The outbreak of acute flaccid myelitis last year was widely considered to be caused by the enterovirus D68 strain, but the condition might be caused by another, less common, enterovirus strain about which doctors should be aware.
Investigators at the University of Virginia Children’s Hospital, Charlottesville, discovered that the C105 strain of enterovirus might cause acute flaccid myelitis in pediatric patients, after a 6-year-old girl presented last October with symptoms of the condition during the outbreak, which affected more than 100 children across the United States.
“We followed Centers for Disease Control and Prevention protocols in evaluating her,” Dr. Ronald B. Turner, who treated the patient in October, said in an interview. However, blood tests yielded the C105 strain, not the more common D68 strain that Dr. Turner had expected. So far, it is still the only known case of acute flaccid myelitis caused by the C105 strain, but that doesn’t mean it will be the last.
When the patient presented at Children’s Hospital, she exhibited a dropping right shoulder and difficulty using her right hand, as well as a cough, headache, and fever of just above 100° F. However, there were no signs of speech, swallowing, or respiratory difficulties, and sensation was intact.
Dr. Turner and his colleagues performed an MRI on the patient, which showed “longitudinally extensive gray matter hyperintensity within the central cord [with] associated edema,” and an MR image of the brain proved “unremarkable.” The patient was put on a regimen of daily 2 g/kg intravenous immunoglobin for 5 days, but pain in her right arm, lower back pain (her back also exhibited a diffuse papular rash when first examined), and bilateral thigh pain when walking continued.
Despite being unresponsive to treatment, there was no further degradation in pain or mobility, and the patient was discharged. However, the patient’s pain resolved itself “spontaneously,” according Dr. Turner and his colleagues, with her right arm strength and movement almost fully healed after nearly 8 months.
Now, Dr. Turner and his colleagues are urging doctors nationwide to keep in mind that enterovirus D68 is not solely responsible for acute flaccid myelitis. “We’re not saying that [enterovirus C105] is the cause of all cases, but D68 is not the final answer on this,” said Dr. Turner, adding that physicians should keep an open mind as to the causes of this condition and make sure to look at all possible causes.
To that end, the investigators at the University of Virginia have published a case study in the CDC’s Emerging Infectious Diseases (2015 Oct. [ doi:10.3201/eid2110.150759 ], detailing the case that brought about the discovery of enterovirus C105’s connection to acute flaccid myelitis. Because the discovery of enterovirus C105 is relatively recent – it was first detected in Peru and the Republic of Congo in 2010 – the need for awareness, particularly among American physicians, is critical.
Why did the C105 strain cause the acute flaccid myelitis, and what explains the patient’s quick recovery? Dr. Turner advises waiting “until the CDC has finished its examination; [the agency has] specimens from over 100 kids with [acute flaccid myelitis]. But in the end, I don’t think we’ll end up with a satisfactory or unifying answer to this,” he said.