Frequency–dependent incidence in models of sexually transmitted diseases: portrayal of pair–based transmission and effects of illness on contact behaviour

Lloyd‐Smith, James O.; Getz, Wayne M.; Westerhoff, Hans V.

doi:10.1098/rspb.2003.2632

Cited by 59 publications

(63 citation statements)

References 53 publications

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“…Infection-induced behavioural changes are prevalent among host-pathogen systems (Moore 2002) and can alter the ability of a disease to invade and persist in a population (Lloyd-Smith et al 2004). The population-level consequences for the observed behavioural changes towards infected house finches are likely to be critical for MG dynamics.…”

Section: Discussionmentioning

confidence: 99%

Sickness behaviour acting as an evolutionary trap? Male house finches preferentially feed near diseased conspecifics

Bouwman

Hawley

2010

Biol. Lett.

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Host behaviour towards infectious conspecifics is a crucial yet overlooked component of pathogen dynamics. Selection is expected to favour individuals who can recognize and avoid infected conspecifics in order to reduce their own risk of infection. However, evidence is scarce and limited to species employing chemical cues. Here, we experimentally examine whether healthy captive house finches ( Carpodacus mexicanus ) preferentially forage near a same-sex, healthy conspecific versus one infected with the directly transmissible pathogen Mycoplasma gallisepticum (MG), which causes lethargy and visible conjunctivitis. Interestingly, male house finches strongly preferred feeding near diseased conspecifics, while females showed no preference. This sex difference appeared to be the result of lower aggression rates in diseased males, but not in females. The reduced aggression of diseased males may act as an ‘evolutionary trap’ by presenting a historically beneficial behavioural cue in the context of a new environment, which now includes a recently emerged, potentially fatal pathogen. Since MG can be directly transmitted during feeding, healthy males may inadvertently increase their risk of contracting MG. This behaviour is likely to significantly contribute to the continued persistence of MG epidemics in wild populations.

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Section: Discussionmentioning

confidence: 99%

Sickness behaviour acting as an evolutionary trap? Male house finches preferentially feed near diseased conspecifics

Bouwman

Hawley

2010

Biol. Lett.

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“…Density-dependent models are frequently used to characterize the transmission of pathogens that require direct contact for transfer (Ryder et al 2005), whereas frequency-dependent models are often used to describe sexually transmitted infections (Lloyd-Smith et al 2004). Population density likely has a significant influence on disease transmission among male tortoises, as males attain sexual maturity at a FIG.…”

Section: Discussionmentioning

confidence: 99%

Social behavior drives the dynamics of respiratory disease in threatened tortoises

Wendland

Wooding

White

et al. 2010

Ecology

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Since the early 1990s, morbidity and mortality in tortoise populations have been associated with a transmissible, mycoplasmal upper respiratory tract disease (URTD). Although the etiology, transmission, and diagnosis of URTD have been extensively studied, little is known about the dynamics of disease transmission in free-ranging tortoise populations. To understand the transmission dynamics of Mycoplasma agassizii, the primary etiological agent of URTD in wild tortoise populations, we studied 11 populations of free-ranging gopher tortoises (Gopherus polyphemus; n = 1667 individuals) over five years and determined their exposure to the pathogen by serology, by clinical signs, and by detection of the pathogen in nasal lavages. Adults tortoises (n = 759) were 11 times more likely to be seropositive than immature animals (n=242) (odds ratio = 10.6, 95% CI = 5.7-20, P < 0.0001). Nasal discharge was observed in only 1.4% (4/296) of immature tortoises as compared with 8.6% (120/1399) of adult tortoises. Nasal lavages from all juvenile tortoises (n=283) were negative by PCR for mycoplasmal pathogens associated with URTD. We tested for spatial segregation among tortoise burrows by size class and found no consistent evidence of clustering of either juveniles or adults. We suggest that the social behavior of tortoises plays a critical role in the spread of URTD in wild populations, with immature tortoises having minimal interactions with adult tortoises, thereby limiting their exposure to the pathogen. These findings may have broader implications for modeling horizontally transmitted diseases in other species with limited parental care and emphasize the importance of incorporating animal behavior parameters into disease transmission studies to better characterize the host-pathogen dynamics. Abstract. Since the early 1990s, morbidity and mortality in tortoise populations have been associated with a transmissible, mycoplasmal upper respiratory tract disease (URTD). Although the etiology, transmission, and diagnosis of URTD have been extensively studied, little is known about the dynamics of disease transmission in free-ranging tortoise populations. To understand the transmission dynamics of Mycoplasma agassizii, the primary etiological agent of URTD in wild tortoise populations, we studied 11 populations of free-ranging gopher tortoises (Gopherus polyphemus; n ¼ 1667 individuals) over five years and determined their exposure to the pathogen by serology, by clinical signs, and by detection of the pathogen in nasal lavages. Adults tortoises (n ¼ 759) were 11 times more likely to be seropositive than immature animals (n ¼ 242) (odds ratio ¼ 10.6, 95% CI ¼ 5.7-20, P , 0.0001). Nasal discharge was observed in only 1.4% (4/296) of immature tortoises as compared with 8.6% (120/1399) of adult tortoises. Nasal lavages from all juvenile tortoises (n ¼ 283) were negative by PCR for mycoplasmal pathogens associated with URTD. We tested for spatial segregation among tortoise burrows by size class and found no consistent evidenc...

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“…While it is acknowledged that disease status can alter behaviour in humans as well (e.g. [95] and references therein), studies allowing quantification of the impact of infection on behaviour for human infections are rare. For the human infection examples presented in §2, the data were collected in experimental settings with little opportunity to observe and measure altered host behaviour.…”

Section: Host Behaviourmentioning

confidence: 99%

Crossing the scale from within-host infection dynamics to between-host transmission fitness: a discussion of current assumptions and knowledge

Handel

Rohani

2015

Phil. Trans. R. Soc. B

110

181

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The progression of an infection within a host determines the ability of a pathogen to transmit to new hosts and to maintain itself in the population. While the general connection between the infection dynamics within a host and the population-level transmission dynamics of pathogens is widely acknowledged, a comprehensive and quantitative understanding that would allow full integration of the two scales is still lacking. Here, we provide a brief discussion of both models and data that have attempted to provide quantitative mappings from within-host infection dynamics to transmission fitness. We present a conceptual framework and provide examples of studies that have taken first steps towards development of a quantitative framework that scales from within-host infections to population-level fitness of different pathogens. We hope to illustrate some general themes, summarize some of the recent advances and—maybe most importantly—discuss gaps in our ability to bridge these scales, and to stimulate future research on this important topic.

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Frequency–dependent incidence in models of sexually transmitted diseases: portrayal of pair–based transmission and effects of illness on contact behaviour

Cited by 59 publications

References 53 publications

Sickness behaviour acting as an evolutionary trap? Male house finches preferentially feed near diseased conspecifics

Sickness behaviour acting as an evolutionary trap? Male house finches preferentially feed near diseased conspecifics

Social behavior drives the dynamics of respiratory disease in threatened tortoises

Crossing the scale from within-host infection dynamics to between-host transmission fitness: a discussion of current assumptions and knowledge

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