Gyro-scope: An individual-based computer model to forecast gyrodactylid infections on fish hosts

Oosterhout, Cock van; Potter, Richard; Wright, Helen; Cable, Joanne

doi:10.1016/j.ijpara.2007.09.016

Cited by 22 publications

(25 citation statements)

References 28 publications

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“…The four main results were: (1) fish density did not significantly affect the probability of an epidemic (2) the probability of an epidemic increased with the product of duration and mean intensity of infection in the primary infected fish, (3) female guppies were infected earlier in the epidemic than males, and (4) not surprisingly, the total parasite population increased with the host population density These findings are most consistent with frequency (rather than density) dependent transmission across the range of densities in our experiment. They can be explained by the fact that guppies are social, such that even at the lowest density in the current study, the contact rates among hosts were sufficiently high to allow transmission and higher densities did not increase contact rates enough to increase the probability of an epidemic [18]–[19], [28]. The importance of social contacts is underscored by the observation that female guppies contracted infections earlier than males [see also 35].…”

Section: Discussionmentioning

confidence: 77%

“…One advantage of the guppy- Gyrodactylus system is that it is possible to count the parasite burden of gyrodactylids on each guppy over time. High parasite burdens are typically lethal to the host [24], [28], [29]. In Trinidad, mark-release-recapture studies have shown that gyrodactylid infections can significantly reduce the recapture rate (survival) of guppies, particularly in spate conditions during the wet season rains [29].…”

Section: Introductionmentioning

confidence: 99%

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Parasite Transmission in Social Interacting Hosts: Monogenean Epidemics in Guppies

et al. 2011

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BackgroundInfection incidence increases with the average number of contacts between susceptible and infected individuals. Contact rates are normally assumed to increase linearly with host density. However, social species seek out each other at low density and saturate their contact rates at high densities. Although predicting epidemic behaviour requires knowing how contact rates scale with host density, few empirical studies have investigated the effect of host density. Also, most theory assumes each host has an equal probability of transmitting parasites, even though individual parasite load and infection duration can vary. To our knowledge, the relative importance of characteristics of the primary infected host vs. the susceptible population has never been tested experimentally.Methodology/Principal FindingsHere, we examine epidemics using a common ectoparasite, Gyrodactylus turnbulli infecting its guppy host (Poecilia reticulata). Hosts were maintained at different densities (3, 6, 12 and 24 fish in 40 L aquaria), and we monitored gyrodactylids both at a population and individual host level. Although parasite population size increased with host density, the probability of an epidemic did not. Epidemics were more likely when the primary infected fish had a high mean intensity and duration of infection. Epidemics only occurred if the primary infected host experienced more than 23 worm days. Female guppies contracted infections sooner than males, probably because females have a higher propensity for shoaling.Conclusions/SignificanceThese findings suggest that in social hosts like guppies, the frequency of social contact largely governs disease epidemics independent of host density.

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Section: Discussionmentioning

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Parasite Transmission in Social Interacting Hosts: Monogenean Epidemics in Guppies

et al. 2011

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“…This study has highlighted how mathematical modelling techniques can be employed in order to investigate salmon- G. salaris interactions, and thus, adds to the findings of previous modelling studies [21], [37]–[44]. Further research is required to incorporate the data derived from the present study into host/parasite models to establish how changes to the parasite's population growth rate may affect transmission and the overall impact to host population.…”

Section: Discussionmentioning

confidence: 83%

Reproductive Trade-Offs May Moderate the Impact of Gyrodactylus salaris in Warmer Climates

et al. 2013

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Gyrodactylus salaris is a notifiable freshwater ectoparasite of salmonids. Its primary host is Atlantic salmon (Salmo salar), upon which infections can cause death, and have led to massive declines in salmon numbers in Norway, where the parasite is widespread. Different strains of S. salar vary in their susceptibility, with Atlantic strains (such as those found in Norway) exhibiting no resistance to the parasite, and Baltic strains demonstrating an innate resistance sufficient to regulate parasite numbers on the host causing it to either die out or persist at a low level. In this study, Leslie matrix and compartmental models were used to generate data that demonstrated the population growth of G. salaris on an individual host is dependent on the total number of offspring per parasite, its longevity and the timing of its births. The data demonstrated that the key factor determining the rate of G. salaris population growth is the time at which the parasite first gives birth, with rapid birth rate giving rise to large population size. Furthermore, it was shown that though the parasite can give birth up to four times, only two births are required for the population to persist as long as the first birth occurs before a parasite is three days old. As temperature is known to influence the timing of the parasite's first birth, greater impact may be predicted if introduced to countries with warmer climates than Norway, such as the UK and Ireland which are currently recognised to be free of G. salaris. However, the outputs from the models developed in this study suggest that temperature induced trade-offs between the total number of offspring the parasite gives birth to and the first birth timing may prevent increased population growth rates over those observed in Norway.

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“…is generally less than 10 worms/host [22], but can be as high as 100 parasites [23]. Larger guppies tend to harbour more parasites [24], and the maximum parasite load increases exponentially with increased host body size [25]. These parasites give birth to a fully-grown offspring, which attaches to the host alongside its parent and already contains a developing embryo (reviewed in [26]).…”

Section: Introductionmentioning

confidence: 99%

Sex-Specific Differences in Shoaling Affect Parasite Transmission in Guppies

2010

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BackgroundIndividuals have to trade-off the costs and benefits of group membership during shoaling behaviour. Shoaling can increase the risk of parasite transmission, but this cost has rarely been quantified experimentally. Guppies (Poecilia reticulata) are a model system for behavioural studies, and they are commonly infected by gyrodactylid parasites, notorious fish pathogens that are directly transmitted between guppy hosts.Methodology/Principal FindingsParasite transmission in single sex shoals of male and female guppies were observed using an experimental infection of Gyrodactylus turnbulli. Parasite transmission was affected by sex-specific differences in host behaviour, and significantly more parasites were transmitted when fish had more frequent and more prolonged contact with each other. Females shoaled significantly more than males and had a four times higher risk to contract an infection.Conclusions/SignificanceIntersexual differences in host behaviours such as shoaling are driven by differences in natural and sexual selection experienced by both sexes. Here we show that the potential benefits of an increased shoaling tendency are traded off against increased risks of contracting an infectious parasite in a group-living species.

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Gyro-scope: An individual-based computer model to forecast gyrodactylid infections on fish hosts

Cited by 22 publications

References 28 publications

Parasite Transmission in Social Interacting Hosts: Monogenean Epidemics in Guppies

Parasite Transmission in Social Interacting Hosts: Monogenean Epidemics in Guppies

Reproductive Trade-Offs May Moderate the Impact of Gyrodactylus salaris in Warmer Climates

Sex-Specific Differences in Shoaling Affect Parasite Transmission in Guppies

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