As a growing number of cases continue to emerge nationwide involving a mysterious, polio-like illness that paralyzes children, federal investigators are expanding their search to identify the likely cause.
The U.S. Centers for Disease Control and Prevention (CDC) issued an update on Monday, indicating that there may be nearly 300 cases of acute flaccid myelitis (AFM) nationwide, with 116 confirmed cases in 31 states, and another 280 reports of paralysis that remain unconfirmed.
The illness was first detected in 2014, and cases of AFM-associated paralysis have increased every year since then. The CDC is continuing to review the reason for the growing number of paralysis cases, with many experts suggesting that the pattern points to a viral cause.
Since 2014, there have been at least 440 confirmed AFM cases throughout the U.S. That first year, 120 cases were identified from August to December. In 2015, 22 cases were confirmed, but in 2016, the number detected increased to 149 confirmed. While only 33 cases were confirmed in 2017, the number of cases has surged yet again this year, establishing an every other year pattern.
The majority of cases, more than 90%, affect children. Since 2014, cases have been detected among individuals in nearly every state.
Of the 440 cases, a total of four have tested positive for a confirmed virus. Viruses detected in the spinal fluid include enterovirus (EV) D68, coxsackievirus A16, and EV-A71. All other cases show no confirmed pathogen, indicating researchers have not found a definitive cause yet.
AFM is a rare condition that affects the nervous system, specifically the area of the spinal cord called gray matter. The condition is marked by a sudden onset and affects the muscles and reflexes, which can make the limbs weak or lead to paralysis. That is why many researchers refer to the illness as “polio-like.” However, the illness is not caused by the polio virus. All stool samples have tested negative for the poliovirus.
Most of the patients impacted by AFM experience a mild respiratory illness or fever about 10 days before they developed paralysis. Thus, researchers believe it could be triggered by a viral infection. Yet, it could be something else completely which is triggering the ailment. One theory is that it could be a person’s immune response to an infection or a genetic factor.
The CDC indicates it is working with state and local health departments to continue the investigation into the cause of the paralysis cases. Furthermore, the agency is focusing on risk factors and attempting to determine why some people with viral infections contract AFM and others don’t.
The agency also launched a new study at seven different pediatric hospitals across the U.S., focusing on enhanced surveillance of the illnesses. CDC officials believe this will allow researchers to compare case counts with current repository viruses in these locations and identify a pattern. They are also exploring potential treatment options.