Conditions Polio (poliomyelitis)

Polio is a highly contagious viral disease that caused many cases of illness and death in children prior to the introduction of a vaccine. The name poliomyelitis is derived from the Latin word for the part of the spinal cord that can be affected by the disease.

Today, polio has been almost completely eradicated across the world thanks to global vaccination campaigns. However, it still occurs in a small number of countries and, with foreign travel, could be carried by people traveling from there to Germany. The risk of infection is particularly high when hygiene conditions are poor. A preventive vaccine will be given to children until the disease is completely eradicated.

Most people who are infected with polio viruses have either mild symptoms or no symptoms at all. However, around 1 in every 200 people infected will suffer from paralysis that does not completely clear up following the infection. If the muscles involved in breathing are affected, this may cause life-threatening respiratory paralysis. Both children and adults who have no immunity can contract the disease.

In over 95 percent of people infected with a polio viruses, there are no symptoms of disease.

If symptoms do occur, there are three different types, which occur in the following sequence:

• Abortive poliomyelitis: this is a mild form that does not involve the nervous system.
• Non-paralytic poliomyelitis: the nervous system is involved but there is no paralysis.
• Paralytic poliomyelitis: the nervous system is involved and paralysis occurs.

Polio not affecting the nervous system

This mild form affects 4 to 8 percent of those infected and is characterized by general symptoms such as nausea, vomiting, diarrhea, high temperature, sore throat, muscle aches and headache.

Polio affecting the nervous system but without paralysis

This occurs in 2 to 4 percent of people infected and its symptoms appear about 3 to 7 days after the mild form begins. The symptoms are high temperature, stiff neck, back ache and muscle cramps.

Polio affecting the nervous system with paralysis

This occurs in 0.1 to 1 percent of people infected and its symptoms appear about 2 to 3 days after the non-paralytic form begins. It causes a renewed increase in temperature and severe pains in the back, neck and muscles. It also causes paralysis. Various leg muscles are often paralyzed. However, muscles in the arms, stomach and eyes and those involved in breathing may also be affected.

Polio is an infectious disease caused by polio viruses. Polio viruses are enteroviruses that live exclusively in the gastrointestinal tract of humans.

Different types of polioviruses can cause the disease; the original form is the wild poliovirus. They are currently only found in Afghanistan and Pakistan. In some countries, there is an oral polio vaccine. Vaccination is carried out using attenuated live viruses. Known as vaccine viruses, they generally do not cause disease, but are excreted in the stool over a period of several weeks. They can undergo genetic changes over time and then trigger disease in exactly the same way as wild polioviruses. They are therefore also referred to as oral polio vaccine-derived polioviruses.

Infection occurs due to fecal contamination – for example, the virus may be contained in fecal particles that are passed from unwashed hands to the mouth. Under poor sanitary conditions, infection can also occur through fecal contamination of drinking water or bathing water. At the start of the infection, the virus multiplies in the throat and can be spread to others in the tiny droplets that are released into the air with a sneeze or cough. Even if a poliovirus infection does not cause any symptoms in a person, that person can infect other people.

Symptoms of the disease can appear 3 to 35 days after infection with polioviruses. The virus can continue to be shed in the stool for up to 6 weeks after an infection, or even longer in isolated cases. The risk of infection is particularly high in unsanitary conditions.

In the past, polio was common worldwide. As children came into contact with these viruses at a very early age, polio was considered a childhood disease. Thanks to vaccines, the virus has been almost entirely wiped out everywhere. Today, the original wild polioviruses are only found in Pakistan and Afghanistan. The last case of infection with this type of poliovirus in Germany occurred in 1990.

The first polio vaccines used weakened living viruses that provided a good level of immunity. The vaccine was either swallowed directly or taken in a sugar cube. This type of vaccine is called an oral vaccine. The disadvantage of these vaccine viruses was that, in rare cases, they could actually cause polio themselves, known as vaccine-associated polio. In Germany, there were approximately one to two such vaccine-related illnesses per year until 1998. 

