Population movements from cholera-affected areas in Port-au-Prince and identification of communes at potentially increased risk of new outbreaks: Situation as of 30 November
Our research on the 2010 cholera outbreak showed that mobility indicators derived from aggregated and anonymised Call Detail Records (CDRs) were predictive (with uncertainty) of the geographic spread of the epidemic. Here, we show mobility patterns from the Port-au-Prince metropolitan area relevant to the ongoing outbreak and replicate our analyses to identify areas potentially at increased risk of new outbreaks. In combination with other evidence, this can help identify areas to be prioritised for surveillance and interventions.
Most trips are short-distance. Travel from the Port-au-Prince metropolitan area, where there are high numbers of suspected cases, is concentrated in nearby communes in the Ouest department but longer trips are also observed, particularly to the Nippes and Sud departments (Map 1 in the PDF). Our modelling of the estimated flows of infectious persons (Map 2) shows large similarities with our previous reports but the frontier of the epidemic has moved and more areas now experience increased infectious pressure. Map 2 highlights communes across Haiti as areas at potentially increased risk of new outbreaks. Infectious pressure remains elevated in central and southern area of Haiti but, compared to previous reports, there are also substantial increases in communes in Nord, Centre and Grande’Anse departments, especially around Cap-Haïtien. We also show that geographic proximity to communes with confirmed cases alone may not equate to higher risk of new outbreaks. However, our methods may overestimate risk in areas along major travel corridors (e.g. highways).
The analyses have limitations and should be used in conjunction with other available evidence (see Considerations). We welcome feedback from responders to help us improve future reports and any requests for specific analyses. As new areas acquire local transmission, the risks shown in this report will change and we aim to update the analyses.