The crowded and unsanitary conditions in working-class urban districts created new habitats in which previously uncommon pathogens thrived. Infectious diseases weren’t receding here. In fact, in the middle of the nineteenth century they accounted for about 40 percent of deaths in England and Wales, with the figures much higher in urban areas.[25] In London they were responsible for 55 percent of deaths, and in parts of Liverpool and Manchester the figure was about 60 percent.
