[Developing countries] At least 600 million urban dwellers in the developing world live in what might be termed "life and health threatening" homes and neighbourhoods, and have inadequate or no access to health care. Infant mortality rates can be as much as five times higher in low income settlements than in the more prosperous middle class areas in the same city. They have the "worst of both worlds" with the traditional infection diseases plus affluent society diseases.
The World Health Organization in 1997 reported the increased incidence in developing countries of diseases usually associated with the industrialized nations: heart disease, stroke, and cancer.