Is It Polio—or a Tick-Borne Infection Like Powassan Virus?
Polio-like symptoms?
But tests are negative?
A tick-borne virus may be missed.
What if it’s not polio? Severe weakness, paralysis, and neurologic symptoms may resemble polio—but can reflect a tick-borne infection such as Powassan virus.
While vacationing in rural Newfoundland, a man developed nausea, vomiting, abdominal pain, double vision (diplopia), and impaired coordination (ataxia).
His condition worsened rapidly. He became febrile and developed slurred speech, weakness, and respiratory distress.
A key pattern is rapid neurologic progression. Symptoms escalated beyond a typical viral illness.
When Initial Testing Is Negative
Cerebrospinal fluid analysis showed pleocytosis and elevated protein levels, consistent with central nervous system inflammation.
Despite this, initial testing for tick-borne infections—including Powassan virus—was negative.
A key pattern is early false-negative testing. Infection may not be detected at the initial stage.
Learn more about tick-borne co-infections and diagnostic challenges.
Progression to Polio-Like Paralysis
The patient worsened, requiring intubation and intensive care support.
He developed flaccid tone with absent strength in the upper extremities and reduced strength in the lower extremities.
A key pattern is motor neuron involvement. Symptoms resembled poliomyelitis.
Electrodiagnostic testing later confirmed diffuse denervation consistent with a poliomyelitis-like presentation.
Delayed Diagnosis Confirmed Infection
Repeat testing one month after symptom onset confirmed Powassan virus infection through seroconversion.
A key pattern is delayed confirmation. Diagnosis required repeat testing after the immune response evolved.
This highlights a broader principle also seen in Lyme disease testing limitations, where early tests may miss infection.
Why This Infection Can Be Missed
- Initial testing performed too early
- Symptoms overlap with other neurologic diseases
- Limited awareness of rare tick-borne infections
A key pattern is diagnostic overlap. Symptoms may be attributed to more familiar neurologic conditions.
Clinical Implications
Powassan virus can cause severe neurologic illness, including polio-like paralysis.
If patients present with rapidly progressing neurologic symptoms and negative early testing, repeat evaluation may be necessary.
Clinical Takeaway
Polio-like symptoms do not always indicate polio. Tick-borne infections such as Powassan virus should be considered—especially when early testing is negative and symptoms worsen.
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.