Powassan virus: an arbovirus (arthropod-borne) virus that is transmitted to humans through infected ticks. Person-to-person transmission does not occur. The infection is rare, with 60 cases reported in the U.S. over the past 10 years. Most U.S. cases have occurred in the Northeast and Great Lakes areas. Severe infection can lead to encephalitis (inflammation of the brain), requiring hospitalization. Signs and symptoms of Powassan infection can include fever, headache, vomiting, weakness, confusion, seizures, and memory loss. Long-term neurologic problems can develop after infection. There is no specific treatment available. Prevention of infection involves taking precautions to avoid exposure to ticks and tick bites.
United States. Centers for Disease Control and Prevention. "Powassan Virus." Feb. 9, 2015. <http://www.cdc.gov/powassan/>.