Due to the semi aquatic habits and the overlap of the geographical
distribution of the water-rat,
Nectomys
spp., with schistosomiasis endemic areas, these wild rodents are very likely
to acquire
Schistosoma mansoni
infection in their daily activities. The role of the water-rat in the
S. mansoni
cycle would be substantiated if one could prove that these rodents acquire
the parasite during their own activity time, a completely independent time
schedule of human activities. To pursue this goal, we performed two field
experiments in the municipality of Sumidouro, State of Rio de Janeiro, Brazil,
a schistosomiasis endemic area where
N.
squamipes
is found naturally infected. One experiment was devised as a series of observations
of activity time of the water-rat. The other experiment was a test of the
occurrence of late transmission of
S. mansoni
to the water-rat. The daily activity pattern showed that the water-rat is
active chiefly just after sunset. At both diurnal and late exposition essays
the water-rat sentinels got infected by
S. mansoni
. These findings clarify ecological and behavioral components necessary
to the adaptation of
S. mansoni
to the water-rat as a non human definitive host and the existence of a transmission
cycle involving this animals as a reservoir.
