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Defolie C, Merkling T, Fichtel C. Patterns and variation in the mammal parasite-glucocorticoid relationship. Biol Rev Camb Philos Soc 2020; 95:74-93. [PMID: 31608587 DOI: 10.1111/brv.12555] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 08/23/2019] [Accepted: 09/03/2019] [Indexed: 01/24/2023]
Abstract
Parasites are ubiquitous and can strongly affect their hosts through mechanisms such as behavioural changes, increased energetic costs and/or immunomodulation. When parasites are detrimental to their hosts, they should act as physiological stressors and elicit the release of glucocorticoids. Alternatively, previously elevated glucocorticoid levels could facilitate parasite infection due to neuroimmunomodulation. However, results are equivocal, with studies showing either positive, negative or no relationship between parasite infection and glucocorticoid levels. Since factors such as parasite type, infection severity or host age and sex can influence the parasite-glucocorticoid relationship, we review the main mechanisms driving this relationship. We then perform a phylogenetic meta-analysis of 110 records from 65 studies in mammalian hosts from experimental and observational studies to quantify the general direction of this relationship and to identify ecological and methodological drivers of the observed variability. Our review produced equivocal results concerning the direction of the relationship, but there was stronger support for a positive relationship, although causality remained unclear. Mechanisms such as host manipulation for parasite survival, host response to infection, cumulative effects of multiple stressors, and neuro-immunomodulatory effects of glucocorticoids could explain the positive relationship. Our meta-analysis results revealed an overall positive relationship between glucocorticoids and parasitism among both experimental and observational studies. Because all experimental studies included were parasite manipulations, we conclude that parasites caused in general an increase in glucocorticoid levels. To obtain a better understanding of the directionality of this link, experimental manipulation of glucocorticoid levels is now required to assess the causal effects of high glucocorticoid levels on parasite infection. Neither parasite type, the method used to assess parasite infection nor phylogeny influenced the relationship, and there was no evidence for publication bias. Future studies should attempt to be as comprehensive as possible, including moderators potentially influencing the parasite-glucocorticoid relationship. We particularly emphasise the importance of testing hosts of a broad age range, concomitantly measuring sex hormone levels or at least reproductive status, and for observational studies, also considering food availability, host body condition and social stressors to obtain a better understanding of the parasite-glucocorticoid relationship.
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Affiliation(s)
- Charlotte Defolie
- Sociobiology/Anthropology Department, University of Göttingen, Kellnerweg 6, 37077, Göttingen, Germany.,Behavioral Ecology & Sociobiology Unit, German Primate Center, Leibniz Institute for Primate Research, Kellnerweg 4, 37077, Göttingen, Germany.,Leibniz ScienceCampus "Primate Cognition", German Primate Center, Kellnerweg 4, 37077, Göttingen, Germany
| | - Thomas Merkling
- Department of Natural Resource Sciences, McGill University, Macdonald-Stewart Building, 21111 Lakeshore Road, Ste. Anne de Bellevue, Québec, H9X 3V9, Canada
| | - Claudia Fichtel
- Behavioral Ecology & Sociobiology Unit, German Primate Center, Leibniz Institute for Primate Research, Kellnerweg 4, 37077, Göttingen, Germany.,Leibniz ScienceCampus "Primate Cognition", German Primate Center, Kellnerweg 4, 37077, Göttingen, Germany
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Seguel M, Perez-Venegas D, Gutierrez J, Crocker DE, DeRango EJ. Parasitism Elicits a Stress Response That Allocates Resources for Immune Function in South American Fur Seals (Arctocephalus australis). Physiol Biochem Zool 2019; 92:326-338. [PMID: 30986114 DOI: 10.1086/702960] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Parasites can cause chronic stress in some animal species, and this type of stress response has been associated with adverse consequences for the host. In order to know whether parasitism elicited a stress response associated with decreased host fitness, hookworm (Uncinaria sp.) infection was studied in a colony of South American fur seals (Arctocephalus australis) in which hookworms infect nearly all pups born in a reproductive season. A parasite-free group was generated by treating a subset of pups with an antiparasitic drug before they developed patent hookworm infection. Stress and metabolic hormones, energy balance, and humoral and cellular immune parameters were measured in this group and hookworm-infected pups. Hookworms elicited a marked increase in plasma cortisol levels in fur seal pups. These hookworm-infected pups were able to maintain constant glucose levels, despite losing body mass over the course of infection potentially because of increased protein catabolism. Infected pups were able to mount an effective immune response against the parasite and eliminated hookworms from the intestine, recovering partial body mass lost as a result of hookworm infection at the end of the study period. As shown in previous studies, adequate glucose levels are critical for proper T lymphocyte reactivity, and it is possible that, through activation of a stress response, energy can be readily available for immune response against the parasite contributing to early recovery from infection. Although there are potential fitness costs to mounting a sustained stress response, these could also be adaptive and promote survival during critical life-history stages.
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De K, Swarnkar CP, Singh D, Prince LLL. Comparative physiological responses of stress in sheep selected for resistance or susceptibility toHaemonchus contortusin semi-arid tropical region during different seasons. BIOL RHYTHM RES 2016. [DOI: 10.1080/09291016.2016.1234802] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Blutke A, Börjes P, Herbach N, Pfister K, Hamel D, Rehbein S, Wanke R. Acaricide treatment prevents adrenocortical hyperplasia as a long-term stress reaction to psoroptic mange in cattle. Vet Parasitol 2015; 207:125-33. [DOI: 10.1016/j.vetpar.2014.10.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 09/27/2014] [Accepted: 10/07/2014] [Indexed: 11/30/2022]
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Richard S, Cabaret J. Primary infection of kids with Teladorsagia circumcincta: susceptibility and blood constituents. Vet Parasitol 1993; 47:279-87. [PMID: 8333133 DOI: 10.1016/0304-4017(93)90029-m] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Fourteen male cross-bred Alpine x Saanen kids were infected with Teladorsagia circumcincta and four were used as controls. Three different levels of susceptibility to infection were apparent: resistant to infection and resilient to its adverse effects; intermediate (poorly resistant and poorly resilient); susceptible and relatively resilient. In the susceptible kids the establishment rate of infective larvae was twice as large and the nematode egg output five times greater during Weeks 4-8 after infection than in resistant kids. Susceptible kids harboured larger females with higher numbers of eggs in utero; the proportion of Teladorsagia trifurcata was higher in susceptible than in resistant kids. The blood constituents were significantly modified in infected compared with control animals: a lower number of leucocytes (particularly lymphocytes and basophils) and a higher complement activity were recorded in the latter. Compared with resistant kids, susceptible kids had higher counts of leucocytes, basophils and lower lymphocyte levels, less depleted complement pathway activity, higher pepsinogen values and lower levels of albumin and glucose.
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Affiliation(s)
- S Richard
- Département de Biologie appliquée, Université de Toulon, France
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MUTAYOBA B, GOMBE S. Effect of African trypanosomiasis on plasma cortisol and thyroxine concentration in goats. Res Vet Sci 1989. [DOI: 10.1016/s0034-5288(18)31253-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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