Second Human Case of Cache Valley Virus Disease

We document the second known case of Cache Valley virus disease in a human.Cache Valley virus disease is rarely diagnosed in North America, in part because laboratories rarely test for it.Its true incidence, effect on public health, and full clinical spectrum remain to be determined.C ache Valley virus (CVV), a mosquitoborne member of the Bunyamwera serogroup, family Bunyaviridae, genus Orthobunyavirus, is geographically widespread in North America, where it circulates between mosquitoes and mammals (1).It has previously been associated with only a single case of human disease, a fatal case of acute encephalitis in the southeastern United States (2).We describe the second documented human case of CVV disease. Case ReportIn late October 2003, a 41-year-old, generally healthy Wisconsin man, who lived near a landfill in the suburbs of a small city on the Lake Michigan shore, became acutely ill with severe headache, nausea, vomiting, and fatigue.The next day, he was hospitalized with a diagnosis of acute aseptic meningitis.On admission, his body temperature was 38.4°C (101.1°F);no neck stiffness, rash, or focal neurologic abnormalities were detected.Computerized tomographic and magnetic resonance imaging scans of the brain were normal.The peripheral leukocyte count was 13,900/mm 3 , with 87% neutrophils and 7% lymphocytes.Cerebrospinal fluid (CSF) examination showed 865 leukocytes/mm 3 , with 73% lymphocytes, 15% monocytes, 12% neutrophils, and no erythrocytes; a protein concentration of 105 mg/dL, (normal 15-45 mg/dL); a glucose concentration of 47 mg/dL (normal 50-80 mg/dL); negative Gram