Age-dependent survival and infectivity of Schistosoma mansoni cercariae

Whitfield, P. J.; Bartlett, A.; Khammo, N.; Clothier, Richard H.

doi:10.1017/s0031182003003263

Cited by 29 publications

(28 citation statements)

References 11 publications

(22 reference statements)

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“…These emergence times correspond to times when their putative hosts are present in the water and available for infection, humans during the day and rodents at night. However, schistosome cercariae remain active and infective in the water column for up to 9 hours in an experimental setting [30]. This longevity creates the potential for overlap in actual transmission times, even if the cercariae emerge at different times.…”

Section: Introductionmentioning

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: Introductionmentioning

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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“…This infection causes Schistosomiasis, a parasitic disease that is comparable to malaria in terms of global socio-economic impact [3,4]. Given that cercariae do not feed and hence have a finite lifetime of around 12 hours [5,6], efficient motility is crucial for the parasite's survival and transmission of the Schistosomiasis disease. However, a first-principles understanding of how cercariae swim is completely lacking.…”

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confidence: 99%

Schistosoma mansoni cercariae swim efficiently by exploiting an elastohydrodynamic coupling

et al. 2016

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The motility of many parasites is critical for the infection process of their host, as exemplified by the transmission cycle of the blood fluke Schistosoma mansoni [1]. In their human infectious stage, immature, submillimetre-scale forms of the parasite known as cercariae swim in freshwater and infect human hosts by penetrating through the skin [1,2]. This infection causes Schistosomiasis, a parasitic disease that is comparable to malaria in terms of global socio-economic impact [3,4]. Given that cercariae do not feed and hence have a finite lifetime of around 12 hours [5,6], efficient motility is crucial for the parasite's survival and transmission of the Schistosomiasis disease. However, a first-principles understanding of how cercariae swim is completely lacking. Via a combined experimental, theoretical and robotics based approach -we demonstrate that cercariae efficiently propel themselves against gravity by exploiting a unique elastohydrodynamic coupling. We show that cercariae beat their tail in a periodic fashion while maintaining a fixed flexibility near their posterior and anterior ends. The flexibility in these regions allows an interaction between the fluid drag and bending resistance -an elastohydrodynamic coupling, to naturally break time-reversal symmetry and enable locomotion at small length-scales [7]. We present a theoretical model, a 'T-swimmer', which captures the key swimming phenotype of cercariae. We further validate our results experimentally through a macro-scale robotic realization of the 'T-swimmer', explaining the unique forked-tail geometry of cercariae.Finally, we find that cercariae maintain the flexibility at their posterior and anterior ends at an optimal regime for efficient swimming, as predicted by our theoretical model. We anticipate that our work sets the ground for linking the swimming of S. mansoni cercariae to disease transmission and enables explorations of novel strategies for Schistosomiasis control and prevention.

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“…Since motility of the cercarial tail is essential for swimming and provides force for skin penetration (20–22), we examined whether SPF prevented infection. We treated ~200 cercariae with different concentrations of SPF for 10 mins, and tested their ability to infect mice after a 30-min exposure to their tails (N=6 for each condition).…”

Section: Resultsmentioning

confidence: 99%

A rotifer-derived paralytic compound prevents transmission of schistosomiasis to a mammalian host

Gao

Yang

Lewis

et al. 2018

Preprint

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Age-dependent survival and infectivity of Schistosoma mansoni cercariae

Cited by 29 publications

References 11 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

Schistosoma mansoni cercariae swim efficiently by exploiting an elastohydrodynamic coupling

A rotifer-derived paralytic compound prevents transmission of schistosomiasis to a mammalian host

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