A vaccine containing inactivated viruses is now available that also provides good protection and cannot result in vaccine-associated polio. Only this vaccine has been used in Germany since 1998. However, in some countries, the live-attenuated vaccine is still being administered. These vaccine viruses are shed in the stool over several weeks. In this way, they can spread and undergo genetic changes over time. Oral vaccine-derived polioviruses can develop as a result and, much like wild polioviruses, can lead to disease.

In addition, not everyone is fully vaccinated against polio. As a result, major disease outbreaks are still possible today in countries where polioviruses are prevalent.

In Germany, polio is considered to be eradicated. However, polioviruses can be brought in from other countries. At the end of 2024, oral vaccine-derived polioviruses were found in wastewater in several German cities. Full vaccination reliably protects against the disease and therefore remains important until there are no more cases of polio and no healthy poliovirus shedders worldwide.

You can find out whether a vaccination is recommended for you or your child with the polio vaccination check.

Answers to frequently asked questions regarding the detection of polioviruses in wastewater are provided by the Robert Koch Institute (RKI).

The mild, non-paralytic form of polio, which does not cause paralysis, can clear up on its own without any lasting effects.

With the paralytic form of polio, the paralysis typically only clears up partially – in other words, the person will not make a full recovery. If the brainstem with its vital control centers is affected or the respiratory muscles are paralyzed, it can be fatal.

Even years or decades after the onset of the disease, muscle wasting accompanied by increased paralysis can recur. This condition is known as post-polio syndrome. Exactly what causes it is still not fully understood.

It is suspected that the nerves not originally affected by the disease take over the function of the nerves that are damaged and become overstrained as a result. This ongoing overexertion eventually damages the originally healthy nerves, causing them to lose their function. As a result, paralysis can also develop in parts of the body that were not affected before.

There is no specific treatment for polio viruses, the pathogens that cause polio. This is why the preventive polio vaccine is so important.

Polio only occurs in a very small number of places in the world today. However, travelers or migrants from these regions may carry polio viruses to other countries with them. The World Health Organization (WHO) aims to wipe out this disease across the globe. Vaccination will be required until polio infections no longer occur.

Germany only uses vaccines with inactivated polioviruses, which cannot cause vaccine-associated polio. The polio vaccine is usually part of the 5-in-1 or 6-in-1 vaccine recommended for infants. Primary vaccination is generally recommended at 2, 4 and 11 months of age and is administered via an injection into the muscle. For complete protection, a booster vaccination is recommended between the ages of 9 and 16. People who receive their primary vaccine in adulthood should receive a booster vaccine after 10 years. 

After this booster vaccination, no further polio vaccination is normally necessary. An additional booster vaccination is sometimes recommended for travel to countries with a high risk of infection.

You can find out whether a vaccination is recommended for you or your child with the polio vaccination check.

You can find further information on travel-related vaccination recommendations on the webpages of the Federal Foreign Office.

A typical feature of polio-related paralysis is that the limbs are affected to varying degrees. In other words, both sides of the body are not equally affected by paralysis. 

For a clear diagnosis, however, the polio virus must be detected. Polioviruses can be detected by analyzing a stool sample in the laboratory. Doctors sometimes also take a throat swab or a sample of cerebrospinal fluid – the fluid surrounding the brain and spinal cord.

There is no effective medication for an infection with polio viruses. Treatment of polio is limited to supportive measures to relieve the symptoms. In the acute phase of the disease, these include medications to reduce temperature and relieve pain. If the muscles used in breathing are affected by paralysis, it may be necessary to provide mechanical respiratory support.

People with lasting paralysis often receive additional and usually long-term treatments from orthopedic specialists and physiotherapists. One goal of the different treatments is, for example, to help patients walk independently, despite their paralysis. The treatment aims to avoid muscle imbalance and joint stiffness.

If a person is suffering from post-polio syndrome (PPS) – a very common complication of a polio infection – endurance training and pain control are other important components of life-long treatment.

The infektionsschutz.de website provides more information about polio.

Further information about the recommended vaccines against polio for children, adolescents, and adults is available from the website of the Federal Center for Health Education (Bundeszentrale für gesundheitliche Aufklärung, BZgA) at impfen-info.de.