Changes in the genetic makeup of the polio virus suggest it has been spreading somewhere in the world for a year, a report from the CDC found.
The report, published Aug. 16, found that genetically similar versions of the virus were detected in Israel in March and in the United Kingdom in June, although the origin of the transmission remains unknown. Researchers also found that an April wastewater sample collected in New York contained the virus, but there was not enough information to genetically link it to other samples.
"This suggests that there is a lot of community spread under the radar," John Dennehy, a virologist and wastewater surveillance expert at Queens College in New York City, told The New York Times on Aug. 16.
The first polio case in the U.S. in nearly a decade was reported July 21, with Mary Bassett, MD, the state’s health commissioner, warning Aug. 4 that it may be the "tip of the iceberg."
"Even a single case of paralytic polio represents a public health emergency in the United States," the CDC report said, adding that "Vaccination plays a critical role in protecting persons from paralysis if they are exposed to poliovirus."