Scary. I had a mild case of Polio as a child back in 1956 and it went undetected for a year.
My wife was born in 1950 when the Polio epidemic was still going. Both Polio and TM attack the Myelin Nerve Sheaths and are similar in damage done. I was with her when the TM hit. She walked into a local mall and collapsed. I carried her out to her car {we were on a date and hadn't married yet} and then went to the hospital under police lights and siren escort.
Some theories on TM link it to previous Polio virus or a virus variant but not contagious to others. I'm going on older info of the top of my head. In my wife's case her limbs showed up probably post Polio with issues such as short arms making transferring from a wheel chair impossible for her.
Back in 1985 Gillian Barre Syndrome was also showing up & was caused mainly by the Swine Flu Vaccine at that time. Her Neurologist kept asking her if she had taken any recent vaccines. He was also at a loss as to the cause of what had happened and he was one of the top notch docs in Knoxville. It took a year to get the Transverse Myelitis diagnoses and six months of hospital and rehab time. She got her arms and hands back about 75% usage. Her legs don't function. GBS hits the respiratory system while TM usually doesn't unless the damage is above C-4 level of the spine. My wife was hit at C-5 C-6 level.