Dr. Marc Siegel: Stop criticizing the CDC on mystery muscle-weakening disease

The number of confirmed cases of acute flaccid myelitis (AFM) in the U.S. this year has reached 90, with an additional 162 cases still under investigation and the total confirmed cases since 2014 rising above 400. AFM is a condition involving sudden onset of weakness and loss of reflexes due to a lesion or inflammation in the spinal cord. It is most commonly found in young children.

Now, the Centers for Disease Control and Prevention (CDC) has begun to receive heated attacks in the media and even from some of its own advisors for not confirming the source of this mysterious condition.

I don’t agree with the critics. In fact, having interviewed the CDC’s director of viral diseases Mark Pallansch a few weeks ago, and determined that the CDC’s investigation is both thorough and extensive, I consider the current attacks on the CDC to be unfounded and unfair.

Here’s why:

First, the incidence of AFM does not appear to have increased since 2014. Rather, it is cycling, with the even years having more cases than the odd years. The condition remains extremely rare, with the overall incidence being less than one in a million people in the U.S. Exact etiologies of rare conditions are often elusive.

Second, there is no reason to believe AFM is contagious. The CDC is tracking that possibility closely and continues to rule it out. This is very useful and important information to the public, where fear spreads more rapidly than any virus.

A lot more scientific work needs to be done, but blaming the CDC along the way is neither fair nor productive. 

One of the CDC’s main roles is to put risk of disease in perspective, and its administrators are performing this role well. This is a huge improvement over the way the CDC handled health scares in the prior decade. As I documented in my book “False Alarm: The Truth About the Epidemic of Fear,” until recently, the CDC would stoke the fear of outbreaks of viruses like bird flu, even though the possibility of outbreak was remote.

And just because the CDC can’t determine an exact cause, it doesn’t mean that its scientists are asleep at the switch.

As Pallansch mentioned, it is possible that AFM is an ultra-rare post-viral syndrome of a common virus. In other words, by the time the inflammation of a spinal motor cell occurs, causing sudden onset of weakness (mostly in children), evidence of the virus in the cerebrospinal fluid or blood may be gone.

The CDC announced Tuesday that almost all patients with acute flaccid myelitis this year first showed signs of viral infections. Further, CDC has tested body fluid specimens from 71 patients this year and 54 percent of these showed positive tests for non-polio enterovirus A71, EV-D68 and several other viruses.

EV-D68 affects the respiratory tract (similar to a rhinovirus which causes the common cold), and the CDC has been keeping a close eye on it since it was found to be associated with some cases of AFM back in 2014. Although it was not found in every patient, these may have been cases in which by the time the medical crime was discovered, the perpetrator had already left the scene.

Still, during this year’s outbreak, the lack of proof of cause and effect from a culprit virus has helped engender the unfair criticism. But speaking to Pallansch gave me the distinct sense that a highly competent group of scientists is hard at work to prove the cause.

Pallansch acknowledged that autopsy studies could provide the missing evidence of spinal cord cross sections. But fortunately, AFM is rarely deadly, and of course no scientist wishes for death to supply the data that science requires.

The symptoms of AFM vary from subtle to profound weakness. It is certainly possible that many cases are not being reported despite extensive CDC tracking. I do believe that reporting of cases to the CDC or state health departments by physicians should be mandatory.

Recovery also varies. Early diagnosis and treatment with physical therapy are useful in improving outcomes.

Identifying a culprit strain (or strains) could lead to earlier diagnosis and possibly a vaccine. A lot more scientific work needs to be done, but blaming the CDC along the way is neither fair nor productive.