Experimental evidence and ecological perspectives for the adaptation of Schistosoma mansoni Sambon, 1907 (Digenea: Schistosomatidae) to a wild host, the water-rat, Nectomys squamipes Brants, 1827 (Rodentia: Sigmodontinae).
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.
D'Andrea
Paulo Sérgio
PS
Laboratório de Biologia e Controle da Esquistossomose, Departamento de Medicina Tropical, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, RJ, 21045-900, Brasil. dandrea@ioc.fiocruz.br
Fernandes
Fabiano Araujo
FA
Cerqueira
Rui
R
Rey
Luis
L
D000818:Animals; D001938:Brazil; D004197:Disease Reservoirs; D004199:Disease Vectors; D005260:Female; D008297:Male; D009115:Muridae / Q000469:parasitology*; D012550:Schistosoma mansoni / Q000502:physiology*; D012555:Schistosomiasis mansoni / Q000635:transmission*; D014867:Water / Q000469:parasitology*
D014867:Water