Spain is preparing an action protocol with different levels of alert in the event that the polio virus is detected in wastewater, as has occurred in other neighboring countries, although if this were to occur, the possibility of transmission would be very low due to the high vaccination coverage.
The Ministry of Health is working on this document, which will be reported today at the regular meeting of the Public Health Commission and to which EFE has had access, due to the "real
risk" of importing poliovirus,
both in our country and in the rest of the world.
After Jerusalem, New York and London isolated the virus in their wastewater last year, Health considered the need to carry out a pilot study within the framework of the National HEBAR Strategy (Epidemiological Tool based on Wastewater) to find out the situation in Spain.
Carried out in the last quarter of 2022 at thirteen treatment plants in twelve towns (Jerez de la Frontera, Huelva, Zaragoza, Tenerife Sur, Las Palmas de Gran Canaria, Barcelona, Lleida, Logroño, Madrid, Melilla, Vitoria and Bilbao), the study Its objective is to determine the presence or absence of the virus and, if so, to know its evolution for at least 4 weeks.
According to the findings,
the protocol establishes a pre-alert level and three alert levels,
each of which links a series of public health actions.
The last case in Spain of poliomyelitis due to autochthonous wild poliovirus occurred in 1988 and both our country and the WHO European Region have been certified as a Region free of this disease since 2002, the year since which several plans have been prepared to maintain this situation. .
During the
last 30 years, only four cases of polio have been detected - in 1999, 2001, 2005 and 2021
- and in 2019, poliovirus was identified in a person without a clinic.
All of them were related to vaccine strains of the virus and in no case resulted in transmission to the population.
The high immunity in the Spanish population, with coverage greater than 95%, as well as the good hygienic-sanitary conditions and the quality of the surveillance systems, ensures the protocol, "make the risk of transmission in our country after a reintroduction of the virus is considered very low".
Currently, polio remains endemic in Pakistan and Afghanistan, and outbreaks of both wild virus (PVS) and vaccine-derived (PVDV) have occurred in non-endemic countries.
More specifically in Malawi and Mozambique, where the first PVS cases were identified in late 2021 and early 2022, to which are added PVDV outbreaks in several countries, especially in Africa and Asia.
Later,
throughout 2022, the United Kingdom, the United States and Israel have detected circulation of circulating PVDV
(PVDVc) in wastewater, and 2 clinical cases of paralytic poliomyelitis have also been identified (one in Israel and one in the USA).
Most cases of PVDV -which come from one of the three strains included in the attenuated oral vaccine against poliomyelitis- are associated with type 2, and epidemic outbreaks of this type are causing worldwide concern.
Hence, one of the objectives of the WHO Strategic Plan is to eliminate this component of the vaccine, in order to eradicate the risks of paralytic poliomyelitis, chronic infections by PVDV in immunosuppressed people, and outbreaks of PVDVc.
But as long as polio is not eradicated from the world and vaccines continue to be used, "there is a real risk of importation in all countries," the document concludes.
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