A Host–Parasite System with Multiple Parasite Strains and Superinfection Revisited: The Global Dynamics

Host-parasite systems offer such a complex behaviour that few quantitative analysis of their coupled dynamics have been performed. Many intertwinned factors play a role, such as intensity-dependent (intra or interspecific competition, pathogeny, immunological reactions) and/or intensity-independent (abiotic factors, host ethology). Most biomathematical approaches to host-parasite systems are concerned with infectious processes. Corresponding epidemiological models are not well-adapted to macroparasites whose demographical behaviour is quite specific: host mortality, parasite fertility and sometimes recruitment mechanisms depend on the amount of already fixed parasites on a given host and not on the mere existence of parasites. Overdispersion processes are fundamental and determine for a large part the regulation of both populations. A central issue is therefore a reliable description of these processes and their interactions with the global dynamics of the system. Our goal is to develop a mixed deterministic and stochastic model describing the dynamics of a host-parasite system (fish-helminth parasite) having a direct cycle within a marine environment. A dynamical analysis combining a deterministic approach and a stochastic one adapted to macroparasites allows the introduction of spatial and temporal heterogeneities. A particular effort is made towards the recruitment process.

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Compatibility and sex in a snail–schistosome system

Parasitology ◽

10.1017/s0031182001007442 ◽

2001 ◽

Vol 122 (4) ◽

pp. 423-432 ◽

Cited By ~ 15

Author(s):

J. P. WEBSTER

Keyword(s):

Schistosoma Mansoni ◽

Reproductive Strategy ◽

Parasitic Infection ◽

Biomphalaria Glabrata ◽

Parasite Strain ◽

Cross Breeding ◽

Infection Dynamics ◽

Rapd Pcr ◽

Host Parasite ◽

Parasite Strains

Knowledge of the genetics underlying resistance to parasitic infection has important repercussions for our understanding of infection dynamics and the mechanisms of host–parasite co-evolution. The aim here was to determine for a Biomphalaria glabrata–Schistosoma mansoni system whether (1) resistance is dominant over susceptibility, (2) it is possible to crossbreed snails to be simultaneously resistant and/or susceptible to more than one parasite strain and (3) compatibility genotype affects reproductive strategy. Using replicate snail strains artificially selected for either resistance or susceptibility to single replicate parasite strains, individual snails from each line were paired with a selected partner of matched or non-matched compatibility status and cross-breeding was identified by RAPD–PCR. The resulting compatibility phenotype of all offspring was determined. Support for all 3 hypotheses were obtained. The results are discussed in terms of their applied and theoretical implications.

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The Pathogenesis of Experimental Mycotic Encephalitis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010006369x ◽

1969 ◽

Vol 27 ◽

pp. 356-357

Author(s):

James A. Swenberg ◽

Adalbert Koestner ◽

R.P. Tewari

Keyword(s):

Electron Microscopy ◽

Pathogenetic Mechanisms ◽

Host Parasite

Previous investigations of pathogenetic mechanisms in mycotic encephalitis have been restricted to light microscopic and mycologic approaches. In this study, electron microscopy was utilized to determine the mode of vascular penetration and the cellular and subcellular host-parasite interrelationships in brains of mice infected with Oidiodendron kalrai. This newly isolated fungus was selected because of its ability to consistently produce encephalitis with gross and microscopic lesions similar to those observed in naturally occuring mycoses.

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Examination of Schistosome Cercariae and Schistosomules by Scanning Electron Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100062154 ◽

1969 ◽

Vol 27 ◽

pp. 50-51

Author(s):

D. Johnson ◽

P. Moriearty

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

High Resolution ◽

Light Microscopy ◽

Surface Structure ◽

Extensive Study ◽

Scanning Microscopy ◽

Host Parasite ◽

Conventional Electron Microscopy ◽

Scanning Electron

Since several species of Schistosoma, or blood fluke, parasitize man, these trematodes have been subjected to extensive study. Light microscopy and conventional electron microscopy have yielded much information about the morphology of the various stages; however, scanning electron microscopy has been little utilized for this purpose. As the figures demonstrate, scanning microscopy is particularly helpful in studying at high resolution characteristics of surface structure, which are important in determining host-parasite relationships.

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