A new outbreak of polio in Syria that has recently been confirmed by the World Health Organization could potentially put neighboring regions, including Europe, at risk. This is according to an article published in The Lancet.

Polio, also known as poliomyelitis, is a highly contagious viral infection that can cause paralysis and breathing problems, with more severe cases leading to death.

Last month, the World Health Organization (WHO) confirmed 10 cases of polio in the Syrian Arab Republic. Infection is said to have been caused by wild poliovirus type 1 (WPV1), which has not been detected in Syria since 1999.

Two infectious disease experts - Martin Eichner of the University of Tübingen and Stefan Brockmann of Reutlingen Regional Public Health Office in Germany - explained in a letter to The Lancet that since large numbers of refugees are leaving Syria and moving to neighboring countries and Europe, this could lead to infection being reintroduced into communities that have been free of polio for decades.

'High IPV coverage needed' to prevent infection

The majority of European countries now use the inactivated polio vaccine (IPV), as opposed to the oral polio vaccine (OPV), which was discontinued in most areas as it was found to cause some cases of acute flacid paralysis (AFP) - the main symptom of polio.

"Only some of the European Union member states still allow its use and none has a stockpile of oral polio vaccines," the experts say.

Although the IPV has proved effective in the prevention of polio disease, it only provides partial infection protection, and there is very low vaccination coverage in some regions.

The experts note that infection can only be prevented in Europe if IPV coverage is very high, and if the European population has low crowding and high hygiene levels.

In European regions where vaccination coverage is low, such as Bosnia and Herzegovina, Ukraine and Austria, the experts say the fact that these regions have been polio-free for decades will not provide a "herd immunity" sufficient enough to stop sustained transmission of the WPV1 infection.

Additionally, they note that because only 1 in every 200 WPV1 infections cause identifiable symptoms of polio, such as AFP, it may be almost a year before one case appears and the disease is detected. By this point, they say hundreds of people could be infected.

While the European Centre for Disease Prevention and Control recommends that only Syrian refugees should be vaccinated, Eichner and Brockmann warn that this is insufficient and "more comprehensive measures should be taken into consideration."

Routine screening of sewage for poliovirus - a precaution that has been carried out in Israel since February this year - could be an option, say the experts:

"Routine screening of sewage for poliovirus has not been done in most European countries, but this intensified surveillance measure should be considered for settlements with large numbers of Syrian refugees."

Earlier this year, Medical News Today reported on a statement from WHO saying they aim to eradicate polio by 2018.