Environmental Factors Influencing Epidemic Cholera

Abstract

Abstract. Cholera outbreak following the earthquake of 2010 in Haiti has reaffirmed that the disease is a major public health threat. Vibrio cholerae is autochthonous to aquatic environment, hence, it cannot be eradicated but hydroclimatology-based prediction and prevention is an achievable goal. Using data from the 1800s, we describe uniqueness in seasonality and mechanism of occurrence of cholera in the epidemic regions of Asia and Latin America. Epidemic regions are located near regional rivers and are characterized by sporadic outbreaks, which are likely to be initiated during episodes of prevailing warm air temperature with low river flows, creating favorable environmental conditions for growth of cholera bacteria. Heavy rainfall, through inundation or breakdown of sanitary infrastructure, accelerates interaction between contaminated water and human activities, resulting in an epidemic. This causal mechanism is markedly different from endemic cholera where tidal intrusion of seawater carrying bacteria from estuary to inland regions, results in outbreaks.

Factors Determining Water Treatment Behavior for the Prevention of Cholera in Chad

“…2 This region features the typical environmental factors for a high risk of cholera outbreaks in river areas: hot air and low rivers that foster the breeding of bacteria, with subsequent inundations during the rainy season that enhance the probability of contact between humans and contaminated water and cause a breakdown of sanitary infrastructure. 35 The country of Chad is located in central Africa, with an area of 1,284,000 km 2 and a total population of 11,175,915. Accessibility to basic social services is hampered by illiteracy, poverty, sociocultural burdens, and the geographic environment.…”

Population Vulnerability to Biannual Cholera Outbreaks and Associated Macro-Scale Drivers in the Bengal Delta

“…For future research, better health surveillance data and higher resolution climate and hydrologic data would be invaluable to understand these processes in more detail. [25][26][27] A cholera warning system based on the geographic specificity of salinity and flood signatures holds the promise of predicting the future intensity and location of epidemics. Such a system can potentially provide public health authorities with spatially specific warnings regarding the extent and magnitude of impending outbreaks, especially in slum areas lacking in necessary water infrastructure, to alert medical personnel and start implementing preventive measures.…”

Predictive Time Series Analysis Linking Bengal Cholera with Terrestrial Water Storage Measured from Gravity Recovery and Climate Experiment Sensors

“…1 Cholera in the Bengal Delta, Indus River basin, and Congo basin, has been strongly associated with variability in large-scale processes, for example, availability of water in rivers. 2 Annual bimodal peaks of cholera 3 in the Ganges-Brahmaputra-Meghna (GBM) basin are related to low flow during months of minimal rainfall when seawater intrusion occurs, carrying cholera bacteria associated with zooplankton 4 from the coast to inland water bodies.…”

“…In contrast, high river flow after heavy rains inundates large terrestrial landscapes, creating conditions favorable for cholera with cross-contamination, and the resulting mixing of bacterialaden water spread over vast spatial scales. [1][2][3][5][6][7][8][9][10][11] Growth of Vibrio cholerae, the causative agent for the disease, in riverine, estuarine, and coastal waters has been shown to be strongly linked to a set of biological parameters namely nutrients in water, temperature, pH, salinity, plankton, and zooplankton 4,12 that are further associated with large-scale climatic processes. 13,14 Because cholera bacteria are autochthonous to the aquatic environment and eradication of the pathogen is not possible, forecasting conditions favorable for growth of the cholera bacteria in the environment is achievable if relevant environmental conditions can be linked to large-scale geophysical phenomena.…”

“…15,16 It provides a valuable indicator of changes that occur in hydrological conditions at the level of large basin scales. 1,7,8 TWS can be used to estimate river discharge, [18][19][20] groundwater abundance and depletion, 17 hydrological droughts, 21 and flooding. 22 However, linking TWS with climate-influenced water-borne diarrheal diseases has not yet been done, especially to establishing association of TWS with cholera, a disease that is in turn strongly linked with low water availability in the basin.…”