Control of pyrethroid‐resistant populations of <i>Triatoma infestans</i>, the main vector of <i>Trypanosoma cruzi</i>, by treating dogs with fluralaner in the Argentine Chaco

Laiño, Mariano Alberto; Cardinal, Marta Victoria; Gaspe, María Sol; Enriquez, Gustavo Fabián; Alvedro, Alejandra; Macchiaverna, Natalia Paula; Gürtler, Ricardo E.

doi:10.1111/mve.12561

Cited by 7 publications

(19 citation statements)

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“…Chagas disease vector control personnel repeatedly sprayed rural houses with pyrethroid insecticides during 2000–2014. High levels of pyrethroid resistance was found to occur throughout the municipality [ 42 ] and in the houses selected for the present trial [ 33 ]. Most houses were constructed with mud walls and metal or thatched roofs, with peridomestic structures (e.g.…”

Section: Methodsmentioning

confidence: 99%

“…We conducted a placebo-controlled, before-and-after, nonblinded efficacy trial in 28 sites infested with T. infestans divided into two spatially segregated groups as described in [ 33 ]. We initially designated a control group based on local triatomines being highly resistant to pyrethroids and there being no other insecticide treatment approved for indoor use.…”

Section: Methodsmentioning

confidence: 99%

“…householder collection) for additional evidence of infestation. The distribution of site infestation by ecotope (domicile, storeroom, kitchen, chicken coop and other) and treatment group, and household and demographic features of the dog population have been reported elsewhere [ 33 ].…”

Section: Methodsmentioning

confidence: 99%

“…In dogs experimentally treated with a single oral dose of fluralaner, early stages of T. infestans were killed up to approximately 2 MPT [ 29 ]; both susceptible and pyrethroid-resistant late stages of T. infestans were killed up to 4 MPT [ 30 ]; third or fourth-instar nymphs of Triatoma brasiliensis were killed over at least 7 MPT [ 31 ]; and adult females of Rhodnius prolixus were killed for 3–4 MPT [ 32 ]. Our initial results led us to conduct a small placebo-controlled trial of fluralaner administered to outbred healthy dogs in a rural district of the Argentine Chaco with pyrethroid-resistant populations of T. infestans [ 33 ]. In the fluralaner-treated group, both site infestation and mean abundance dropped significantly to 19–24% of its pre-treatment values by 10 MPT while in the placebo group, both metrics remained stable between 0 and 1 MPT and strongly declined after a rescue treatment with fluralaner to 27–50% of its pre-treatment values [ 33 ].…”

Section: Introductionmentioning

confidence: 99%

“…Our initial results led us to conduct a small placebo-controlled trial of fluralaner administered to outbred healthy dogs in a rural district of the Argentine Chaco with pyrethroid-resistant populations of T. infestans [ 33 ]. In the fluralaner-treated group, both site infestation and mean abundance dropped significantly to 19–24% of its pre-treatment values by 10 MPT while in the placebo group, both metrics remained stable between 0 and 1 MPT and strongly declined after a rescue treatment with fluralaner to 27–50% of its pre-treatment values [ 33 ]. To date, the early and medium-term effects of fluralaner on triatomine abundance combined with T. cruzi infection and contact with humans have not been investigated.…”

Section: Introductionmentioning

confidence: 99%

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Treatment of dogs with fluralaner reduced pyrethroid-resistant Triatoma infestans abundance, Trypanosoma cruzi infection and human-triatomine contact in the Argentine Chaco

