There are currently no medications or approved vaccines to treat or prevent the POWV. People affected by "Powassan virus" generally first show symptoms 1 to 3 weeks after infection. The initial symptoms include fever, headache, nausea, occasional confusion, and weakness. With severe Powassan illnesses the victims should be hospitalized, because the symptoms do worsen. If not treated, symptoms could extend to meningoencephalitis, which may include: seizures, aphasia, cranial nerve palsies, paresis and altered mental status. Currently, the best ways to treat POWV illnesses include medications to reduce brain swelling, respiratory support and intravenous fluids. About 10% of POWV encephalitis cases are fatal and half the survivors have permanent symptoms that affect their brain. There were 33 confirmed cases of "Powassan virus" infection in the U.S. between 2001 and 2010.