Colorado health officials expect the number of cases involving a rare viral infection that has hospitalized dozens of children in the state to dwindle as winter draws nearer.
Earlier this month, health officials warned that they were investigating an unprecedented number of cases involving enterovirus A-71, and that some of those cases involved acute flaccid myelitis, a polio-like condition that affects the nervous system.
Health officials said they expect the number of enterovirus A-71 cases to taper off because the virus is seasonal.
“There is usually an increase in enteroviruses in the summer and early fall,” said Shannon Barbare, spokeswoman for the state Department of Public Health and Environment, in an email. “Enterovirus season is over, so we don’t expect these numbers to increase significantly.”
Health officials don’t know why they saw upticks in enterovirus A-71 or acute flaccid myelitis across the U.S. in recent months. But the number of acute flaccid myelitis cases has tended to spike every other year since 2014.
In 2014, there were 11 cases of acute flaccid myelitis, or AFM, in Colorado, “and that was the most we’ve seen until this year,” said Dr. Rachel Herlihy, a state communicable disease epidemiologist.
As of Monday, there have been 42 confirmed cases of enterovirus A-71 and 15 cases of acute flaccid myelitis in Colorado. Twelve of the acute flaccid myelitis cases have tested positive for enterovirus A-71, according to the health department.
There have been no deaths from the condition and almost all of the children have fully recovered, Herlihy said.
Enteroviruses are common and can cause cold-like illnesses, along with hand, foot and mouth disease and skin rashes. Some types can cause more serious illnesses, such as the rarer acute flaccid myelitis.
Acute flaccid myelitis affects a person’s spinal cord and can cause weakness in their limbs. Symptoms are similar to complications of other viruses, such as enteroviruses, poliovirus and West Nile virus, according to the U.S. Centers for Disease Control and Prevention.
The number of cases involving enterovirus A-71 and acute flaccid myelitis might go up slightly in the coming weeks as more diagnoses are confirmed, Herlihy said.
The health department is waiting on confirmation of about three potential cases of acute flaccid myelitis, she said.
Herlihy said the outbreak of enterovirus A-71 and acute flaccid myelitis appears to have started earlier in the Colorado than it did in other states.
Acute flaccid myelitis cases have been confirmed in at least 24 states so far, with the CDC saying it saw a jump in reports for possible cases of acute flaccid myelitis in August, September and October.
Across the U.S., there have been 191 reports of acute flaccid myelitis, including 72 confirmed cases. A large number of these cases have involved individuals 18 years and younger, according to the CDC.
Officials at the federal agency said they did not know why there’s been an increase in acute flaccid myelitis, and that most of the causes of the condition are unknown.
“CDC continues to actively investigate the AFM cases, test specimens and monitor disease activity,” said Kate Fowlie, a spokeswoman for the CDC, in an email.
