Diagnosis is made by isolation of the virus in serum or throat culture. CSF shows a pleocytosis. Viremia is typically absent in patients with encephalitis. Preventative and postexposure treatments are limited. Vaccines that have been shown to have some protective efficacy [75] are available for laboratory personnel at high risk of exposure. Pegylated interferon-α (IFN-α) improves survival in mice [76] , but data for humans are not available.