Type 2 poliovirus was detected in the sewage systems of 14 cities across five European countries in 2024, including Spain, Poland, Germany, the UK, and Finland. The discovery placed Europe on alert due to an unprecedented increase in polio cases, with an unusually high number of detections in several countries in recent months.
The European Centre for Disease Prevention and Control (ECDC) urged for greater vigilance after detecting poliovirus in wastewater from several EU countries, including Spain, as reported by La Razón. "Polio is highly infectious and can be transmitted silently over large geographical areas," said ECDC Director Pamela Rendi-Wagner, according to La Razón.
Laboratory analyses indicated that the poliovirus was repeatedly introduced from an unknown area where the variant continued to circulate. The viruses detected in Europe were linked to a lineage first identified in Nigeria in 2020 and circulated in 21 other African countries, causing outbreaks in 15 of them. Genetic sequencing analysis showed that before being detected in Europe, the virus circulated elsewhere for a year.
From 2015 to 2022, the poliovirus was detected in at least one European country every year, indicating a concerning trend of resurgence. While there were no indications of widespread circulation of the virus in Europe due to these importations, these introductions could lead to an outbreak if unvaccinated individuals are exposed, as happened recently in Tajikistan, Ukraine, Israel, and the UK, reported Proto Thema.
The ECDC expressed concern about insufficient vaccination of children in Europe, estimating that 2.4 million children in the EU and European Economic Area may not have received the required vaccination schedule for protection against the poliovirus during 2012-2021, according to Euro2day. Additionally, approximately 600,000 children aged 12 to 23 months may not have received a complete primary vaccination cycle against poliomyelitis in 2022 and 2023.
"While most EU/EEA countries report vaccination coverage above 90% at the national level, regional data show significant differences," stated La Razón. The ECDC emphasized that the overall risk of spread among vaccinated populations is very low, but in communities with low vaccination coverage, it could increase to a moderate level.
The agency recommended that member states strengthen childhood vaccination programs to ensure coverage of at least 90% in all regions. The ECDC suggested campaigns targeted at individuals with incomplete or unknown vaccination status and maintaining adequate reserves of inactivated poliomyelitis vaccines (IPV). "By improving data collection and surveillance systems, countries can identify vaccination deficiencies and adapt response strategies," stated the ECDC report.
Pamela Rendi-Wagner, the ECDC Director, and Hans Kluge, the Regional Director of the World Health Organization for Europe, emphasized in an article in the journal Eurosurveillance the necessity of remaining vigilant to keep Europe free of poliomyelitis. They noted that "every country must remain vigilant for the detection of the presence of the poliovirus through surveillance systems, be ready to act quickly if any circulation of the virus is detected, and commit to maintaining high vaccination coverage in every community annually until global eradication of poliomyelitis is achieved."
Although Europe has been polio-free since 2002, the ECDC recommended maintaining high vaccination rates to prevent the return of the disease. Polio had been a forgotten disease for the majority of people in Europe since 2002, thanks to successful vaccination programs, extensive surveillance, and outbreak response.
The detected strain was related to the weakened live poliovirus contained in the oral poliovirus vaccine (OPV). When the weakened poliovirus circulates in populations that have not been immunized for a long time or is transmitted to individuals with immunodeficiency, it can revert to a form that causes disease or even paralysis.
This article was written in collaboration with generative AI company Alchemiq