Using Big Data to Monitor the Introduction and Spread of Chikungunya, Europe, 2017

Joacim Rocklöv; Yesim Tozan; Aditya Ramadona; Maquines O. Sewe; Bertrand Sudre; Jon Garrido; Chiara Bellegarde de Saint Lary; Wolfgang Lohr; Jan C. Semenza


Emerging Infectious Diseases. 2019;25(6):1041-1049. 

In This Article

Long-range Importation: Air Passenger Volume

On average, ≈50,000 air passenger-journeys (1 passenger flight, including all legs of travel) were taken each month from areas with active chikungunya transmission worldwide to the outbreak zones (Figure 3). Specifically, in August, 56,300 passengers from outbreak zones were estimated to arrive in Rome, 6,484 in Nice, and 5,629 in Marseille. The passenger-journey volume into Europe when the outbreak started in June is shown in Appendix 2 Figure 2. The countries with the highest number of departing passengers in August were Thailand (352,332 passengers), Brazil (255,439 passengers), and India (301,298 passengers). According to molecular epidemiology, the genome sequence of a chikungunya virus isolate from the Lazio region of Italy revealed the East/Central/South African lineage, Indian Ocean sublineage, which is similar to that of recent sequences from Pakistan and India.[23] We also extracted air passenger-journey data for flights from the outbreak zones in southeastern France and central Italy to other areas in Europe (Figure 3). The top 5 destinations with the highest volume were the larger metropolitan areas of Europe, most of which were outside the boundaries of areas where the vector is known to be present (Figure 4). However, high flight connectivity was observed from the outbreak zones to Barcelona (Spain) and Catania and Palermo (Italy).

Figure 3.

Incoming passengers from chikungunya active transmission areas and outgoing passengers to other airports in Europe from Rome (FCO), Marseille (MRS), and Nice (NCE) airports, August 2017. The stable vector presence area is highlighted in yellow.

Figure 4.

MP estimates from the Lazio region, Italy, to areas in Europe with stable populations of Aedes albopictus mosquitoes, July–September 2017. Heavy outlines indicate the chikungunya outbreak areas. MP, mobility proximity.