Killer disease flares again

Published date01 October 2022
Publication titleHawkes Bay Today
Polio was eradicated in the United States in 1979 thanks to high vaccination rates. But now the disease has been detected in wastewater samples in multiple counties, one man has been irreversibly paralysed, and a state of emergency has been declared

The unidentified individual, who was unvaccinated, is thought to be one of hundreds of New Yorkers who have contracted the virus, as paralysis affects only one in every 200 people.

“We know this is the tip of the iceberg, there are probably hundreds and hundreds of cases,” said Dr Patricia Schnabel Ruppert, the health commissioner of Rockland county, where the man lives.

“One case of polio essentially is an outbreak because one case of paralytic polio means you almost certainly have hundreds of other people who are infected,” added Dr Emily Lutterloh, director of epidemiology at the Wadsworth Centre, the lab which detected the case.

The polio vaccination rate in New York state is 79 per cent.

But in Rockland county, which has a population of 330,000 people, it falls to just 61 per cent. Some zip codes in Rockland have “much lower rates,” Schnabel Ruppert warned.

“There are areas that are quite dense. One zip code has a vaccination rate of 37.2 per cent. It’s very concerning,” she told the Telegraph last week.

The samples have led to an “all hands-on-deck effort”, Schnabel Ruppert said, with the New York State department and the Centre for Disease Control moving in to increase surveillance.

Wastewater testing has since detected the virus in New York City, and the counties of Orange, Sullivan, and Nassau. Similar testing has also found poliovirus circulating in London and Jerusalem, in the latter a second person has been paralysed.

Unlike past outbreaks, the virus detected in all three countries is not wild polio, but vaccine-derived.

When a person is immunised with an oral polio vaccine — which is no longer used in the US or the UK — the weakened vaccine-virus replicates in the gut, generating an immune response. The vaccine is then excreted and very rarely can mutate and spread to other unvaccinated people, especially where coverage is low. This can then result in outbreaks of polio.

A newer, inactivated vaccine (which does not contain live virus) does not result in this shedding process.

But it is not as effective at halting outbreaks, and is harder to administer and distribute, meaning countries still battling wild poliovirus tend to use the oral vaccine.

Experts have suggested the cases may, therefore, have...

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