Public health authorities have warned health care workers to be alert for polio, but most doctors will not be familiar with the presentation of this highly infectious and potentially deadly disease. An article in CMAJ ( Canadian Medical Association Journal )
1. The oral polio vaccine is used internationally, but not in Canada since 1996
The poliovirus used in the oral polio vaccine is excreted in feces for weeks and is transmissible. When it circulates among underimmunized populations, it can mutate and revert to a form that causes paralysis in underimmunized or immunocompromised people. Communities with low vaccination coverage are at risk of outbreaks. The inactivated polio vaccine is used in Canada and cannot cause the disease.
2. Poliovirus could be circulating in Canada
Vaccine-derived polio was detected in 2022 in the United States and the United Kingdom in wastewater.
3. People who have received less than 4 doses of the vaccine are at risk of infection
Poliovirus is highly infectious, spread through the fecal-oral route , and people can shed the virus asymptomatically for weeks. The incubation period is 3 to 6 days, with onset of paralysis in 7 to 21 days. Children under 5 years old are most at risk.
4. The clinical presentation of polio varies from asymptomatic to paralysis and death
The majority of poliovirus infections (75%) are asymptomatic . Symptoms in the remaining 24% may include gastrointestinal illness, followed in 1 to 3 weeks by rapid weakness and then paralysis. One in 200 patients develops paralytic poliomyelitis and between 5% and 15% of paralyzed patients die from paralysis of the respiratory muscles.
5. Poliomyelitis should be considered in all patients with sudden flaccid paralysis
The stool sample should be submitted for enterovirus polymerase chain reaction and enterovirus molecular serotyping. Patients and public health should be notified immediately if there is clinical suspicion, even without laboratory confirmation.
“Polio is a rare infectious disease due to the success of global immunization,” says Dr. Marina Salvadori, Department of Pediatrics, McGill University, Montreal, Quebec and the Public Health Agency of Canada. “Given that elimination is within our reach, healthcare workers should be alert to this diagnosis in any patient with acute flaccid paralysis.”
