A rare infection, commonly known as polio, that can affect the nervous system
Poliomyelitis is a highly infectious disease that varies in severity from a mild condition with few or no symptoms to a disease that can lead to paralysis. The polio virus is most commonly transmitted by contact with the faeces of an infected person but can also be spread through saliva and airborne droplets.
Since routine immunization began in the 1950s, polio has been virtually eliminated from developed countries. However, in some parts of Africa and Asia the disease remains a serious risk for travellers who do not have up-to-date immunization.
For most infected people, polio produces no symptoms or results in a mild illness with a slight fever and sore throat that develops 3–21 days after infection. However, in about 1 in 75 adults and 1 in 1,000 children, the brain and spinal cord become inflamed. In a few cases, one or more limbs may be paralysed, and the muscles of the respiratory system may be affected.
In most cases, polio is undiagnosed and untreated. If the disease is suspected it can be confirmed by tests on the faeces. There is no specific treatment. People who have severe symptoms are admitted to hospital, and if the respiratory muscles are paralysed, mechanical ventilation may be given.
Most people make a full recovery from milder forms of the disease. Of those who become paralysed, many improve within 6 months.
In the UK, vaccination against polio is given at ages 2, 3, and 4 months, with booster doses between the ages of 3 years 4 months and 5 years, and again at 13–18 years. The polio vaccine is combined with other vaccines and given as part of the routine childhood immunization programme. Since 2004, inactivated polio vaccine (given by injection) has been used; this is safer than the previously used live oral vaccine. Before travelling to areas where infection with polio is still a risk, adults may need a booster dose of vaccine (see Travel immunizations).
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.