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What is poliomyelitis?
Poliomyelitis, commonly known as polio, is a highly contagious viral disease caused by the poliovirus. It predominantly affects young children under the age of 5. Cases of wild poliovirus now occur only in 2 countries worldwide following global vaccination efforts.
However, there is another form of poliovirus, known as circulating vaccine-derived poliovirus (cVDPV), that has been increasing in recent years. Unlike wild poliovirus, which occurs naturally, cVDPV develops from the weakened virus used in the Oral Polio Vaccine (OPV). In areas with low vaccination coverage, many people in the community remain unprotected, which allows this weakened vaccine virus to spread from person to person over extended periods, gradually mutating to a form that can cause paralysis, similar to the wild poliovirus. This mutated virus can then spread in communities, leading to cVDPV.
This is why maintaining high vaccination rates in all communities is so important for preventing polio outbreaks.
How is poliomyelitis transmitted?
Polio is primarily transmitted via the faecal-oral route (i.e. through food, water or other objects that are contaminated with the stool of an infected person). Less commonly, it can also be transmitted via infectious respiratory particles when an infected person coughs or sneezes.
The incubation period is typically 7 to 14 days, ranging from 3 to 35 days.
What are the symptoms of poliomyelitis?
Poliovirus infection presents with a wide clinical spectrum, with the majority of cases being asymptomatic. About 25% will have a mild flu-like illness such as sore throat, fever and fatigue that is self-resolving.
Polio infection can lead to complications in a small proportion of cases, including paralysis, which may present differently depending on the affected muscle groups. In rare cases, the infection can affect the brain, leading to seizures.
What are the risk factors?
Risk factors include:
Persons who are partially vaccinated or unvaccinated against polio;
Persons with weakened immune systems; and
Persons travelling or living in areas with ongoing transmission or outbreaks.
How is poliomyelitis treated?
Treatment focuses on managing and relieving the symptoms of the disease. Treatment may involve supportive interventions to address the complications of the disease for example, managing seizures. Antispasmodic drugs are used to relax affected muscles and improve mobility but permanent polio paralysis cannot be reversed.
How to prevent poliomyelitis?
Vaccination is the most effective preventive measure for polio. The polio vaccine in the form of inactivated polio vaccine (IPV) is recommended under the National Childhood Immunisation Schedule (NCIS).
Other preventive measures include:
Practise good personal hygiene at all times.
Wash your hands regularly with soap, especially before handling food or eating, after going to the toilet, or when hands are dirty from coughing or sneezing.
Avoid touching your face, including eyes, nose and mouth with unwashed hands.
Avoid sharing food, drinks, or eating utensils.
Please refer to Health advice for travellers for additional precautions to take when travelling.