POLIOMYELITIS (POLIO)

Poliomyelitis (commonly shortened to ‘polio’, also known as infantile paralysis) is an easily transmissible viral disease. A poliovirus infection can lead to permanent paralysis and even death. Before the introduction of vaccines, wild poliovirus was widespread around the world. Exposure to this virus would usually already have occurred in childhood. This led to it being called infantile paralysis.

There are safe and effective vaccines against this illness. Since 1998, only inactivated polio vaccines have been administered in Germany. In some countries, attenuated live-virus vaccines (oral polio vaccine) are still used. After receiving an oral polio vaccine, that person may excrete the vaccine virus in their stool for several weeks. That vaccine virus usually does not lead to illness. It can, however, genetically mutate and trigger the same illness in nerve tissue as the wild poliovirus. This is referred to as a vaccine-derived poliovirus.

These days, wild poliovirus only still exists in Afghanistan and Pakistan. However, vaccine-derived poliovirus is detected time and again around the world.

By water

Drinking water or bathing water contaminated with faeces can be a possible source of infection. Waste water generally does not constitute a source of infection for the general population in Germany.

• A large proportion of people who have been infected (over 70 percent) do not experience any symptoms at all.
• Around 4 to 8 percent of those infected temporarily experience fever, nausea, a sore throat, abdominal pains, sore muscles or headaches between 6 to 9 days after the infection.

In rare cases, the central nervous system may also be affected:

• In around 2 to 4 percent of those infected, the infection leads to meningitis without symptoms of paralysis. Typical symptoms include fever, a stiff neck, back pains and muscle cramping.
• Very rarely (in between 0.1 to 1 percent of those infected) in addition to severe back pain, neck ache and muscular pain, paralysis and/or weakness in the arms, legs or other muscles occur, often only on one side. Sometimes such paralysis is permanent.
• Late effects (post-polio syndrome): Years after a polio infection, muscle weakness and muscle loss can emerge or accelerate.

For infections without symptoms of paralysis, it takes on average between 3 to 6 days from the infection to the onset of symptoms (incubation period). Symptoms of paralysis usually appear between 7 to 14 days following infection.

Infected people can infect others even if they do not show any symptoms themselves. The virus can be detected in throat secretions at the earliest 36 hours after an infection, where it can remain for a week. Virus excretion in the stool commences after 2 to 3 days and can last up to 6 weeks. In individual cases, for instance in case of an immunodeficiency, this may even last for months or years.

Anyone who is not vaccinated or not fully vaccinated can become infected with polio. The full vaccination provides protection from infection by wild poliovirus as well as vaccine-derived poliovirus.