Powassan Virus


The transmission of Powassan virus — unlike many other tick-borne microbes — can occur very quickly, as soon as 15 minutes after tick attachment. Powassan virus has been found in one to two percent of Ixodes scapularis ticks in specific regions of the upper mid-west and northeastern U.S. Given that so few patients in the United States are known to develop Powassan Virus Disease (7-8 cases/year), it is assumed that most people who get infected after a tick bite create natural antibodies that neutralize the infection and do not even know they were infected.

Signs and Symptoms

Symptoms may include fever, vomiting, muscle weakness, headaches, confusion, lack of coordination, speech problems, memory problems, and seizures. When the infection spreads to the central nervous system, meningitis or encephalitis with seizures may occur. When Powassan virus affects the nervous system, it can be fatal (ten percent of patients). Among those who survive neurologic infection, persistent symptoms such as muscle wasting, chronic headaches, and memory problems may occur.


Tests are available in state labs that identify antibodies in the blood and/or cerebrospinal fluid.