ABSTRACT
Historically, the spread, prevalence, and very existence of contagious disease have wholly depended on the growth and concentration of human populations. And though the last half-century has witnessed substantial worldwide success in combating many past scourges such as polio and smallpox, infectious diseases still claim more lives than any other group of diseases. In both industrial and developing nations, incidences of a wide range of infectious diseases, including tuberculosis, diarrheal diseases, and HIV/AIDS, are considerably higher in urban slums where poverty and compromised health define the way of life than in the rest of the city. Overcrowding the increased proximity of susceptible individuals is a principal risk factor for the incidence and spread of all major infectious diseases, including tuberculosis, dengue fever, malaria, and acute respiratory illnesses, which are unable to spread and survive in low population densities.
