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Biomphalaria tenagophila: dynamics of populations of resistant and susceptible strains to Schistosoma mansoni, with or without pressure of the parasite

2006; Instituto Oswaldo Cruz, Ministério da Saúde; Volume: 101; Issue: suppl 1 Linguagem: Inglês

10.1590/s0074-02762006000900038

1678-8060

Florence Mara Rosa, Ana Lúcia Brunialti Godard, Deborah Aparecida Negrão‐Corrêa, Horácio Antonio Rodrigues, Omar dos Santos Carvalho, Roberta Lima Caldeira, Horácio M. Santana Teles, Engels Maciel, Liana Konovaloff Jannotti-Passos, Paulo Marcos Zech Coelho,

Helminth infection and control

Resistant (Taim, RS) and susceptible albino (Joinville, SC) Biomphalaria tenagophila populations were kept together, at different proportions, throughout a 18-month-period. Some of the snail groups were submitted to Schistosoma mansoni infection. The targets of this study were (a) to analyze the populational dynamics among resistant and susceptible individuals to S. mansoni; (b) to study the resistance phenotype in descendants of cross-breeding; (c) to observe whether the parasite could exert any kind of selection in those snail populations. Throughout the experiment it could be observed that the susceptible B. tenagophila strain (Joinville) underwent a selective pressure of the parasite that was negative, since the individuals showed a high mortality rate. Although B. tenagophila (Taim) population presented a higher mortality rate without pressure of the parasite, this event was compensated by a reproductive capacity. B. tenagophila Taim was more fecund than B. tenagophila Joinville and was able to transmit the resistance character to their descendants. F1 generation obtained by cross-breeding between resistant and susceptible lineages was completely resistant to S. mansoni infection, irrespective of the Taim proportion. Moreover, less than 5% of F2 progeny were susceptible to S. mansoni infection.