Is polio back in Europe and Italy? Here's why the virus is circulating again
The National Medical Association's team of doctors and anti-fraud experts answers the most important health questions
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Recent news from Germany has raised new concerns: the wild polio virus has been found in a sample of sewage water in the city of Hamburg. What does this mean? Should we also be worried in Italy? Polio is a highly contagious disease caused by a virus that is transmitted via the fecal-oral route, often through contaminated water or food. In most cases it causes no symptoms, but in a small percentage the virus penetrates the central nervous system and causes permanent paralysis, especially in young children, who are the most vulnerable. After decades of global health efforts, Europe was declared free of endemic transmission of the wild virus in 2002. By 'wild virus' is meant the poliovirus in its natural form, i.e. unmodified or vaccine-derived. It is the original strain that has historically caused polio epidemics worldwide. Unlike oral vaccine-derived polioviruses (attenuated viruses that under rare circumstances and low vaccine coverage can mutate and acquire the ability to spread), the wild virus is always potentially dangerous. Currently, wild strains still circulate endemically only in certain areas of Asia, such as Afghanistan and Pakistan.
Is it true that polio is back in Europe?
Yes, it is true that the polio virus has recently been detected in Europe. In detail, a wastewater sample collected in Hamburg showed the presence of wild poliovirus type 1. This is the first case of this type in Europe since 2010. The genetic sequence of the virus matches that of a strain identified in Afghanistan, where polio is still endemic. The detection came about thanks to a very effective environmental surveillance system. No clinical cases of the disease have been reported in Germany, and health authorities have reiterated that the risk to the population remains very low thanks to high vaccination coverage.
Should we also be concerned in Italy?
In Italy, there have been no cases of wild polio virus for over forty years. Our country uses the inactivated vaccine (IPV), which effectively protects against severe forms of the disease but does not completely block transmission of the virus. The detection of the virus in Germany is therefore an important signal: it reminds us that as long as the virus circulates in the world, there is always the possibility that it will be reintroduced even in areas considered free of the disease. Moreover, the presence of unvaccinated people, even if it is a minority, represents a real vulnerability.
How do you explain the return of the virus to Europe?
As already mentioned at the beginning, 'wild virus' refers to the poliovirus that circulates in nature, unmodified by man: it is the 'original' virus that caused the major polio epidemics worldwide in the past. The wild virus is no longer transmitted in Europe, but can be imported from countries where it is still present, such as Afghanistan and Pakistan. Oral vaccines, on the other hand, use a live but attenuated poliovirus, i.e. made much less aggressive, which serves to stimulate the defences without provoking the disease in vaccinated persons. In contexts with very low vaccination coverage, this attenuated virus can, very rarely, change (mutate), regain the ability to spread and, in exceptional cases, cause disease: one then speaks of 'vaccine-derived polioviruses'. The wild virus, on the other hand, possesses from the outset a full capacity to spread and cause severe forms of polio. The Hamburg case was not accompanied by any clinical cases, but it is proof that an infected person, probably asymptomatic, passed through the city. Polio does not cause symptoms in most cases, but the virus can still be eliminated with faeces. If there are communities with low vaccination coverage, the risk of transmission increases. This is not the first time that poliovirus has been found in sewage: in recent years, viruses derived from the oral vaccine (no longer used in Europe, but still used in other countries) have been found in the sewage of several European countries, including the United Kingdom (we reported on this here) Poland, Spain and Germany itself.
What can we do to protect ourselves and our children?
The most important measure remains vaccination. The polio vaccine is part of the Italian vaccination calendar and is mandatory for children. Making sure your children have completed their vaccination cycle is the most effective way to protect them. Adults can also ask their doctor if a booster is necessary, especially when travelling to countries where polio is still present. It is also important to keep the focus on surveillance: health systems must be able to detect any signs of the virus returning early. It is not a matter of being alarmed, but of remaining alert and informed.
