The polio case in Rockland County revealed last month remains a mystery, but so far no one else has turned up with the virus, the CDC said Tuesday.
New York health officials disclosed the case on July 21; an unvaccinated man in his 20s presented with symptoms that included partial paralysis, and the once-dreaded disease was confirmed with follow-up testing.
Subsequently, authorities indicated that wastewater samples from Rockland and Orange counties as far back as April showed the presence of the virus. Just last week, New York City said the virus was in its wastewater as well.
The CDC, in a new report on the case Tuesday, said it was only the second confirmed community transmission of polio in the United States since 1979, and the first of vaccine-derived polio virus type 2 (VPDV2).
Get Tri-state area news and weather forecasts to your inbox. Sign up for NBC New York newsletters.
While it's still not clear where the one known patient got the virus, the authors said there is at least some indication of where it started.
"Because the patient had not traveled internationally during the potential exposure period, detection of VDPV2 in the patient’s stool samples indicates a chain of transmission within the United States originating with a person who received a type 2-containing oral polio vaccine (OPV) abroad; OPV was removed from the routine immunization schedule in the United States in 2000," the authors wrote.
"Genome sequence comparisons have identified a link to vaccine-related type 2 polioviruses recently detected in wastewater in Israel and the United Kingdom."
News
Retrospective testing of wastewater samples found copies of the virus genetically linked to the one infecting the Rockland patient at least seven days before the person's possible exposure period, suggesting the virus was circulating well before he was infected.
The CDC also said investigators had identified three more people as of Aug. 10 with symptoms and possible geographic exposure, but none of the three had tested positive for polio.
