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 Sao 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 Sao 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.