The city's Department of Health and Mental Hygiene announced on Friday that polioviruses were found in New York City wastewater. That means polio is likely to be circulating in the city.
The virus was detected in May, June and July in Orange County and Rockland County, north of New York City. One case of polio was found in Rockland County last month in an unvaccinated adult.
The New York City Health Commissioner Dr. Ashwin Vasan said that the defense is so simple - get vaccinated against polio.
The Centers for Disease Control and Prevention recommends a three-dose series of vaccines in early childhood, plus a booster dose between 4 and 6 years old.
Almost all people get shots as part of their routine childhood immunizations. Around 86% of children ages 6 months to 5 years old have received all three doses in New York City. Statewide, 79% of New Yorkers have received three or more doses by the age of 2.
The polio vaccine rates in Orange and Rockland counties are lower, at around 60% among children under 2 years old.
New York State Health Commissioner Dr. Mary Bassett said the discovery of polio in New York City wastewater was alarming but not surprising. In a statement, Bassett said that hundreds more could be unnoticed for every case of polio identified.
The Rockland County patient was infected with vaccine-derived polio, a strain linked to live, weakened virus used in an oral polio vaccine that is no longer administered in the U.S.
A person who takes the oral polio vaccine can briefly shed the live virus, so if a community has a low vaccination rate, the virus can spread. If it circulates widely enough, it can be more virulent.
Vincent Racaniello, a professor at Columbia University, said we need to do some sewer surveillance to find out how extensive it is. I would guess that in major cities where people are traveling from countries where they are using the infectious vaccine, you'd find it in the sewers. Polio is highly infectious, but around 72% of people infected have no visible symptoms, according to the CDC. Another 25% may have flulike symptoms that tend to resolve within a few days. Polio rarely causes permanent paralysis of the arms and legs. It can also cause meningitis swelling of the brain and spinal cord membranes or paresthesia of the feeling of pins and needles in the legs. The CDC estimates that between 2% and 10% of cases of polio are fatal. The fatality rate for adolescents and adults is higher: 15% to 30%.