Polio could have been widespread for a year, and was present in New York’s sewage as early as April, according to a new report from the Centers for Disease Control and Prevention.
A wastewater sample collected in April in Orange County, NY, tested positive for the virus, pushing back the earliest known detection in the area. Officials have previously announced that the virus was found in wastewater samples dating back to May in neighboring Rockland County.
Changes in the virus’s genome suggest that this version has been circulating, somewhere in the world, for up to a year. Genetically similar versions of the virus were discovered in Israel in March and in the UK in June.
New research provides more details from the ongoing investigation into a polio case discovered in New York last month, when officials announced that a young man in Rockland County was paralyzed by polio. This is the first report of polio in the United States since 2013.
Joseph Eisenberg, an infectious disease epidemiologist at the University of Michigan, said the finding was not surprising, especially given that polio is highly contagious, often spreading without causing serious symptoms. important. “It can circulate quite widely, be in the spotlight, before you really start to see cases of paralysis,” he said.
Officials had previously warned that the Rockland County patient was most likely “tip of the iceberg, the tip of the iceberg. “
New research reveals that polio vaccination rates are as low as 37% in some county ZIP codes.
According to the study, the unvaccinated patient was hospitalized in June after developing symptoms including fever, stiff neck and lower extremity weakness. Poliovirus, which is spread primarily through feces, was later detected in the patient’s stool.
Gene sequencing revealed that the patient was infected with a version of the virus derived from the oral polio vaccine, containing a weakened version of the virus. Oral vaccines have not been used in the United States since 2000. (American children are routinely vaccinated with injectable vaccines.)
Oral vaccines are safe and effective, but people who get them can shed the weakened virus in their stools for weeks, potentially infecting others. In communities with many unvaccinated people, the virus can continue to circulate and eventually acquire enough mutations to become dangerous.
The discovery of the Rockland case prompted health professionals to begin examining wastewater samples collected in the area, including those previously collected for coronavirus monitoring.
Officials previously announced that they had found the virus in 20 wastewater samples collected in Rockland and Orange counties and all were genetically related to the patient sample.
New research reveals that a 21st sample, collected in Orange County in April, also tested positive for the virus. However, there is not enough information about the genome to link it to other samples with certainty.
Two hundred and sixty wastewater samples from Rockland and Orange Counties had been tested as of August 10, and polio had been detected in 8% of them, according to the new study.
“This shows that there is a lot of community transmission under observation,” said John Dennehy, a virologist and wastewater monitoring expert at Queens College.
Virus was also found in six wastewater samples from New York City.
The report notes that the Rockland County patient was exposed to polio for one to three weeks before developing symptoms. According to the study, the patient did not travel abroad during this time, but attended “a large gathering of people”.
Polio was detected in wastewater in Rockland County 25 days before the patient developed symptoms, indicating that others had been infected before.
“The fact that we saw it in wastewater 25 days earlier means that he may not be the second case,” said Dr. Eisenberg.
People who have received three doses of inactivated polio vaccine are very well protected against the virus, but the virus can be dangerous to unvaccinated people, including children too young to vaccinated.
Nationally, polio vaccination rates are relatively high. But there are many places in the country, including New York, where vaccination rates are much lower, and the pandemic has pushed back childhood immunization campaigns.
As of July 2020, only 67% of Rockland County children over 24 months of age had received three doses of the polio vaccine, a number that has dropped to 60% this month, according to the study.
After the discovery of the case in Rockland County, the local Department of Health began a vaccination campaign, but the number of injections was “not sufficient to significantly increase” vaccination rates, researchers report. study report.