You've probably heard about the scary polio-like illness that's infected at least 155 people across the country. Acute flaccid myelitis, or AFM, is a very rare but very serious virus that affects mostly children. Symptoms include muscle weakness and even paralysis, and the disease seems to come on very suddenly. What's even more concerning is that up until very recently, the Centers for Disease Control has been unable to identify what, exactly, is causing the illness.

However, doctors who've been treating kids with AFM believe they've figured out the cause, even if the CDC is hesitant to make the connection.

As more and more cases have been confirmed, the CDC has been trying to find a common link between the kids with AFM. But doctors who have been treating the patients seem pretty sure that enterovirus D68, or EV-D68, is the common denominator among the cases. The CDC has been hesitant to say that enterovirus D68 is the cause, because the virus has not been found in all confirmed cases of acute flaccid myelitis.

But doctors say that means that the virus has simply evolved over the years. This could explain why the CDC isn't catching it. It can also explain why the virus seems to be attacking children's spines more that it has in the past.

Additionally, the doctors involved in treating cases of AFM have traced an increase in enterovirus D68 to outbreaks of acute flaccid myelitis.

Enterovirus D68 doesn't normally attack the nerve tissue in the spine. But tests on the virus conclude that it is indeed possible. Even if the CDC doesn't want to conclude that the virus causing AFM is, in fact, enterovirus D68, doctors are sure whatever is causing it is viral. But, it's important to remember: as scary as acute flaccid myelitis is, it's still incredibly rare.

And while there is no vaccine to prevent AFM, there are several treatments that have been effective as reversing the damaged caused to the nerve tissue in the spine. If your child experiences sudden muscle weakness, difficulty using their limbs, or paralysis, seek medical treatment immediately to have them tested for AFM.

The sooner they're tested and treated, the better the chances they have of making a full recovery.

READ MORE: Several Kids Have Developed This Rare, Polio-Like Illness