Since 2014 there has been a nationwide increase in cases of acute flaccid myelitis (AFM), mostly in children. It is a rare condition, affecting one in one million people. It results in weakness in one or more limbs. It is likely caused by an infectious agent or toxin. We say likely because the cause remains unknown. And the reason for the increase in cases over the past several years is a mystery. To date all investigations have failed to yield a virus or bacteria. It seems to resemble poliovirus, or enterovirus infections, but the spinal fluid has not been positive for any of these.
Acute flaccid myelitis affects the spinal cord. Onset can be abrupt and in many cases recovery may be seen quickly. Recovery may be complete or otherwise leaving residual weakness in affected limbs. Why it has affected children more than adults remains unknown, but may be attributable to the fact a developing nervous system or incomplete immune response provides an easy target for the inciting agent. In all patients identified and tested thus far, neither poliovirus nor enteroviruses which may cause meningitis, have been identified in spinal fluid. Other environmental agents may eventually be identified.
While weakness of limb muscles is the presenting symptom in most cases, involvement of facial muscles resulting in weakness of eye opening, speech, and even respiratory difficulties is seen as well. Some patients have required respiratory support. Presently the Centers for Disease Control recommends that vaccinations be updated, and good health precautions be observed: hand washing is exspecially key.
Until the inciting agent is found and adequate treatment plans formulated, it is important to remember that thus far AFM is exceedingly rare. But it does remind us that continual vigilance is a necessary component of public health. While the debate rages in some quarters over the need or even the safety of vaccines, their effectiveness in curtailing the dreaded diseases of the past that cut short the lives of countless children can not be overstated. Vaccines have become victims of their own success: some are dismissive of the need precisely because they lived through a period where they never got to see firsthand the effects of pandemics of measles, or typhoid fever, or polio. One hopes that this rise in cases of acute flaccid myelitis is not the start of such a pandemic.