New York health officials say they're keeping an eye on nearly two dozen polio-like illnesses in California, but infectious-disease experts say it's unlikely the cases are a sign of widespread disease.
Word of the illnesses emerged last week as five cases are to be presented in April at the annual meeting of the American Academy of Neurology, which convenes in Philadelphia.
Dr. Keith Van Haren of Stanford University, lead author of the upcoming study, said he uncovered the cases in a state database known as the Neurologic and Surveillance Testing program. The children's illnesses occurred between August 2012 and July 2013 and were not part of an outbreak. All had been vaccinated against polio.
The infections are impervious to anti-viral medications, the California study shows.
Dr. Gil Chavez, California's state epidemiologist, said there are at least 20 known cases, and doctors are being asked to report any others.
In New York, the State Health Department confirmed no known cases of a polio-like paralytic disease have been reported on Long Island or elsewhere in the state. New York City's health department, which is separate, also confirmed no such illnesses have been reported.
Dr. David Hirschwerk, a specialist in infectious diseases at North Shore University Hospital in Manhasset, said although polio was eradicated in this country in 1979, other pathogens remain injurious to the central nervous system.
California officials, he said, are still investigating which pathogenic agent infected the children, but at least two of the illnesses may have been caused by enterovirus-68, Hirschwerk said.
"There are a number of enteroviruses and in this [region] we often see enteroviral infections in the spring, usually viral meningitis.
"But most patients recover without any sequelae," he said, referring to aftereffects.
Paralysis linked to enteroviruses, he said, is marked by flaccidity in the limbs. It is not to be confused with a condition called Guillain-Barre syndrome, which in rare instances occurs after vaccination, causing weakness in the feet, hands and trunk.
Hirschwerk said enteroviruses -- like the poliovirus -- are passed through the fecal-oral route, which means someone ingests fecal matter containing the pathogen.
"Enteroviruses are ubiquitous and are found everywhere," said Dr. Pascal Imperato, dean of the School of Public Health at SUNY Downstate in Brooklyn.
Enterovirus-71, he said, is another pathogen linked to polio-like illness, Imperato said.
"Outbreaks have occurred in settings of resource poor areas of the world -- Cambodia, parts of China and Taiwan," Imperato said.
He said there is no reason for panic in this country because outbreaks do not occur here and may be associated with malnutrition and other cofactors.
"This cluster in California is of some concern, albeit a small cluster," Imperato said. "We still have a lot to learn about certain enteroviruses and their behavior."