Epidemiology and Infection

Original Papers

Viruses

Measles hotspots and epidemiological connectivity

N. BHARTIa1 c1, A. DJIBOa2, M. J. FERRARIa1, R. F. GRAISa3, A. J. TATEMa4, C. A. McCABEa5, O. N. BJORNSTADa1a6a7 and B. T. GRENFELLa1a7

a1 Penn State University, Biology Department and Center for Infectious Disease Dynamics, University Park, PA, USA

a2 Director General, Ministry of Health, Niamey, Niger

a3 Epicentre, Paris, France

a4 University of Florida, Emerging Pathogens Institute and Department of Geography, Gainesville, FL, USA

a5 Penn State University, Department of Geography and GeoVISTA Center, University Park, PA, USA

a6 Penn State University, Department of Entomology, University Park, PA, USA

a7 Fogarty International Center, National Institutes of Health, Bethesda, MD, USA

SUMMARY

Though largely controlled in developed countries, measles remains a major global public health issue. Regional and local transmission patterns are rooted in human mixing behaviour across spatial scales. Identifying spatial interactions that contribute to recurring epidemics helps define and predict outbreak patterns. Using spatially explicit reported cases from measles outbreaks in Niger, we explored how regional variations in movement and contact patterns relate to patterns of measles incidence. Because we expected to see lower rates of re-introductions in small, compared to large, populations, we measured the population-size corrected proportion of weeks with zero cases across districts to understand relative rates of measles re-introductions. We found that critical elements of spatial disease dynamics in Niger are agricultural seasonality, transnational contact clusters, and roads networks that facilitate host movement and connectivity. These results highlight the need to understand local patterns of seasonality, demographic characteristics, and spatial heterogeneities to inform vaccination policy.

(Accepted November 13 2009)

(Online publication January 25 2010)

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