A health official has issued a stark warning that there could be hundreds or even thousands of undiagnosed cases of polio in New York. The alarming intervention comes after an announcement last month revealed an unvaccinated man was paralyzed by the virus in Rockland County, prompting urgent calls for vaccination against the potentially lethal illness. “There isn’t just one case of polio if you see a paralytic case. The incidence of paralytic polio is less than 1%,” Rockford County Health Commissioner Patricia Schnabel Ruppert told the BBC. “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.”