Powassan Virus Cases Reach Record High in US as Tick-Borne Diseases Spread

Powassan virus infections have reached a record high in the United States, with 76 confirmed cases in 2025 compared to a historical annual average of seven to eight. Transmitted by infected ticks in as little as 15 minutes, the virus can cause severe neurological complications like encephalitis and meningitis. Approximately 10% to 15% of symptomatic cases are fatal, and half of survivors suffer long-term neurological issues. With no vaccine or specific antiviral treatment available, medical care is limited to supportive therapy, making tick bite prevention and prompt removal critical.

Powassan virus transmission characteristics

• ▪Powassan virus is primarily transmitted to humans through the bites of infected deer ticks, woodchuck ticks, groundhog ticks, or squirrel ticks
• ▪Powassan virus can transmit to humans in as little as 15 minutes after an infected tick bites, whereas Lyme disease generally requires 16 to 48 hours of attachment

Geographic spread patterns

• ▪Powassan virus cases in the United States are primarily recognized and reported in the Northeast and Great Lakes regions
• ▪The United States recorded 76 confirmed cases of Powassan virus in 2025, which is the highest annual total on record compared to a historical average of seven to eight cases annually
• ▪As of June 16, 2026, the Centers for Disease Control and Prevention recorded 15 preliminary Powassan virus cases across five states, including Massachusetts, New York, Wisconsin, Maine, and Rhode Island

Neurological complications

• ▪Approximately 10% to 15% of Powassan virus cases that involve severe neurological disease are fatal
• ▪Severe Powassan virus infections can cause encephalitis or meningitis, leading to symptoms such as confusion, slurred speech, loss of coordination, seizures, or paralysis
• ▪About half of Powassan virus survivors of severe infections experience long-term neurological complications, including memory loss, muscle weakness, and difficulties with speech, walking, or eating

Diagnostic testing limitations

• ▪Powassan virus testing is not widely available at standard medical laboratories, which can cause delays in confirming a diagnosis
• ▪Definitive diagnosis of Powassan virus typically requires blood or spinal fluid testing for specific antibodies, which is often performed at specialized laboratories

Supportive care approaches

• ▪Clinical care for Powassan virus is limited to supportive therapy, such as intravenous fluids, respiratory support, and sometimes steroids to reduce brain inflammation
• ▪There are currently no specific antiviral medications or vaccines available to treat or prevent Powassan virus infection

Tick bite prevention strategies

• ▪Running outdoor clothing in a hot dryer for 10 minutes after returning indoors is recommended to kill any hitchhiking ticks
• ▪Health officials recommend preventing tick bites by wearing long sleeves and pants, tucking pants into socks, using EPA-registered insect repellents, and performing full-body tick checks