Powassan virus (POWV), discovered in Powassan, Ontario, has appeared in America mostly in the Great Lakes and Northeast regions. The CDC reports only 50 cases in the past decade, but it is important to note that these are only reported cases, so there is almost certainly a significant, yet unknown number of other cases that have gone undiagnosed or misdiagnosed.

POWV is of the genus Flavivirus, and symptoms include fever, weakness, vomiting, headache, seizures, confusion, swelling of the brain, and memory loss. Unlike many tick-borne infections, this is a virus and therefore does not respond to antibiotics. As of now, treatment includes supporting the patient and relieving symptoms.