Several hundred undiagnosed cases? Silent spread of polio alarms US authorities

Several hundred cases of undiagnosed polio must be circulating in the US, a senior official of the American health agency, the Centres for Disease Control and Prevention (CDC), said on Friday. Polio has also been detected in the sewage of New York City, indicating a silent circulation of the highly contagious virus.

The alarm by the authorities comes after a report of an unvaccinated man suffering paralysis due to the virus in New York, last month. This was the US’ first case of polio in almost a decade after the last reported case in 2013. 

The case in New York was termed as "just the very, very tip of the iceberg" by the director of the CDC’s National Centre for Immunisation and Respiratory Diseases, Dr Jose Romero. He also said it was an indication that there  "must be several hundred cases in the community circulating".

"There are a number of individuals in the community that have been infected with poliovirus. They are shedding the virus," he said. 

"The spread is always a possibility because the spread is going to be silent,” Dr Romero added.

As per  CDC, about 3 in 4 people infected with polio don’t have symptoms, but they’re still capable of spreading the very contagious virus to others. Paralysis occurs in a relatively small number of infected people, only about 1 in 200. Some of the paralysed cases may turn fatal as the people can’t breathe.

"There isn’t just one case of polio if you see a paralytic case. The incidence of paralytic polio is less than 1 per cent," health commissioner for Rockland County Dr Patricia Schnabel Ruppert said.

"Most cases are asymptomatic or mildly symptomatic, and those symptoms are often missed. So there are hundreds, perhaps even thousands of cases that have occurred in order for us to see a paralytic case," she added.

Similar to New York, polio virus was also discovered in sewage in north and east London. The health authorities in the UK are set to offer targeted inactivated polio vaccine (IPV) booster doses to all children between 1 and 9 years of age to curb the spread. 

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(With inputs from agencies)