Last week, the World Health Organization declared that Zika virus is no longer a global public health emergency. While last year’s outbreaks and Zika’s rapid spread to new areas prompted “urgent and coordinated” research and action under International Health Regulations, authorities have agreed to transition to a more sustained response to address the continued threat of Zika. WHO still stresses that Zika remains a serious public health problem.
It is too soon to know yet whether health authorities at multiple scales will continue to support a strong response to Zika now that WHO has declared the emergency over, though observers have expressed fear of reduced funding for research. The history of public health and infrastructure suggests some patterns to watch out for. Outbreaks such as this have often been symptoms, at least in part, of long-term official neglect of sanitation, housing, or water infrastructure. Consider, for example, the 1993 epidemic of cryptosporidiosis in Milwaukee, WI, most frequently blamed on poorly-maintained water filtration systems.
While Milwaukee’s outbreak was quite generalized throughout the population, many others strike poor neighborhoods and regions the hardest as infrastructure degrades because of injustices beyond the control of resident communities. In such cases, diseases become a constant part of the health landscape – much as Zika appears to be doing. Tuberculosis plagued black neighborhoods in Baltimore in the early twentieth century as racial segregation practices crowded African-Americans into the city’s most depreciated housing. Similarly, Zika has afflicted Brazilian favelas and their counterparts in other countries the most severely – poor neighborhoods where inadequate municipal sanitation leaves trash that collects standing water where Aedes aegypti mosquitoes breed. Streets and informal housing may be riddled with pockets that also collect water, and holes that allow Aedes inside. Communities in Latin America have struggled for decades with other viruses borne by the same mosquito, notably dengue fever, chikungunya, and yellow fever.
I have since 2012 been the environmental historian/urban geographer on a research team examining the distribution of a related mosquito, Aedes albopictus, in Baltimore. A. albopictus has yet to transmit a local case of Zika in Baltimore (there have been travel-related cases), but decades of racial segregation and infrastructure neglect has cast a long shadow on mosquito ecology here. Illegal trash dumping, inadequate waste collection, and most of all abandoned buildings are prevalent in neighborhoods deprived of loans for home maintenance by redlining in the 1930s. These areas have three times as many mosquitoes as mostly-white neighborhoods privileged with fairly constant levels of investment in infrastructure.
Reflecting on the history of outbreaks from typhoid to smallpox to SARS, Judith Walzer Leavitt and Lewis Leavitt have challenged governments and the public to seize upon infectious disease crises as opportunities to reinvest in robust public health infrastructure, broadly conceived, for the benefit of all. Global and local societies have left their poorest members to live with persistent threats to health and well-being. Zika’s continued threat presents yet another chance to funnel fear of disease into support for communities from Brazil to Baltimore.