After eight children in Washington state were diagnosed with acute flaccid myelitis (AFM) last week, doctors are scrambling to find answers about the polio-like condition that has recently surged in the United States.

AFM first garnered attention in 2014, when more than 120 people were diagnosed across the country. The number of cases fell to 21 in 2015, but the disease has spiked again this year: Last week the U.S. Centers for Disease Control and Prevention (CDC) announced a total of 89 cases between January and September.

Even with the increase in cases, AFM is an extremely rare disease, the CDC points out. Still, the organization is concerned because it does not know what causes AFM or how to prevent it.

“It appears that AFM is not just one disease,” Malcolm Thaler, MD, a primary care physician at One Medical Group in New York City, explained in an email to Health. “Rather, it’s the most severe manifestation of infection with a number of different viruses, including some that typically cause uncomplicated respiratory infections (adenoviruses), West Nile virus, and a class of viruses called enteroviruses, which includes polio.”

RELATED: 15 Diseases Doctors Often Get Wrong

What’s most disturbing is how swiftly the disease can damage the nervous system. “People who have AFM syndrome experience a rapid onset of weakness in one or more limbs,” says Aileen Marty, MD, a professor of infectious diseases at Florida International University.

“The median age of victims is 7 to 9 years old, and most report having suffered from an illness, usually one that includes a fever about five days, before they begin to get better for a little bit, and then develop headaches, stiff neck, or pain in the neck and back,” Dr. Marty explained in an email. Respiratory symptoms (such as a runny nose, cough, and sore throat), as well as vomiting and diarrhea, may also occur.

“Initial presentations vary,” says Dr. Marty, but the clinical symptoms of AFM include weakness or paralysis and reduced muscle tone in the arms or legs, drooping eyelids, facial droop, slurred speech, and difficulty swallowing and moving the eyes. “The signs and symptoms are indistinguishable [from polio] on clinical grounds,” she says.

RELATED: 12 Vaccines Your Child Needs

Why some people develop this condition with devastating consequences is difficult to pin down. “It’s usually a combination of time, place, exposure, environment, and personal risk factors (including genetics) that determine if an individual becomes ill with AFM,” says Dr. Marty.

There is no specific treatment for AFM, but it may involve immunosupressors, steroids, and plasmapheresis, a blood replacement procedure. Five of the eight children with AFM in Washington state have been sent home with their families; three are still being treated at the hospital. (The sudden death of a six-year-old boy last week was thought to be the first in this cluster of cases, but tests have shown he did not have AFM, CNN reports.)

Despite the troubling spike in AFM, it’s important to keep in mind that the odds of getting the disease are less than one in a million. “I can't stress enough that AFM is very, very uncommon,” says Dr. Thaler. “While concern is certainly appropriate, anxiety and panic are not indicated and never do anyone any good in any case.”

RELATED: I Survived the Bubonic Plague (Yes, You Read That Correctly)

Dr. Thaler suggests simply following your normal stay-well routine to protect your family from germs. “Take the usual steps to avoid mosquito bites, make sure to wash your hands and your child's hands frequently (especially after changing diapers), and avoid touching young children with unwashed hands in order to minimize exposure to and transmission of viral infections.” If you’re around someone who’s under the weather, he adds, it’s best to avoid kissing, hugging, and sharing glasses and eating utensils.

Finally, make sure you and your kids are up to date on recommended vaccinations, especially the polio vaccine.  “Getting a polio virus vaccine greatly reduces your risk of AFM,” says Dr. Marty.