The CDC said the New York State Department of Health was notified on Monday, July 18, that an unvaccinated young adult from Rockland County tested positive for polio.
The patient was hospitalized with possible acute flaccid myelitis, a serious neurologic condition that causes muscle weakness.
Since then, related polioviruses have been detected in Rockland and Orange counties.
As of Wednesday, Aug. 10, 260 wastewater samples from treatment plants in Rockland and Orange counties have been tested for poliovirus, according to an update from the CDC on Tuesday, Aug. 16.
The CDC said 21 of these samples, meaning about 8 percent, tested positive for poliovirus.
Thirteen of the positive samples were from Rockland County, and eight were from Orange County.
Health officials reported that 20 of the specimens from wastewater samples collected during May, June, and July were genetically linked to the virus from the patient’s stool samples.
Another sample from April in Orange County was sequenced as poliovirus type 2, but the sequence was incomplete, precluding assessment of genetic linkage to the case, the CDC said.
"The occurrence of this case, combined with the identification of poliovirus in wastewater in neighboring Orange County, underscores the importance of maintaining high vaccination coverage to prevent paralytic polio in persons of all ages," the CDC said.
The New York State Immunization Information System indicates that the three-dose polio vaccination coverage among children younger than 24 months in Rockland County was 67 percent in July 2020, and it declined to 60.3 percent by August 2022, the CDC said.
New York City health officials announced last week that the virus has also been detected in the city's wastewater.
“For every one case of paralytic polio identified, hundreds more may be undetected,” State Health Commissioner Dr. Mary Bassett said. “The detection of poliovirus in wastewater samples in New York City is alarming, but not surprising."
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