Potential for Populations ofAedes j. japonicusto Transmit Rift Valley Fever Virus in the USA¹

Abstract

Aedes japonicus japonicus was introduced into the northeastern USA in 1998 and has since spread to more than 25 states. Because this species has been shown to be a competent laboratory vector of several viruses, readily feeds on large mammals, and has become a pest in several areas, there is concern that it might serve as a vector of Rift Valley fever virus (RVFV) should that virus be introduced into North America. Infection with RVFV causes mortality in > 90% of young domestic ungulates (e.g., calves, kids, and lambs), as well as causing a febrile illness and occasional deaths in humans. Therefore, we evaluated Ae. j. japonicus captured in North Carolina and in Maryland for their ability to serve as potential vectors for RVFV. After feeding on infected adult hamsters, these mosquitoes were tested for infection, dissemination, and the ability to transmit RVFV after incubation at 26 degrees C for 7-28 days. Both the Maryland and North Carolina populations of Ae. j. japonicus were highly efficient laboratory vectors of RVFV, with infection rates > 90% and dissemination rates > 84% for those mosquitoes that fed on hamsters with viremias > or = 10(8.5) plaque-forming units/ml. Thus, Ae. j. japonicus should be targeted for immediate control should RVFV be introduced into an area where this mosquito is now present.

Unexpected Patterns of Admixture in German Populations of Aedes japonicus japonicus (Diptera: Culicidae) Underscore the Importance of Human Intervention

“…j. japonicus is a potential vector of several human encephalitis viruses as well as of dengue, chikungunya and Rift Valley fever viruses [20], [25], [26], it is important to understand the routes of introduction and expansion of the species in Europe. Compared to the Asian tiger mosquito Aedes albopictus , Ae.…”

Predicting the Mosquito Species and Vertebrate Species Involved in the Theoretical Transmission of Rift Valley Fever Virus in the United States

“…tarsalis and Ae. j. japonicus are the most competent vectors with the highest risk to transmit RVFV should it arrive in the U.S.; however, vector competence does not directly imply a significant role in disease transmission [21], [30]–[33], [36], [68]. The vector amplification fraction provides a means to quantitatively compare theoretical risk of various mosquito species based on their potential to contribute to RVFV transmission in the U.S. Vector-host contact rates, as dictated by mosquito feeding patterns, is a key component to consider when evaluating the risk of a mosquito vector, as illustrated by the Cx.…”

“…tarsalis is one of the most competent vectors of RVFV in the U.S. (Table 1), which feeds mainly on avian hosts (Table S2), and therefore, is predicted to have a low amplification fraction in comparison to other vectors as seen in Table 2 (0.2% of total risk). Recent transmission experiments by Turell et al [30] suggest that Ae. j. japonicus mosquitoes are the most competent vector of RVFV in the U.S. (previously Cx.…”

“…Should RVFV spread to the U.S., Ae. j. japonicus populations should be carefully monitored for infection and potentially targeted for mosquito control [30].…”

Evidence that implicit assumptions of ‘no evolution’ of disease vectors in changing environments can be violated on a rapid timescale

“…B 370: 20140136 warmer. Aedes j. japonicus has been implicated as a competent vector of several diseases in laboratory studies, including chikungunya and dengue viruses [28], eastern equine encephalitis [29], Japanese encephalitis [30], La Crosse virus [31], Rift Valley fever [32], St. Louis encephalitis [33] and West Nile virus [34,35], and because it feeds on both humans and nonhuman mammals [36] may act as a bridge vector to humans of these and other diseases.…”