The geography of imported malaria to non-endemic countries: a meta-analysis of nationally reported statistics

Abstract

SummaryBackgroundMalaria remains a problem for many countries classified as malaria free through cases imported from endemic regions. Imported cases to non-endemic countries often result in delays in diagnosis, are expensive to treat, and can sometimes cause secondary local transmission. The movement of malaria in endemic countries has also contributed to the spread of drug resistance and threatens long-term eradication goals. Here we focused on quantifying the international movements of malaria to improve our understanding of these phenomena and facilitate the design of mitigation strategies.MethodsIn this meta-analysis, we studied the database of publicly available nationally reported statistics on imported malaria in the past 10 years, covering more than 50 000 individual cases. We obtained data from 40 non-endemic countries and recorded the geographical variations.FindingsInfection movements were strongly skewed towards a small number of high-traffic routes between 2005 and 2015, with the west Africa region accounting for 56% (13 947/24 941) of all imported cases to non-endemic countries with a reported travel destination, and France and the UK receiving the highest number of cases, with more than 4000 reported cases per year on average. Countries strongly linked by movements of imported cases are grouped by historical, language, and travel ties. There is strong spatial clustering of plasmodium species types.InterpretationThe architecture of the air network, historical ties, demographics of travellers, and malaria endemicity contribute to highly heterogeneous patterns of numbers, routes, and species compositions of parasites transported. With global malaria eradication on the international agenda, malaria control altering local transmission, and the threat of drug resistance, understanding these patterns and their drivers is increasing in importance.FundingBill & Melinda Gates Foundation, National Institutes of Health, UK Medical Research Council, UK Department for International Development, Wellcome Trust.

Malaria Surveillance — United States, 2015

“…An analysis of the GeoSentinel global surveillance network, which monitors travel-related illness, showed that 83% of travelers who contracted malaria were exposed in sub-Saharan Africa ( 56 ). Likewise, a meta-analysis with data from 2005–2015 showed that among imported malaria infections in 40 countries where malaria is not endemic, 56% of cases were from West Africa ( 57 ). …”

Measuring mobility, disease connectivity and individual risk: a review of using mobile phone data and mHealth for travel medicine

“…Although malaria is a mosquito-borne disease, human travel-mediated transmission on spatial scales that exceed the limits of mosquito dispersal has been undermining the success of malaria control and elimination programmes that have been implemented in many countries. [10][11][12]68 The early detection and treatment of imported parasites due to human travel become high priorities for informing malaria elimination policy. A variety of models, integrating CDR-derived human mobility and malaria epidemiological and entomological data, have investigated the dynamics of human carriers to identify importation routes and locate transmission foci that contribute to malaria epidemiology for endemic countries in sub-Saharan Africa, Mesoamerica and South-East Asia.…”

“…The pathogens introduced by travellers may lead to secondary transmission and local outbreaks, as has been observed in severe acute respiratory syndrome, influenza, Ebola, Zika, yellow fever and measles, among others, or to the appearance of diseases such as malaria in non-endemic areas following migration for work or travel to visit friends and relatives. [3][4][5][6][7][8][9][10][11][12][13] The spread of infectious diseases and their potential health risk in travellers has resulted in substantial concerns and challenges to global health systems and economies, [14][15][16][17] with a need to place more emphasis on understanding population mobility, infectious disease connectivity and the individual health risk of travellers.…”

Plasmodium falciparum malaria importation from Africa to China and its mortality: an analysis of driving factors

“…The international spread of infectious diseases including Plasmodium falciparum malaria has been accelerated by increasing human mobility via air travel over recent decades123. With many countries moving towards national malaria elimination, global eradication has risen up the international agenda45.…”