Severe La Crosse meningoencephalitis in children: report of two cases

La Crosse virus is an arbovirus of the California Serogroup (Family Bunyaviridae), transmitted by the "tree-hole mosquito," Aedes triseriatus. La Crosse encephalitis cases occur annually from July to October. The majority of cases are asymptomatic, only a minority (< 4%) present with symptomatic disease. The aim of this study is to analyze the clinical manifestations of two cases with severe La Crosse meningoencephalitis. The first case was a 12-year-old male, who presented with meningoencephalitis, which was complicated by personality changes, stroke, aphasia and convulsions. The second one was a 5-year-old male, whose meningoencephalitis was complicated by recurrent seizures. Both had history of mosquito bites. Cerebrospinal fluid revealed pleocytosis with predominant polymorphonuclear leukocytes. In the first case, brain computed tomography scan and brain magnetic resonance imaging showed focal, right-sided frontal and temporal lobes cerebritis; they were normal in the second case. Electroencephalogram showed focal slowing in the first case and diffuse pattern in the second. Both had positive serology (immunoglobulin M) for La Crosse virus. Both recovered completely.