Expected rise in virus that can cripple children hasn’t happened, baffle experts

This is a story from MedPage Today.

In September, MedPage Today reported an increase in enterovirus D68 (EV-D68) cases in American children, which has been linked to a rare neurological disease that can cause polio-like paralysis in children. In this report, we follow up on what has happened since those initial reports.

The Centers for Disease Control and Prevention sounded the alarm over EV-D68 with a Health Alert Network advisory in September announcing that cases were on the rise.

Later that month, the agency reported surveillance data showing that rhinovirus, enterovirus or both were detected in 26.4% of children and adolescents with acute respiratory illnesses requiring emergency care. or requiring hospitalization. Of these, 260 (17.4%) tested positive for EV-D68, and that rate jumped to 56% by mid-August.

The most serious concern was the threat of possible acute flaccid myelitis (AFM), a rare disease associated with EV-D68 that affects the central nervous system primarily in children, causing weakening of muscles and reflexes and possibly leading to a paralysis. Previous AFM outbreaks had increased in even-numbered years (2014, 2016, and 2018).

However, as of December 1, 2022, the CDC reported that AFM had not increased as expected.

PHOTO: This 2014 electron microscope image made available by the Centers for Disease Control and Prevention shows numerous spheroid-shaped enterovirus-D68 (EV-D68) virions.

This 2014 file electron microscope image made available by the Centers for Disease Control and Prevention shows numerous spheroid-shaped enterovirus-D68 (EV-D68) virions. Scientists have found the strongest evidence yet that a virus is responsible for a mysterious and rare disease called acute flaccid myelitis, or AFM, which can start as the sniffles but quickly paralyze children.

Cynthia S. Goldsmith, Yiting Zhang/CDC via AP, FILE

“AFM cases remained low in 2022, despite an increase in circulation and enterovirus D68 infections,” said Dr. Janell Routh, who leads the AFM and national polio team for the Division of Diseases. viruses from the CDC.

“This is the first year that such a significant disconnect between EV-D68 and AFM has been observed since the association was first noted in 2014,” she said in email correspondence. with MedPage Today. The 30 AFM cases confirmed to the CDC so far this year are similar to numbers in other years without an outbreak, Routh pointed out.

“Given that enteroviruses tend to circulate in late summer and early fall, we anticipate that we won’t see an increase in AFM this late in the year,” Routh added. . “However, circulation of EV-D68 has been noted during the winter months of 2021-2022, so the CDC remains on high alert.”

As for why the two-year model didn’t hold up, “no one knows the answer to that question yet,” Routh told MedPage Today. “In general, it could be changes in the virus, host factors, or other cofactors that have changed this year to alter the course of AFM,” she suggested.

Dr. Amy Moore, of Ohio State Wexner Medical Center in Columbus, who works with patients with AFM, agreed that the decline was disconcerting. “Although we saw more patients affected than in 2021 and 2022, these are not the numbers we expected to see given that children are back in school and masks are not mandatory.

The AFM’s historical trends certainly warranted the warning. AFM has been tracked by the CDC since 2014, when 120 cases were reported in 34 states between August and December. The following year, 22 cases were reported, then the number increased again in 2016 to 153 cases.

In 2017, it was down again, with 38 cases; then cases increased in 2018 to 238.

The expectation of a flare-up had also been high in 2020. In August of that year, the CDC called a press conference warning of an expected outbreak of life-threatening acute flaccid myelitis. In particular, the CDC was concerned that the cases could be mistaken for COVID-19.

“AFM can progress rapidly and patients can become paralyzed over hours or days and need a ventilator to help them breathe,” warned then-CDC director Dr. Robert Redfield. of the briefing. “Some patients will be permanently disabled… The virus that most often causes this disease, enterovirus D68, tends to appear in 2-year cycles. This means it will circulate along with the flu and d other infectious diseases, including COVID-19.19, and could be another outbreak for clinicians, parents, and children to manage.”

However, CDC surveillance in 2020 reported 33 cases of AFM for 2020 – fewer than expected.

“The low numbers were due to the use of masking and the lack of ‘in-person’ activities due to COVID,” Moore told MedPage Today. “This trend was also observed with the RSV [respiratory syncytial virus] and the flu.”

It is now unclear whether the two-year model is predictive.

From 2014 to December 1, 2022, the CDC reported a total of 709 cases of AFM.

Cases of this rare but very serious neurological condition have coincided with respiratory disease caused by EV-D68, antibodies to which are found in the mucous membranes and cerebrospinal fluid of some AFM patients.

Researchers recently reopened the case of a boy who died of suspected AFM disease in 2008 and found EV-D68 RNA in the anterior horn neurons of his spinal cord. They reported the results earlier this year in the New England Journal of Medicine, noting that “these results support the idea that EV-D68 infection is a cause of AFM. The pathogenesis of AFM may involve a combination of the direct effects of viral infection of motor neurons in the spinal cord and damage resulting from local inflammation.”

Research is ongoing to better understand the causes and treatment of the condition.

“At this time, the CDC is finishing collecting data on confirmed cases and will review how they compare to cases from previous years,” Routh told MedPage Today. “Our partners will examine how the virus interacts with their animal models of AFM. We continue to work collaboratively with other agencies and academic centers nationwide to better understand AFM.”

Leave a Comment