NOTE: This article was corrected to indicate that around 25 cases of polio-like symptoms have been reported in children in California, of which five cases have caused paralysis and will be the focus of an upcoming neurology conference in Philadelphia.  

Original story begins here: 

Health experts baffled by the recent cases of about 25 children in California partially paralyzed with polio-like symptoms have ruled out the rare, crippling, vaccine-preventable infection and are focusing on a strain of enterovirus as the possible cause. If it is, these would be the first confirmed cases in North America of a viral strain reported in other parts of the world.

The children, whose median age is 12, haven't recovered full use of their paralyzed limbs. Researchers have ruled out diseases that cause similar symptoms, like Guillain-Barré syndrome and botulism. California health officials have been quick to point out that these cases are isolated and rare.

“Although poliovirus has been eradicated from most of the globe, other viruses can also injure the spine, leading to a polio-like syndrome,” Keith Van Haren, a medical doctor at Stanford University, in Palo Alto, Calif., and a member of the American Academy of Neurology and Emanuelle Waubant, with the University of California-San Francisco, said in a case report released Sunday. “In the past decade, newly identified strains of enterovirus have been linked to polio-like outbreaks among children in Asia and Australia. These five new cases highlight the possibility of an emerging infectious polio-like syndrome in California.”

Five of these cases will be addressed at an annual meeting of the American Academy of Neurology in Philadelphia, to be held April 26-May 3.

The Los Angeles Times reported on Monday that two of the five children tested positive for enterovirus-68, a new strain of a virus that strikes millions of people worldwide annually. Researchers haven't ruled out the possibility that the other three children also contracted the virus, but the test samples weren’t good enough to detect it. All five of the children had been vaccinated against the poliovirus, which is just one version of the enterovirus. Dozens of other strains can cause diseases in humans, from mild, cold-like symptoms to potentially fatal paralysis.

Polio, a vaccine-preventable illness, has been eradicated in much of the world, but it continues to hit people in the developing world. Since the start of the year, 18 cases of polio have been reported worldwide, according to the Council on Foreign Relations: one case in Karachi, Pakistan, and the rest in southeastern Afghanistan and northwestern Pakistan.

In 2012, polio was identified in the following countries: Nigeria, Niger, Chad, Democratic Republic of Congo, Afghanistan, Pakistan and one case in India. Polio is considered an epidemic in Nigeria. In Afghanistan and Pakistan, polio has emerged in clusters. Elsewhere the infectious disease outbreaks have been isolated cases.