“Hundreds of thousands of people are fleeing Syria and seek refuge in neighboring countries and Europe,” the authors state in their article published today in The Lancet. “Vaccinating only Syrian refugees—as has been recommended by the European Centre for Disease Prevention and Control—must be judged as insufficient; more comprehensive measures should be taken into consideration.”
Community Immunity
In their article, Professor Martin Eichner of the University of Tübingen and Stefan Brockmann of Reutlingen Regional Public Health Office explain that there may not be sufficient ‘community immunity’ in all parts of Europe to prevent an outbreak if polio is reintroduced. They have identified Austria, the Ukraine, Bosnia, and Herzegovina as having particularly inadequate coverage. Worse, because so few cases of polio — one in 200 infections — cause symptomatic disease, calculations suggest polio could be circulating for nearly a year before an outbreak might be detected. By that time, hundreds of individuals could be carrying the virus.
Most European countries use inactivated polio vaccine (IPV) rather than oral polio vaccination, which was discontinued because there were a few incidences where the latter was found to cause the main symptom of polio, acute flacid paralysis. IPV is most effective when vaccination coverage is continually very high and when the population has low crowding and solid hygienic standards. Until now, inoculation with IPV has been a successful strategy in Europe, where circulating polio viruses have been eliminated for decades. However, with an influx of refugees IPV may not be sufficient and, currently, none of the European Union member states have a stockpile of oral polio vaccines.
Fears of Infections Disease Spread from the Middle East
Since June, the World Health Organization (WHO) has been warning of increasing cases of communicable diseases inside Syria as well as among those Syrians displaced by political strife. WHO reported new cases of vaccine-preventable diseases in Syria at that time, including laboratory-confirmed cases of measles. Then in late October, WHO confirmed 10 new cases of polio in Deir al-Zor — the first outbreak in Syria in 14 years. Prior to this, WHO had reported wild poliovirus type 1 (WPV1), a naturally occurring polio, in Israel. Israel began a vaccination program for children under nine in August and so far, no cases of paralytic polio have been reported there. Nevertheless, WHO assessed the risk of international spread from Israel to be ‘high’ because the virus has been circulating there for some time.
Although the vast majority of people who become infected with poliovirus don’t become sick, some people may contract nonparalytic polio, which causes mild, flu-like symptoms. Those most susceptible to infection include pregnant women, the very young, and those with weakened immune systems. The authors of theLancet study believe the threat from the Middle East warrants an earnest response. “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,” the authors state.
Source: Eichner M, Brockmann S. Polio Emergence in Syria and Israel Endangers Europe. The Lancet. 2013.
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