Polio, also known as Poliomyelitis, is caused by one of three poliovirus (PV) serotypes belonging to the Picornaviridae family. It is a highly contagious illness transmitted by close person to person contact, mainly through the oral-fecal route – an infected person who does not practice proper hand or body hygiene passes the infection to another person. It can also spread through infected saliva and respiratory system secretions. Polioviruses grow in the intestinal system and are shed through feces. The infection typically spreads in areas with poor water and sewage sanitation; wild poliovirus is found in this type of environment and puts unvaccinated people at risk.
As a result of global eradication efforts, Polio is now only endemic in Afghanistan, Nigeria, and Pakistan. However, countries with low vaccination rates continue to be at risk for re-introduction of the virus due to imported cases resulting from travel. Unvaccinated travellers, especially children, pregnant women, and those with a weakened immune system going to areas with Polio outbreaks are at risk.
In the majority of cases, the infection is asymptomatic – persons do not exhibit symptoms. Those that do have very mild symptoms and the infection may go unnoticed. Symptoms include fever, headache, fatigue, stiff neck, muscle pain, and vomiting. In some cases, the virus enters the bloodstream to attack the Central Nervous System which causes paralysis, usually in the legs. This is also known as Acute Flaccid Paralysis where the limbs become floppy. In severe cases, patients can become quadriplegic when the thorax and abdomen muscles become paralyzed and have difficulty breathing, swallowing, or speaking. Post-Polio Syndrome, characterized by muscle weakness, joint and muscle pain, and severe fatigue, can occur in survivors 15 to 40 years after being exposed to the virus. Treatment includes supportive care of symptoms, antispasmodic medication, physiotherapy, and even orthopedic surgery.
Travellers of all ages should ensure that they are up-to-date with their Polio vaccination. A primary vaccination series is necessary for those not previously or only partially vaccinated. If you have been fully vaccinated as a child, you should get a Polio booster once as an adult. To prevent the international spread of Polio, some countries require travellers to get an additional Polio booster 4 weeks to 12 months prior to entering the country. A booster dose is also recommended for long-term travellers (4 weeks or more) going to countries with risk of Polio virus transmission. The inactivated injectable vaccine is available in Canada and the USA and the live attenuated oral vaccine is available in some countries. Polio-containing combination vaccines are also available for children. All provide life-time protection.
Information last updated: October 23, 2020