Potential for North American Mosquitoes to Transmit Rift Valley Fever Virus

The rapid spread of West Nile viral activity across North America since its discovery in 1999 illustrates the potential for an exotic arbovirus to be introduced and widely established across North America. Rift Valley fever virus (RVFV) has been responsible for large outbreaks in Africa that have resulted in hundreds of thousands of human infections and major economic disruption. However, little is known about the potential for North American mosquitoes to transmit this virus should it be introduced into North America. Therefore, we evaluated selected mosquito species from the southeastern US for their ability to serve as potential vectors for RVFV. Mosquitoes were fed on adult hamsters inoculated 1 day previously with RVFV. These mosquitoes were tested for infection and ability to transmit RVFV after incubation at 26C for 7-21 days. None of the species tested (Aedes taeniorhynchus, Ae. vexans, Culex erraticus, Cx. nigripalpus, Cx. quinquefasciatus, and Cx. salinarius) were efficient vectors after they fed on hamsters with viremias 106.9 plaque-forming units (PFU)/ml. However, Ae. taeniorhynchus, Ae. vexans, and Cx. erraticus all developed disseminated infections after they fed on hamsters with viremias between 108.5 and 1010.2 PFU/ml, and both Ae. vexans, and Cx. erraticus transmitted RVFV by bite. These studies illustrate the need to identify the ability of individual mosquito species to transmit RVFV so that correct decisions can be made concerning the application of appropriate control measures during an outbreak. Pub. in Journal of the American Mosquito Control Association, v24 n4, p502-507, 2008.