Giardia survey in live-trapped small domestic and wild mammals in four regions in the southwest region of the state of São Paulo, Brazil.

For the first time, a survey on Giardia in live-trapped small domestic and wild mammals was performed in four regions of State of the São Paulo, Brazil, with special attention to the parasitism of Rattus rattus rattus by Giardia. This species was found infected in all studied sites: Botucatu (15.4%), Conchas (28.5%), Itaporanga (38.7%) and São Roque (100%). Two new hosts and their frequency of infection were described for Giardia in Nectomys squamipes, an aquatic rodent and in Bolomys lasiurus, a forest rodent (100% and 14.3%, respectively). Both G. muris and G. duodenalis groups were found in scrapings of intestinal mucosa of those rodents. Mixed infection was observed in some animals. It is important to emphasize the infection by G. duodenalis in the black rat as this species lives as a comensal with man and in N. squamipes as it may contaminate small streams used for domestic consumption. Therefore, further investigation will be necessary to elucidate the potencial of these rodents to act as reservoirs of Giardia for man.