Powassan Virus Causes Polio-Like Illness in Adult Patient
Powassan virus can cause severe neurologic disease
A Canadian patient developed a rare polio-like illness
Repeat testing was required to confirm the diagnosis
While vacationing in rural Newfoundland, a man developed nausea, vomiting, abdominal pain, double vision (diplopia), and impaired coordination (ataxia). He was admitted to a hospital where his symptoms worsened. The patient became febrile and experienced slurred speech (dysarthria), weakness, and respiratory distress.
According to Picheca and colleagues from the University of Ottawa, Canada, “Cerebrospinal fluid analysis showed pleocytosis (159 × 106 total nucleated cells: 42% neutrophils, 43% lymphocytes) and elevated protein levels (0.79 g/L).”1
The patient was empirically treated with ceftriaxone, ampicillin, acyclovir, and dexamethasone.
[bctt tweet=”The first reported case of Powassan virus causing a polio-like illness.” username=”DrDanielCameron”]
Initial testing for Lyme disease and arthropod-borne viruses, including Powassan virus, was 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.”
Early Powassan Virus Testing May Be Negative
Initial testing for Powassan virus was negative despite the patient’s worsening neurologic symptoms. The diagnosis was confirmed only after repeat testing demonstrated seroconversion, highlighting a challenge that can occur with tick-borne infections when testing is performed too early.
Re-testing one month after symptom onset revealed infection with Powassan virus.
Picheca explains that the initial testing was performed too early, “because paired serology 4 weeks later demonstrated seroconversion and confirmed diagnosis.”
Powassan Virus Causes a Polio-Like Illness
Electrodiagnostic (EMG) testing six 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.
This finding demonstrated that Powassan virus infection can mimic a polio-like illness, resulting in severe weakness and neurologic dysfunction.
The case also highlights the importance of considering neurologic manifestations of tick-borne disease in patients presenting with unexplained weakness, respiratory failure, or motor neuron involvement.
Importance of Repeat Testing
The authors emphasize that clinicians should consider the limitations of early testing when evaluating suspected tick-borne illnesses.
“Our findings emphasize the need to include POWV infection in the differential diagnosis for patients with polio-like symptoms in tick-endemic regions,” the authors conclude.
Frequently Asked Questions
What is Powassan virus?
Powassan virus is a rare tick-borne virus that can cause encephalitis, meningitis, and severe neurologic complications.
Can Powassan virus cause paralysis?
Yes. In rare cases, Powassan virus can affect motor neurons and lead to weakness, paralysis, or a polio-like illness.
Can Powassan virus testing be negative early?
Yes. Early testing may be negative, and repeat testing may be necessary to confirm infection.
How is Powassan virus different from Lyme disease?
Powassan virus is a viral infection, while Lyme disease is caused by the bacterium Borrelia burgdorferi. Both can be transmitted by ticks but require different management approaches.
Clinical Takeaway
This case report describes the first reported Powassan virus infection presenting as a polio-like illness with motor neuron involvement.
The case also illustrates an important diagnostic lesson: early testing may be negative, and repeat testing may be required to confirm Powassan virus infection in patients with progressive neurologic symptoms.
Related Articles
Case report: Fatal Powassan virus infection
No neurologic damage in three children with Lyme disease and Powassan virus
Relying on a negative Lyme disease test can prove deadly
Powassan virus: symptoms, diagnosis, and complications
References
- 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;25(8). doi:10.3201/eid2508.190399.
Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.
Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention
Where can i get a test for powassan virus?
There are a growing number of tests for the Powassan virus. I am not sure how reliable the various tests are.
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.
Regards,
Patti-Lou
I am happy his strength is improving.