A virus appears to be the cause behind a rash of polio-like illnesses that struck Minnesota last fall, causing paralyzing symptoms in several children, including one girl who lost all motor function and remains hospitalized.

Researchers from Minnesota and the U.S. Centers for Disease Control and Prevention reported Thursday that they found Enterovirus-D68 in the spinal fluid of one of six children who suffered acute flaccid myelitis, or AFM.

The virus caused the condition in that child and is presumed to be the cause in the other five, according to the researchers, who described their finding as a key development in addressing a puzzling national outbreak.

“[AFM] is incredibly scary for patients and families,” said Dr. Heidi Moline, the lead author of the report and the University of Minnesota’s chief pediatrics resident. “The fact that we were able to definitively identify the EV-D68 virus as the cause of paralysis in one of our Minnesota patients does suggest this virus as a probable cause in our other recent AFM cases.”

Moline said the researchers are working with public health officials to better understand the virus and how it affects children.

Quinton Hill, 7, was one of the Minnesota children affected by acute flaccid myelitis last year. He lost movement in one arm and was undergoing treatment at the time at Children's Hospital.

EV-D68 has been suspected for some time as a cause, in part because of surveillance data since 2012 showing that spikes in AFM cases emerged in lockstep with the virus every other fall in 2014, 2016 and 2018.

The virus was previously found in the spinal fluid of a California child, but contamination of the fluid had tainted those results, Moline said.

“This is the first true confirmation that we’ve had,” she added.

AFM is a neurological disorder that affects the spongy gray matter surrounding the spinal cord and damages nerves and their communication with muscles. The first public reports of AFM in 2018 showed up in Minnesota, which ended the year with 10 of the nation’s 228 confirmed cases.

The new research report was based on six children, ages 1 to 9, who were hospitalized between Sept. 19 and Oct. 1 after suffering headaches or flu symptoms that devolved into limb weakness or paralysis. The CDC released the findings in its Morbidity and Mortality Weekly Report.

Rapid deterioration

Limb weakness was reported in the left arms of two children, the right arms of two others and the left legs of two others. Five of the children improved after receiving infusions of immunoglobulin to boost their immune systems and physical therapy exercises.

One 7-year-old girl suffered rapid paralysis that has not improved. The report indicates that she has lost all voluntary limb movements but remains cognitively intact.

James Hill of Lakeville said he still can’t believe how quickly his active 7-year-old son, Quinton, went from flu-like symptoms to loss of motion in his upper left arm.

“It’s hard looking at pictures, looking back, because he was the healthiest kid you ever met,” Hill said.

Research like the study released this week, together with public awareness about AFM, should help clinicians if the pattern holds and cases surge again in the fall of 2022, but doctors still don’t know for certain the best ways to treat it, even with the role of the virus being confirmed, said Dr. Anupama Kalaskar, a co-author of the report and an infectious disease specialist for Children’s Hospitals and Clinics of Minnesota.

“Some patients received multiple treatments,” she said, “so it’s hard to tease out which may have worked and which didn’t work.”

Hill’s son regained some movement in his left elbow over the winter through physical therapy at clinics and exercises at home designed to kick-start the nerves damaged by AFM. He still can’t lift his arm from his shoulder, though.

Quinton underwent surgery in Los Angeles a week ago to transplant healthy nerves into his dormant upper left arm. The procedure was something of a disappointment, his father said, because the ideal nerves for transfer were found during the operation to be unusable. The Hills are hoping the procedure still will restore mobility after Quinton’s cast is removed.

While Quinton has been resilient and upbeat, and even showed some signs of strength-building in his biceps this winter, he still can’t push himself up with his left arm or raise it above his head.

“From our standpoint,” his father said, “we felt strongly that we needed to be able to give him every single chance to be able to move.”

Despite suspicions about EV-D68, doctors and clinicians had struggled to find it in the spinal fluid of afflicted children. The virus was found in their noses, but that doesn’t prove that it played a role in a neurological disorder, Moline said. One possibility is that the virus has already exited the spinal fluid before the paralyzing symptoms emerge, so tests simply occur too late.

The confirmation of EV-D68 does not rule out other viruses as potential causes. Nor does it rule out the possibility of environmental factors, which could explain why just one in 1 million children contract AFM due to the exposure, while most children simply suffer common colds.

Moline said it does underscore the importance of basic public health measures to reduce the spread of germs. “Our guidance at this time is really to cover coughs, wash hands, and try to prevent the spread of respiratory diseases, especially in the fall,” she said.

Cases of AFM were confirmed last year in 41 states but mostly occurred in regional clusters, presumably in states where EV-D68 and other viruses are prevalent. California and Colorado have both reported high numbers of cases since 2014.

A frustration for disease investigators is that the afflicted children seem to have little in common. In Minnesota, four of the children had no underlying health conditions, while one had cerebral palsy and suffered from seizures. Five of the six were girls. One had no prior cold symptoms, while the others had reported headaches, vomiting or diarrhea before their loss of movement.

“These children didn’t go to the same day care; they didn’t live in the same street,” Moline said. “Aside from living here in Minnesota, there wasn’t anything that was a common factor.”