Powassan Virus: Reporting and Surveillance

Powassan virus is a category II reportable condition in Wisconsin. Health care providers should report to the patient's local public health department:
  • Electronically, through the Wisconsin Electronic Disease Surveillance System (WEDSS).
  • By calling the Bureau of Communicable Diseases at 608-267-9003.

Reporting should be completed within 72 hours upon recognition of a case. For more information, please visit the DHS Disease Reporting page.

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 Guidance resources

DHS surveillance resources
Provider resources

Powassan Virus Information for Healthcare Providers: Information on clinical and laboratory evaluations, and diagnostic testing for Powassan virus from the Centers for Disease Control and Prevention (CDC).


Laboratory diagnosis of Powassan virus most often involves the detection of antibodies against Powassan virus in serum or cerebrospinal fluid (CSF). Diagnostic testing for Powassan virus is not widely available at commercial laboratories, but an arbovirus IgM antibody panel can be requested through the Wisconsin State Laboratory of Hygiene (WSLH) and includes testing for West Nile, St. Louis encephalitis, Jamestown Canyon, La Crosse encephalitis, eastern equine encephalitis, and Powassan viruses. If Powassan virus infection is suspected, concurrent testing for other domestic arboviruses should be considered, since clinical features of these viruses overlap.

The WSLH arbovirus IgM antibody panel screens for evidence of infection through IgM antibody capture enzyme-linked immunosorbent assay (MAC-ELISA) or microsphere immunoassay (MIA) performed on serum or CSF. The WSLH will forward specimens with positive IgM results to CDC for confirmatory testing by plaque reduction neutralization test (PRNT).

The arbovirus IgM antibody panel is available at the WSLH both fee-exempt and fee-for-service. It is not required for patients’ symptoms to meet the Division of Public Health (DPH) clinical criteria to submit serum or CSF specimens to the WSLH for fee-for-service arboviral screening.


DPH continues to monitor for Powassan virus as part of our enhanced arbovirus surveillance. Testing for Powassan virus as part of a DHS investigation may be fee-exempt. Please contact a vectorborne disease epidemiologist at 608-267-9003 for fee-exempt approval.

Fee-exempt arboviral testing will be considered for patients who meet ONE of the following criteria:

  • Positive IgM and/or IgG commercial test results (performed as laboratories other than the WSLH).
  • The patient has signs and symptoms of meningitis (fever, headache, nuchal rigidity) or encephalitis (fever, headache, altered mental status ranging from confusion to coma), or acute flaccid paralysis (AFP) with no other laboratory diagnosis.
  • The patient has a diagnosis of Guillain-Barré syndrome and no other laboratory diagnosis.
  • The patient lacks insurance coverage or the ability to pay for testing, but meets the DPH arboviral disease clinical criteria.

Instructions for collection and shipping of clinical specimens to the WSLH:

  • Collect specimens between three days and 12 weeks after symptom onset for reliable antibody detection. Samples collected less than eight days after illness onset may not demonstrate IgM reactivity due to the time required for the development of an antibody response, and a convalescent sample may be indicated.
  • Submit 3-7 mL of serum and/or >1 mL of CSF in sterile screw-capped vials on cold packs using a WSLH kit #22 or equivalent with five days of collection. It is recommended that a paired serum specimen be submitted with a CSF specimen. Specimens should be triple packaged as a Category B Biological Substance (include UN3373 label).
  • Fee-exempt testing submissions must include a WSLH Enhanced Wisconsin Arbovirus Surveillance form provided by a DPH vectorborne disease epidemiologist.
  • Fee-for-service testing submissions must include a WSLH CDD Requisition Form B. Please contact the WSLH Clinical Orders at 800-862-1088 or 608-224-4275 to obtain blank copies of WSLH CDD Requisition Form B and to order specimen shipping kits.
  • It is essential that the lab requisition form be as complete as possible, including patient name, city, date of birth, specimen type, submitting agency, onset date, signs and symptoms, and collection date. Note: Testing for Powassan virus may be delayed on specimens missing the above data until information is available.
  • Ships specimens with appropriate completed form to:

Wisconsin State Laboratory of Hygiene
2601 Agriculture Drive, PO Box 7904
Madison, WI 53718
Customer Service: 800-862-1013


Clinical diagnosis of Powassan virus can be difficult since many of the signs and symptoms of Powassan virus are very similar to other viral infections. A patient's clinical signs and symptoms, travel history, and risk activities can help to inform a preliminary diagnosis prior to laboratory diagnosis.


There is currently no treatment or vaccine for Powassan virus. Over-the-counter pain relievers may be given to relieve symptoms. In severe cases, patients may need to be hospitalized to receive supportive treatment. For more information, visit the CDC Powassan Virus Symptoms and Treatment page.

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Last Revised: October 26, 2021