What The CDC Knows & Does not Know About AFM 

What We Know as of July 2017
What we know about the AFM cases for which CDC has received information:

* Most patients are children.

* The patients’ symptoms have been most similar to complications of infection with certain viruses, including poliovirus, non-polio enteroviruses, adenoviruses, and West Nile virus. See a list of viruses associated with AFM.

    * Enteroviruses can cause neurologic illness, including meningitis. However, more severe disease, such as encephalitis and AFM, is not common. Rather, they most commonly cause mild illness.

* CDC has tested many different specimens from the patients for a wide range of pathogens (germs) that can cause AFM. To date, we have not consistently detected a pathogen (germ) in the patients’ spinal fluid; a pathogen detected in the spinal fluid would be good evidence to indicate the cause of AFM since this illness affects the spinal cord.

* The increase in AFM cases in 2014 coincided with a national outbreak of severe respiratory illness among people caused by enterovirus D68 (EV-D68). Among the people with AFM, CDC did not consistently detect EV-D68 in the specimens collected from them. In 2015 no cases of EV-D68 were detected. CDC did not receive information about large outbreaks of illness associated with EV-D68 detections in the United States in 2016. But information about sporadic cases of EV-D68 infections were sent during that time. Learn more about EV-D68.
What We Don’t Know

What we don’t know about the AFM cases for which CDC has received information:

* Despite extensive testing, CDC does not yet know the cause of these AFM cases.

* It is unclear what pathogen (germ) or immune response is causing the weakness and paralysis.

* CDC has not yet determined who is at higher risk for developing AFM, or the reasons why they may be at higher risk.

See Prevention for information about how to protect your family from viral infections that may cause AFM.
What CDC Is Doing

CDC is actively investigating AFM cases and monitoring disease activity. We are working closely with healthcare providers and state and local health departments to increase awareness for AFM and encourage sending information about AFM cases to CDC. CDC actively investigates the AFM cases, risk factors, and possible causes of this illness.