The US Centers for Disease Control and Prevention (CDC) has expressed concern over an increase in the number of cases reported across the United States of a rare, polio-like illness.
The disease in question?
Acute flaccid myelitis, an extremely rare condition that affects the nervous system—specifically the spinal cord—and causes weakness in the arms or legs.
From August 2014 to September 2018, a total of 386 cases of acute flaccid myelitis have been confirmed throughout the country, with 62 cases reported in 22 states for 2018 alone, Nancy Messonnier, MD, the director at the CDC’s National Center for Immunization and Respiratory Diseases, said in a telebriefing held earlier this week.
Although the CDC has not been able to pinpoint the cause for the majority of these cases, they have launched an active investigation to find more answers.
Many of the patients are presenting with symptoms similar to those of poliovirus, non-polio enteroviruses, adenoviruses, and West Nile virus. The sudden onset of weakness leads patients to seek medical care, and patients are then assessed by neurologists, infectious disease doctors, and pediatricians.
Milder cases of the disease might not be reported; however, Dr. Messonnier explained that the CDC is likely receiving information pertaining to the majority of cases. Their efforts to promote awareness of the issue is working to encourage those who might be infected with the illness to seek medical care. The CDC does not believe that the growing awareness of the rare disease is contributing to the increase in cases.
As part of their investigation, officials tested all suspected cases for poliovirus—all came back negative. Furthermore, although enteroviruses are capable of causing neurological illnesses such as meningitis, and acute flaccid myelitis, the investigators state that instances of this happening are few and far between.
Specimens collected from those affected were tested for a wide array of pathogens that can potentially cause acute flaccid myelitis. To date, none of the pathogens have been consistently detected in any of the patients’ spinal fluid, which would provide a strong indication of the cause of the condition because acute flaccid myelitis affects the spinal cord.
An influx of acute flaccid myelitis cases reported in 2014 coincided with a large national outbreak of enterovirus D68 associated with severe respiratory illness, according to the CDC. However, officials did not identify EV-D68 in every patient confirmed to have acute flaccid myelitis.
Officials will continue to explore other viruses, environmental toxins, and other avenues, in order to identify the cause of these cases, Dr. Messonnier said.
The CDC is also working on verifying clinical information reported to them by health departments and testing specimens collected from suspected cases. Other efforts are dedicated to gaining a better understanding of the disease and its potential causes, providing new information to providers, health departments, policymakers, and the public, and further exploring the potential association of the rare condition with possible causes as well as risk factors.
To do this, officials will be working with experts to review MRI scans taken from people over the last 10 years to identify how many cases of acute flaccid myelitis occurred previous to 2014. The CDC also aims to update treatment and management guidance for the disease and to work with academic centers across the country to conduct active surveillance for the condition as well as respiratory viruses.