Spatio-Temporal Dynamics of Cholera during the First Year of the Epidemic in Haiti

Abstract

BackgroundIn October 2010, cholera importation in Haiti triggered an epidemic that rapidly proved to be the world's largest epidemic of the seventh cholera pandemic. To establish effective control and elimination policies, strategies rely on the analysis of cholera dynamics. In this report, we describe the spatio-temporal dynamics of cholera and the associated environmental factors.Methodology/Principal findingsCholera-associated morbidity and mortality data were prospectively collected at the commune level according to the World Health Organization standard definition. Attack and mortality rates were estimated and mapped to assess epidemic clusters and trends. The relationships between environmental factors were assessed at the commune level using multivariate analysis. The global attack and mortality rates were 488.9 cases/10,000 inhabitants and 6.24 deaths/10,000 inhabitants, respectively. Attack rates displayed a significantly high level of spatial heterogeneity (varying from 64.7 to 3070.9 per 10,000 inhabitants), thereby suggesting disparate outbreak processes. The epidemic course exhibited two principal outbreaks. The first outbreak (October 16, 2010–January 30, 2011) displayed a centrifugal spread of a damping wave that suddenly emerged from Mirebalais. The second outbreak began at the end of May 2011, concomitant with the onset of the rainy season, and displayed a highly fragmented epidemic pattern. Environmental factors (river and rice fields: p<0.003) played a role in disease dynamics exclusively during the early phases of the epidemic.ConclusionOur findings demonstrate that the epidemic is still evolving, with a changing transmission pattern as time passes. Such an evolution could have hardly been anticipated, especially in a country struck by cholera for the first time. These results argue for the need for control measures involving intense efforts in rapid and exhaustive case tracking.

Temporal Changes in Environmental Health Risks and Socio-Psychological Status in Areas Affected by the 2011 Tsunami in Ishinomaki, Japan

“…The global attack rate of V. cholerae O1 Cholera epidemic in Haiti after the 2010 earthquake and hurricanes was 488.9/10,000 inhabitants and the mortality rate was 6.2/10,000 inhabitants (Gaudart et al, 2013). Although V. cholerae and V. vulnificus was isolated in Ishinomaki, toxigenic V. cholerae was not.…”

On the probability of extinction of the Haiti cholera epidemic

“…The analysis of epidemiological reports at the communal level [which are recorded but not yet available to the scientific community, see e.g. Barzilay et al (2013), Gaudart et al (2013)] perspectively represents a possible way to reduce structural errors of the model. Such data could shed light on specific transmission processes that become blurred when zooming out at the departmental level.…”

“…We therefore develop a novel individual-based spatially-explicit stochastic model that accounts for the dynamics of susceptible, infected and recovered individuals hosted in different local communities connected through hydrologic and human mobility networks. The model also accounts for enhanced cholera transmission mediated by rainfall ), a critical factor for the seasonality of the epidemic cycle (Eisenberg et al 2013;Gaudart et al 2013). Moreover, we model the possible effect of the progressive decrease of population exposure to cholera due to intervention strategies (e.g.…”

Agent-based modelling of cholera diffusion

“…During periods of rainfall, Kumasi suffers from sporadic water shortage, leading to a higher use of river water. The booster effect of rainfall on cholera outbreaks has been reported for a number of other countries like Haiti and Guinea-Bissau (Gaudart et al 2013;Luquero et al 2011). Effect of extreme precipitation on waterborne diseases in the United States was reported by Curriero et al (2001).…”