Statistics & Maps
Human Powassan virus infections have been recognized in the United States, Canada, and Russia. In the United States, cases of Powassan virus disease (Powassan) have been reported primarily from northeastern states and the Great Lakes region. These cases occur primarily in the late spring, early summer, and mid-fall when ticks are most active.
Powassan cases are rare but the reported number of cases have increased in recent All residents of and visitors to areas where Powassan virus activity has been identified are at risk of infection. People who engage in outdoor work and recreational activities in endemic areas are at increased risk of infection.
Powassan is a nationally notifiable condition. To ensure standardization of reporting across the country, CDC recommends that the national surveillance case definition be consistently applied by all state health departments.
Source: ArboNET, Arboviral Diseases Branch, Centers for Disease Control and Prevention
Source: ArboNET, Arboviral Diseases Branch, Centers for Disease Control and Prevention
Source: ArboNET, Arboviral Diseases Branch, Centers for Disease Control and Prevention
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This map shows the distribution of Powassan virus neuroinvasive disease (encephalitis and/or meningitis) average annual incidence by county of residence from 2010 through 2019. Counties are shaded according to incidences ranging from less than 0.20, 0.20 to 0.49, and greater than 0.50 per 100,000 population. Shaded counties are primarily in Minnesota, Wisconsin, and New England states. Top of Page
Additional Maps, Charts, and Tables
Powassan virus disease cases and deaths reported to CDC by year and clinical presentation, 2010-2019
| Neuroinvasive disease | Non-neuroinvasive disease | Total | ||||
|---|---|---|---|---|---|---|
| Year | Cases No. |
Deaths No. (%) |
Cases No. |
Deaths No. (%) |
Cases No. |
Deaths No. (%) |
| 2010 | 8 | 0 (0) | 0 | 0 (0) | 8 | 0 (0) |
| 2011 | 12 | 1 (8) | 4 | 0 (0) | 16 | 1 (6) |
| 2012 | 7 | 0 (0) | 0 | 0 (0) | 7 | 0 (0) |
| 2013 | 12 | 2 (17) | 3 | 0 (0) | 15 | 2 (13) |
| 2014 | 7 | 0 (0) | 1 | 0 (0) | 8 | 0 (0) |
| 2015 | 6 | 1 (17) | 1 | 0 (0) | 7 | 1 (14) |
| 2016 | 21 | 3 (14) | 1 | 0 (0) | 22 | 3 (14) |
| 2017 | 33 | 2 (6) | 1 | 0 (0) | 34 | 2 (6) |
| 2018 | 21 | 3 (14) | 0 | 0 (0) | 21 | 3 (14) |
| 2019 | 39 | 9 (23) | 4 | 0 (0) | 43 | 9 (21) |
| Total | 166 | 21 (12) | 15 | 0 (0) | 181 | 21 (11) |
Source: ArboNET, Arboviral Diseases Branch, Centers for Disease Control and Prevention
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Powassan virus disease cases reported to CDC by state of residence, 2010–2019
| State | 2010 | 2011 | 2012 | 2013 | 2014 | 2015 | 2016 | 2017 | 2018 | 2019 | Total |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Alabama | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Alaska | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Arizona | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Arkansas | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| California | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Colorado | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Connecticut | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 2 | 5 | 8 |
| Delaware | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Dist. of Columbia | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Florida | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Georgia | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Hawaii | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Idaho | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Illinois | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Indiana | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 1 |
| Iowa | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Kansas | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Kentucky | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Louisiana | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Maine | 0 | 0 | 0 | 1 | 0 | 1 | 1 | 3 | 0 | 2 | 8 |
| Maryland | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Massachusetts | 0 | 0 | 0 | 1 | 4 | 3 | 5 | 3 | 6 | 9 | 31 |
| Michigan | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Minnesota | 3 | 11 | 4 | 1 | 0 | 0 | 5 | 7 | 3 | 7 | 41 |
| Mississippi | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Missouri | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Montana | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Nebraska | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Nevada | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| New Hampshire | 0 | 0 | 0 | 1 | 0 | 0 | 1 | 1 | 0 | 2 | 5 |
| New Jersey | 0 | 0 | 0 | 1 | 1 | 1 | 0 | 4 | 1 | 4 | 12 |
| New Mexico | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| New York | 1 | 0 | 1 | 5 | 1 | 1 | 2 | 6 | 4 | 5 | 26 |
| North Carolina | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 1 |
| North Dakota | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 2 |
| Ohio | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Oklahoma | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Oregon | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Pennsylvania | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 4 | 1 | 0 | 6 |
| Puerto Rico | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Rhode Island | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 2 | 0 | 1 | 4 |
| South Carolina | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| South Dakota | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Tennessee | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Texas | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Utah | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Vermont | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Virginia | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Washington | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| West Virginia | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Wisconsin | 4 | 4 | 2 | 5 | 2 | 1 | 5 | 3 | 3 | 7 | 36 |
| Wyoming | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Total | 8 | 16 | 7 | 15 | 8 | 7 | 22 | 34 | 21 | 43 | 181 |
Source: ArboNET, Arboviral Diseases Branch, Centers for Disease Control and Prevention
To request data for previous years, please email dvbid2@cdc.gov.