"Any weakness, including trouble swallowing, weakness of an extremity, especially in a child who has recently gone through signs of an infection, those would be the main red flags", said Sarah Hopkins.
"For some previous cases, we have identified one pathogen or another, but we have no unifying diagnosis", said Dr. Nancy Messonnier of the National Center for Immunization and Respiratory Diseases.
"We have not been able to find a cause for the majority of these AFM cases", she said.
"There is a lot we don't know about AFM and I am frustrated that despite all of our efforts, we haven't been able to identify the cause of this mystery illness", Messonnier said.
Physicians first began noticing an increase in AFM patients in 2014, with roughly 120 confirmed cases. AFM appears to be seasonal, occurring mostly in the late summer and fall, but appears in greater numbers every other year.
The long-term effects are unknown.
Acute flaccid myelitis, also called AFM, is a rare but serious condition that affects the nervous system, with a particular focus on the gray matter of the spinal cord. The CDC still has not pin-pointed exactly what's causing this disorder, but they suspect a virus that circulates this time of the year.
There is no known cause or treatment, a state Department of Public Health advisory said. The first case in Maryland this year was contracted September 21, a spokeswoman for the department said in an email.
In research developments, a team based at the J. Craig Venter Institute conducted experiments to see if a specific EV-D68 genotype is linked to neurologic symptoms and found that some viruses from the 2014 outbreak can infect neuronal cells. "We recommend seeking medical care right away if you or your child develop sudden weakness of the arms and legs".
The condition is not new, but officials started to see a rise in cases in 2014; and there was another spike in 2016. The agency had a teleconference with health providers slated for later today, and it provided a toolkit for diagnosing AFM, along with instructions for reporting suspected cases. Fifteen states said they'd confirmed cases this year. But the data reported Tuesday represents "a substantially larger number than in previous months this year", Messonnier said. Less than one in a million people get it each year nationwide, the CDC estimates.
"As a parent myself I understand what it's like to be scared for your child", Messonnier said.
AFM is still extremely rare.
After testing patients' stool specimens, the CDC determined poliovirus is not the cause of the AFM cases.
The agency says there are several possible causes, including "viruses, environmental toxins, and genetic disorders". However, experts say that initial indications from a small number of cases suggest a grim outlook.
"My husband that noticed her arm was kind of just hanging there", her mother, Carlene, said.
But Messonnier said that, in general, parents can help protect their children from diseases by washing their hands, making sure their children are up to date with vaccinations and applying insect repellent to protect against mosquito bites, which can spread viruses.
In some cases children have recovered, but in others the paralysis has lingered.