When children come down with an illness that renders them temporarily paralyzed, public health officials tend to want to know why.

In 2014, there was a nationwide outbreak of a viral illness known as enterovirus D68. Part of a family of viruses that often spread during the summer, this particular outbreak caused respiratory illnesses in thousands (possibly millions) of children across the country, in many cases quite severe. Around the same time, a number of children were afflicted with some form of paralysis, leading to concern that the two phenomena were connected. This connection was not firmly established at the time, though ultimately over 100 children were affected.

A new case study reported in the journal Emerging Infectious Diseases suggests that a different virus may have been responsible for at least one case of virally-induced paralysis. Researchers from the University of Virginia School of Medicine describe the case of a 6-year-old girl who was admitted to their medical center with weakness of her right arm in fall of last year. These symptoms had been preceded by a mild upper respiratory illness, with low fever, cough, and runny nose. Shortly before she started having trouble moving her right arm, she also had pain in the limb and under the arm.

When a sample taken from the back of her nose was analyzed, it came back positive for the enterovirus C105. Though from the same family as the virus that caused the outbreak of respiratory illnesses last year, this virus is different.

As the authors of the study note, enterovirus C105 was first detected five years ago in patients from both South America and Africa. Though it is newly discovered, thus far most identified infected patients have had some kind of respiratory illness. However, for some patients in the Congo, it was associated with fatal flaccid paralysis.

Though the symptoms some of the paralyzed patients experienced last year were polio-like, and the poliovirus is part of the same family of viruses as this new virus, it is important to note that these patients did not have polio. That illness, which caused paralysis in tens of thousands of patients in the middle of the past century (PDF), is nearing worldwide eradication thanks to a vigilant vaccination campaign. Children who came down with a paralytic illness last year weren’t infected with a vaccine-preventable illness.

In the case of the girl in Virginia, after several months she had made a near-complete recovery. Whether or not enterovirus C105 was responsible for any of the other cases of paralysis in children last year has not been established. However, there also appears to be little evidence linking the outbreak of the respiratory infection to those cases, either. Of 41 patients tested for enterovirus D68, only eight were positive, and no patients were found to have that virus in their spinal fluid. Though the authors cannot totally exclude the possibility that the D68 strain had also infected the patient they describe, they note that there was no outbreak of that illness in Virginia in 2014.

Whatever the cause of the paralytic illness in children last summer, there is no cause for anyone to be alarmed now. While it’s important to determine as best as possible what causes any illness that threatens public health, and the appearance in this country of a virus previously only identified in patients on other continents is an interesting development, it was only confirmed in one patient. While vigorously knocking on wood, I note that this summer has thus far been free of another outbreak of either form of enterovirus.

But even if enterovirus C105 never causes another illness in the United States, it’s good to be closer to an answer as to what paralyzed over 100 children last year. While the Ebola scare dominated the headlines at the time, these illnesses actually affected many more people in this country. This new case report may be an important clue in figuring out why.