Will AFM Cases Decline in 2019?

The number of confirmed cases of the polio-like disorder known as acute flaccid myelitis (AFM) reached 196 in 2018 in the United States. This was up significantly from 35 confirmed cases in 2017, 149 in 2016, 22 in 2015 and 120 in 2014. Strictly on the basis on this up-and-down annual cycle, some “experts” are predicting that cases of AFM may hit “unprecedented levels” in 2020.^{1 2}

It sounds ominous. Are we talking slightly more than 197 AFM cases or a lot more than that? Nobody knows. According to a recent article in the Daily Mail, “The illness appears to surge every other year with every resurgence worst than the last.”²

“We don’t know what’s going to happen in 2020 but seeing the pattern every other year for the past four years means we need to prepare,” said infectious disease pediatrician Kevin Messacar, MD of the University of Colorado School of Medicine.³

There is also an underlying sense by some infectious disease experts that cases of AFM may be down in 2019, compared to last year. Why? Because that would be consistent with past cycles. But this is little more than speculation. The rationale for the downward forecast is based largely on past trends.

An article in Infosurhoy confidently predicted, “After a record-setting […] cases of the polio-like disease, acute flaccid myelitis (AFM) in 2018, the peak has passed and instances of it are expected to continue to decline—until 2020.”⁴ Another article in The Dallas Morning News stated, “Experts say we should expect the condition to return again in 2020, following a pattern of sickening patients every other year from summer through fall.”^{5 6}

Has the peak passed? It’s hard to tell for sure. Despite the appointment of a 16-member AFM Task Force by the Centers for Disease Control and Prevention (CDC) on Nov. 19, 2018 to investigate the cause of AFM, the cause of the disorder is still unknown.^1 7 So there is no solid scientific basis for assuming AFM has temporarily peaked in the U.S. and that we are now headed for a drop in the number of new cases.

Only time will tell if the U.S. will really have a respite from outbreaks of AFM in 2019 or if that prediction is more wishful thinking than anything else.