Cholera, caused by Vibrio cholerae serogroups O1 and O139, is the most severe of diarrheal diseases and continues to cause significant morbidity and mortality throughout the developing world. Presently, it is reported in approximately 52 countries worldwide. During our first study, we carried out biweekly clinical and environmental surveillance in four rural areas of Bangladesh. Analysis of our accumulated clinical and environmental data identified factors that are significantly predictive for occurrence of cholera outbreaks, including water temperature, pH, and conductivity of surface water, along with concentrations of plankton and cholera toxin- producing bacteria in surface waters. A significant finding was that zooplankton, namely copepods, serve as an effective host for V. cholerae. By tracking their phytoplankton food source, using satellite monitoring of chlorophyll a concentration, it is possible to estimate zooplankton populations. With our successes to date, we will conduct epidemiological and ecological surveillance in Chattak and Mathbaria, two widely separated geographical sites, where we have documented predictable seasonal cholera outbreaks: one in the spring and the other in the fall. Using improved assays, we will enumerate multiple morphologies and life stages of V. cholerae in environmental samples, including the viable but nonculturable form (VBNC). Characterization of genetic associations between clinical and environmental isolates and GIS surveillance will be conducted to establish key epidemiological relationships that have been difficult to document at the genomic level. To elucidate local variability in cholera outbreaks, we will investigate factors recognized from our previous study, as well as those identified by other investigators, but not yet included in our predictive model, namely microbial community dynamics, increased competence of V. cholerae attached to chitinous surfaces, and plankton community dynamics. Using environmental variables identified from our previous studies and incorporating the new variables that prove to be correlated with cholera cases, we will refine our model of cholera transmission with the intent to render it useful for predicting cholera outbreaks, thereby allowing early mobilization of preventative and treatment measures. The very recent availability of inexpensive oral cholera vaccines makes this objective even more relevant.

Public Health Relevance

This project is being done to find reasons why the disease cholera occurs in epidemics. We postulate that factors in the marine environment play important roles in triggering the onset of epidemics. The study is being done in rural Bangladesh, using recently developed technology to further define these factors.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI039129-14
Application #
8469810
Study Section
Infectious Diseases, Reproductive Health, Asthma and Pulmonary Conditions Study Section (IRAP)
Program Officer
Hall, Robert H
Project Start
1996-09-01
Project End
2015-05-31
Budget Start
2013-06-01
Budget End
2014-05-31
Support Year
14
Fiscal Year
2013
Total Cost
$1,794,507
Indirect Cost
$137,404
Name
Johns Hopkins University
Department
Public Health & Prev Medicine
Type
Schools of Public Health
DUNS #
001910777
City
Baltimore
State
MD
Country
United States
Zip Code
21218
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Senoh, Mitsutoshi; Ghosh-Banerjee, Jayeeta; Ramamurthy, Thandavarayan et al. (2010) Conversion of viable but nonculturable Vibrio cholerae to the culturable state by co-culture with eukaryotic cells. Microbiol Immunol 54:502-7
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