis. The neuroinvasive disease presents with confusion, somnolence, coma, and occasionally, death. Infants are affected more commonly than adults. Older adults, infants, and young children are more likely to develop severe disease with neurologic involvement. Most patients with mild neurologic symptoms will recover, and adults tend to have a better prognosis than children who are more likely to develop persistent seizures, cognitive and behavioral impairment, and spasticity.