Environmental signatures associated with cholera epidemics

Abstract

The causative agent of cholera, Vibrio cholerae, has been shown to be autochthonous to riverine, estuarine, and coastal waters along with its host, the copepod, a significant member of the zooplankton community. Temperature, salinity, rainfall and plankton have proven to be important factors in the ecology of V. cholerae, influencing the transmission of the disease in those regions of the world where the human population relies on untreated water as a source of drinking water. In this study, the pattern of cholera outbreaks during 1998 -2006 in Kolkata, India, and Matlab, Bangladesh, and the earth observation data were analyzed with the objective of developing a prediction model for cholera. Satellite sensors were used to measure chlorophyll a concentration (CHL) and sea surface temperature (SST). In addition, rainfall data were obtained from both satellite and in situ gauge measurements. From the analyses, a statistically significant relationship between the time series for cholera in Kolkata, India, and CHL and rainfall anomalies was determined. A statistically significant one month lag was observed between CHL anomaly and number of cholera cases in Matlab, Bangladesh. From the results of the study, it is concluded that ocean and climate patterns are useful predictors of cholera epidemics, with the dynamics of endemic cholera being related to climate and/or changes in the aquatic ecosystem. When the ecology of V. cholerae is considered in predictive models, a robust early warning system for cholera in endemic regions of the world can be developed for public health planning and decision making.ecology ͉ epidemiology ͉ microbiology ͉ remote sensing

The Role of Temperature Inversions in the Generation of Seasonal and Interannual SST Variability in the Far Northern Bay of Bengal

“…Furthermore, the northern Bay of Bengal is surrounded by densely populated areas, and environmental fluctuations can have important impacts on society. For example, earlier studies demonstrated that SST off Bangladesh was associated with cholera incidence in Dhaka, the capital and largest city in Bangladesh (Lobitz et al 2000;Constatin de Magney et al 2008;Hashizume et al 2011).…”

Relatedness of Vibrio cholerae O1/O139 Isolates from Patients and Their Household Contacts, Determined by Multilocus Variable-Number Tandem-Repeat Analysis

“…This new serogroup continues to cocirculate with El Tor V. cholerae O1 serotypes Ogawa and Inaba as a cause of disease in humans, although it accounts for a smaller proportion of all cholera now than in its first years of circulation (16,20). Recently, comparative genomics has revealed an extensive amount of lateral gene transfer between strains, suggesting that genomic classification may be an alternative to serogrouping for classifying pathogenic V. cholerae strains (11).Toxigenic V. cholerae may be present in environmental sources in regions of endemicity and emerge, often seasonally, to cause cholera in humans (12,18). Once an outbreak has begun, organisms from one infected individual are more infectious for the next individual, a property termed hyperinfectivity, and these forms may be able to pass directly from human to human through fecal-oral contamination (35).…”

“…Toxigenic V. cholerae may be present in environmental sources in regions of endemicity and emerge, often seasonally, to cause cholera in humans (12,18). Once an outbreak has begun, organisms from one infected individual are more infectious for the next individual, a property termed hyperinfectivity, and these forms may be able to pass directly from human to human through fecal-oral contamination (35).…”

Cholera in Papua New Guinea and the importance of safe water sources and sanitation

“…Vibrio cholerae is highly adapted to the aquatic environment, and lives naturally in riverine and estuarine ecosystems. 4 With the sustained and widespread transmission of cholera for over two years in Papua New Guinea, it is likely that an environmental reservoir will be, or already has been, established. Cholera endemicity has broad implications beyond the health risk to its citizens, including the possibility of temporary trade barriers, reduction in tourist numbers and an increased burden on the health care systems.…”

“…Factors such as rainfall, salinity, temperature and copepod (zooplankton) blooms have all been linked to periodic outbreaks in countries such as Bangladesh and India. 4 Papua New Guinea is likely to face further challenges from cholera outbreaks and the extent of…”