Emerging disease burdens and the poor in cities of the developing world.

Patterns of future urban growth, combined with advances in the treatment of traditional scourges of communicable diseases, will cause a shift in the burden of disease toward category 2 (noncommunicable) and 3 (injury) conditions over the next 30 years. Communicable diseases, particularly HIV/AIDs, will continue to be the most important killers among the poor. However, new risks will emerge for several reasons. First, the marked sprawl of cities in the developing world will make access to care more difficult. Second, increasing motor vehicles and the likelihood of inadequate infrastructure will make air pollution and accidents in road traffic more common than in the past. Third, impoverished urban populations have already shown a propensity toward undernourishment, and its obverse, obesity, is already emerging as a major risk. Also, the large projected increase in slums suggests that violence and homicide will become a more important burden of health, and very large hazards will be created by fire-prone, insubstantial dwellings that will house nearly two billion people by 2030. In addition, decentralized governance will exacerbate the tensions and discontinuities that have plagued the management of health issues on the urban fringe over the past decade. Accordingly, public health agencies will need to adjust to the regional and country-specific factors to address the changing profile of risk. This analysis suggests that four factors--levels of poverty, speed of city growth, sprawl in cities, and degree of decentralization--will have importance in shaping health strategies. These factors vary in pace and intensity by region, suggesting that health care strategies for Category II and III conditions will need to be differentiated by region of the world. Also, interventions will have to rely increasingly on actors outside the ranks of public health specialists.