Cities and infectious diseases: Controls and challenges

From the 19th century to the present, cities have played a central role in the introduction, transmission, and control of infectious diseases. Throughout this period, immigration, commerce, transportation, and an expanding habitat have introduced infectious agents into urban populations. Transmission is enhanced through concentrated poverty and segregation, decaying infrastructure, and patterns of social behavior and substance abuse. Despite advances in diagnostic and therapeutic medical technologies and public health interventions, infectious diseases present an ongoing threat to urban populations. Multiple levels of factors can affect the introduction and spread of disease, including individual factors, local social and physical environments, municipal policies, and national and international trends. In the short run, few public health authorities have the capacity or resources to intervene on all levels to achieve control of infectious diseases. Reducing poverty, segregation, and substance abuse are worthy but long-term goals. Fortunately, evidence from the public health responses to resurgence and outbreaks of disease, such as multidrug-resistant tuberculosis and AIDS, shows that even limited activities can make an immediate difference. Aggressive case finding, isolation, and treatment accomplished a reversal of the resurgence of multidrug-resistant tuberculosis in New York City.123 Some evidence suggests that outreach education and programs such as needle exchange resulted in drastically lower incidence of HIV infection in New York and other cities.124, 125 To build on these successes and short-term strategies, funding for surveillance (locally and nationally), detection (including state, national, and international reference laboratories), clinician training, public education, and accessible and affordable preventive and therapeutic services applied broadly at the local and national levels is needed to achieve sustained control of infectious diseases. Social supports, community agencies, civic association, and market influences have received limited attention in the public health literature for the role they might play, but they hold great potential for incorporation into a strong long-term strategy. The example of the mobilization of the gay community to educate about AIDS, provide supportive services, and lobby for successful modifications of regulatory practices for novel medications is instructive and should be developed for use by other populations. In the development and implementation of a strategy for immediate as well as sustained responses to the spread of infectious diseases in cities, a broad conceptual approach should be considered that takes into account control at multiple levels.