By Stan Deresinski, MD, FACP, FIDSA
Clinical Professor of Medicine, Stanford University
SYNOPSIS: Poliovirus is present in wastewater in London and New York and has caused polio in a man in the New York City metropolitan area.
SOURCES: GOV.UK. All children aged 1 to 9 in London to be offered a dose of polio vaccine. Published Aug. 10, 2022. https://www.gov.uk/government/news/all-children-aged-1-to-9-in-london-to-be-offered-a-dose-of-polio-vaccine
Hussain Z. Polio vaccine is offered to all children in London aged 1 to 9 after virus detected in sewage. BMJ 2022;378:o2007.
Link-Gelles R, Lutterloh E, Schnabel Ruppert P, et al. Public health response to a case of paralytic poliomyelitis in an unvaccinated person and detection of poliovirus in wastewater — New York, June–August 2022. MMWR Morb Mortal Wkly Rep. ePub: Aug. 16, 2022. doi: http://dx.doi.org/10.15585/mmwr.mm7133e2
The United Kingdom government reported in June 2022 that type 2 vaccine-derived poliovirus (PV2) had been detected at the Beckton sewage treatment works in east London. Further sampling identified 116 poliovirus isolates in 19 sewage samples collected between February 8 and July 5 in multiple London boroughs. Most isolates were vaccine-like, but only a few were sufficiently mutated to be considered as vaccine-derived PV2. As a consequence, the National Health Service is offering booster or catch-up inactivated vaccine doses to children 1 to 9 years of age, with prioritization of those living in areas where the virus has been identified and/or where vaccination rates are low. Preliminary evidence has suggested that the virus in London is genetically related to virus in Jerusalem, where cases of polio have occurred recently.
On July 21, 2022, public health officials in Rockland County, which is close to the Bronx and is part of the New York City metropolitan area, reported the case of vaccine-derived paralytic polio in a young man. The patient has presented with a five-day history of low-grade fever, neck stiffness and back pain, and constipation, as well as bilateral lower extremity weakness for two days. Poliovirus type 2 was identified in the patient’s stool, while additional sequencing identified it as vaccine-derived poliovirus 2 (VDPV2). Further sequencing of the region encoding the viral capsid protein found that it differed from the Sabin 2 vaccine strain by 10 nucleotides.
The patient, who was unvaccinated, had not had international travel, but had attended a large gathering eight days before the onset of his symptoms.
Identification of this case led to examination of wastewater samples that had been collected in June for the purpose of COVID-19 surveillance and the detection of poliovirus. The virus was confirmed by the Centers for Disease Control and Prevention (CDC) to be a revertant polio Sabin type 2 virus. As of August 10, examination of 260 wastewater samples from the two counties identified poliovirus in 21 (8%). Twenty samples detected viruses that were genetically linked to the virus in the patient’s stool sample.
COMMENTARY
Polio was last identified in the United Kingdom in 1984, and the last case of wild-type poliovirus infection in the United States was seen in 1979. Prior to the case described earlier, the last detection of poliovirus infecting a person in the United States occurred in 2013 in an immunocompromised infant who had received oral polio vaccine (OPV) in India prior to emigration to the United States. As indicated by the CDC and World Health Organization (WHO), it is hoped that infection with wild-type poliovirus (WPV) is approaching global elimination, with cases currently limited to Pakistan and Afghanistan, where rare cases of type 1 WPV persist.
VDPVs result from ongoing replication of OPV in the gastrointestinal tracts of immunocompromised patients and may emerge in communities with low vaccination coverage after receipt of OPV. The virus may revert to a potentially neurovirulent state and cause paralytic polio in unvaccinated individuals who are exposed.
Complete three-dose vaccination coverage in infants and children younger than 24 months of age in Rockland County was only 60.3% in August 2022, a decrease from 67.0% in the previous two years. For one zip code area, this proportion was only 30.3%. This can be compared to a national vaccine coverage of 92.7%.
Global eradication of type 2 WPV (WPV2) was declared in 2015; type 3 WPV (WPV3) was last detected in 2012. The number of detected WPV1 cases has reached a historic low (22 cases in 2017 and 18 as of September 2018) in two of the three countries with endemic WPV1 transmission (Afghanistan and Pakistan); in Nigeria, WPV1 was last detected in September 2016. After the emergence of multiple cVDPV2 outbreaks during the preceding 15 years, in April 2016, all OPV-using countries switched from using trivalent OPV (tOPV; Sabin types 1, 2, and 3) to bivalent OPV (bOPV; Sabin types 1 and 3), and the use of injectable inactivated polio vaccine was introduced. To plug the resultant gap, a monovalent type 2 OPV was introduced, and all OPV-using countries switched from using trivalent OPV (tOPV; Sabin types 1, 2, and 3) to bivalent OPV (bOPV; Sabin types 1 and 3).
Of interest is that detection of poliovirus in sewage samples is not a new finding — it was first detected in sewage samples during a period of polio outbreaks in 1939.1 While it has been suggested that the virus was introduced into New York from someone who had been vaccinated abroad, the continued finding in wastewater appears indicative of local circulation and persisting risk.
REFERENCE
- Nelson B. What poo tells us: Wastewater surveillance comes of age amid covid, monkeypox, and polio. BMJ 2022;378:o1869.
