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)

D’Andrea, Paulo Sérgio; Fernandes, Felipe Amorim; Cerqueira, Rui; Rey, Luís

doi:10.1590/s0074-02762002000900003

Cited by 16 publications

(11 citation statements)

References 24 publications

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“…In some cases both peaks occurred, but in others, only one peak occurred. Intraspecific differences in emergence time may correspond to differential definitive host use as this characteristic is likely selected for by the time that definitive hosts are present in the water and available for transmission [17],[54]. Therefore, we suspect that in Kenya S. rodhaini infects a host or group of hosts that are most active in the water just after sunset and right before sunrise.…”

Section: Discussionmentioning

confidence: 99%

Interactions between Natural Populations of Human and Rodent Schistosomes in the Lake Victoria Region of Kenya: A Molecular Epidemiological Approach

et al. 2008

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Background Schistosoma mansoni exists in a complex environmental milieu that may select for significant evolutionary changes in this species. In Kenya, the sympatric distribution of S. mansoni with S. rodhaini potentially influences the epidemiology, ecology, and evolutionary biology of both species, because they infect the same species of snail and mammalian hosts and are capable of hybridization.Methodology/Principal FindingsOver a 2-year period, using a molecular epidemiological approach, we examined spatial and temporal distributions, and the overlap of these schistosomes within snails, in natural settings in Kenya. Both species had spatially and temporally patchy distributions, although S. mansoni was eight times more common than S. rodhaini. Both species were overdispersed within snails, and most snails (85.2% for S. mansoni and 91.7% for S. rodhaini) only harbored one schistosome genotype. Over time, half of snails infected with multiple genotypes showed a replacement pattern in which an initially dominant genotype was less represented in later replicates. The other half showed a consistent pattern over time; however, the ratio of each genotype was skewed. Profiles of circadian emergence of cercariae revealed that S. rodhaini emerges throughout the 24-hour cycle, with peak emergence before sunrise and sometimes immediately after sunset, which differs from previous reports of a single nocturnal peak immediately after sunset. Peak emergence for S. mansoni cercariae occurred as light became most intense and overlapped temporally with S. rodhaini. Comparison of schistosome communities within snails against a null model indicated that the community was structured and that coinfections were more common than expected by chance. In mixed infections, cercarial emergence over 24 hours remained similar to single species infections, again with S. rodhaini and S. mansoni cercarial emergence profiles overlapping substantially.Conclusions/SignificanceThe data from this study indicate a lack of obvious spatial or temporal isolating mechanisms to prevent hybridization, raising the intriguing question of how the two species retain their separate identities.

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Section: Discussionmentioning

confidence: 99%

Interactions between Natural Populations of Human and Rodent Schistosomes in the Lake Victoria Region of Kenya: A Molecular Epidemiological Approach

et al. 2008

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“…These results show that use of unusual mammalian hosts is not unique to a certain lineage, and that morphological or behavioural adaptations observed (Théron et al . 1997; D’Andrea et al . 2002; Freire et al .…”

Section: Discussionmentioning

confidence: 99%

“…Yet, variability in host use, morphology, and behaviour have been described in the New World (Théron et al . 1997; D’Andrea et al . 2002; Freire et al .…”

Section: Introductionmentioning

confidence: 99%

Origin and diversification of the human parasite Schistosoma mansoni

et al. 2005

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Schistosoma mansoni is the most widespread of the human-infecting schistosomes, present in 54 countries, predominantly in Africa, but also in Madagascar, the Arabian Peninsula, and the Neotropics. Adult-stage parasites that infect humans are also occasionally recovered from baboons, rodents, and other mammals. Larval stages of the parasite are dependent upon certain species of freshwater snails in the genus Biomphalaria, which largely determine the parasite's geographical range. How S. mansoni genetic diversity is distributed geographically and among isolates using different hosts has never been examined with DNA sequence data. Here we describe the global phylogeography of S. mansoni using more than 2500 bp of mitochondrial DNA (mtDNA) from 143 parasites collected in 53 geographically widespread localities. Considerable within-species mtDNA diversity was found, with 85 unique haplotypes grouping into five distinct lineages. Geographical separation, and not host use, appears to be the most important factor in the diversification of the parasite. East African specimens showed a remarkable amount of variation, comprising three clades and basal members of a fourth, strongly suggesting an East African origin for the parasite 0.30-0.43 million years ago, a time frame that follows the arrival of its snail host. Less but still substantial variation was found in the rest of Africa. A recent colonization of the New World is supported by finding only seven closely related New World haplotypes which have West African affinities. All Brazilian isolates have nearly identical mtDNA haplotypes, suggesting a founder effect from the establishment and spread of the parasite in this large country.

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“…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 .…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2016

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Schistosomiasis is a neglected tropical disease of a significant public health impact. The water rat Nectomys squamipes is one of the most important non-human hosts in the schistosomiasis mansoni transmission in Brazil, being considered a wild reservoir. Cellular mechanisms that contribute to the physiological adaptation of this rodent to the Schistosoma mansoni parasite are poorly understood. Here we identified, for the first time, that a hepatic steatosis, a condition characterized by excessive lipid accumulation with formation of lipid droplets (LDs) within hepatocytes, occurs in response to the natural S. mansoni infection of N. squamipes, captured in an endemic region. Significant increases of LD area in the hepatic tissue and LD numbers/hepatocyte, detected by quantitative histopathological and ultrastructural analyses, were paralleled by increased serum profile (total cholesterol and triglycerides) in infected compared to uninfected animals. Raman spectroscopy showed high content of polyunsaturated fatty acids (PUFAs) in the liver of both groups. MALDI-TOFF mass spectroscopy revealed an amplified pool of omega-6 PUFA arachidonic acid in the liver of infected animals. Assessment of liver functional activity by the levels of hepatic transaminases (ALT and AST) did not detect any alteration during the natural infection. In summary, this work demonstrates that the natural infection of the wild reservoir N. squamipes with S. mansoni elicits hepatic steatosis in the absence of liver functional harm and that accumulation of lipids, markedly PUFAs, coexists with low occurrence of inflammatory granulomatous processes, suggesting that lipid stores may be acting as a protective mechanism for dealing with the infection.

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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)

Cited by 16 publications

References 24 publications

Interactions between Natural Populations of Human and Rodent Schistosomes in the Lake Victoria Region of Kenya: A Molecular Epidemiological Approach

Interactions between Natural Populations of Human and Rodent Schistosomes in the Lake Victoria Region of Kenya: A Molecular Epidemiological Approach

Origin and diversification of the human parasite Schistosoma mansoni

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

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