This is the first record of immature stages of species belonging to the subgenus Nyssorhynchus (Blanchard) in eutrophized breeding habitats. Larvae of Anopheles (Nys.) evansae (Brethes), Anopheles (Nyssorhynchus) rangeli (Gabaldon et al), Culex nigripalpus (Theobald) and Culex quinquefasciatus (Say) (Diptera: Culicidae) were collected in a rural eutrophized dam in Rio de Janeiro State, in Southeastern Brazil. Eutrophication was substantiated by the low diversity of mosquitoes, the high incidence of Cx. quinquefasciatus (42%) and of Daphinia sp. and, the high levels of both organic nitrogen (0.28 mg/l) and total phosphorus (0.02 mg/l).

Foi realizada infecção experimental de camundongos albinos ("Swiss inbred") com cercárias de Schistosoma mansoni, cepa LE, submetidas à ação do adubo termofosfato magnesiano (Tfm), usualmente utilizado em latossolos tropicais e capaz, quando ingerido, de provocar o bloqueio da ovogênese de moluscos planorbídeos. Nas condições do experimento, observou-se a infecção dos roedores. Porém, o número de ovos eliminados pelo grupo controle, representado por cinco camundongos, foi sensivelmente maior que o do grupo Tfm, ainda que a recuperação de vermes, por perfusão, tenha sido bem menor. Do grupo Tfm, foram recuperados 163 (98,2%) vermes adultos machos e apenas 3 (1,8%) fêmeas, isoladas. Do grupo controle, a perfusão proporcionou 53 vermes adultos, sendo 13 machos, 18 fêmeas e 11 casais. Cada camundongo foi exposto a 150 cercárias.

Experimental infection of white mice (Swiss inbred) with LE strain Scistosoma mansoni cercariae submitted to the action of magnesium thermophosphate (Tfm), usually used in tropical latosoils, was performed. This product is able to block ovogenesis of planorbid molluscs. In these experimental conditions, rodents were infected. But, the number of eggs released by the control group (five mice) was markedly greater than that of the Tfm group, although a short number of worms were recovered by perfusion. From the Tfm group, 163 adult worms (98,2%) were recovered and only 3 females (1,8%). Of the control group, perfusion recovered 62 adult worms (22 male worms, 18 female and 11 couples). Each mice was exposed to 150 cercariae.

Foi realizada infecção experimental de camundongos albinos ("Swiss inbred") com cercárias de Schistosoma mansoni, cepa LE, submetidas à ação do adubo termofosfato magnesiano (Tfm), usualmente utilizado em latossolos tropicais e capaz, quando ingerido, de provocar o bloqueio da ovogênese de moluscos planorbídeos. Nas condições do experimento, observou-se a infecção dos roedores. Porém, o número de ovos eliminados pelo grupo controle, representado por cinco camundongos, foi sensivelmente maior que o do grupo Tfm, ainda que a recuperação de vermes, por perfusão, tenha sido bem menor. Do grupo Tfm, foram recuperados 163 (98,2%) vermes adultos machos e apenas 3 (1,8%) fêmeas, isoladas. Do grupo controle, a perfusão proporcionou 53 vermes adultos, sendo 13 machos, 18 fêmeas e 11 casais. Cada camundongo foi exposto a 150 cercárias.

Experimental infection of white mice (Swiss inbred) with LE strain Scistosoma mansoni cercariae submitted to the action of magnesium thermophosphate (Tfm), usually used in tropical latosoils, was performed. This product is able to block ovogenesis of planorbid molluscs. In these experimental conditions, rodents were infected. But, the number of eggs released by the control group (five mice) was markedly greater than that of the Tfm group, although a short number of worms were recovered by perfusion. From the Tfm group, 163 adult worms (98,2%) were recovered and only 3 females (1,8%). Of the control group, perfusion recovered 62 adult worms (22 male worms, 18 female and 11 couples). Each mice was exposed to 150 cercariae.