Detroit is no stranger to excessive contagion.
The cholera epidemics of 1832 and 1834 led the city to develop a sewerage (yes that is the correct term) system that most comprised of cementing over historic rivers and creeks (i.e. Connors Creek). Cholera was found to spread when human waste was dumped into the river and collected along the wharfs that no longer jut out from the riverfront.
The 1918 spanish flu pandemic led to mass support for investment in the public health system with additional funding for the Herman Kiefer Health Complex, which opened in 1919. The complex was shuttered in 2013 and has since been sold to a developer in 2015.
The map above is from the [Michigan] State Board of Health – Report of Secretary, 1893 showing:
[…] instances where diphtheria was reported to have been carried from one locality to another; the lines connect the localities, and the arrow-heads indicate the direction of movement in each case. […]
It will be noted that in 1892 Detroit was the greatest source of contagium. The evidence in this map bears upon statements made later in this article, that “The evidence of the spread of diphtheria from cities is conclusive, etc.”