Baffled by the sudden increase in children with arm or leg paralysis in the United States, health officials said on Tuesday they were investigating whether a virus or an autoimmune disorder might be the cause.
252 cases of conditions known as acute flaccid myelitis (MFA) are being investigated throughout the country, up from 33 since last week, said Nancy Messonnier, director of the National Center for Immunization and Respiratory Disease at the Control Center. and Disease Prevention (CDC).
With 80 cases confirmed so far this year, 2018 seems to be at the same pace as in previous peak years such as 2014 (120 cases) and 2016 (149 cases), compared to the Messonnier.
Since 2014, the year in which the syndrome appeared, more than 400 cases have been confirmed through laboratory tests.
Several dozen cases were registered in 2015 and 2017.
Messonnier said he understood parents' alarms, but stressed that the interference was still "rare" in terms of frequency.
The majority of cases occur in children between two and eight years. Almost everyone has fever and respiratory disease for three to ten days before suddenly experiencing paralysis in their arms or legs.
In some children, paralysis then disappears, but at least half has not recovered, said Messonnier.
The center analyzed 125 spinal fluid samples and half of them tested positive for rhinovirus or enterovirus, which usually produces symptoms such as fever, runny nose, vomiting, diarrhea and body aches.
However, scientists are still confused about the exact cause of sudden paralysis, because this virus is common, but the MFA does not.
"We tried to find out what were the triggers that could cause someone to develop an MFA," Messonnier told reporters.
"This might be one of the viruses that we detected, maybe a virus that we haven't detected, or maybe the virus triggered another process that actually activates MFA, through an autoimmune process," he said.
"The CDC is a science-driven agency, and nowadays, science doesn't give us answers," he added.
Perhaps the most frustrating thing for parents is that there is no way to prevent it, or special therapy or intervention.
"Parents and caregivers are encouraged to seek immediate medical attention for a child who develops sudden weakness of the arm or leg," said the latest CDC report on the MFA, published on Tuesday.
Messonnier said the CDC has not followed up on all MFA cases since 2014, which has resulted in some gaps in federal agency knowledge about the disease, which is now being resolved by experts.
A child with MFA died in 2017, the report said.