Parents around the U.S. are concerned about new reports this week of a frightening and mysterious – but still extremely rare – muscle-weakening disease that is primarily striking children.

Fear is a normal and understandable response in this situation, but it is not entirely rational or helpful. My message to parents: Your children have almost zero chance of getting this disease – approximately one or two chances in a million.

The disease is called acute flaccid myelitis, or AFM. It is a polio-like condition, but it is not polio, which has been gone from the U.S. since 1979.

Today the polio vaccine has almost eradicated polio around the globe, except in certain parts of Afghanistan, Pakistan and Nigeria. Worldwide cases have dramatically decreased from 350,000 in 1988 to only 22 in 2017.

The U.S. Centers for Disease Control and Prevention has been tracking AFM since 2014 and has confirmed 386 cases since then.

The CDC announced this week that at least 62 cases have been confirmed in 22 states this year and at least 65 additional children in those states may have contracted the disease. These numbers are in keeping with previous years and do not represent an increased over 2016 so far.

About 90 percent of the cases of AFM are children under age 18, with an average age of 4. Many have experienced severe muscle weakness or even paralysis in parts of their bodies, including their legs and arms, back, neck and face. These symptoms sometimes show up about a week after someone with AFM has had a fever and respiratory illness.

AFM poses a devastating and debilitating health problem for the children stricken with the disease and for their families. For the rest of us, every time there is an outbreak of a mystery disease that attacks healthy people – or especially their children – everyone worries that their children will be next in line to be afflicted.

But the rest of us need to keep the risk level in perspective. While there are 62 cases of AFM in the U.S. and 65 possible cases this year, there are more than 328.8 million people in the United States.

It is important to realize that fear is more powerful than any virus. As I wrote in my book, “False Alarm: The Truth About the Epidemic of Fear,” we in the media (even when we report carefully and accurately) magnify the fear problem simply by putting a spotlight on it.

We also must keep in mind that whatever virus, toxin or autoimmune reaction may be causing AFM, it is almost definitely not contagious. If it was, we would be seeing far greater numbers of people with the disease by now. Unfortunately, the fear AFM causes is highly contagious.

I spoke about AFM Thursday to Mark Pallansch, Ph.D., director of the Division of Viral Diseases at the Centers for Disease Control.

Pallansch is playing a major Sherlock Holmes-like role in tracking and analyzing AFM. He is a great example of a calm, informed scientist who knows how to keep risks in perspective.

Pallansch affirmed that the size of the AFM outbreak has not increased over previous cycles since 2014.

He also told me there is no current evidence that the disease is spread to people from mosquitos on other insects, or through something toxic in the environment. That’s in part because people stricken with AFM are not clustered together, but rather spread out over the 22 states.

While the cause of AFM remains unknown, Pallansch said it’s possible that the disease is caused by a virus known as a non-polio enterovirus that millions of us sometimes have in our bodies. This virus may rarely cause neurological problems, including brain swelling, meningitis or – yes, AFM.

Pallansch said the CDC has not been able to discover evidence of this virus in the bodily fluids of victims this year. Nevertheless, he believes that an enterovirus and its effects are still one possible explanation for this outbreak.

Pallansch told me that a virus like West Nile, carried by mosquitos, has not been found to be a likely cause of these cases of  AFM.

The disease is called acute flaccid myelitis, or AFM. It is a polio-like condition, but it is not polio, which has been gone from the U.S. since 1979.

In addition, Pallansch said there is no evidence whatsoever that routine vaccinations have played a role in this outbreak. In fact, there is much evidence to the contrary.

One way of learning more about a disease is to conduct autopsies on people with the disease who have died. A dissection of the spinal cord could reveal a lot. But fortunately, deaths for AFM are very rare – there was only one in 2017. This is good news, of course, even if it slows the wheels of science.

Like polio, the clinical course of AFM is unpredictable, and can range from mild symptoms that go away to severe weakness approaching paralysis, where the effects remain.

Rehabilitation can go a long way towards helping patients with AFM recover to the fullest extent possible. The term post-polio syndrome, where a new weakening of muscles can occur years later, may be applicable to AFM as well. Current patients need to be on the lookout for this.

The tiny number of AFM cases pales in comparison to the spread of polio across the U.S. before Dr. Jonas Salk developed a vaccine to protect us from the diseases in the 1950s. Before development of the vaccine, “polio outbreaks cause more than 15,000 cases of paralysis each year in the United States,” the CDC reports

In Philip Roth’s final brilliant novel, “Nemesis,” the antagonist is not a person – it is the polio virus that besieged his Newark neighborhood in the 1940s. Polio spread panic that was far more contagious than the virus was. Panic erupted from not knowing who was at risk and why.

Fear enveloped Newark because polio attacked and paralyzed young children who were in the prime of life. There was nothing anyone could do to prevent it and nothing anyone could do to treat it. The children clung to life and many were permanently afflicted.

Thankfully, the polio vaccine changed all that.

The current outbreak of AFM, though extremely small when compared to the societal devastation of polio, nevertheless brings back the horrible dread of what it’s like for a parent to see a young child stricken without warning in the midst of a day of happy playing.