Comment Digging through the soil? (Score 2) 270
The way I heard it was that it was the use of untreated fertilizer in the fields and gardens that was the primary cause of the infections.
I suppose, sitting barefoot in an outhouse with no floor, that the hookworms working their way up from the pit could be a contributive factor.
But, shoes, yes. One of the reasons for the tradition of wooden geta in Japan was the general use of untreated (human) fertilizer in the rice paddies. The tradition of taking the shoes off on entering the house was also in no small part derived from the problems with the dirt.
And most parasites have a debilitating effect on the host, which is going to effect IQ and behavior in general.