Longitudinal dynamics of co-infecting gastrointestinal parasites in a wild sheep population – CORRIGENDUM

Sweeny, Amy R.; Corripio-Miyar, Yolanda; Bal, Xavier; Hayward, Adam D.; Pilkington, Jill G.; McNeilly, Tom N.; Nussey, Daniel H.; Kenyon, Fiona

doi:10.1017/s0031182022000324

Cited by 4 publications

(3 citation statements)

References 1 publication

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“…Most inferences on sex differences have been drawn from studies of wild populations (e.g. [ 20 , 39 , 40 ]) where underlying pathogen dose can only be approximated [ 41 ], or from laboratory studies where sex-specific infection rates are often inferred from limited doses (e.g. [ 16 , 17 , 19 , 23 , 42 ]).…”

Section: Introductionmentioning

confidence: 99%

Is there a sicker sex? Dose relationships modify male–female differences in infection prevalence

Butterworth,

Heffernan,

Hall

2024

Proc. R. Soc. B.

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Throughout the animal kingdom, there are striking differences in the propensity of one sex or the other to become infected. However, precisely when we should expect males or females to be the sicker sex remains unclear. A major barrier to answering this question is that very few studies have considered how the susceptibility of males and females changes across the full range of pathogen doses encountered in nature. Without quantifying this ‘dose–susceptibility’ relationship, we have likely underestimated the scope for sex differences to arise. Here, we use the Daphnia magnia – Pasteuria ramosa system to reveal that sex differences in susceptibility are entirely dose-dependent, with pathogens having a higher probability of successfully establishing an infection in mature males at low doses, but mature females at high doses. The scope for male–female differences to emerge is therefore much greater than previously appreciated—extending to sex differences in the upper limits to infection success, per-propagule infectivity risks and density-dependent pathogen behaviour. Applying this expanded scope across the animal kingdom will help us understand when and why a sicker sex emerges, and the implications for diseases in nature—where sex ratios, age structure and pathogen densities vary drastically.

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Section: Introductionmentioning

confidence: 99%

Is there a sicker sex? Dose relationships modify male–female differences in infection prevalence

Butterworth,

Heffernan,

Hall

2024

Proc. R. Soc. B.

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“…Elements of populations that create structure such as classes of individuals of specific ages, sexes or breeding stages can have profound effects on disease dynamics [3,[5][6][7][8][9]. Sex is an especially important factor because sex-biases in infections can contribute to differential transmission within populations due to behaviour [10][11][12][13][14][15], amplify outbreaks due to seasonal changes in susceptibility [16][17][18][19] and modify population impacts through disproportionate mortality [20][21][22]. Differences in infection and mortality can also modulate virulence evolution through sex-specific immune responses that affect pathogen replication and growth [23,24].…”

Section: Introductionmentioning

confidence: 99%

“…Sex hormones can also have strong effects on host immunity [29], such that testosterone suppresses immune responses while estrogens enhance it, resulting in weaker immune responses in males and increased susceptibility to pathogen infection [25,30,31]. As such, the majority of empirical studies find that infections are typically male-biased [28,32,33], although this generalization is sometimes reversed [34][35][36][37][38][39][40] or weak [41] and may be linked to seasonal reproductive stress associated with pregnancy, parturition or parental care [16,17]. Thus, it is likely that the effects of sex-biased infections may be highly pronounced in disease systems where host reproductive strategies differ seasonally among sexes [19].…”

Section: Introductionmentioning

confidence: 99%

Sex-biased infections scale to population impacts for an emerging wildlife disease

et al. 2023

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Demographic factors are fundamental in shaping infectious disease dynamics. Aspects of populations that create structure, like age and sex, can affect patterns of transmission, infection intensity and population outcomes. However, studies rarely link these processes from individual to population-scale effects. Moreover, the mechanisms underlying demographic differences in disease are frequently unclear. Here, we explore sex-biased infections for a multi-host fungal disease of bats, white-nose syndrome, and link disease-associated mortality between sexes, the distortion of sex ratios and the potential mechanisms underlying sex differences in infection. We collected data on host traits, infection intensity and survival of five bat species at 42 sites across seven years. We found females were more infected than males for all five species. Females also had lower apparent survival over winter and accounted for a smaller proportion of populations over time. Notably, female-biased infections were evident by early hibernation and likely driven by sex-based differences in autumn mating behaviour. Male bats were more active during autumn which likely reduced replication of the cool-growing fungus. Higher disease impacts in female bats may have cascading effects on bat populations beyond the hibernation season by limiting recruitment and increasing the risk of Allee effects.

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Long-term temporal trends in gastrointestinal parasite infection in wild Soay sheep

et al. 2022

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Monitoring the prevalence and abundance of parasites over time is important for addressing their potential impact on host life histories, immunological profiles and their influence as a selective force. Only long-term ecological studies have the potential to shed light on both the temporal trends in infection prevalence and abundance and the drivers of such trends, because of their ability to dissect drivers that may be confounded over shorter time scales. Despite this, only a relatively small number of such studies exist. Here, we analysed changes in the prevalence and abundance of gastrointestinal parasites in the wild Soay sheep population of St. Kilda across 31 years. The host population density (PD) has increased across the study, and PD is known to increase parasite transmission, but we found that PD and year explained temporal variation in parasite prevalence and abundance independently. Prevalence of both strongyle nematodes and coccidian microparasites increased during the study, and this effect varied between lambs, yearlings and adults. Meanwhile, abundance of strongyles was more strongly linked to host PD than to temporal (yearly) dynamics, while abundance of coccidia showed a strong temporal trend without any influence of PD. Strikingly, coccidian abundance increased 3-fold across the course of the study in lambs, while increases in yearlings and adults were negligible. Our decades-long, intensive, individual-based study will enable the role of environmental change and selection pressures in driving these dynamics to be determined, potentially providing unparalleled insight into the drivers of temporal variation in parasite dynamics in the wild.

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Longitudinal dynamics of co-infecting gastrointestinal parasites in a wild sheep population – CORRIGENDUM

Cited by 4 publications

References 1 publication

Is there a sicker sex? Dose relationships modify male–female differences in infection prevalence

Is there a sicker sex? Dose relationships modify male–female differences in infection prevalence

Sex-biased infections scale to population impacts for an emerging wildlife disease

Long-term temporal trends in gastrointestinal parasite infection in wild Soay sheep

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