You have the theory reversed. It's that hookworms caused lethargy, which was perceived as laziness. As a result, the southern accent has become associated with

You have the theory reversed. It's that hookworms caused lethargy, which was perceived as laziness. As a result, the southern accent has become associated with laziness. Personally, I think it's more related to negative opinions about the South following the Civil War, which is why even upper-class southern accents face the same stigma.