https://en.wikipedia.org/wiki/Trichuriasis#Vector
From reading that, seems to me it would have been strange for them not to have been infected.
Back in the early 1950s, I was walking through the woods with my 5 year old brother when he had a sudden need to take a dump. As I prepared to cover it with some dirt I saw these little white worms squirming around in it. About 1/2 to 1 inch long. We ran home and called the doctor. He said “pin worms” and subscribed a medicine. None of the rest of the family—parents, other brother and myself had them. They cleared up quickly. Doctor said probably gotten from playing in the dirt as they come from other animals.