et al. 2022

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Background Triatomine elimination efforts and the interruption of domestic transmission of Trypanosoma cruzi are hampered by pyrethroid resistance. Fluralaner, a long-lasting ectoparasiticide administered to dogs, substantially reduced site infestation and abundance of pyrethroid-resistant Triatoma infestans Klug (Heteroptera: Reduviidae) in an ongoing 10-month trial in Castelli (Chaco Province, Argentina). We assessed the effects of fluralaner on vector infection with T. cruzi and blood meal sources stratified by ecotope and quantified its medium-term effects on site infestation and triatomine abundance. Methods We conducted a placebo-controlled, before-and-after efficacy trial of fluralaner in 28 infested sites over a 22-month period. All dogs received either an oral dose of fluralaner (treated group) or placebo (control group) at 0 month post-treatment [MPT]. Placebo-treated dogs were rescue-treated with fluralaner at 1 MPT, as were all eligible dogs at 7 MPT. Site-level infestation and abundance were periodically assessed by timed manual searches with a dislodging aerosol. Vector infection was mainly determined by kDNA-PCR and blood meal sources were determined by enzyme-linked immunosorbent assay. Results In fluralaner-treated households, site infestation dropped from 100% at 0 MPT to 18–19% over the period 6–22 MPT while mean abundance plummeted from 5.5 to 0.6 triatomines per unit effort. In control households, infestation dropped similarly post-treatment. The overall prevalence of T. cruzi infection steadily decreased from 13.8% at 0–1 MPT (baseline) to 6.4% and subsequently 2.3% thereafter, while in domiciles, kitchens and storerooms it dropped from 17.4% to 4.7% and subsequently 3.3% thereafter. Most infected triatomines occurred in domiciles and had fed on humans. Infected-bug abundance plummeted after fluralaner treatment and remained marginal or nil thereafter. The human blood index of triatomines collected in domiciles, kitchens and storerooms highly significantly fell from 42.9% at baseline to 5.3–9.1% over the period 6–10 MPT, increasing to 36.8% at 22 MPT. Dog blood meals occurred before fluralaner administration only. The cat blood index increased from 9.9% at baseline to 57.9–72.7% over the period 6–10 MPT and dropped to 5.3% at 22 MPT, whereas chicken blood meals rose from 39.6% to 63.2–88.6%. Conclusion Fluralaner severely impacted infestation- and transmission-related indices over nearly 2 years, causing evident effects at 1 MPT, and deserves larger efficacy trials. Graphical Abstract

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Treatment of dogs with fluralaner reduced pyrethroid-resistant Triatoma infestans abundance, Trypanosoma cruzi infection and human-triatomine contact in the Argentine Chaco

et al. 2022

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Abundant triatomines in Texas dog kennel environments: Triatomine collections, infection with Trypanosoma cruzi, and blood feeding hosts

Busselman,

Curtis-Robles,

Meyers

et al. 2024

Acta Tropica

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Extended stage duration and diminished fecundity in deltamethrin‐resistant Triatoma infestans (Klug, 1834) of the Argentinean Chaco

Maza,

Nattero,

Gaspe

et al. 2023

Medical Vet Entomology

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Pyrethroid‐resistance is an emergent trait in populations of various insect species. For Triatoma infestans (Klug, 1834) (Heteroptera: Reduviidae), the major vector of Chagas disease in the southern part of South America, hotspot areas of pyrethroid‐resistance have recently been found in the Chaco Province of Argentina. Resistant condition can reduce fitness of individuals in the absence of insecticide exposure, that is, fitness costs. We evaluated the existence of developmental and/or reproductive costs in T. infestans collected from two areas of pyrethroid‐resistance in Chaco Province, Argentina. Three toxicological groups were defined from field‐collected insects: susceptible (survival <20%), moderately resistant (survival between 20% and 80%) and highly resistant (survival >80%). Cohorts of the three toxicological groups were followed‐up to study life cycle and reproductive parameters. Additionally, we parameterized matrix population growth models. First and IV nymphal stages of the resistant groups exhibited a longer stage duration than susceptible ones. The reproductive days and hatching success showed significant lower values revealing reproductive costs for the resistant groups. Matrix analysis showed lower population growth rates for the resistant groups. Our results support developmental and reproductive costs for pyrethroid‐resistant individuals. This trait could be interpreted as lower population recovery ability for pyrethroid‐resistant individuals compared to susceptible insects after alternative vector control actions.

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Control of pyrethroid‐resistant populations of Triatoma infestans, the main vector of Trypanosoma cruzi, by treating dogs with fluralaner in the Argentine Chaco

Cited by 7 publications

References 50 publications

Treatment of dogs with fluralaner reduced pyrethroid-resistant Triatoma infestans abundance, Trypanosoma cruzi infection and human-triatomine contact in the Argentine Chaco

Treatment of dogs with fluralaner reduced pyrethroid-resistant Triatoma infestans abundance, Trypanosoma cruzi infection and human-triatomine contact in the Argentine Chaco

Abundant triatomines in Texas dog kennel environments: Triatomine collections, infection with Trypanosoma cruzi, and blood feeding hosts

Extended stage duration and diminished fecundity in deltamethrin‐resistant Triatoma infestans (Klug, 1834) of the Argentinean Chaco

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