A terrifying outbreak of a polio-like illness appears to be caused by a new strain of a common virus, according to what researchers say is the strongest evidence yet linking enterovirus-68 to the cases of child paralysis. The outbreak of limb paralysis has hit 115 children in 34 states since August, and researchers who looked at dozens of patients found the genetic signature of the new strain of the virus, reports the New York Times. The researchers, whose work was published in the Lancet Infectious Diseases journal, believe the strain they've called B1 emerged around four-and-a-half years ago, right around the time when the first mysterious cases of paralysis appeared.
The researchers say they didn't find any other germ that could be responsible, although it's tough to find definitive proof of B1 infection. "This is a virus that causes the common cold," researcher Dr. Charles Chiu of the University of California, San Francisco tells NBC News. "Parents don't bring their kids in until they are really sick. By that time, typically, the viral levels may be very, very low or undetectable." He says the illness may also be linked to the genetic makeup of patients, with the paralysis caused by a "hit-and-run" immune system reaction to the virus instead of the virus itself. "I can't emphasize how scary this is," the chief of infectious diseases at Children's Hospital Los Angeles tells the Times. "You have a normal child, and then all of [a] sudden they are pretty incapacitated."