BOSTON — The number of suspected cases of a rare polio-like disease known as acute flaccid myelitis has decreased by one in Massachusetts while confirmed cases in the state remain at two.
“We are still at two confirmed but down to four under investigation because the fifth case has just been determined not to be AFM and has been revoked,” a spokesperson for the Massachusetts Department of Public Health said Monday.
Nationwide, the number of confirmed cases of the condition that is most common in children and in its most severe form can result in paralysis has climbed to 80 confirmed cases in 25 states since the start of 2018, according to this week’s report from the Centers for Disease Control and Prevention.
The 80 cases are among the total of 219 reports that the CDC has received of patients under investigation for AFM.
This means the number of confirmed cases has increased by 18 in recent weeks with the number of reports of patients under investigation for AFM increasing by 92 and in an additional three more states.
In 2017, CDC received information for 33 confirmed cases of AFM in 16 states across the U.S.
The highest number of confirmed cases in recent years were 120 in 2014 in 34 states and 149 in 2016 in 39 states.
The CDC held a media briefing on AFM Oct. 16 over concerns at the increasing number of confirmed cases to date then in the country since the beginning of the year – 62 among a total of 127 cases of patients under investigation in 22 states, including a spike in August.
A week later the CDC said it had received a total of 155 reports of patients under investigation.
Last week, the CDC said there were 72 confirmed cases of AFM among a total of 191 reports received of patients under investigations in 24 states across the U.S.
The Massachusetts Department of Public Health reported Oct. 17 two confirmed cases and four suspected cases.
The following with the DPH said confirmed cases remained at two, but suspected cases had increased by one to five.
It said Monday it was the suspected diagnosis of this fifth case that had been “revoked.”
The CDC notes on its website that it has recently received increased reports for patients under investigation for AFM with onset of symptoms in August, September and October, and it had said in October it would be releasing weekly Monday updates “so people can better anticipate increases in confirmed cases over the coming months.”
Its data now shows that from August 2014 through October 2018 it has received information on a total of 404 confirmed cases of AFM across the country with most of the cases in children.
It notes on its website that it is “concerned about AFM, a serious condition that causes weakness in the arms or legs” but that “even with an increase in cases since 2014, AFM remains a very rare condition.”
It is said less than one in a million people in the United States get AFM each year.
The condition, which sometimes presents first as a respiratory condition and then progresses to muscle weakness, causes inflammation in the spinal cord and interferes with the transmission of nerve signals to and from the brain. It is partially diagnosis through an MRI.
There is no specific treatment, though some hospitals are said to have treated with immunotherapy, including corticosteroids, intravenous immunoglobulin and/or plasma exchange to improve patient outcome on a long-term basis.
There is a graph on the CDC website of confirmed AFM cases that CDC has been made aware of as of Nov. 2 with onset of the condition through Oct. 31.
The CDC said the data shown on the graph from August 2014 to July 2015 is based on the AFM investigation case definition: onset of acute limb weakness on or after Aug. 1, 2014, and a magnetic resonance image showing a spinal cord lesion largely restricted to gray matter in a patient age under 21 years.
The data shown from August 2015 to present is said to be based on the AFM case definition adopted by the Council of State and Territorial Epidemiologists – acute onset of focal limb weakness and an MRI showing spinal cord lesion largely restricted to gray matter and spanning one or more spinal segments, regardless of age.
The CDC notes that It is “currently difficult to interpret trends of the AFM data as “collecting information about patients under investigation for AFM is relatively new” and that “there may initially be more variability in the AFM data from year to year making it difficult to interpret or compare case counts between years.”
CDC has said it is “encouraging healthcare providers to recognize and report to their health department patients who they suspect may have AFM, and for health departments to send this information to CDC to help us understand the nationwide burden of AFM.”
Under “what we know” since 2014, when the CDD began tracking AFM, the CDC on its website says the following has been learned about AFM cases:
- 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.
- All of the AFM cases have tested negative for poliovirus.
- Enteroviruses most commonly cause mild illness. They can also cause neurologic illness, such as meningitis, encephalitis, and AFM, but these are rare.
- CDC has tested many different specimens from AFM patients for a wide range of pathogens (germs) that can cause AFM. To date, no pathogen (germ) has been consistently detected in the patients’ spinal fluid; a pathogen detected in the spinal fluid would be good evidence to indicate the cause of AFM since this condition affects the spinal cord.