Stay up-to-date on your vaccinations, avoid getting bit by mosquitoes — and wash your hands.

This isn’t just good advice from Mom — these are universal recommendations for all Americans as flu season approaches, and as the Zika virus continues to spread. But federal health officials are also offering the reminders as cases of acute flaccid myelitis (AFM) — or a polio-like illness — are back and continue to spread.

Children are coming down with a febrile illness, followed by headaches, stiff neck, pain and weakness in the arms, legs, and muscles of the face and throat.

As of Aug. 31, 2016, the Centers for Disease Control and Prevention reported a total of 50 people in 24 states with confirmed AFM. The illness is occurring almost exclusively in children — the median age of those affected is seven years old. AFM can cause limb weakness, loss of muscle tone, paralysis, and in extreme cases, respiratory failure.

“We have treated a few cases, thus far,” Dr. Kevin Messacar, infectious diseases physician and researcher at Children’s Hospital Colorado, told LifeZette.

“The majority of children are presenting with a febrile illness, often with respiratory symptoms, followed several days later by headaches, stiff neck, and the development of pain and weakness in the arms, legs, and muscles of the face and throat. The imaging findings in the gray matter of the spinal cord and brainstem are the most distinctive feature of this condition.”

Dozens more cases are being observed across the country but are not yet confirmed. The CDC recorded only 21 cases of AFM in 2015.

“The disease we are currently seeing, acute flaccid myelitis … is caused by several different viruses. It is important to clarify that while polio is an AFM, the disease outbreak we are currently experiencing is not truly polio,” said Meghan May, Ph.D., an associate professor of microbiology and infectious diseases at the University of New England in Maine.

[lz_bulleted_list title=”Acute Flaccid Myelitis” source=”http://www.cdc.gov”]CDC has not yet determined who is at higher risk for developing AFM, or the reasons why they may be at higher risk.|Despite extensive testing, CDC does not yet know the cause of the AFM cases.[/lz_bulleted_list]

“There is not yet one single infectious agent that has been found in all 50 of this year’s cases, which indicates we either haven’t found it yet, or more likely perhaps we are looking at very similar clinical presentations that are caused by a few different viruses,” May added.

Since 2014, however, several studies have strengthened the association between a virus known as EV-D68 and acute flaccid myelitis, both from an epidemiological and biological standpoint. May and Messacar both believe it is likely that EV-D68 is one of several viruses causing the uptick in cases.

Who do you think would win the Presidency?

By completing the poll, you agree to receive emails from LifeZette, occasional offers from our partners and that you've read and agree to our privacy policy and legal statement.

The majority of those infected with AFM-causing viruses have a mild, flu-like illness for a few days and then recover fully. For others, while this outbreak is not polio, May said it can be just as severe an experience.

Related: Mumps Make the Rounds of College Campuses

“For those children who develop AFM, the effects are far more devastating. Clinically it’s very concerning. That said, it is an exceedingly rare event. Even though we have seen far more cases in the last few years (especially 2014 and 2016), it is still an infection rate of less than 1 in 1 million,” May told LifeZette.

[lz_ndn video=31468805]

Wash your hands, health experts say. Transmission of most AFM-causing viruses can be disrupted by simple hand washing.

“For parents and the general public, it is important to remember this is a very rare condition. Washing hands, staying home from school or work when ill, and covering the mouth and nose while coughing and sneezing are the best methods to prevent spread of illness. If a child develops weakness in the arms, legs, or muscles of the face or throat, medical care should be sought immediately,” said Messacar.

Though AFM is a rare disease, the condition merits further research into better prevention, treatment, and rehabilitation methods.