Strongyloides venezuelensis Brumpt, 1934 : avaliação de alguns aspectos do ciclo indireto
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Data
2018-05-17
Autores
Rossi, Debora Goldner
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Universidade Federal do Espírito Santo
Resumo
Introduction. Strongyloides venezuelensis (Brumpt, 1934) has been used as an experimental model of strongyloidiasis and its life cycle is complex and poorly known, with alternating generations of parasite and free-living stages. Many aspects of the parasite biology are not clear, especially regarding the existence of free-living males. Objectives. The goal of this study is to verify which factors, related to the host or to the culture environment, can influence the development of adults of free-living stages in the indirect cycle of the parasite. Methods. Environmental factors were evaluated, such as: (a) vermiculite cultures and agar plates (Koga agar) and; (b) culture temperature. Regarding host factors, we evaluated: (c) experimental infection of the parasite in Swiss mice, Wistar rats, gerbils and hybrid rats from the crossing of Wistar rats with wild rats; (d) host age; (e) amount of inoculated larvae and; (f) immunological sensibilization with larvae inoculation. The ability to maintain the indirect cycle of the parasite was also evaluated by monitoring the positive cultures for free-living females for longer periods, as well as the cloning of freeliving females in order to verify whether parthenogenetic females may or may not maintain the free-living cycle. Results and Conclusions. (1) Firstgeneration free-living males were absent in different fecal culture conditions, maintained for three days, from the hosts. (2) The frequency of free-living females in the faeces cultures from different hosts was low at different culture conditions, except when faeces from wild hybrid rats were first submitted to temperature reduction (6°C) before incubation at 28°C, when the frequency of those females increased significantly. (3) First-generation free-living females were able to maintain the heterogeneous cycle of the nematode, including males in later generations. (4) The free-living cycle of S. venezuelensis was maintained in the laboratory, in successive cultures, apparently by parthenogenetic free-living females.
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Stool culture , Freeliving , Parthenogenesis , Strongyloides venezuelensis , Cultura de fezes , Vida livre , Partenogênese