Dec 13, 2018 - Health

Hunting down the cause of AFM

Data: CDC; Chart: Harry Stevens/Axios
Data: CDC; Chart: Harry Stevens/Axios

Public and private health officials are dedicating a good chunk of resources toward investigating acute flaccid myelitis (AFM), the rare polio-like illness that mainly strikes young children, not only because it's devastating but also due to concerns it could develop into something affecting larger numbers of people, an expert at Children's National Health System tells Axios.

Why it matters: While AFM reached a record high this year, the illness remains rare and some question the public resources dedicated to it. But "there's some concern that it could evolve to something larger" due to its similarity to polio, says Roberta DeBiasi, CNHS chief of the division of pediatric infectious diseases. "It's better not to start when there's a large number of patients."

What's new: Cases of AFM have reached a record high in the U.S., with 158 confirmed in 36 states this year so far, according to the Centers for Disease Control and Prevention. While CDC spokesperson Jason McDonald says there's been a "marked reduction" of new cases since October, numbers may go up as the agency reviews more files.

The biggest concern is causation. The CDC is looking into 3 main tracts: a viral infection directly in the motor neurons, an indirect infection that leads to an immune response affecting the motor neurons, and genetic factors that may increase a patient's susceptibility.

  • The task force, which presented its initial findings to the CDC last week, says enterovirus D68 (EV-D68) remains the "leading hypothesis for virus trigger" despite the fact that a majority of cases tested negative for the virus in respiratory specimens and only 1 patient had it in their spinal fluid
  • An immune response is less likely although still possible due to the short period between illness and paralytic symptoms, DeBiasi says. Usually a secondary immune response hits patients 1–2 weeks later, but these patients are experiencing symptoms 1–7 days later. "It's still plausible, but not classic."
  • Getting samples and diagnostics early may be key to determining the cause, the task force said, so it recommends stronger provider education and earlier diagnostics testing.

What we know: Data collected since 2014 indicates ...

  • Patients are young (between 2–12) and tend to be boys (61%) more than girls (39%).
  • 87% have a respiratory illness or low-grade fever shortly before the limb weakness suddenly strikes.
  • The limb weakness and paralysis appear to strike more quickly than other paralyzing illnesses and poliovirus has been ruled out.
  • The cases so far have been spiking every other year.

The bottom line: "The task force's deliberations thus far further demonstrate the complexity of AFM in children and the long road ahead in finding the cause and treatment of this condition," McDonald says. Besides the CDC's task force, there's a large multi-institution organization of U.S. and Canadian providers examining clinical evidence and recommendations, DeBiasi adds.

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