Fast recovery of house infestation with Triatoma brasiliensis after residual insecticide spraying in a semiarid region of Northeastern Brazil

Bezerra, Claudia Mendonça; Barbosa, Silvia Ermelinda; Souza, Rita de Cássia Moreira de; Feijão, Levi Ximenes; Gürtler, Ricardo E.; Ramos, Alberto Novaes; Diotaiuti, Liléia

doi:10.1371/journal.pntd.0008404

Cited by 13 publications

(11 citation statements)

References 44 publications

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“…A multi-country research project sponsored by Tropical Disease Research (TDR/WHO) sought to identify the main sources of house reinfestation with major Chagas disease vectors after insecticide spraying across the Gran Chaco and the Brazilian cerrado and caatinga ecoregions [35,44,45]. Following its implementation in a rural section of Pampa del Indio (Chaco Province), the Argentine arm scaled up the interventions to the municipality-wide level (divided in four operational areas) to test whether intensified, high-quality vector control actions were able to suppress T. infestans from all rural villages in a sustained fashion and to interrupt the domestic transmission of T. cruzi infection before launching mass etiologic treatment of T. cruzi-seropositive children.…”

Section: Introductionmentioning

confidence: 99%

The Pampa del Indio project: District-wide quasi-elimination of Triatoma infestans after a 9-year intervention program in the Argentine Chaco

et al. 2023

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Background The elimination of Triatoma infestans, the main domestic vector of Trypanosoma cruzi, is lagging behind expectations in the Gran Chaco region. We implemented an insecticide-based intervention program and assessed its long-term effects on house infestation and bug abundance in a resource-constrained municipality (Pampa del Indio, northeastern Argentina) inhabited by creole and the Qom indigenous people (2007–2016). Key questions were whether district-wide data integration revealed patterns concealed at lower spatial levels; to what extent preintervention infestation and pyrethroid resistance challenged the effectiveness of insecticide-based control efforts, and how much control effort was needed to meet defined targets. Methods Supervised vector control teams i) georeferenced every housing unit at baseline (1,546); ii) evaluated house infestation using timed-manual searches with a dislodging aerosol across four rural areas designated for district-wide scaling up; iii) sprayed with pyrethroid insecticide 92.7% of all houses; iv) periodically monitored infestation and promoted householder-based surveillance, and v) selectively sprayed the infested houses, totaling 1,823 insecticide treatments throughout the program. Results Baseline house infestation (mean, 26.8%; range, 14.4–41.4%) and bug abundance plummeted over the first year postintervention (YPI). Timed searches at baseline detected 61.4–88.0% of apparent infestations revealed by any of the methods used. Housing dynamics varied widely among areas and between Qom and creole households. Preintervention triatomine abundance and the cumulative frequency of insecticide treatments were spatially aggregated in three large clusters overlapping with pyrethroid resistance, which ranged from susceptible to high. Persistent foci were suppressed with malathion. Aggregation occurred mainly at house compound or village levels. Preintervention domestic infestation and abundance were much greater in Qom than in creole households, whereas the reverse was recorded in peridomestic habitats. House infestation, rare (1.9–3.7%) over 2–6 YPI, averaged 0.66% (95% confidence interval, 0.28–1.29%) at endpoint. Conclusions Upscale integration revealed multiple coupled heterogeneities (spatial, sociodemographic and biological) that reflect large inequalities, hamper control efforts, and provide opportunities for targeted, sustainable disease control. High-coverage, professional insecticide spraying combined with systematic surveillance-and-response were essential ingredients to achieve the quasi-elimination of T. infestans within 5 YPI and concomitant transmission blockage despite various structural threats and constraints.

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Section: Introductionmentioning

confidence: 99%

The Pampa del Indio project: District-wide quasi-elimination of Triatoma infestans after a 9-year intervention program in the Argentine Chaco

et al. 2023

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“…infestans one to two months after alpha-cypermethrin spraying [ 29 ]; in this study, household reinfestation in 12J and CL began to rise by three months post-spraying, strongly reinforcing the need to evaluate alternate insecticides and longer-lasting formulations for improved triatomine control in the Gran Chaco. Rapid population recovery has also been demonstrated for pyrethroid susceptible Triatoma brasiliensis in Brazil [ 84 ] and T . infestans in Argentina [ 85 ], with household infestations returning to baseline levels by 14 months and 2–3 years post-spraying, respectively.…”

Section: Discussionmentioning

confidence: 99%

“…infestans from 12J have been collected from up to 2.5 km away from community dwellings and shown to have obtained blood meals from multiple sources, including chickens and humans, further demonstrating the capacity for these populations to mobilize, disperse widely and survive in different microhabitats [ 26 ]. Studies from Argentina, Bolivia and Brazil support the hypothesis that triatomine reinfestation dynamics may be strongly associated with features of the peridomestic environment, which constitute suitable artificial ecotopes that provide shelter, blood meal sources and contiguity between domestic and sylvatic environments [ 29 , 84 , 89 ].…”

Section: Discussionmentioning

confidence: 99%

Dynamics of Triatoma infestans populations in the Paraguayan Chaco: Population genetic analysis of household reinfestation following vector control

