(CNN) Six children in Minnesota have been diagnosed with a rare "polio-like" disease since mid-September, state health officials said.
Acute flaccid myelitis, known as AFM, affects the body's nervous system -- specifically, the spinal cord -- and can cause paralysis. Unlike polio, there is no vaccine for AFM.
Minnesota typically sees less than one case a year, the state Department of Health reported. The disease typically affects children; all the recent cases in Minnesota were in children younger than 10.
AFM can develop from a viral infection, although its exact cause is unknown. Symptoms include limb weakness, facial drooping and trouble swallowing or talking. Doctors stress the importance of recognizing the early signs of AFM and seeking care as soon as possible.
Treatment focuses only on alleviating symptoms.
AFM cases first spiked in the United States in August 2014. By the end of that year, 120 people had been diagnosed in 34 states.
The increase coincided with a national outbreak of severe respiratory illness caused by enterovirus D68. From August 2014 through August 2018, the US Centers for Disease Control and Prevention received information on 362 cases of AFM across the United States.
Thirty-eight cases of AFM have been confirmed in the United States so far this year, according to the CDC. They have been reported in 16 states. There were 33 in 2017 and 149 in 2016.
The CDC says it's important to practice disease prevention steps: staying up to date on vaccines, washing hands and preventing mosquito bites.