Statistical modeling of chikungunya virus intra-vector infection dynamics in a FrenchAedes albopictuspopulation reveals an explosive epidemic potential

Abstract

AbstractArbovirus emergence and epidemic potential, as approximated by the vectorial capacity formula, depends on several host and vector parameters including vector intrinsic ability to transmit the pathogen. Such ability, called vector competence is influenced by biotic (e.g. virus and vector genotype) and abiotic (e.g. temperature). Vector competence is often evaluated as a qualitative phenotype although it is a multistep, time-dependent, quantitative phenotype. Combination of experimental and modelling approaches can i) capture intra-vector dynamics of arboviral infection and ii) use data to estimate arbovirus epidemic potential. Here, we measured individualAedes albopictus(Lyon, France) mosquitoes infection, dissemination, and transmission rate upon oral exposure to chikungunya virus (CHIKV, La Reunion Island isolate) at eleven time-points from day 2 to day 20 post-exposure (dpe) for a range of CHIKV infectious doses spanning human viremia. Statistical modelisation indicates an explosive CHIKV intra-vector dynamics mainly due to an absence of dissemination barrier with 100% of the infected mosquitoes ultimately exhibiting a disseminated infection regardless of the viral dose. Transmission rate data revealed a time and dose-dependent but overall weak transmission barrier with individuals transmitting as soon as 2 dpe and >50% infectious mosquitoes at 6 dpe for the highest dose. Epidemiological simulations conducted with an Agent-Based Model based on experimental intra-vector dynamics data showed that even at low mosquito biting rates, CHIKV triggers explosive outbreaks. Together, this reveals the high epidemic potential of this CHIKV isolate with this French metropolitan population ofAedes albopictus.