Disease shaped cities in many subtle and not so subtle ways, from water systems to public health institutions.  Cholera Epidemic in New York City in 1832 – New York Times. Curiously, though, attitudes about the sick–marginalizing them and blaming them–appear to have been based in preexisting societal norms. They demonstrate how those at the margins of society have been blamed for the sickness in different times and places.  To wit, quoted from the article linked above:

"Unlike most upper-class residents, John Pintard, the respected civic
leader who was the historical society’s founder, remained in the
stricken city. His letters to one of his daughters are included in the
exhibition.

The epidemic, he wrote in an attitude typical of his
peers, “is almost exclusively confined to the lower classes of
intemperate dissolute & filthy people huddled together like swine
in their polluted habitations.”

In another letter, his judgment
was even harsher. “Those sickened must be cured or die off, & being
chiefly of the very scum of the city, the quicker [their] dispatch the
sooner the malady will cease.”

Dr. David D. Ho, a biomedical scientist at Rockefeller University, noted the similarities between the views on cholera and the initial
reaction to a more recent epidemic that took science by surprise: AIDS.

When the first AIDS cases were reported in 1981, the victims were almost all white gay men. They were treated as outcasts."

For a slideshow of primary documents, see: http://www.nytimes.com/slideshow/2008/04/15/science/20080415_CHOLERA_SLIDESHOW_index.html