So far this year, 127 confirmed or suspected cases of acute flaccid myelitis, or AFM, have been reported to the Centers for Disease Control and Prevention - a significant increase over 2017 and a worrying perpetuation of a disease for which there is little understanding. But she stressed that despite the increase in cases, the illness is still very rare, occurring in fewer than 1 in a million people in the US each year.
"We understand that people particularly parents are concerned", Nancy Messonnier, director of the National Center for Immunization and Respiratory Diseases, said in a here media briefing on Tuesday.
Messonnier stressed that while she understands how frightening this situation is for parents, they should remember that the infections are, in fact, rare.
The long-term effects of the disease are also unknown. There have been cases each year since, but the numbers have been higher on alternate years.
Still, officials saw an uptick in cases in 2014 and 2016, with peaks around late summer and fall. Cases of AFM are characterized by a sudden onset of arm or leg weakness and loss of muscle tone and reflexes. "Right now we know that poliovirus is not the cause of these AFM cases", she said.
There are now more than 125 confirmed or suspected cases of acute flaccid myelitis - the "mystery illness" that's been affecting children across the United States and leaving them paralyzed.
More than 120 confirmed or possible cases of the mysterious and rare condition have been documented so far this year, mostly since August, a top federal health official said Tuesday.
Boston Children's Hospital has evaluated all of the confirmed and suspected AFM cases that occurred in MA this year. Messonnier said West Nile virus, which had been listed as a possible cause on the CDC's website, is not causing the illnesses.
The CDC is investigating the outbreak.
The agency doesn't know who may be at higher risk for developing this condition or the reasons they may be at higher risk. Also, she said there can be lags in reporting because of the time it takes to review a patient's clinical syndrome and radiographic findings. But so far, no pathogen has been consistently detected in the patients' spinal fluid.
The CDC is investigating the cases and monitoring the disease, and encourages people to prevent the disease by staying up to date on vaccines, washing hands and protecting against mosquito bites.
The illness affects the patient's spinal cord.
AFM appears to target children at around age 4. "So we're very lucky that he had (physical therapy) through early intervention".
Cases have been reported in 22 states, including some in our area. Nor can they explain why only a handful of infected children developed AFM.
CNN reached out to health departments in every state; 48 states responded, plus the District of Columbia.
Washington Post writers Dana Hedgpeth and Justin Wm.