Polio is an infectious disease caused by a virus. The virus reproduces itself in the gut and can spread easily to the nervous system. It can result in very serious consequences including meningitis, paralysis or death.
Before a vaccine was introduced in the 1950s, epidemics would result in up to 7760 cases of paralytic polio in the UK each year, with up to 750 deaths. Once a vaccine was routinely available, cases of polio rapidly fell to very low levels. The last outbreak of polio in the UK was in the late 1970s, and the last case of naturally-occurring polio in the UK was in 1984.
Vaccination has eliminated polio in almost all countries in the world. Only three countries still officially have polio circulating in the population: Afghanistan, Pakistan and Nigeria. However, Syria, which was polio-free for 14 years, was re-infected with the virus from Pakistan. Polio cases there have increased as a result of the civil war, which has had a major impact on sanitation and on routine vaccination. Other countries have had a few polio cases in recent years, often linked to war or civil unrest.
Europe has been certified as 'polio free' since 2002, and the risk of importing polio into the UK is considered to be low at the moment. However there have been at least two outbreaks of polio in Europe since 2002, both linked to cases imported from other parts of the world. In 2018 the World Health Organization's view is that three European countries (Bosnia and Herzegovina, Romania and Ukraine) are of special concern because of lower vaccination rates and other issues.