According to a report and updated count released November 13, the Centers for Disease Control and Prevention confirmed 90 cases of acute flaccid myelitis in 27 states so far this year, triple the number in 2017. Most of the cases have affected children. The rare but serious condition affects the nervous system, causing the muscles and reflexes in the body to become weak. Cases also surged in 2014 and 2016, to 120 and 149 respectively. About half of the 2018 cases have tested positive for enterovirus or rhinovirus, but more research is needed to better understand the condition and what is triggering the increase.