(CNN) - The Centers for Disease Control and Prevention says it appears the number of cases of a polio-like illness called AFM (acute flaccid myelitis) has peaked for the year.
In its weekly update on the disease, the CDC said there have been 134 confirmed cases in 33 states this year.
That's 18 more confirmed cases than reported last week.
It also said there are 165 patients under investigation for possibly having it.
AFM is found mainly in children and attacks the nervous system, leading to severe muscle weakness and in some cases paralysis.
The average age of patients this year is five years old.
There is no cure or vaccine for the disease.
It has seen a spike in the U.S. generally every other year since 2014, with a sharp increase in cases in the late summer before dropping off again in the fall and winter.