Mobile phone data highlights the role of mass gatherings in the spreading of cholera outbreaks

PNAS – Proceedings of the National Academy of Sciences of the United States of America
(Accessed 28 May 2016)

Physical Sciences – Environmental Sciences:
Mobile phone data highlights the role of mass gatherings in the spreading of cholera outbreaks
Flavio Finger, Tina Genolet, Lorenzo Mari, Guillaume Constantin de Magny, Noël Magloire Manga, Andrea Rinaldo, and Enrico Bertuzzo
PNAS 2016 ; published ahead of print May 23, 2016, doi:10.1073/pnas.1522305113
Big data and, in particular, mobile phone data are expected to revolutionize epidemiology, yet their full potential is still untapped. Here, we take a significant step forward by developing an epidemiological model that accounts for the spatiotemporal patterns of human mobility derived by directly tracking properly anonymized mobile phone users. Such data allow us to investigate, with an unprecedented level of detail, the effect that mass gatherings can have on the spreading of waterborne diseases like cholera. Identifying and understanding transmission hotspots opens the way to the implementation of novel disease control strategies.

The spatiotemporal evolution of human mobility and the related fluctuations of population density are known to be key drivers of the dynamics of infectious disease outbreaks. These factors are particularly relevant in the case of mass gatherings, which may act as hotspots of disease transmission and spread. Understanding these dynamics, however, is usually limited by the lack of accurate data, especially in developing countries. Mobile phone call data provide a new, first-order source of information that allows the tracking of the evolution of mobility fluxes with high resolution in space and time. Here, we analyze a dataset of mobile phone records of ∼150,000 users in Senegal to extract human mobility fluxes and directly incorporate them into a spatially explicit, dynamic epidemiological framework. Our model, which also takes into account other drivers of disease transmission such as rainfall, is applied to the 2005 cholera outbreak in Senegal, which totaled more than 30,000 reported cases. Our findings highlight the major influence that a mass gathering, which took place during the initial phase of the outbreak, had on the course of the epidemic. Such an effect could not be explained by classic, static approaches describing human mobility. Model results also show how concentrated efforts toward disease control in a transmission hotspot could have an important effect on the large-scale progression of an outbreak.