Global study maps how trade and travel are fueling global spread of disease-carrying mosquitoes

A comprehensive global analysis reveals how non-native mosquito vectors hitchhike across continents via shipping, tourism and trade, identifying areas where prevention and early detection could have the greatest impact.

Study: Global invasion patterns and dynamics of disease-carrying mosquitoes. Image credit: GE_4530 / Shutterstock

In a recent study published in the journal Nature communicationsa team of researchers mapped when, where and how non-native disease-carrying mosquitoes were introduced and established globally and identified pathways, hotspots and socio-environmental factors.

Background

Nearly a quarter of mosquito species that transmit human pathogens now occur beyond their native ranges, a stark message of how trade, travel and urbanization are reshaping risk. Enter vectors like Aedes aegypti, Aedes albopictusand Culex quinquefasciatus allow dengue, chikungunya, Zika and other arthropod-borne viruses to emerge in new places, with local outbreaks increasingly following hot summers. The previous reference to “heavy tourism” was removed because it was not analyzed in the study. For health systems already stretched by climate-sensitive diseases, unexpected indigenous transmission can trigger costly responses. Communities care because prevention depends on knowing where vectors arrive, how they persist, and which gateways matter. Further research needs to resolve pathways and socio-environmental factors. This study does not analyze disease incidence or tourism. models socio-environmental drivers of import and settlement hotspots.

About the study

The study compiled a global database of the first records of non-native mosquito vectors of human disease and whether these populations were established. Sources included bibliography and peer-reviewed reviews. Dates were standardized to four-digit years with transparent rules for approximate periods. Records were assigned to 477 regions (countries plus major subnational units) to track imports consistently using the Global Administrative Regions (GADM) database. Carriers of transport were classified as ships, aircraft, ground transport, trains or secondary spread. Contaminants included water containers, plants, tires, lucky bamboo, used machinery, containers and miscellaneous goods, summed over 25-year intervals. Many modes of transport were recorded as unknown, reflecting gaps in reporting. The identity and certainty of the species was recorded. Spatial spread was characterized by Principal Component Analysis (PCA), followed by k-means species clustering based on area size and distance between invaded areas.

Continental flows connected native regions with destinations to illustrate donor-recipient patterns. To identify hot and cold spots, a Generalized Linear Mixed Model (GLMM) related first registration counts by country to region and a proxy for registration effort, with continent as a random effect. Drivers of hotspot intensity were modeled using per capita Gross Domestic Product (GDP), population size, temperature, rainfall, wetlands and agriculture, insularity and latitude. Analyzes were done in R and maps were created in QGIS.

Study results

In 184 recognized mosquito vectors of human diseases, the database recorded 697 first records in 288 regions and, specifically, 612 records (87.8%) led to establishment. In total, 45 species – 24.5% of known vectors – were introduced somewhere and 28 were established. Imports dominated five genera: Aedes, Anopheles, Mosquito, Armigersand Mansions. Aedes accounted for 469 regional introductions and now ten species are established in 409 regions. Mosquito contributed to 192 introductions, with 9 species established in 184 areas. Anopheles were introduced in 33 areas, with seven species established in 17 areas, while Armigers and Mansions each had imports of one species with limited establishment. The most widespread non-native species were Aedes aegypti (192 districts), Aedes albopictus (189), and Culex quinquefasciatus (111), with Aedes albopictus established in 173 districts.

Temporal trends revealed a sharp increase after 1950: 49% of all first records occurred after 1950, and 12 species were first recorded outside their range after 2000. The mode of movement diversified from ship-dominated dispersal to increasing roles for aircraft, land transport and unassisted secondary spread from the original bridge. The goods involved shifted from containers of stagnant water on the ships to used tires, ornamental plants (including lucky bamboo) and various containers. The odds of establishment after air travel were low, while shipping remained a significant contributor even as its relative importance declined.

Spatial analyzes showed that species occupying more areas generally had longer global residence times. However, this correlation weakened for species that emerged after 1900 and 1950, signaling different dynamics for recent invaders. PCA and k-means clustering of species into four patterns: cosmopolitan distributions (Aedes aegypti, Aedes albopictus, Culex quinquefasciatus) widespread invaders that span many areas or long distances (for example, Aedes japonicus, Culex pipiens sensu strict, Culex tritaeniorhynchus) medium-range colonizers (incl Useless Stefansi) and many narrow-range species were introduced to one or two areas. Intercontinental flows showed Asia and Africa as the dominant donors, with Europe, North America and Australia as consistent recipients. After 1900, Asia became the main donor, and intracontinental movements are evident in Australia and the Americas.

The hotspot analysis identified New Zealand, the Netherlands, the United States of America (US), France, and Mauritius as import hotspots, while Guam, several eastern US states, and Cuba were ranked among facility hotspots. Coldspots included the Cook Islands, Norway, Poland, Ukraine and Canada. GLMMs showed that GDP per capita and population size were positively associated with imports and that population size was positively associated with settlement, while insularity also increases the propensity to import.

conclusions

This global synthesis shows that introductions and establishments of non-native mosquito vectors are increasing, diversifying in pathways and concentrated in predictable hotspots. For public health, the signal is active: target the management of pathways such as shipping containers, used tires and live facilities, intensify surveillance in hotspots, and fund rapid response before invasions scale. Planning must look beyond Aedes aegypti and Aedes albopictus to other relevant agencies, while incorporating land use, climate, trade and travel data. Coordinated international efforts can reduce imports and mitigate the disease burden of arboviruses and malaria in an increasingly connected world.