Health officials still don't know what causes a mysterious polio-like illness that hospitalized nearly 130 children in a year.

After an outbreak of a rare virus called acute flaccid myelitis (AFM) last year, medical experts are no closer to understanding the sickness than when it was discovered in 2014.

With around 130 cases reported last year, the CDC still does not know what causes the sickness, how it progresses or even who is most at risk for contracting it.

The syndrome affects the spinal cord and is caused by a fever which can lead to paralysis and children being hospitalized for months.

Children across the country are still recovering since they fell, with many left partially paralyzed and have difficulties walking.

There have been five cases of AFM reported so far this year but the organization has no way of knowing if it should expect another outbreak.

The CDC still has no idea behind the cause of a rare polio-like illness called acute flaccid myelitis (AFM) since it was first detected in 2014 and there was an outbreak in 2016 (file photo)

WHAT IS TRANSVERSE MYELITIS AND AFM? The term 'myelitis' means inflammation of the spinal cord. Transverse myelitis is the broad name of the disease, and there are various sub-types. It is a neurological disorder which inflames the spinal cord across its width destroying the fatty substance that protects nerve cells. That can lead to paralysis. AFM is an unusual sub-type of transverse myelitis. Patients starts with the same spinal inflammation, but their symptoms are different and the disease develops differently. Primarily, AFM patients are weak and limp, while patients with general transverse myelitis tend to be rigid. Most AFM patients start to struggle with movement of the limbs, face, tongue, and eyes, and eventually their whole body. Advertisement

The first case of AFM was detected in 2014 after scores of children were hospitalized due to the polio-like illness.

Typically, the first signs of the sickness is that patients start to struggle with movement of the limbs, face, tongue and eyes.

They then begin to lose control of one limb or sometimes the whole body - though many maintain control of their sensory, bowel and bladder functions.

Unlike transverse myelitis, which has been around for years, doctors are still in the dark about why and how AFM manifests itself.

Anthony DeCristoforo, five, and Lucas Detloff, one, are two victims who have to live with their new disability.

The two little boys from Lower Bucks County in Pennsylvania are now learning how to walk again after they both were diagnosed with AFM last year.

Anthony is learning to get around with the help of a walker and Lucas uses a wheelchair, reported the Bucks County Courier Times.

Both were left partially paralyzed in their legs due to the virus infection.

The boys are just two of the many children whose lives were altered from the rare and mysterious disease.

Tracy Ayers of the CDC revealed to a meeting of the CDC’s Epidemic Intelligence Service that there has been no progress in understanding the illness since 2014.

She said to reporters: 'We have tested for over 250 different organisms that could be causing this. We are also expanding to look at non-infectious diseases.

'After a decrease in 2015, acute flaccid myelitis cases increased during 2016 raising concerns of a resurgence.

The organization insisted that the disease is still very rare, with less than one in a million chance of contracting it.

Still the CDC issued a report warning about the illness in 2016 due to the surge in cases - a total of 138 people in 37 states for the year.

Experts don't know much about the sickness so they can't predict if this year's rates are on the rise or declining. Last year, cases rocketed in the late summer months.

Now the CDC is asking doctors to collect blood and spinal fluid samples from suspected patients at first signs of AFM because the body can quickly fight off the infection and leave no traces.

Keith Van Haren, a child neurologist at Stanford University School of Medicine, told The Atlantic in 2015 that doctors don't know how to treat or prevent the illness.

'It actually looks just like polio, but that term really freaks out the public-health people,' he said.

Although officials do not know the specific cause of the illness, the CDC reports that the polio-like illness is most similar to illnesses caused by enteroviruses, West Nile virus, herpesvirus, and the adenovirus.