What is polio?

Polio is an infection with the poliovirus. There are three types of poliovirus. In many cases, the infected person does not have any noticeable symptoms. In other individuals, poliovirus causes only flu-like symptoms. However, in a small group, poliovirus leads to an infection of the spinal cord and sometimes the brain stem as well. This can cause paralysis and/or meningitis. The time between exposure and the first symptoms of illness is usually 7-14 days, never longer than 35 days.

Polio – also known as infantile paralysis – is caused by the poliovirus. People who are infected have the virus in their throat, but it is also present in their stool (faeces or poop).

As a result, the disease can spread via toilets, contaminated food and drinking water, hand contact and the air.

Most people who have a poliovirus infection do not become ill or only have flu-like symptoms.

In some people, the virus gets into their nervous system and brain. If that happens, your arms, legs or breathing muscles may become paralysed. You could become disabled, or even die.

In the Netherlands, almost all children have been vaccinated against polio, and polio is no longer found here. But infected travellers from countries in Asia and Africa where polio is still present can could bring the virus here, allowing the disease to return.

That is why children are still immunised against polio. Babies receive three of these vaccinations in their first year of life. Children get another vaccination against polio when they are four and again when they are nine.

Would you like to know more? Go to National Immunisation Programme.

Symptoms of the disease

Most poliovirus infections (90-95%) do not cause any symptoms. In the cases that do lead to illness, polio often starts with flu-like symptoms. These usually go away on their own. Sometimes the symptoms may grow worse: headache, muscle pain and vomiting. If that happens, the virus is spreading through the bloodstream and penetrating into the spinal cord. In 1 out of 100-200 people who have polio, this leads to paralysis, usually in the legs or arms; this is because the nerves that control the movements of these parts of the body have been damaged. About 2-10% of patients with paralysis die because the infection has affected the nerves of their swallowing or breathing muscles. The remaining patients are left with permanent paralysis and often recover only partially through intensive physiotherapy. In about 20-30% of people with paralysis, they may experience recurring muscle weakness, muscle pain, atrophy and fatigue that occurs years after the infection. This is also known as post-polio syndrome.

Polio transmission and prevention

People can infect each other via the mouth (talking, shouting). Someone who has been in contact with stool material from an infected person can transfer the virus to their mouth via their hands, thus becoming infected. Washing hands is therefore an important measure to prevent transmission and infection.
A person who has already had poliomyelitis is only protected against the same type that they already had, but is not protected against future infections with one of the other 2 types. Vaccination with an inactivated polio vaccine (IPV) provides effective and probably lifelong protection against infection with all 3 types of poliovirus. Vaccination with IPV has been part of the National Immunisation Programme since 1957.

How common is polio in the Netherlands?

Poliomyelitis has been completely eradicated in the Netherlands. The last outbreak was in 1992-93 and occurred among people who did not get vaccinated for religious reasons. During this outbreak, 71 cases of poliomyelitis were reported and 2 people died. Many more people were infected but did not become ill, since poliovirus infection does not usually cause symptoms. Before vaccination was introduced in 1957, polio was common, and people regularly died of polio.