At least 90 cases spread across 27 states of acute flaccid myelitis (AFM), a rare disease which can mimic the symptoms of polio, have been reported in the US this year according to the Centers for Disease Control (CDC).

At least six children in Minnesota and 14 in Colorado contracted the disease in the span of just a few weeks this past September. Minnesota's department of health says normally it only sees about one case of the disease, which can lead to paralysis or even death in some cases, every year.

The Colorado Department of Public Health and Environment's Shannon Barbare said in a statement "nearly all" of the children there have "fully recovered" from initial symptoms. All of the children are under the age of 10 and the first symptoms appeared for some of them as they recovered from a cold or a bout with the flu. There have been no AFM-related deaths reported in either state.

Nancy Messonnier, the CDC's director of the National Center for Immunization and Respiratory Diseases, said though respiratory illnesses are common this time of year, "what we don’t know is what's triggering AFM. It may be one of the viruses we have already tested. It may be a virus we haven’t yet detected. Or it could be the virus is kicking off another process and it is actually triggering (AFM) through an autoimmune process."

An incredibly rare disease

Kris Ehresmann with the Minnesota Department of Health told CBS News that the disease was "very, very rare – it's about one in a million”.

Since 2014, more than 360 cases have been reported around the US.

The US Centers for Disease Control (CDC)’s website said “this condition is not new, but the increase in cases we saw starting in 2014 is new.”

In Minnesota, there is usually only one case reported per year.

Symptoms

The disease “affects the nervous system, specifically the area of the spinal cord called gray matter”, according to the CDC.

Muscles and reflexes in the body become weak and children may exhibit signs of facial drooping, difficulty in moving their eyes, swallowing, or speaking.

They may also have trouble keeping their eyes open or have slurred speech.

Elaine and Michael Young’s four-year-old son Orville has been unable to move his right arm.

70-year-old polio survivor has used an iron lung for 64 years

They told CBS News he also had difficulties moving his legs and sitting up on his own.

Numbness is rare in patients, but some could experience limb pain or have trouble controlling their bladder.

When AFM can prove fatal is if there is a weakening of the muscles required to breathe. At that point patients would require the use of a breathing machine.

Causes and Diagnosis

State health officials have warned if any child is experiencing any of these symptoms they should be evaluated by a doctor immediately.

Like many neurological diseases, it can be brought on by viruses, environmental toxins, or genetic disorders.

The CDC warned: “Oftentimes, despite extensive lab tests, the cause of a patient’s AFM is not identified” because of it can be mistaken for other related illnesses like Guillain-Barre syndrome and transverse myelitis.

National Polio Immunisation Day in New Delhi, India

Doctors examine a patient’s nervous system, particular the places on the body where there is weakness, pain, numbness, or paralysis.

They also take pictures of the spinal cord in order to notice any abnormalities.

In some cases, doctors will do magnetic resonance imaging (MRI) to look at the brain and spinal cord more clearly.

Lab tests are also usually conducted on the cerebrospinal fluid, the liquid surrounding the brain and spinal cord.

Treatment

Though AFM is likened to polio, there is no vaccine to prevent it.

The current treatment mostly involves seeing a neurologist who may recommend physical therapy to accommodate the limb weakness.

Unfortunately research on the long-term effects of the rare disease have not been established through extensive medical studies.

Polio: iron lungs, leg braces and vaccination Show all 8 1 /8 Polio: iron lungs, leg braces and vaccination Polio: iron lungs, leg braces and vaccination A hospitalised child suffering from polio shows off his biceps to a doctor in 1947 Getty Images Polio: iron lungs, leg braces and vaccination Children being given an oral vaccine for polio, known then as infantile paralysis, in Hull during the 1961 epidemic Rex Features Polio: iron lungs, leg braces and vaccination A boy suffering from polio being treated with a type of 'iron lung' in hospital. A nurse operates the equipment at the end of the bed which controls the flow of air pressure Getty Images Polio: iron lungs, leg braces and vaccination A woman sees her new born baby whilst lying inside an iron lung as part of her treatment for Polio Getty Images Polio: iron lungs, leg braces and vaccination Polio victim Margaret Dixon watching the opening matches of the 1957 Wimbledon championships from her invalid chair Rex Features Polio: iron lungs, leg braces and vaccination Young children polio patients doing physiotherapy exercises wearing calipers against their outside beds at Wingfield Nuffield Orthopaedic hospital in Oxfordshire Rex Features Polio: iron lungs, leg braces and vaccination A five year old polio victim walks into the outstretched arms of Doctor George Deaver, faculty member of the New York University College of Medicine, during a demonstration at the Institute of Rehabilitation and Physical Medicine Getty Images Polio: iron lungs, leg braces and vaccination 6 May 1956: First injections for children against polio at the Hendon clinic Getty Images

According to the patient advocacy group the Transverse Myelitis Association some treatments are the same for the associated AFM disease since both involve an inflammation of the spinal cord.

These could be administering a “high dose [intravenous] steroids...[or] plasma exchange” according to its website.

Ms Barbare said: “There is no vaccination or specific treatment for enteroviruses. People with mild illness typically need treatment only for symptoms. However, some illnesses caused by EV-A71 and EV-D68 [viruses] can be severe enough to require" being put in hospital.

Colorado health officials said 11 of the 14 recent cases tested positive for the enterovirus A71, one tested positive for enterovirus D68, and two did not have any virus detected.

Prevention

The CDC said the poliovirus can lead to AFM so health officials in Minnesota have still urged people to keep children up-to-date on all their vaccinations.