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Transmission dynamics of the ongoing chikungunya outbreak in Central Italy: from coastal areas to the metropolitan city of Rome, summer 2017 
On 7 September 2017, Italian public health authorities reported three autochthonous cases of chikungunya in Anzio, a coastal city 50 km south of Rome, located in the Lazio region [1]. However, the symptom onset for the first cases was retrospectively considered to have occurred between 26 and 27 June. The outbreak continued spreading in the Lazio region with the number of notified cases reaching 297 (of which 170 were confirmed) on 13 October. Although most cases were reported from Anzio, a distinct cluster of transmission was also detected in the metropolitan area of Rome [2]. The index case has not been identified, but the mosquito vector implicated in the chikungunya virus (CHIKV) transmission was confirmed to be Aedes albopictus, as was the case in a previous Italian CHIKV outbreak, which occurred in the region of Emilia Romagna in 2007 [1]. In the same period than the Lazio outbreak in 2017, a further outbreak was detected in Guardavalle Marina, a small coastal town in the Calabria region [2], 600 km south of Anzio, with 54 additional notified cases (nine confirmed). It is still unknown whether the Guardavalle outbreak is epidemiologically linked to the epidemic occurring in Lazio. Here, we provide a quantitative characterisation of the ongoing outbreak, using available epidemiological data [2] and a transmission dynamics model [3-5] informed with data on mosquito abundance [6] and biting rate on humans [7] from previous collections in 18 sites within Lazio region.
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- Mattia Manica1,2,3, Giorgio Guzzetta3,4, Piero Poletti3,4, Federico Filipponi2, Angelo Solimini2, Beniamino Caputo2, Alessandra della Torre2, Roberto Ros?1, Stefano Merler4
On 7 September 2017, Italian public health authorities reported three autochthonous cases of chikungunya in Anzio, a coastal city 50 km south of Rome, located in the Lazio region [1]. However, the symptom onset for the first cases was retrospectively considered to have occurred between 26 and 27 June. The outbreak continued spreading in the Lazio region with the number of notified cases reaching 297 (of which 170 were confirmed) on 13 October. Although most cases were reported from Anzio, a distinct cluster of transmission was also detected in the metropolitan area of Rome [2]. The index case has not been identified, but the mosquito vector implicated in the chikungunya virus (CHIKV) transmission was confirmed to be Aedes albopictus, as was the case in a previous Italian CHIKV outbreak, which occurred in the region of Emilia Romagna in 2007 [1]. In the same period than the Lazio outbreak in 2017, a further outbreak was detected in Guardavalle Marina, a small coastal town in the Calabria region [2], 600 km south of Anzio, with 54 additional notified cases (nine confirmed). It is still unknown whether the Guardavalle outbreak is epidemiologically linked to the epidemic occurring in Lazio. Here, we provide a quantitative characterisation of the ongoing outbreak, using available epidemiological data [2] and a transmission dynamics model [3-5] informed with data on mosquito abundance [6] and biting rate on humans [7] from previous collections in 18 sites within Lazio region.
full article