New York state health officials on Thursday stepped up their push for people who have not been immunized against polio to vaccinate “immediately,” saying a confirmed case of the disease found in the state could be the “tip of the iceberg” of a much wider threat.
The emergency call came after officials said polio had been detected in sewage samples taken at different locations and times in two counties north of New York City, potentially signaling the spread of the disease in the community.
“Based on previous polio outbreaks, New Yorkers should know that for every observed case of paralytic polio, there may be hundreds of other people infected.” Dr. Mary T. Bassett, the state’s health commissioner, said in a statement.
“Along with the latest wastewater findings,” added Dr. Bassett, “the department is treating the single case of polio as just the tip of the iceberg of a much larger potential spread.”
Polio is caused by the poliovirus and children under 5 are most at risk of contracting it, but anyone who is unvaccinated is at risk. Polio is highly contagious, usually spreading from person to person when someone comes into contact with the feces of an infected person and then touches their mouth.
The fight against Polio
The highly contagious virus was one of the most feared diseases until the 1950s, when the first vaccine was developed.
Many cases are asymptomatic and some can cause flu-like symptoms, but the disease, also known as polio, can be disabling and even life-threatening. There is no cure.
Paralysis is a rare outcome, but before vaccines were widely available in the 1950s, polio outbreaks caused more than 15,000 cases of paralysis per year.
Last month, a case of polio – the first to be reported in the United States in nearly a decade – was identified in an unvaccinated adult male in Rockland County. No cases have originated in the United States since 1979.
state and county health officials said infection in Rockland County was transmitted by someone who had received the oral polio vaccine, which has not been administered in the United States since 2000.
The virus circulating in New York may have originated outside the United States, where the oral vaccine is still administered, officials said. The oral vaccine contains weakened virus. It is safe, but if the vaccine-derived virus circulates in a community, it can infect unvaccinated people and spread the disease.
In announcing the case, officials noted that the infected person was no longer contagious and said their efforts will focus on increasing vaccination rates and determining whether anyone else may have been infected.
Officials have said polio was found in Rockland County sewage samples taken in June, before the polio case was confirmed. On Thursday, they said evidence of the disease was also found in sewage samples taken in June and July from two “geographically different” parts of Orange County, which is adjacent to Rockland.
“The findings,” the state Department of Health said in a press release, “provide further evidence of local — not international — transmission of a polio virus.”
There was no indication that the man infected in Rockland County was the source of the polio found in the sewage samples, officials said. The investigation into the origin of the virus is ongoing.
Because widespread vaccination has proven to be an effective prevention strategy, areas with low immunization rates may be at particular risk of an outbreak.
In both Rockland and Orange counties, approx 60 percent of 2-year-olds have received all three doses of the polio vaccine, according to state data — a rate significantly lower than the 80 percent in the rest of the state, with the exception of New York City. (To achieve herd immunity for polio, target vaccination rate it’s 80 percent, according to the World Health Organization.)
Most adults in the United States do not need to be vaccinated against polio because they were most likely immunized as children, although some may be eligible for booster shots if they have an increased risk of exposure.