Biological implications of the phenotypic plasticity in the Schistosoma mansoni - Nectomys squamipes model

Abstract

SUMMARYThe water-rat Nectomys squamipes is mostly important non-human host in schistosomiasis mansoni transmission in Brazil, due to its susceptibility, high abundance and water-contact pattern. During experimental infection of N. squamipes with Schistosoma mansoni, adult worms show phenotypic plasticity. This finding led us to investigate whether biological behavior is also affected. This was assessed comparing the biological characteristics of four S. mansoni strains: BE (State of Belém do Pará), CE (State of Pernambuco), CMO (State of Rio Grande do Norte) and SJ (State of São Paulo) using laboratory-bred N. squamipes. The infection was monitored by determination of the pre-patent period, fecal egg output, egg viability, intestinal egg count and, infectivity rate. No biological modification was observed in these parameters. Overall results highlight that N. squamipes was susceptible to several S. mansoni strains, suggesting that it might contribute to the maintenance of schistosomiasis mansoni in Brazil.

Natural Schistosoma mansoni Infection in the Wild Reservoir Nectomys squamipes Leads to Excessive Lipid Droplet Accumulation in Hepatocytes in the Absence of Liver Functional Impairment

“…squamipes is highly susceptible to the experimental S . mansoni infection [11, 43–45] and that both experimental and natural infection of this wild reservoir reproduce the granulomatous reaction observed in experimental infections in other models, such as mice [21, 22]. Moreover, S .…”

“…mansoni infection, long-term field studies of N . squamipes populations, based on mark-recapture technique, showed no influence of this parasite on the survival and reproductive capacity of the water-rat [8, 10, 11]. Indeed, early studies have indicated that N .…”

Research Note. The wild water-rats and their relevance in the context of schistosomiasis mansoni in Brazil: what we know and recommendations for further research

“…The infection in these animals shows that they were not strongly affected by parasitism and elimination of viable eggs was constant during the whole infection period (Machado-Silva et al, 1994). Highly susceptible to various strains also was demonstraded (Rodrigues-Silva et al, 1992;Martinez et al 2008). According to Martins (1958), in order to have a real parameter of the importance of these wild reservoirs in the epidemiology of schistosomiasis, it is necessary that studies are based on the following objectives: a) To determine the relative susceptibility of rodents that are frequently found with natural infection in different endemic areas, performing serial euthanasias to establish the number of infected and uninfected animals; the number, sex, stage of maturation of worms; size and location in the host body; presence of viability and non-viability eggs in different organs, feces and urine; and duration of infection; b) To infect mollusks with miracidia from eggs obtained from naturally infected rodents and to perform infection on laboratory and wild animals with cercariae of these mollusks; c) Determine whether these rodents are capable of maintaining the infection in the absence of infected humans.…”

The Role of Wild Rodents in the Transmission of Schistosoma mansoni in Brazil

“…Costa- Silva (2000) observed that N. squamipes was susceptible to several S. mansoni strains, confirming its potential to act as a natural reservoir in some endemic areas and its utility as an experimental model for morphologic studies of S. mansoni. Martinez et al (2008) compared biological characteristics of four S. mansoni strains using N. squamipes as the experimental model. They concluded that this rodent was susceptible to different strains because the rodent did not present differences in biological parameters of infection when the different strains were compared.…”