Towards predicting cholera disease outbreaks within the Mediterranean Basin

Abstract number: 1133_238

Guégan J.F., Constantin de Magny G.

New insights into population dynamics of infectious diseases have shown the existence of regular cycles in the number of cases over time, with alternance of periods of booms and busts. The dynamics of infectious diseases is determined by a large number of complex processes acting over a large range of spatio-temporal scales. However, studies have been restricted so far to tiny hierarchical scales, which cannot really capture what may still happen at upper scales. Recent discoveries on both Vibrio cholerae life-cycle and cholera cases dynamics started to disentangle the many intrinsic and extrinsic environmental factors that may be involved in the evolution of disease within communities. Findings show that cholera cases may fluctuate with periods of outbreaks and quasi-extinction, depending on both local and large-scale environmental conditions, which influence V. cholerae kinetics within the environment. Based on statistical analysis and ecological modelling, we will show how we can model cholera cases dynamics within the Mediterranean area in taking account large-scale environmental conditions. Both studying the evolution of cholera cases in countries of northern Africa (using sophisticated wavelet analyses), and modelling the Vibrio life-cycle (using differential equations systems) based on environmental, ecological parameters obtained from remote-sensing and oceanographic surveys, we here present models that really mimic cholera disease patterns observed over time within the area. Results on cholera time-series in the southern part of the basin indicate that outbreaks are mainly associated with an elevation of local sea surface. The ecological modelling of outbreaks, which considers the many processes involved, shows that the existence of an environmental reservoir may help to explain cholera dynamics. This work constitutes one of the few studies on cholera dynamics which clearly show the influence of large-scale environmental factors on the evolution of cholera cases. More specifically, it is the first study which really demonstrates for the Mediterranean Sea that common processes to other regions of the World are at work in producing more or less periodic cholera outbreaks in the sub-southern region of the Basin. As climate temperature should increase in the future, the consequences on cholera outbreaks might be highly sensitive. Accordingly, this study is then the first step towards producing a predictive model of Vibrio bacteria emergence within the Mediterranean basin based on an integrated environmental surveillance.

Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Location: Oxford, UK
Presentation type:
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