Posted Oct. 9, 2024. Past health advisories and alerts are archived for historical purposes and are not maintained or updated.
AFM is a rare but serious acute-onset paralytic disease. Although AFM can occur in people of any age, it mainly affects children.
As we enter the fall season, increased circulation of respiratory pathogens, including enteroviruses, is anticipated. Circulation of Enterovirus D-68 (EV-D68) has been associated with an increase in cases of AFM in previous years. While Washington has had zero AFM cases reported so far in 2024, at least 14 cases of AFM have been reported in the US, and wastewater monitoring has indicated increased circulation of EV-D68 in recent weeks.
Cases of AFM were first reported to the CDC in 2014; surveillance for AFM in Washington was implemented in 2015.
AFM is a rare condition that affects the spinal cord, resulting in muscle and nerve weakness similar to the clinical presentation for polio. Most people with AFM have sudden onset of arm or leg weakness with loss of muscle tone and reflexes in the affected limb (or limbs). Although AFM has a variety of possible causes, it is strongly suspected that AFM is caused by a viral respiratory pathogen such as enterovirus.
Enterovirus D-68 (EV-D68) is believed to be the main enterovirus circulating in prior years with elevated cases (including 2014, 2016, and 2018). In past years, increases in EV-D68 respiratory disease have preceded cases of AFM by about 2 weeks. Although we are seeing increases in EV-D68 detections in the United States this year, the number of reported cases of AFM has remained relatively low to date. As of September 18, 2024, CDC has received 23 reports of suspected AFM, with 14 confirmed cases in 11 states. There have been no cases of AFM reported in Washington for 2024. Cases of AFM were reported in Washington in 2016 (10 confirmed cases), 2018 (11), and 2023 (1).
The identification of a paralytic polio case in an unvaccinated person in New York in 2022 reinforced the need to also consider polio in the differential diagnosis of patients with sudden onset of limb weakness. Clinicians should obtain whole stool samples from all patients with suspected AFM to rule out poliovirus infection. This is particularly important if the patient is under-vaccinated or unvaccinated against polio, and if the patient has a history of recent travel to an area at high risk for polio.
For additional questions, or to report suspect cases, please contact SRHD Epidemiology at 509-324-1442 (business hours) or 509-869-3133 (after hours).