Cases of a rare and mysterious infectious disease that primarily strikes youngsters has been on a dramatic decline for more than a month, a signal to public health officials the polio-like illness is waning for now but is not gone for good.
Acute flaccid myelitis — AFM — tends to crop up in the fall and move across the United States and elsewhere in the world, disappearing in winter. From the fall through late December, there were 215 cases, seven of which were confirmed in New York, but only 11 are under investigation nationwide this year, according to the Centers for Disease Control and Prevention.
New York State health officials, citing patient confidentiality laws, have not revealed any details about the cases other than three having occurred in New York City and four elsewhere in the state. No information regarding ages, gender or other identifying details have been released. The condition is most often diagnosed in children and teens.
While most affected youngsters develop mild respiratory illness, similar to the common cold, others are affected by lethargy and muscle weakness. Still others are so adversely impacted, they develop paralysis from which they may or may not recover.
Dr. Stefan Hagmann, a specialist in pediatric infectious diseases at Cohen Children’s Medical Center in New Hyde Park, said the affliction is similar to polio but is a distinct illness caused by a yet-to-be named pathogen in the family of microbes known as enteroviruses. The infectious agent circulates episodically and tends to affect more youngsters — for unexplained reasons — in even-numbered years.
“The condition is on a biennial cycle, every two years. For us in our practice, it is not a very common condition. But in reading the [medical] literature and reports from the CDC, there is an increase in AFM cases every other year,” Hagmann said. “Many people have compared this condition to polio for obvious reasons. This reference for us is historical because my generation [of physicians] has not seen polio in the United States.”
The disease is such a conundrum that the CDC has formed a special task force of experts to help answer questions about it. Although no definitive infectious agent has been found, some young people have tested positive for exposure to the enterovirus known as EV-D68, which circulates from late summer through early winter. EV-D68 is not considered to be the disorder’s cause, however.
“The brunt of the cases are in the warmer months,” Hagmann said. “As you get into winter, you don’t see as many cases. And that’s consistent with what we know about polio.”
Prior to the polio vaccine’s development in the 1950s, children were the usual targets of the poliovirus — an enterovirus — that generally caused illness in warmer months, especially summer.
The problem facing medical science is how to best aid patients who have permanent disabilities because of AFM.
In Manhattan, Dr. Scott Wolfe, director of the Center for Brachial Plexus and Traumatic Nerve Injury at Hospital for Special Surgery, has developed a delicate form of surgery in which healthy nerves are transferred to paralyzed areas of the body to help AFM patients regain useful function.
The bracial plexus is the complex network of nerves that send impulses from the spinal cord to the shoulders, arms and hands.
"We have been performing nerve transfers for patients with brachial plexus injuries, so it made sense to try it for AFM patients," Wolfe said. “But it’s more challenging since the disease causes almost random patterns of muscle paralysis."
Wolfe recently published his research involving two AFM cases in the journal Pediatric Neurology to demonstrate to the medical community that young people do not have to endure paralysis.
One of those patients, Kale Hyder, now 18, had paralysis in both arms and hands caused by an AFM-like disorder in 2015. AFM, Wolfe said, is a subtype of the condition called transverse myelitis, also caused by viral infection.
Hyder, a resident of Iowa, had undergone other procedures without success. His parents learned of Wolfe's research and brought their son to New York.
Wolfe performed nerve transfer surgery on each arm in 2016, followed by tendon transfer surgery a year later. The operations have restored function to Hyder's hands and have enabled him to lift his arms over his head.
"Since the procedure is so highly specialized and performed by very few surgeons, most people, even doctors, are unaware that nerve transfer could potentially help AFM patients," Wolfe said.