A few children in California have been affected with an emerging polio-like illness that causes paralyzed limbs and leaves "little hope for recovery," USA Today reported.

Five children were treated for an illness that resulted in the development of paralysis in one or more arms or legs and did not see improvements in their symptoms. They still had poor limb function after six months.

"What's we're seeing now is bad. The best-case scenario is complete loss of one limb, the worst is all four limbs, with respiratory insufficiency, as well. It's like the old polio," Keith Van Haren, a pediatric neurologist at Lucile Packard Children's Hospital in Palo Alto, Calif., told USA Today reported.

Polio is a contagious, viral disease that sometimes causes paralysis. The United States experienced a polio epidemic in the 1950s until a vaccine was introduced. In a prepared statement, Van Haren said that although the poliovirus has been eradicated from most of the globe, there are other viruses that can also injure the spine and cause polio-like syndrome.

Two children tested positive for enterovirus-68, a rare virus previously associated with polio-like symptoms. No cause was identified in the remaining three children. All of the children had been previously vaccinated against poliovirus.

Doctors do not expect an epidemic of the polio-like virus. They said infection remains rare and parents should not panic, CNN reported.

"This is really very rare," Van Haren told USA Today. "But we are asking any families who notice a sudden onset of weakness to see their doctors immediately. Their doctors should contact the California Department of Public Health."

Van Haren said he and his colleagues noticed several of these cases at their medical centers and decided to look for similar cases.

They reviewed all polio-like cases among children who had samples referred to California's Neurologic and Surveillance Testing program from August 2012 to July 2013. Cases were included in the analysis if the children had paralysis affecting one or more limbs with abnormal MRI scans of the spinal cord that explained the paralysis.

"Our findings have important implications for disease surveillance, testing and treatment," said Van Haren. "We would like to stress that this syndrome appears to be very, very rare. Any time a parent sees symptoms of paralysis in a child, the child should be seen by a doctor right away."