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United States Department of Agriculture

Agricultural Research Service

Research Project: POTENTIAL FOR NORTH AMERICAN MOSQUITOES TO TRANSMIT AND MAINTAIN RIFT VALLEY FEVER VIRUS (RVFV)

Location: Mosquito and Fly Research Unit

2012 Annual Report


1a.Objectives (from AD-416):
Evaluate selected mosquito species from the U.S. for their ability to serve as potential vectors for RVFV.


1b.Approach (from AD-416):
We will select mosquito species that have the potential to be important vectors of RVFV (i.e., feed readily on large mammals and occur in large numbers) for these studies. Mosquitoes will be captured by a variety of means, but principally by dry ice-baited miniature light traps and shipped overnight to USAMRIID. Upon arrival at USAMRIID, they will be transferred to an Animal Biological Safety Level (ABSL)-3 laboratory. The extent of viral infection in mosquitoes will be determined by assaying a mosquito’s body separately from its legs. In addition to the studies on vector competence, we will also evaluate selected mosquito species for their ability to vertically transmit RVFV.


3.Progress Report:

This research is related to in-house Objective 6 - "Discover and characterize environmental predictors of the distribution of mosquitoes in order to assess the risk of invasive species and pathogen transmission. Apply to the development of methods and techniques to accurately assess mosquito population density, to deploy vector surveillance systems, and to detect exotic invasive species."

More than 8,000 potential Rift Valley Fever (RVF) vector mosquitoes, representing 13 species have been trapped in the field in central Florida in high numbers in areas with significant human and domestic animal populations. Specimens were processed in the field, and sorted, tentatively identified and prepared, packaged and shipped from the laboratory to maintain viability to the U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID), Ft. Detrick, Maryland for RVF virus (RVFV) vector competence testing. Approximately 70% of the specimens collected represent populations of species that occurred in significant numbers during the North American winter. This is highly significant since the northern hemisphere winter is the typical time of year when Rift Valley outbreaks occur in much of sub-Saharan Africa. A novel collection cage was designed, developed and deployed in the trapping to minimize trauma to the mosquito specimens. The collection cage permitted trapping and processing of specimens in the field to remove dead mosquitoes without damaging viable specimens. This same trap was eventually shipped to USAMRIID where mosquitoes could be exposed to RVFV infected hamsters without further manipulation of specimens, enhancing survival and longevity required to fully assess vector competence. The 13 mosquito species collected and shipped: include Mansonia dyari, Aedes infirmatus, Aedes vexans, Culex nigripalpus, Anopheles crucians, Culex erraticus, Psorophora columbiae, Psorophora ferox, Cx. quinquefasciatus, Psorophora ciliata, Uranotaenia lowii, Uranotaenia sapphrina, and Coquillettidia perturbans.

This report is based upon meetings, site visits, email communications, telephone calls and progress reports.


Last Modified: 4/23/2014
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