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McCarthy ML, Wallace DI. Optimal control of a tick population with a view to control of Rocky Mountain Spotted Fever. MATHEMATICAL BIOSCIENCES AND ENGINEERING : MBE 2023; 20:18916-18938. [PMID: 38052583 DOI: 10.3934/mbe.2023837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
In some regions of the Americas, domestic dogs are the host for the tick vector Rhipicephalus sanguineus, and spread the tick-borne pathogen Rickettsia rickettsii, which causes Rocky Mountain Spotted Fever (RMSF) in humans. Interventions are carried out against the vector via dog collars and acaricidal wall treatments. This paper investigates the optimal control of acaricidal wall treatments, using a prior model for populations and disease transmission developed for this particular vector, host, and pathogen. It is modified with a death term during questing stages reflecting the cost of control and level of coverage. In the presence of the control, the percentage of dogs and ticks infected with Ri. rickettsii decreases in a short period and remains suppressed for a longer period, including after treatment is discontinued. Risk of RMSF infection declines by 90% during this time. In the absence of re-application, infected tick and dog populations rebound, indicating the eventual need for repeated treatment.
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Affiliation(s)
- Maeve L McCarthy
- Department of Mathematics & Statistics, Murray State University, 203A Industry & Technology, Murray KY 42071, USA
| | - Dorothy I Wallace
- Department of Mathematics, Dartmouth College, 27 N. Main Street, 6188 Kemeny Hall, Hanover, NH 03755-3551, USA
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2
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Gürtler RE, Gaspe MS, Macchiaverna NP, Enriquez GF, Rodríguez-Planes LI, Fernández MDP, Provecho YM, Cardinal MV. The Pampa del Indio project: District-wide quasi-elimination of Triatoma infestans after a 9-year intervention program in the Argentine Chaco. PLoS Negl Trop Dis 2023; 17:e0011252. [PMID: 37093886 PMCID: PMC10159358 DOI: 10.1371/journal.pntd.0011252] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 05/04/2023] [Accepted: 03/19/2023] [Indexed: 04/25/2023] Open
Abstract
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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Affiliation(s)
- Ricardo Esteban Gürtler
- Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales, Laboratorio de Eco-Epidemiología, Buenos Aires, Argentina
- CONICET-Universidad de Buenos Aires, Instituto de Ecología, Genética y Evolución de Buenos Aires (IEGEBA), Buenos Aires, Argentina
| | - María Sol Gaspe
- Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales, Laboratorio de Eco-Epidemiología, Buenos Aires, Argentina
- CONICET-Universidad de Buenos Aires, Instituto de Ecología, Genética y Evolución de Buenos Aires (IEGEBA), Buenos Aires, Argentina
| | - Natalia Paula Macchiaverna
- Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales, Laboratorio de Eco-Epidemiología, Buenos Aires, Argentina
- CONICET-Universidad de Buenos Aires, Instituto de Ecología, Genética y Evolución de Buenos Aires (IEGEBA), Buenos Aires, Argentina
| | - Gustavo Fabián Enriquez
- Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales, Laboratorio de Eco-Epidemiología, Buenos Aires, Argentina
- CONICET-Universidad de Buenos Aires, Instituto de Ecología, Genética y Evolución de Buenos Aires (IEGEBA), Buenos Aires, Argentina
| | - Lucía Inés Rodríguez-Planes
- Instituto de Ciencias Polares, Ambiente y Recursos Naturales, Universidad Nacional de Tierra del Fuego, Ushuaia, Argentina
| | - María Del Pilar Fernández
- Paul G. Allen School for Global Animal Health, Washington State University, Pullman, Washington, United States of America
| | - Yael Mariana Provecho
- Ministerio de Salud de la Nación, Dirección de Control de Enfermedades Transmitidas por Vectores, Buenos Aires, Argentina
| | - Marta Victoria Cardinal
- Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales, Laboratorio de Eco-Epidemiología, Buenos Aires, Argentina
- CONICET-Universidad de Buenos Aires, Instituto de Ecología, Genética y Evolución de Buenos Aires (IEGEBA), Buenos Aires, Argentina
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Gual-Gonzalez L, Medina M, Valverde-Castro C, Beltrán V, Caro R, Triana-Chávez O, Nolan MS, Cantillo-Barraza O. Laboratory Evaluation and Field Feasibility of Micro-Encapsulated Insecticide Effect on Rhodnius prolixus and Triatoma dimidiata Mortality in Rural Households in Boyacá, Colombia. INSECTS 2022; 13:insects13111061. [PMID: 36421964 PMCID: PMC9697714 DOI: 10.3390/insects13111061] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 11/02/2022] [Accepted: 11/03/2022] [Indexed: 06/02/2023]
Abstract
Chagas disease is a neglected vector-borne zoonosis caused by the parasite Trypanosoma cruzi that is primarily transmitted by insects of the subfamily Triatominae. Although control efforts targeting domestic infestations of Rhodnius prolixus have been largely successful, with several regions in Boyacá department certified free of T. cruzi transmission by intradomicile R. prolixus, novel native species are emerging, increasing the risk of disease. Triatoma dimidiata is the second most important species in Colombia, and conventional control methods seem to be less effective. In this study we evaluated the efficacy and usefulness of micro-encapsulated insecticide paints in laboratory conditions and its applicability in rural communities to avoid triatomine domiciliation. Laboratory conditions measured mortality at 6 months and 12 months, with an average mortality between 93-100% for T. dimidiata and 100% for R. prolixus. Evaluation of triatomine infestation in rural households was measured after one year, with an overall perception of effectiveness in reducing household domiciliation. Although triatomines were still spotted inside and around the homes, our findings demonstrate the ability of micro-encapsulated insecticide to prevent colonization inside the households when comparing infestation rates from previous years. Current control measures suggest insecticide spraying every six months, which implies great economic cost and logistical effort. Complementary triatomine control measures with insecticide spraying and micro-encapsulated insecticide paint would make public health efforts more efficient and reduce the frequency of treatment.
