This year, more than half of all US states have had confirmed or possible cases of acute flaccid myelitis, the polio-like illness that can cause paralysis and mostly affects children, according to an exclusive CNN analysis.
In total, CNN found 47 confirmed cases and 49 more that were suspected or being investigated, for a total of 96.
CNN found that Colorado had 14 confirmed cases, more than any other state, followed by Texas with eight and Minnesota with six.
Acute flaccid myelitis, also called AFM, is a rare but serious condition that affects the nervous system, with a particular focus on the gray matter of the spinal cord.
The CDC has seen an increase in cases since August 2014. Although the cause remains a mystery in the majority of cases, the 2014 jump coincided with "a national outbreak of severe respiratory illness among people caused by enterovirus D68," though it wasn't found in all patients, according to the CDC.
Other enteroviruses have also been found in patients with AFM. For example, 11 of the Colorado cases of AFM this year have tested positive for EV A71, a rare type of enterovirus not usually seen in the US, rather in Asia and other parts of the world, according to state epidemiologist Dr. Rachel Herlihy.