Powassan virus infection causes polio-like illness


Evidence of a Powassan virus infection affecting the spinal cord has, until now, only been seen in mouse studies. But a new article describes the first known case of a 62-year-old man from Canada who developed a polio-like illness caused by the Powassan virus (POWV).

While vacationing in rural Newfoundland, the man developed nausea, vomiting, abdominal pain, double vision (diplopia) and impaired coordination (ataxia). He was admitted to a hospital where his symptoms worsened. The man became febrile and experienced slurred and slow speech (dysarthria), weakness, and respiratory distress.

“Cerebrospinal fluid analysis showed pleocytosis (159 × 106 total nucleated cells: 42% neutrophils, 43% lymphocytes) and elevated protein levels (0.79 g/L),” states Picheca and colleagues, from the University of Ottawa in Ontario, Canada. [1]

The man was empirically treated with ceftriaxone, ampicillin, acyclovir, and dexamethasone.

[bctt tweet=”The first case reported of the tick-transmitted Powassan virus causing polio-like illness.” username=”DrDanielCameron”]

Test results for Lyme disease and arthropod-borne viruses, which included the Powassan virus, were negative.

“The patient worsened, requiring intubation and transfer to an intensive care unit,” the authors write. “He had flaccid tone and absent power in his upper extremities and reduced strength in his lower extremities.”

Re-testing one month after symptom onset revealed an infection with the Powassan virus.

Electrodiagnostic (or EMG) testing 6 months after symptom onset revealed “diffuse denervation in all cervical myotomes including the paraspinal muscles, confirming a motor neuronopathy consistent with a poliomyelitis-like presentation of POWV,” the authors write.

Initial testing was performed too early, Picheca explains, “because paired serology 4 weeks later demonstrated seroconversion and confirmed diagnosis.”

“Our findings emphasize the need to include POWV infection in the differential diagnosis for patients with polio-like symptoms in tick-endemic regions.”

  1. Picheca C, Yogendrakumar V, Brooks JI, Torres C, Pringle E, Zwicker J. Polio-like manifestation of Powassan virus infection with anterior horn cell involvement, Canada. Emerg Infect Dis. 2019 Aug [date cited]. https://doi.org/10.3201/eid2508.190399.

4 Replies to "Powassan virus infection causes polio-like illness"

  • Shay Castro
    07/11/2019 (12:21 am)

    Where can i get a test for powassan virus?

    • Dr. Daniel Cameron
      07/11/2019 (12:40 am)

      There are a growing number of tests for the Powassan virus. I am not sure how reliable the various tests are.

      • Patti-Lou Fowlow
        08/03/2022 (10:32 pm)

        Hello Dr Cameron,

        The patient you are referring to is my husband, it’s the first time I see it. My husband has made great progress, but still does not have the functuality of his arms. His vision is impaired and he still can’t hold his head up totally. He has recovered strength in his legs and is able to walk on his own . Thought you might be interested in knowing.



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