The polio virus was present in the wastewater of a New York City suburb a month before a case was detected in July, according to health officials as residents in the area are urged to ensure they're vaccinated against the disease.
An unnamed patient from Rockland country was diagnosed with the virus last month in the first US case since 2013.
But water samples collected in June also showed a presence of polio, which indicates that there still could be other people with the virus in the community who are shedding it in their stools.
Although the CDC say there have been no new polio cases reported, it remains unclear if the virus has spread in New York and the US.
According to laboratory results, the strain in the confirmed case was genetically linked to one found in Israel, but health officials say that it doesn't mean the patient travelled there.
Another was also linked to samples of the virus in the UK, where the country's health officials said last month that poliovirus was detected in sewage from North and East London.
Polio is a life-threatening disease that mainly affects young children but any age can get infected and is said to spread through contact with the poo of an infected person, according to the NHS.
People with polio can be asymptomatic and may not appear ill but can still spread the virus. While it can produce mild, flu-like symptoms, such as headache, muscle pain, and extreme fatigue.
More rare and serious symptoms include paralysis as a result of the virus spreading to the infected person’s brain and spinal cord, the CDC says.
While there is no cure for polio, there is an effective vaccine against it and thanks to its introduction back in 1955 along with a successful vaccine programme most cases were eradicated and by 1979 the US was polio-free.
Now, Americans are being urged to get the polio vaccine, with vaccine clinics being opened in light of the recent findings.
"Given how quickly polio can spread, now is the time for every adult, parent, and guardian to get themselves and their children vaccinated, State Health Commissioner Dr. Mary Bassett said.
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