Effects of Culling on<i>Leptospira interrogans</i>Carriage by Rats

Lee, Michael J.; Byers, Kaylee A.; Donovan, Christina M.; Bidulka, Julie; Stephen, Craig; Patrick, David M.; Himsworth, Chelsea G.

doi:10.3201/eid2402.171371

Cited by 34 publications

(37 citation statements)

References 10 publications

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“…It is possible that urban rats benefit from sharing colonies with closely related individuals (e.g., territory defense, stable social structure), and may avoid some inbreeding tradeoffs by having relatively accelerated reproductive life cycles. One benefit may be less diverse parasite and pathogen communities harbored by isolated rats, and dispersal and culling can disrupt these relatively insular colonies (Angley et al, 2018;Lee et al, 2018;Minter et al, 2019).…”

Section: Increasing Relatedness and Fitness Consequencesmentioning

confidence: 99%

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Significant Genetic Impacts Accompany an Urban Rat Control Campaign in Salvador, Brazil

et al. 2019

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Rats thrive in human-dominated landscapes and have expanded to a near global distribution. Norway rats (Rattus norvegicus) contaminate food, damage infrastructure, and are reservoirs for zoonotic pathogens that cause human diseases. To limit these negative impacts, entities around the world implement intervention and control strategies designed to quickly and drastically reduce the number of rats in a population. While the primary goal of these interventions is to reduce rat numbers and their detrimental activities, there are important, yet unexplored, population genetic implications for these rapid population declines. Here, we compare the population genetics of R. norvegicus before, immediately after, and several months following a rodenticide-based eradication campaign targeting rats in an urban slum of Salvador, Brazil. This slum has been the focus of long-term research designed to understand and reduce the risk of leptospirosis for people in this area. We also look for a clear source of rats contributing to population recovery, by either rebounding through breeding of local survivors, or by immigration/reinvasion of the site. We found evidence of severe genetic bottlenecks, with the effective population size dropping 85-91% after eradication, consistent with declines in population sizes. These rapid declines also led to a strong shift in the genetic structure of rats before and after the eradication campaign. Relatedness increased in two of the three study areas after eradication, suggesting reduced population sizes and an uneven impact of the campaign across colonies within the population. Lastly, dozens of low-frequency alleles (mean frequency of 0.037) observed before the campaign were undetected after the campaign, potentially lost from the population via drift or selection. We discuss the public health and ecological implications of these rapid genetic impacts of urban control efforts. Our data suggests that targeting the genetic viability of rat populations may be another important component for integrated pest management (IPM) strategies, designed to reduce urban rats.

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Section: Increasing Relatedness and Fitness Consequencesmentioning

confidence: 99%

“…Eradication campaigns likely disrupt these social structures (Clapperton, 2006), which have the potential to alter the relatedness levels of individuals repopulating an area post-intervention. Lethal control of rats has been linked to novel social interactions and transmission of pathogens (Himsworth et al, 2013a;Lee et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Significant Genetic Impacts Accompany an Urban Rat Control Campaign in Salvador, Brazil

et al. 2019

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“…Trapping was carried out in an urban neighborhood in Vancouver, British Columbia, Canada. Rats were trapped from June 2016-January 2017 in 31 proximal city blocks (Figure 1) which were selected as part of a larger CMR study (e.g., Byers et al, 2017;Donovan et al, 2018;Lee et al, 2018). Briefly, ten Tomahawk Rigid Traps (Tomahawk Live Traps, Hazelhurst, USA) were deployed in each city block.…”

Section: Trappingmentioning

confidence: 99%

“…Leptospira species] was performed as outlined previously in Lee et al (2018). Samples were classified as negative (cycle threshold [Ct]) ≥ 40, suspect positive (Ct = 37-39.99), or positive (Ct ≤ 36.99).…”

Section: Of Pathogenicmentioning

confidence: 99%

Rat in a Cage: Trappability of Urban Norway Rats (Rattus norvegicus)

et al. 2019

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Understanding the local ecology of urban Norway rats (Rattus norevgicus) is necessary to inform effective rat mitigation strategies. While Capture-Mark-Recapture (CMR) methods can be used to acquire such ecological information (e.g., abundance, movement patterns, and habitat use), these techniques assume that all individuals of the study population are equally trappable. To test whether urban rats adhere to this assumption, we conducted a 4-week CMR study in an urban neighborhood of Vancouver, Canada, to evaluate whether rat characteristics (i.e., age, sex, size, wound status, and infection with the pathogen Leptospira spp.) were associated with trappability. We found that the majority of rats entered traps in the first 2 weeks of trapping, and that larger rats were caught earlier in the trapping period. However, smaller, sexually immature rats were recaught more often than were larger, sexually mature rats, suggesting that prior capture affects the ability to recapture urban Norway rats. This highlights the need for CMR studies to account for size, sexual maturity, and prior capture when interpreting data.

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“…In literature it is stated that removing rat populations by reactive culling is often ineffective (Colvin & Jackson, 1999;Cowan, D. P., Quy, & Lambert, 2003;Meyer, 2003). A recent study on Leptospira (Lee et al, 2018) in urban rats even found that lethal, urban rat control was associated with a significant increase in the odds that surviving rats carry Leptospira. These results suggest that human interventions have the potential to affect and even increase the prevalence of zoonotic pathogens within rat populations.…”

Section: Rodent Managementmentioning

confidence: 99%

Rodent-borne health risks in farming systems

Krijger

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Effects of Culling onLeptospira interrogansCarriage by Rats

Cited by 34 publications

References 10 publications

Significant Genetic Impacts Accompany an Urban Rat Control Campaign in Salvador, Brazil

Significant Genetic Impacts Accompany an Urban Rat Control Campaign in Salvador, Brazil

Rat in a Cage: Trappability of Urban Norway Rats (Rattus norvegicus)

Rodent-borne health risks in farming systems

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