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

Climate Suitability: Vectorial Capacity

The vectorial capacity of Ae. albopictus mosquitoes to transmit chikungunya virus in areas of Europe where the vector is established,[17] such as the outbreak zones in France and Italy, was estimated to be high in July and August but lower in September and October. Estimates of suitability were low in October for most areas, except those in southern Italy and Greece and southeastern Spain (Figure 1). Overall, warmer than average temperatures led to a substantial increase in vectorial capacity during the study period (June–October 2017) (Appendix 2 Figure 1). Using empirical data from the outbreaks in Italy,[22] we estimated R0 to be 2.28 (95% CI 2.01–2.59) for the Anzio region, 3.54 (95% CI 2.62–4.97) for the Rome region, and 3.11 (95% CI 2.16–4.79) for the Calabria region (Figure 2).

Figure 1.

Vectorial capacity estimates based on average temperature conditions in Europe with stable populations of Aedes albopictus mosquitoes around chikungunya outbreak zones, Italy and France, July–October 2017. Heavy outlines indicate the outbreak areas. The vectorial capacity translates to an average basic reproduction number in the range of 2–3 in Anzio and Rome and in the range of 3–4 in Calabria during the months of July and August for an infectious period of 4 days.

Figure 2.

Notified chikungunya cases in the Anzio (A), Rome (B), and Calabria (C) regions and basic reproduction number (R0) estimates of outbreaks, June–October 2017, Italy.