(Uploaded by Plazi for the Bat Literature Project) Probably all warm blooded animals are susceptible to rabies virus (RV) infections. However, most of these species will end up as terminal hosts for the virus, since a fatal outcome is the rule and usually no virus dissemination from such hosts occur. Nevertheless, in nature, RV has become adapted to certain species, referred to as "natural hosts", which act as reservoirs for the virus. During the process of virus adaptation to such hosts, genomic and eventually antigenic modifications are generated that can be used as markers which may help to identify the natural host which acted as source of infection, along with other characteristics peculiar to such modified viruses, denominated RV "variants". Such variants may bear alterations that can be used as epidemiological markers, allowing for instance the identification of the source of infection or the establishment of associations between a particular variant and a defined ecological niche. In this brief review, some of the recent data on the virus and the occurrence of variants are presented, with emphasis on the findings of a parcel of the various studies on the subject that have been carried out in Brazil. Epidemiologic data on reported cases of rabies in the country in the last ten years (1997-2006) are presented and discussed, highlighting the marked decrease in the numbers of urban cases of rabies in dogs and humans, what was unfortunately compensated by an increase in the number of human cases associated to vampire bat transmission in the trienium 2004-2006.