MONDAY, Oct. 21, 2019 (HealthDay News) — A new antibody test appears to have honed in on the most likely cause of a mysterious polio-like disease that regularly sweeps through the United States.
The new test detected antibodies for two types of enteroviruses in the spinal fluid of dozens of patients diagnosed with acute flaccid myelitis (AFM), a disease that causes potentially permanent and sometimes life-threatening paralysis in young children.
The two viruses, EV-D68 and EV-A71, previously had been found in cases of AFM, but this study provides the clearest evidence to date that the disease is caused by an enterovirus, researchers said.
“It certainly lays the groundwork for further testing so we can be confident that most, if not all, of AFM cases are caused by enteroviruses,” said lead researcher Dr. Ryan Schubert, a clinical fellow with the University of California, San Francisco’s (UCSF) department of neurology.
This explanation would make sense, since polio itself belongs to the family of enteroviruses.
AFM usually causes weakness in the arms and legs, but in rare cases can cause life-threatening respiratory failure, according to the U.S. Centers for Disease Control and Prevention.
AFM has tended to strike in the United States every other year, with 236 cases reported in 41 states in 2018, the CDC said.
The first wave of AFM hit in 2014, when 120 children across 34 states were stricken with mysterious muscle weakness. Another wave hit in 2016, with 149 patients affected in 39 states.
Until now, researchers looking into the causes of AFM have searched for the presence of enteroviruses by looking for direct genetic evidence of the viruses in people’s spinal fluid, Schubert said.
Enterovirus outbreaks are common and usually cause nothing more severe than common cold-like symptoms, but experts realized that these outbreaks tended to coincide with spikes in AFM, the study authors explained in background notes.
Unfortunately, tests looking for the RNA of enteroviruses in AFM patients tended to be less-than-adequate, Schubert said.
The virus could not be found in 98% of AFM patients who had their spinal fluid tested, and even when found the viruses are “detected at very low levels,” Schubert said.