Host age modulates within-host parasite competition

Izhar, Rony; Routtu, Jarkko; Ben‐Ami, Frida

doi:10.1098/rsbl.2015.0131

Cited by 23 publications

(24 citation statements)

References 24 publications

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“…; Izhar & Ben‐Ami ; Izhar et al . ) formed the basis of a compartmental model showing that increasing extrinsic mortality, and thus decreasing total host population density, can lead to increasing transmission. The relationship between mortality and transmission that is classically seen, where higher host densities generate greater transmission, is so pervasive it has become a central assumption of the epidemiological theory that contributes to our understanding of pathogen traits and virulence.…”

Section: Discussionmentioning

confidence: 99%

“…; Izhar & Ben‐Ami ; Izhar et al . ). Host population demography and environmental factors, such as baseline mortality rates, predation and density, have been shown to influence transmission rates and pathogen virulence evolution.…”

Section: Epidemiological Modelmentioning

confidence: 97%

“…; Izhar & Ben‐Ami ; Izhar et al . ). The consideration of age‐related effects on epidemiological processes has contributed greatly to disease prevention strategies (Anderson & May ; Katzmann & Dietz ; Müller ).…”

Section: Introductionmentioning

confidence: 97%

“…) and others (Izhar & Ben‐Ami ; Izhar et al . ) showed that older mothers themselves are more resistant to this pathogen. We used these two observations – that older mothers are both more resistant and give birth to offspring that are more resistant – to develop a compartmental model describing how population age structure, the effects of age and maternal effects combine to influence the spread of infection.…”

Section: Introductionmentioning

confidence: 99%

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Disease spread in age structured populations with maternal age effects

Clark

Garbutt

McNally³

et al. 2017

Ecology Letters

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Fundamental ecological processes, such as extrinsic mortality, determine population age structure. This influences disease spread when individuals of different ages differ in susceptibility or when maternal age determines offspring susceptibility. We show that Daphnia magna offspring born to young mothers are more susceptible than those born to older mothers, and consider this alongside previous observations that susceptibility declines with age in this system. We used a susceptibleinfected compartmental model to investigate how age-specific susceptibility and maternal age effects on offspring susceptibility interact with demographic factors affecting disease spread. Our results show a scenario where an increase in extrinsic mortality drives an increase in transmission potential. Thus, we identify a realistic context in which age effects and maternal effects produce conditions favouring disease transmission.

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Section: Discussionmentioning

confidence: 99%

Section: Epidemiological Modelmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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Disease spread in age structured populations with maternal age effects

Clark

Garbutt

McNally³

et al. 2017

Ecology Letters

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“…; Izhar et al. ; Louhi et al. ), as well as their capacity to exclude or coexist with other competitors (de Roode et al.…”

Section: Description Of the Four Infection Types Used In This Study mentioning

confidence: 99%

Host sexual dimorphism affects the outcome of within‐host pathogen competition

2019

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Natural infections often consist of multiple pathogens of the same or different species. When coinfections occur, pathogens compete for access to host resources and fitness is determined by how well a pathogen can reproduce compared to its competitors. Yet not all hosts provide the same resource pool. Males and females, in particular, commonly vary in both their acquisition of resources and investment in immunity, but their ability to modify any competition between different pathogens remains unknown. Using the Daphnia magna–Pasteuria ramosa model system, we exposed male and female hosts to either a single genotype infection or coinfections consisting of two pathogen genotypes of varying levels of virulence. We found that coinfections within females favored the transmission of the more virulent pathogen genotype, whereas coinfections within male hosts resulted in equal transmission of competing pathogen genotypes. This contrast became less pronounced when the least virulent pathogen was able to establish an infection first, suggesting that the influence of host sex is shaped by priority effects. We suggest that sex is a form of host heterogeneity that may influence the evolution of virulence within coinfection contexts and that one sex may be a reservoir for pathogen genetic diversity in nature.

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Costs of resistance and infection by a generalist pathogen

Dallas

Holtackers²,

Drake

2016

Ecology and Evolution

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Pathogen infection is typically costly to hosts, resulting in reduced fitness. However, pathogen exposure may also come at a cost even if the host does not become infected. These fitness reductions, referred to as “resistance costs”, are inducible physiological costs expressed as a result of a trade‐off between resistance to a pathogen and aspects of host fitness (e.g., reproduction). Here, we examine resistance and infection costs of a generalist fungal pathogen (Metschnikowia bicuspidata) capable of infecting a number of host species. Costs were quantified as reductions in host lifespan, total reproduction, and mean clutch size as a function of pathogen exposure (resistance cost) or infection (infection cost). We provide empirical support for infection costs and modest support for resistance costs for five Daphnia host species. Specifically, only one host species examined incurred a significant cost of resistance. This species was the least susceptible to infection, suggesting the possibility that host susceptibility to infection is associated with the detectability and size of resistance cost. Host age at the time of pathogen exposure did not influence the magnitude of resistance or infection cost. Lastly, resistant hosts had fitness values intermediate between unexposed control hosts and infected hosts. Although not statistically significant, this could suggest that pathogen exposure does come at some marginal cost. Taken together, our findings suggest that infection is costly, resistance costs may simply be difficult to detect, and the magnitude of resistance cost may vary among host species as a result of host life history or susceptibility.

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Host age modulates within-host parasite competition

Cited by 23 publications

References 24 publications

Disease spread in age structured populations with maternal age effects

Disease spread in age structured populations with maternal age effects

Host sexual dimorphism affects the outcome of within‐host pathogen competition

Costs of resistance and infection by a generalist pathogen

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