The commonly used pesticide before DDT has been blamed for causing the same symptoms. I don't recall the name of the compound, but it is covered in the book Virus Mania.

To flesh out:

Neurologist Alfred Vulpian in 1878 discovered that dogs poisoned by lead suffered from the same symptoms as human polio victims

Miezeyeski Popow in 1883 showed that the same paralysis could be produced with arsenic

Arsenic-based pesticide Paris green had been widely used in agriculture to fight “pests” like caterpillars since 1870

The insecticide Paris green, it was replaced by the even more toxic pesticide: lead arsenate around 1892

"DDT or any of several neurotoxic organochlorines already discovered could have caused the first polio epidemic if they had been used experimentally as a pesticide. DDT’s absence from early literature is little assurance that it was not used."

The commonly used pesticide before DDT has been blamed for causing the same symptoms. I don't recall the name of the compound, but it is covered in the book Virus Mania.