A new polio-like illness has hit at least 20 children in California in the past 18 months, according to reports compiled by state public health researchers and neurologists from Stanford and UCSF.
The American Academy of Neurology released a brief study (PDF) Monday describing cases of sudden paralysis in five of the children. The cases suggest that a new virus that causes the polio-like symptoms could be emerging, although the researchers have not yet identified the cause of illness.
Polio is caused by a viral infection. It reached epidemic levels in the United States and other parts of the world in the early 20th century, before a vaccine wiped it out in developed countries. The illness is still widespread in some parts of the world.
The first case of the new polio-like illness was identified in late 2012. So far no cases have been found outside of California. At least one of the children is from the Bay Area.
Of the five children who have been studied so far, all had received a polio vaccination. The children experienced sudden paralysis of one or more limbs, and six months later they had recovered very little motor function, doctors reported. Three of the children were sick with a respiratory illness before they developed paralysis.
Two of the children tested positive for a rare virus — called enterovirus-68 — that has been associated with polio-like symptoms before. Other strains of enterovirus have been tied to polio-like outbreaks in Asia and Australia; in fact, the virus that causes polio is also a type of enterovirus. But most people infected with any type of enterovirus, including one that causes polio, won’t experience any symptoms.
Scientists say they need more aggressive surveillance to identify other new cases and do viral testing on children with polio-like symptoms as soon as possible.
The scientists, led by Dr. Keith Van Haren at Stanford’s Packard Children’s Hospital, will discuss their report in more detail at a meeting of the American Academy of Neurology in Philadelphia, which takes place April 26 to May 3.
