Polio
The August case of paralytic polio in Rockland County, N.Y., is “the first case of polio reported in the United States in nearly 10 years, and only the second instance of community transmission identified in the U.S. since 1979,” a spokesperson for the Centers for Disease Control and Prevention said in an email. “Although no additional cases of polio have been reported at this time, recent wastewater findings elevate concerns that poliovirus is present in these communities, posing a risk to those who are unvaccinated.”
Poliovirus has now been found in the wastewater of New York City and three surrounding counties: Rockland, Orange, and Sullivan.
Unlike COVID, which is spread through air and respiratory secretions, polio has primarily fecal-oral transmission, meaning it is spread by people ingesting food or water contaminated with stool.
According to the World Health Organization, up to 90% of infections are unrecognized because the person has no to minimal symptoms. Symptoms are nonspecific in the remainder. Only a small proportion of those infected go on to develop paralysis.
Paul Offit, MD, a virologist and director of the Vaccine Education Center at the Children’s Hospital of Philadelphia, told this news organization that before widespread immunization, polio “caused 25,000 – 30,000 children every year to be paralyzed and 1,500 to die. Roughly 1 of every 200 children who was infected was paralyzed. We had the inactivated vaccine followed by the oral polio vaccine (OPV). The price that we paid for the OPV was that rarely it could revert to the so-called neurovirulent type, a paralytic type.”
Use of the OPV was discontinued in 2000 in the United States but is still widely used worldwide because it is inexpensive and easier to administer than injections. It appeared that we were close to completely eradicating polio, as we had smallpox, but then vaccine-derived polio virus (VDPV) started cropping up in Africa, the Middle East, and Asia. They are mainly from the type 2 virus, as is the New York case. There have been three other cases of VDPV in the United States since 2000.
Now, Dr. Offit estimates that only 1 in 2,000 of those infected become paralyzed. This is why the CDC and epidemiologists are so concerned about the Rockland patient – that one case of paralysis could represent a large pool of people who are infected with polio and are asymptomatic, continuing to shed infectious virus into the sewage.
The CDC confirmed that it began conducting wastewater testing for polio in August 2022. In their interviews for this article, Dr. Offit and Dr. Racaniello were both critical of this, stressing that it is essential to do wastewater testing nationally, since asymptomatic polio can be expected to crop up from international travelers who have received OPV.
Many countries conduct that kind of wastewater surveillance. Dr. Racaniello was particularly critical of the CDC. “We’ve been telling CDC for years, at least a decade, Why don’t you check the wastewater?,” Dr. Racaniello said, “It’s been known for many years that we should be looking to monitor the circulation of these viruses. So we are using paralysis as a sentinel to say that this virus is in the wastewater, which is just not acceptable!”
Apparently there was some concern that the public would not understand. Dr. Offit viewed it as one more piece of necessary education: “You shouldn’t be alarmed about this as long as you’re vaccinated. If you’re not vaccinated, realize that this is a risk you’re taking.”