Scientists have finally found evidence of a virus in patients suffering from the mysterious polio-like disease that has caused almost 600 people – mostly children – to become paralyzed temporarily and offer hope that they can find a cause and a cure.
The condition, known as acute weak myelitis (AFM), has long been suspected of having links to certain strains of enteroviruses, common causes of colds.
But doctors rarely could have found the virus lurking in the brain fluids of patients who sometimes had life-threatening, progressive paralysis.
Researchers from the University of California, San Francisco (UCSF), have found fragments of these viruses never seen before in the spinal fluid of patients.
Since the AFM was established in 2014, doctors have little more than guesses about how to treat temporarily paralyzed patients who did not test positive for a certain trigger for their conditions.
Now that the team has proven that the common virus can cause AFM, they note that the development of a vaccine against this cold-causing bug is probably the best hope to prevent AFM.
Julia Payne from Chicago, Illinois, was two when she was diagnosed with AFM, a mysterious polio-like disorder that scientists now think is caused by a common virus
AFM was first recognized in 2014, when 120 people, mainly children, were brought to hospitals across the country with staggering, sudden muscle weakness or paralysis in their limbs.
One of those children was the son of a co-author of the new study, Dr. Riley Bove.
His entire family caught what they thought it was so very cold.
But for Dr. Bove's son, then four, the disease turned into something much worse.
A few days after he started coughing, sneezing and sniffing, the boy struggled to breathe. Soon he could not move at all and could hardly breathe without the help of a gas mask.
Eventually the symptoms disappeared and the boy is now a healthy nine-year-old.
But because so little is known about AFM, Dr. Bove still lives in fear that some previously unknown complications can lift their heads at any time in the long term.
The polio-like disease that made at least 233 American children sick last year, causing many to be temporarily paralyzed.
And it could return this fall, warned the Centers for Disease Control and Prevention (CDC) in July.
Doctors must be alert to acute weak myelitis (AFM), the mysterious disease that pops up every two years, usually between August and December.
This year, 2019, should be a bad year.
Nevertheless, the CDC was concerned enough to provide a study and advice to encourage parents, and doctors in particular, to take the weakness of children's limbs seriously and act quickly.
Although there were a handful of cases of the already rare disease the following year, the AFM seemed to be declining in 2015.
But it was back in 2016, making even more people – 149 – sick than the first recognized outbreak.
And last year was the worst for AFM so far.
A total of 590 cases of the rare disease have been confirmed since it was first recognized in 2014.
Most people with AFM have associated symptoms of viral respiratory infections such as congestion, cough, runny nose and fever.
Testing samples from these patients has helped doctors to wipe out the list of potential perpetrators.
WHAT IS ACUTE FLACCID MYELITIS?
Acute limp myelitis (AFM), which is believed to be an acute limp paralysis, is a rare and poorly understood but serious condition.
The condition is thought to be caused by viruses such as enteroviruses that infect the brain or spinal cord and cause nerve damage.
Viruses that are thought to cause the condition usually only cause mild flu-like symptoms, but can cause the more severe AFM.
Symptoms include drooping / weakness in the face, difficulty in moving the eyes, drooping eyelids, or difficulty in swallowing or unclear speech.
Patients may also have a cold or fever.
Because the causes are unclear, there is no standard treatment for AFM and therapy is usually given on a case-by-case basis.
There are usually only one & # 39; handful & # 39; cases in England every year, while the US tends to go through a biennial cycle in which there will be one year with only about a dozen cases, the next year will be more than 100.
The Enterovirus D68 virus is believed to be linked to the infection and has been found in patients in both the US and the UK.
Various types of enteroviruses – which cause respiratory tract infections – have been associated with AFM cases, but there is not enough hard, consistent evidence to establish that this is the cause of the disease.
The first suspect was EV-D68, which was linked to the AFM case of 2012 that preceded the CDC's recognition of the disease.
About 90 percent of the people who developed AFM had a type of respiratory infection, but not all of them had EV-D86. Not all of them tested positive for a known enterovirus.
In attempts to prove that the virus could be the cause, doctors tested brain fluid from the spines of AFM patients for evidence of the virus, which they suspected ended up in this region and caused devastation.
& # 39; People stuck to the fact that enteroviruses were rarely detected in the brain fluid of AFM patients & # 39 ;, said Dr. Michael Wilson, senior author of the new study and professor of neurology at UCSF.
& # 39; They wanted to know how someone could get neurological symptoms without detecting a virus in their central nervous system.
& # 39; If we could detect something specific for a virus in the spinal fluid of AFM patients, we would feel safer if we claim that the neurological symptoms of the disease are virally mediated. & # 39;
He and his team started their own quest like so many others had: by trying – and failing – to find all traces of the virus themselves in the spinal fluid they took from patients.
Instead, they decided to try a new test method not looking for signs of the virus itself, but for signs of the patient's immune system responses to enteroviruses.
To double the certainty of the conclusions they could draw from those tests, the research team has compiled a library of proteins from each virus that is known to infect humans, animals, ticks and mosquitoes.
When they exposed it to the spinal cord samples from 42 children with AFM diagnosis.
Almost 70 percent of the samples had antibody responses against the enteroviruses – and not against any of the other viruses.
After the record burden of last year, the CDC has intensified its investigation into the disease, but the cause remains a mystery.
& # 39; If there is an infection in the spinal cord, antibody-producing immune cells travel there and make more antibodies. We think that finding antibodies against enterovirus in the spinal fluid of AFM patients means that the virus actually goes to the spinal cord. This helps us blame these viruses & # 39 ;, said Dr. Ryan Schubert, lead author of the study.
It is a huge step in the right direction, but there are many unanswered questions in the aftermath of the study.
Enteroviruses make so many people sick with the common cold every year, it is hardly possible to say how much they strike.
Even fewer percent of children who have a cold develop the virus, AFM is developing and scientists do not understand why the effects of the virus are primarily specific to young children.
And perhaps most frustratingly, this evidence means that the disease is caused by a virus that there is no treatment, because there are no antiviral drugs to fight enteroviruses.
The CDC has taken the tactic of reminding people to pay attention to the signs of the disease and to continue applying good hygiene to reduce the risk of transmitting all germs, including the ubiquitous viruses that activate AFM.
& # 39; Public health education is important, but it is not enough to prevent AFM, & # 39; said Dr. Bove.
& # 39; The virus is too common to avoid. A vaccine is the only way to meaningfully prevent the disease. & # 39;
If patterns from the past are an indicator, 2019 should offer a little delay in cases of AFM.
Nevertheless, 2020 is approaching, especially on the timeline of vaccine development, and if trends continue in the past, this could be the worst year for the AFM to date.
& # 39; We all hold our breath before 2020, & # 39; said Dr. Schubert.
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