Using cell phone data to improve disease targeting and mitigate the negative externality of internal population movement.

Population mobility within a country can lead to a number of externalities, from the spread of information and goods, to the transmission of disease. Yet until recently, the only data that would allow the study of population movement within a country for large parts of the population were census data or other survey data which only provide a snapshot of movement and do not make it possible to study short term movements and their consequences at a high frequency. Using a unique dataset of Call Detail Records (CDRs) within Senegal for 9 million users over the course of a year, this paper is able to directly study the relationship between mobility and the spread of disease. In addition, using Senegal as a case study, the paper demonstrates how this relationship can be used to specifically target certain areas of the country which are the leading importers of the disease to low malaria areas of the country. This paper also contributes to the literature on movement and disease more generally, demonstrating how as areas approach elimination of a disease, environmental factors decrease in importance and human factors like travel play an increasing role in the propagation of the disease. This highlights the importance of differentiated interventions based on the elimination stage of the area in order to achieve the most cost effective drop in the disease burden.