Why did crowded Industrial Revolution cities experience outbreaks of typhoid fever and dysentery?

During the Industrial Revolution, rapid urbanization led to population growth that far outpaced available housing and infrastructure, creating conditions where sanitary facilities were primitive and inadequate. In these crowded cities, human waste was often discharged into open ditches or improperly managed, which frequently resulted in the contamination of the water supply used for drinking, cooking, and cleaning.123

Outbreaks of typhoid fever and dysentery occurred because these diseases are transmitted through the ingestion of food or water contaminated by the feces of an infected person. Without modern sewage treatment or separate, underground water and sewage systems, pathogens thrived in the densely populated urban environments. It was not until the development of sanitary reforms, such as the Public Health Act of 1848, that cities began to implement the necessary infrastructure to curb these epidemics by effectively separating waste from the water supply.4521