Arias¹,

Messenger

Rolón³

et al. 2022

PLoS ONE

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Background Although domestic infestations by Triatoma infestans have been successfully controlled across Latin America, in areas of the Gran Chaco region, recurrent post-spraying house colonization continues to be a significant challenge, jeopardizing Chagas disease vector control and maintaining active Trypanosoma cruzi transmission. Methodology/Principal findings To investigate the dynamics of triatomine reinfestation in a rural area of the Paraguayan Chaco, genetic characterization (based on 10 microsatellite loci and cytochrome B sequence polymorphisms) was performed on baseline and reinfestant T. infestans (n = 138) from four indigenous communities and adjacent sylvatic sites. House quality and basic economic activities were assessed across the four communities. Significant genetic differentiation was detected among all baseline triatomine populations. Faster reinfestation was observed in the communities with higher infestation rates pre-spraying. Baseline and reinfestant populations from the same communities were not genetically different, but two potentially distinct processes of reinfestation were evident. In Campo Largo, the reinfestant population was likely founded by domestic survivor foci, with reduced genetic diversity relative to the baseline population. However, in 12 de Junio, reinfestant bugs were likely derived from different sources, including survivors from the pre-spraying population and sympatric sylvatic bugs, indicative of gene-flow between these habitats, likely driven by high human mobility and economic activities in adjacent sylvatic areas. Conclusions/Significance Our results demonstrate that sylvatic T. infestans threatens vector control strategies, either as a reinfestation source or by providing a temporary refuge during insecticide spraying. Passive anthropogenic importation of T. infestans and active human interactions with neighboring forested areas also played a role in recolonization. Optimization of spraying, integrated community development and close monitoring of sylvatic areas should be considered when implementing vector control activities in the Gran Chaco.

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“…This epidemiological scenario gained more complexity over the 1990s with the emergence of pyrethroid resistance in T. infestans and associated control failures across northern Argentina and Bolivia [ 14 – 18 ]. The issue of rapid recovery of triatomine populations following insecticide spraying campaigns cuts across the major triatomine vector species, such as Triatoma dimidiata , Triatoma brasiliensis , Rhodnius ecuadoriensis and Rhodnius prolixus (e.g., [ 19 – 23 ]).…”

Section: Introductionmentioning

confidence: 99%

Improved vector control of Triatoma infestans limited by emerging pyrethroid resistance across an urban-to-rural gradient in the Argentine Chaco

et al. 2021

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Background The sustainable elimination of Triatoma infestans in the Gran Chaco region represents an enduring challenge. Following the limited effects of a routine pyrethroid insecticide spraying campaign conducted over 2011–2013 (first period) in Avia Terai, an endemic municipality with approximately 2300 houses, we implemented a rapid-impact intervention package to suppress house infestation across the urban-to-rural gradient over 2015–2019 (second period). Here, we assess their impacts and whether persisting infestations were associated with pyrethroid resistance. Methods The 2011–2013 campaign achieved a limited detection and spray coverage across settings (< 68%), more so during the surveillance phase. Following community mobilization and school-based interventions, the 2015–2019 program assessed baseline house infestation using a stratified sampling strategy; sprayed all rural houses with suspension concentrate beta-cypermethrin, and selectively sprayed infested and adjacent houses in urban and peri-urban settings; and monitored house infestation and performed selective treatments over the follow-up. Results Over the first period, house infestation returned to pre-intervention levels within 3–4 years. The adjusted relative odds of house infestation between 2011–2013 and 2015–2016 differed very little (adj. OR: 1.17, 95% CI 0.91–1.51). Over the second period, infestation decreased significantly between 0 and 1 year post-spraying (YPS) (adj. OR: 0.36, 95% CI 0.28–0.46), with heterogeneous effects across the gradient. Mean bug abundance also dropped between 0 and 1 YPS and thereafter remained stable in rural and peri-urban areas. Using multiple regression models, house infestation and bug abundance at 1 YPS were 3–4 times higher if the house had been infested before treatment, or was scored as high-risk or non-participating. No low-risk house was ever infested. Persistent foci over two successive surveys increased from 30.0 to 59.3% across the gradient. Infestation was more concentrated in peridomestic rather than domestic habitats. Discriminating-dose bioassays showed incipient or moderate pyrethroid resistance in 7% of 28 triatomine populations collected over 2015–2016 and in 83% of 52 post-spraying populations. Conclusions The intervention package was substantially more effective than the routine insecticide spraying campaign, though the effects were lower than predicted due to unexpected incipient or moderate pyrethroid resistance. Increased awareness and diagnosis of vector control failures in the Gran Chaco, including appropriate remedial actions, are greatly needed. Graphical abstract

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Fast recovery of house infestation with Triatoma brasiliensis after residual insecticide spraying in a semiarid region of Northeastern Brazil

Cited by 13 publications

References 44 publications

The Pampa del Indio project: District-wide quasi-elimination of Triatoma infestans after a 9-year intervention program in the Argentine Chaco

The Pampa del Indio project: District-wide quasi-elimination of Triatoma infestans after a 9-year intervention program in the Argentine Chaco

Dynamics of Triatoma infestans populations in the Paraguayan Chaco: Population genetic analysis of household reinfestation following vector control

Improved vector control of Triatoma infestans limited by emerging pyrethroid resistance across an urban-to-rural gradient in the Argentine Chaco

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