‘Polio-like’ virus not linked to poliovirus

Dear Dr. Roach: I am reading about an illness called acute flaccid myelitis that is baffling scientists. Isn’t this just polio renamed? — V.A.

Acute flaccid myelitis is indeed a medical mystery. The current outbreak absolutely is not caused by polio, however. Many people are referring to it as “polio-like” because it causes sudden neurological symptoms, especially weakness and especially in young children, just as polio did before the vaccine was adopted. However, the diagnosis of polio requires finding poliovirus, and the people affected in the current outbreak have been tested for, and do not have, poliovirus.

The last case of polio originating in the United States was in 1979. Vaccination for polio is still important, however, because it potentially can be brought by a traveler from one of the few areas where there is still wild polio.

There have been outbreaks of acute flaccid myelitis in the United States and Canada every fall for years; however, it seems to have be increasing in incidence since 2014. It remains a rare disease, on the order of one person per million per year.

There is a virus related to poliovirus called enterovirus D68 that is suspected to be one of several causes of acute flaccid myelitis. West Nile Virus is another suspected cause. The Centers for Disease Control and Prevention tests samples from affected children with the condition and has not consistently found a single cause.

There is no specific treatment for AFM, just as there is no treatment for polio when it affects the nerves. Supportive treatment in the early phase, and physical and occupational therapy during convalescence are the only accepted treatments. The prognosis is variable, with some children having excellent recoveries and others having more significant neurological impairment.