Global malaria connectivity through air travel

Abstract

BackgroundAir travel has expanded at an unprecedented rate and continues to do so. Its effects have been seen on malaria in rates of imported cases, local outbreaks in non-endemic areas and the global spread of drug resistance. With elimination and global eradication back on the agenda, changing levels and compositions of imported malaria in malaria-free countries, and the threat of artemisinin resistance spreading from Southeast Asia, there is a need to better understand how the modern flow of air passengers connects each Plasmodium falciparum- and Plasmodium vivax-endemic region to the rest of the world.MethodsRecently constructed global P. falciparum and P.vivax malaria risk maps, along with data on flight schedules and modelled passenger flows across the air network, were combined to describe and quantify global malaria connectivity through air travel. Network analysis approaches were then utilized to describe and quantify the patterns that exist in passenger flows weighted by malaria prevalence. Finally, the connectivity within and to the Southeast Asia region where the threat of imported artemisinin resistance arising is highest, was examined to highlight risk routes for its spread.ResultsThe analyses demonstrate the substantial connectivity that now exists between and from malaria-endemic regions through air travel. While the air network provides connections to previously isolated malarious regions, it is clear that great variations exist, with significant regional communities of airports connected by higher rates of flow standing out. The structures of these communities are often not geographically coherent, with historical, economic and cultural ties evident, and variations between P. falciparum and P. vivax clear. Moreover, results highlight how well connected the malaria-endemic areas of Africa are now to Southeast Asia, illustrating the many possible routes that artemisinin-resistant strains could take.DiscussionThe continuing growth in air travel is playing an important role in the global epidemiology of malaria, with the endemic world becoming increasingly connected to both malaria-free areas and other endemic regions. The research presented here provides an initial effort to quantify and analyse the connectivity that exists across the malaria-endemic world through air travel, and provide a basic assessment of the risks it results in for movement of infections.

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

“…The level of importation from SSA to China is contrary to the previous perception that China’s imported malaria mainly originates in neighbouring countries of southeast Asia2223. Volume of air travel from African countries to China, prevalence of malaria in origin countries and Chinese investments in African countries were all associated with the number and distribution of imported cases, with diverse risk factors for mortality found.…”

“…For example, identifying which regions tend to import cases from certain parts of Africa more than others means that local health facilities can be aware of risks and make more rapid diagnoses to save lives, undertake proactive interventions, such as prophylaxis to high risk travellers, and tailoring public health awareness campaigns2223. The majority of imported P. falciparum malaria cases in China have been reported in those with a history of labour-related travel to Africa12131920, and thus, identifying potential high risk groups of travellers and the factors driving these risks facilitates both the tailoring of interventions2425 and an understanding of how these risks might impact future importation rates, supporting strategy design.…”

“…Despite the public health relevance, existing analyses of P. falciparum malaria connectivity and importation have only considered China in the context of neighbouring countries in Asia2223, and the patterns and driving factors of P. falciparum malaria importation from sub-Saharan Africa (SSA) to China have not been addressed. We therefore sought to quantify the patterns of malaria importation to China from Africa and explore these as a function of key driving factors, including volume of air travellers, parasite prevalence in Africa, and investments from China.…”

Mosquitoes and Culicoides biting midges: vector range and the influence of climate change

“…Next to windborne displacement, the transport of Plasmodium-infected Anopheles mosquitoes on board aircraft is a cause of airport malaria throughout the world (84,85). The tremendous global connectivity and rapid rise in new connections between endemic and disease-free areas is of great concern for the spread of vector-borne diseases.…”

Understanding population displacements on location-based call records using road data

“…Following the methods described in [8,10], We calculated and compared various commonly used metrics such as degrees, closeness centrality, betweenness centrality, eigenvector centrality, authority index, hub rank and page rank at the node level for all the cellphone towers in Abijan between two networks. A Spearman rank test was utilized to calculate the correlations between metrics generated from the road network [20].…”