Interest in mapping the global distribution of malaria is motivated by a need to define populations at risk for appropriate resource allocation 1,2 and to provide a robust framework for evaluating its global economic impact 3,4 . Comparison of older [5][6][7] and more recent 1,4 malaria maps shows how the disease has been geographically restricted, but it remains entrenched in poor areas of the world with climates suitable for transmission. Here we provide an empirical approach to estimating the number of clinical events caused by Plasmodium falciparum worldwide, by using a combination of epidemiological, geographical and demographic data. We estimate that there were 515 (range 300-660) million episodes of clinical P. falciparum malaria in 2002. These global estimates are up to 50% higher than those reported by the World Health Organization (WHO) and 200% higher for areas outside Africa, reflecting the WHO's reliance upon passive national reporting for these countries. Without an informed understanding of the cartography of malaria risk, the global extent of clinical disease caused by P. falciparum will continue to be underestimated.The Global Burden of Diseases programme of the WHO has attempted to enumerate the health consequences of malaria infection 8,9 . Because the African region has a notoriously weak system of reporting infectious diseases, epidemiological evidence from carefully conducted prospective, 'active' case-detection studies of malaria morbidity, disability and mortality in populations living under different transmission intensity risks have been compiled to estimate the disease burden 10 . A different approach was adopted for WHO regions outside Africa, where the burden was computed from 'passive' national disease and mortality notifications to WHO regional offices without precisely defining the populations exposed to varied malaria infection risks 9,11,12 . This use of national disease registration systems to provide accurate reflections of disease rests on three assumptions: that there is complete temporal coverage (every month is reported by a facility), that there is complete spatial coverage (every health facility reports nationwide), and that all disease events present to, and are reported by, health facilities. In reality, passive detection of disease events in most resource-poor countries is incomplete, even outside Africa. Competing interests statementThe authors declare competing financial interests: details accompany the paper on www.nature.com. Europe PMC Funders GroupAuthor Manuscript Nature. Author manuscript; available in PMC 2011 July 01. Here we provide a standard global approach to deriving clinical malaria burden by using evidence of the epidemiological risks of disease outcome from active case-detection studies in combination with estimates of populations at risk of various P. falciparum transmission conditions. A comprehensive outline of these procedures is given in Methods. A conservative approach is defined to further account for the confounding of malaria diagno...

In African children with malaria, the presence of impaired consciousness or respiratory distress can identify those at high risk for death.

Human movements contribute to the transmission of malaria on spatial scales that exceed the limits of mosquito dispersal. Identifying the sources and sinks of imported infections due to human travel and locating high-risk sites of parasite importation could greatly improve malaria control programs. Here we use spatially explicit mobile phone data and malaria prevalence information from Kenya to identify the dynamics of human carriers that drive parasite importation between regions. Our analysis identifies specific importation routes that contribute to malaria epidemiology on regional spatial scales.