Sen. Amy Klobuchar, D-Minn., has asked the Centers for Disease Control and Prevention to investigate a rare, polio-like illness spreading in her state.

The illness, known as acute flaccid myelitis, affects the nervous system by weakening patients' muscles, making moving difficult and causing a facial droop as well as slurred speech.

At least six children in Minnesota have been infected since mid-September, two of whom ended up hooked up to a ventilator in the intensive care unit to help them breathe. Some children recover while others can become paralyzed.

Klobuchar asked CDC director Robert Redfield to share how the agency was responding to the infections, saying that it appeared the rate of infections was climbing. She asked whether research was taking place and whether additional resources could be used to make the work go faster. She requested a response by Oct. 16.

Other than Minnesota, data show Colorado appears to be having a rise in infections this year. Sixteen states in all have reported cases, with 38 infections. This surpasses last year's total of 2017 but is still short of the 149 cases reported in 2016.

At least 362 patients have been infected with the illness since 2014, and it has no cure. Scientists aren't precisely sure what causes it, but they think it may result from a viral infection. The CDC has issued guidance saying people need to be up to date on vaccines, wash their hands, and prevent mosquito bites.