Abstract
Between 2014 and 2016 more than 3,800 imported human cases of chikungunya fever in Florida highlight the high risk for local transmission. To examine the potential for sustained local transmission of chikungunya virus (CHIKV) in Florida we tested whether local populations of Aedes aegypti and Aedes albopictus show differences in susceptibility to infection and transmission to two emergent lineages of CHIKV, Indian Ocean (IOC) and Asian genotypes (AC) in laboratory experiments. All examined populations of Ae. aegypti and Ae. albopictus mosquitoes displayed susceptibility to infection, rapid viral dissemination into the hemocoel, and transmission for both emergent lineages of CHIKV. Aedes albopictus had higher disseminated infection and transmission of IOC sooner after ingesting CHIKV infected blood than Ae. aegypti. Aedes aegypti had higher disseminated infection and transmission later during infection with AC than Ae. albopictus. Viral dissemination and transmission of AC declined during the extrinsic incubation period, suggesting that transmission risk declines with length of infection. Interestingly, the reduction in transmission of AC was less in Ae. aegypti than Ae. albopictus, suggesting that older Ae. aegypti females are relatively more competent vectors than similar aged Ae. albopictus females. Aedes aegypti originating from the Dominican Republic had viral dissemination and transmission rates for IOC and AC strains that were lower than for Florida vectors. We identified small-scale geographic variation in vector competence among Ae. aegypti and Ae. albopictus that may contribute to regional differences in risk of CHIKV transmission in Florida.
Highlights
Native to Africa, chikungunya virus (CHIKV) emerged to produce intermittent outbreaks from the 1950s in Southeast Asia (Asian CHIKV lineage) and regional outbreaks in India in the 1960s and 1970s [1, 2]
Transmission of chikungunya virus in the U.S is a major public health risk, especially in Florida where the environmental conditions are favorable for the two main mosquitoes involved in transmission
Chikungunya emerged in Kenya in 2004 (Eastern/Central/ Southern African, East/Central/South Africa (ECSA), CHIKV lineage), followed by an outbreak of chikungunya fever on the island of La Reunion in 2005–2006 involving the Indian Ocean CHIKV (IOC) lineage, a descendent of the ECSA CHIKV lineage [2, 3]
Summary
Native to Africa, chikungunya virus (CHIKV) emerged to produce intermittent outbreaks from the 1950s in Southeast Asia (Asian CHIKV lineage) and regional outbreaks in India in the 1960s and 1970s [1, 2]. The Old-World outbreaks of CHIKV in Kenya in 2004 [3] and islands of the Indian Ocean in 2005 subsequently spread to India and Europe including Italy and France [7, 8] involving more than one million cases. The outbreaks in Europe were one of the first demonstrations that CHIKV could extend its tropical/subtropical distribution into temperate regions using the Asian tiger mosquito vector Aedes albopictus (Skuse). The virus is native and endemic to Africa, where arboreal mosquitoes are part of its sylvan cycle, including members of the Ae. furcifer-taylori group [11, 13]
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