1013 GMT March 22, 2019
It is still not clear what’s causing the kids to lose the ability to move their face, neck, back, arms or legs. The symptoms tend to occur about a week after the children had a fever and respiratory illness.
No one has died from the rare disease this year, but it was blamed for one death last year and it may have caused others in the past.
What’s more, Centers for Disease Control and Prevention officials say many children have lasting paralysis. Close to half the kids diagnosed with it this year were admitted to hospital intensive care units and hooked up to machines to help them breathe.
The condition has been likened to polio, a dreaded paralyzing illness that once struck tens of thousands of US children a year. Those outbreaks ended after a polio vaccine became available in the 1950s. Investigators of the current outbreak have ruled out polio, finding no evidence of that virus in recent cases.
The current mystery can be traced to 2012, when three cases of limb weakness were seen in California. The first real wave of confirmed illnesses was seen in 2014, when 120 were reported. Another, larger wave occurred in 2016, when there were 149 confirmed cases. So far this year, there have been 158 confirmed cases.
In 2015 and 2017, the counts were far lower, and it is not clear why.
The condition is called acute flaccid myelitis, or AFM. Investigators have suspected it is caused by a virus called EV-D68. The 2014 wave coincided with a lot of EV-D68 infections and the virus ‘remains the leading hypothesis’, said Dr. Ruth Lynfield, a member of a 16-person AFM taskforce that the CDC established last month to offer advice to disease detectives.
Why would the virus suddenly be causing these paralyzing illnesses?
“This is a key question that has confounded us,” said the CDC’s Dr. Nancy Messonnier, who is overseeing the agency’s outbreak investigation.
Experts also said it’s not clear why cases are surging in two-year cycles.
Another mystery: more than 17 countries have reported scattered AFM cases, but none have seen cyclical surges like the US has.
Last week, CDC officials said the problem had peaked, but they warned that the number of cases would go up as investigators evaluated – and decided whether to count – illnesses that occurred earlier.