1 23 Bulletin of Mathematical Biology A Journal Devoted to Research at the Junction of Computational, Theoretical and Experimental Biology Official Journal of The Society for Mathematical Biology ISSN 0092-8240 Bull Math Biol DOI 10.1007/s11538-014-9998-7 A Modeling Approach to Investigate Epizootic Outbreaks and Enzootic Maintenance of Rift Valley Fever Virus Farida Chamchod, Robert Stephen Cantrell, Chris Cosner, Ali N. Hassan, John C. Beier & Shigui Ruan