Fertilizer Use and the Epidemiology and Evolution of Cholera in Bangladesh
The use of chemical fertilizers in developing countries made possible the Green Revolution, and as a result many regions once visited by periodic famines are now food self-sufficient. However, there is a growing recognition that the injudicious use of chemical fertilizers may have adverse environmental consequences including toxic algal blooms and damage to productive ocean fisheries. This project examines the possible consequence of fertilizer-dependent intensive agriculture on the worsening of infectious disease epidemics by pathogens--especially Vibrio cholerae, the cause of Asiatic cholera--that live in the same aquatic habitats that also harbor algae and other components of these complex ecosystems.
The epicenter of all cholera pandemics is the delta formed by the confluence of the Ganges, Meghna and Brahmaputra rivers and the Bay of Bengal in southern Bangladesh, one of the most densely populated countries in the world. Outbreaks of cholera have long been noted to occur during two specific periods of the year: following the monsoon rains and just after the main cropping season. Once every 50 years on average these outbreaks spread to all continents of the habitable world. A suite of observations has led to the conclusion that in the Bay of Bengal, V. cholerae resides as a normal member of riverine, estuarine and coastal marine habitats; seasonal changes in the physicochemical characteristics of these habitats and regional environment effects cause it to emerge periodically as a human pathogen.
The purpose of this project is to gain deeper understanding of 1) the physiochemical changes in the aquatic habitat that initiate these outbreaks, 2) the broader ecosystem-level changes, such as the addition of commercial fertilizers, that may be driving the physiochemical changes and thus spreading the disease, and 3) the impact of changes in both the international and domestic food economies, especially the price of fertilizer, on local fertilization practices and the spread of disease.