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Health consequences of living in cities
INFECTIOUS DISEASES
Infectious diseases are a major threat in many cities due to population density, overcrowding, lack of safe water and sanitation systems, international travel and commerce, and poor health-care access, particularly in urban slums. The 2003 outbreak of SARS (Severe Acute Respiratory Syndrome) is a case in point. Other infectious conditions, such as the human immunodeficiency virus (HIV), tuberculosis, pneumonia and diarrhoeal infections, have an ongoing presence in cities. Frequently, it is the urban poor who suffer the greatest burden. Slums are productive breeding grounds for tuberculosis, hepatitis, dengue, pneumonia, cholera and diarrhoeal diseases, which spread easily in highly concentrated populations. Women face particular vulnerability to HIV infection, stemming from a combination of biological factors and gender inequality. Female drug users and sex workers are particularly at risk; stigma, discrimination and punitive policies only increase their vulnerability.
Source: Hidden cities: unmasking and overcoming health inequities in urban settings. World Health Organization, 2010.
The most important reason why infectious diseases are a problem in big cities is the
