Conflating disability and disease in HE

One of the things I find most interesting about this story is the way in which the titular character's family (and larger community) associates developmental disability with disease and, to some extent, infection. As modern readers, most of us went to inclusive public schools as children and many grew up with disabled schoolmates, friends, siblings, etc. We know that a mental handicap has nothing to do with disease, upbringing or some sort of moral 'predestination'. He's family, however, constantly assumes that his body is inherently unwell, to the point that they neglect his physical needs (because he's "like that") and he actually does become sick. During the hard winter, Mrs. Whipple's daughter's need warm clothes, but instead of procuring some new coats she gives the boy's warm clothes to the daughters, explaining, "He won't need so much." The implication is that His body is intrinsically different, with separate needs from the "healthy" bodies of His sisters.
Inevitably, without warm clothes for the cold, He becomes sick. This prompts a visit from the local doctor, who pronounces, "He isn't as stout as he looks...you've got to watch them when they're like that." For the reader, the reason for He's illness is apparent, but the family and the community (as represented by the doctor) do not even consider this blatantly obvious conclusion, opting instead to blame his difference, accepting poor health as part of his disability.

Before this, every raw description of the boy seems to indicate a strong, healthy young body who can lead a bull by himself and do more heavy work than any one else in his family. Nonetheless, the community (neighbors) considers Him doomed from the beginning, saying, "A Lord's Pure Mercy if he should die...It's the sins of the fathers." It is expected that He will die from this disability, which is given a transmittable (infectious) property: like a hereditary disease, He's handicap has passed down through the family, a kind of moral virus. These bullheaded, medieval attitudes towards difference/disability lead directly to the neglect He receives; lack of warm clothing, lack of care for his many injuries (because, "He never got hurt."), and the final sending away to the horrors of a state mental institution.

This conflation present in the family and community of "He" is ultimately epitomized by the conduct of the neighbor who drives He and his mother to the institution. While He weeps in impotent despair in the backseat, the driver stares ahead, "not daring to look behind him." The driver is afraid of catching whatever it is that, in the communal mind, has infected this family and manifested itself in the boy.