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Affiliation(s)
- Lídia Gual-Gonzalez
- Arnold School of Public Health, University of South Carolina, Columbia, SC 29208, USA
| | - Manuel Medina
- Unidad de Control de Enfermedades Transmitidas por Vectores, Secretaría de Salud Boyacá, Tunja 150001, Colombia
| | - César Valverde-Castro
- Grupo de Investigación en Medicina Tropical, Universidad del Magdalena, Santa Marta 470003, Colombia
- Grupo Biología y Control Enfermedades Infecciosas, Universidad Antioquia, Medellín 050010, Colombia
| | - Virgilio Beltrán
- Unidad de Control de Enfermedades Transmitidas por Vectores, Secretaría de Salud Boyacá, Tunja 150001, Colombia
| | - Rodrigo Caro
- Unidad de Control de Enfermedades Transmitidas por Vectores, Secretaría de Salud Boyacá, Tunja 150001, Colombia
| | - Omar Triana-Chávez
- Grupo Biología y Control Enfermedades Infecciosas, Universidad Antioquia, Medellín 050010, Colombia
| | - Melissa S. Nolan
- Arnold School of Public Health, University of South Carolina, Columbia, SC 29208, USA
| | - Omar Cantillo-Barraza
- Grupo Biología y Control Enfermedades Infecciosas, Universidad Antioquia, Medellín 050010, Colombia
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Gürtler RE, Laiño MA, Alvedro A, Enriquez GF, Macchiaverna NP, Gaspe MS, Cardinal MV. Treatment of dogs with fluralaner reduced pyrethroid-resistant Triatoma infestans abundance, Trypanosoma cruzi infection and human-triatomine contact in the Argentine Chaco. Parasit Vectors 2022; 15:257. [PMID: 35831874 PMCID: PMC9277862 DOI: 10.1186/s13071-022-05343-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 05/23/2022] [Indexed: 11/16/2022] Open
Abstract
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 ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s13071-022-05343-2.
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Affiliation(s)
- Ricardo Esteban Gürtler
- Laboratory of Eco-Epidemiology, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina. .,Instituto de Ecología, Genética y Evolución de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Universitaria, Buenos Aires, Argentina.
| | - Mariano Alberto Laiño
- Laboratory of Eco-Epidemiology, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina.,Instituto de Ecología, Genética y Evolución de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Universitaria, Buenos Aires, Argentina
| | - Alejandra Alvedro
- Laboratory of Eco-Epidemiology, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina.,Instituto de Ecología, Genética y Evolución de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Universitaria, Buenos Aires, Argentina
| | - Gustavo Fabián Enriquez
- Laboratory of Eco-Epidemiology, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina.,Instituto de Ecología, Genética y Evolución de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Universitaria, Buenos Aires, Argentina
| | - Natalia Paula Macchiaverna
- Laboratory of Eco-Epidemiology, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina.,Instituto de Ecología, Genética y Evolución de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Universitaria, Buenos Aires, Argentina
| | - María Sol Gaspe
- Laboratory of Eco-Epidemiology, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina.,Instituto de Ecología, Genética y Evolución de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Universitaria, Buenos Aires, Argentina
| | - Marta Victoria Cardinal
- Laboratory of Eco-Epidemiology, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina. .,Instituto de Ecología, Genética y Evolución de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Universitaria, Buenos Aires, Argentina.
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Grijalva MJ, Moncayo AL, Yumiseva CA, Ocaña-Mayorga S, Baus EG, Villacís AG. Evaluation of Selective Deltamethrin Application with Household and Community Awareness for the Control of Chagas Disease in Southern Ecuador. JOURNAL OF MEDICAL ENTOMOLOGY 2022; 59:1421-1433. [PMID: 35604412 PMCID: PMC9278838 DOI: 10.1093/jme/tjac050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Indexed: 05/25/2023]
Abstract
Chagas disease is endemic in ~70% of Ecuador. Rhodnius ecuadoriensis and Triatoma carrioni (Hemiptera: Reduviidae) are the primary vectors of Chagas disease in Southern Ecuador. This study tested the effectiveness of selective deltamethrin application of Domiciliary Units (DUs) infested with triatomines, coupled with community education activities and a community-based surveillance system. Ten communities were selected in Loja Province, 466 DUs were examined, of these, 5.6% were infested with R. ecuadoriensis (Density [D] = 4 triatomines/DUs searched, Crowding [CR] = 71 triatomines/infested house, Colonization Index [CI] = 77% infested DUs with nymphs) and 8% with T. carrioni (D = 0.6, CR = 7, CI = 64%). Infested DUs were sprayed with deltamethrin. Subsequent visits were conducted at 6 and 12 mo after spraying. At each time point, new entomological searches were carried out in all DUs. All entomological indexes dropped significantly for the primary vector species one year after the initial intervention (R. ecuadoriensis: I = 2%, D = 0.1, CR = 7, CI = 100%; T. carrioni: I = 1.6%, D = 0.1, CR = 5.5, CI = 50%). Fifteen min educational talks were conducted in every DUs and workshops for schoolchildren were organized. Community-based surveillance system was established. However, there is a high risk of DUs reinfestation, possibly from sylvatic habitats (especially of R. ecuadoriensis) and reinforcing educational and surveillance activities are necessary.
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Affiliation(s)
- Mario J Grijalva
- Centro de Investigación para la Salud en América Latina, Escuela de Ciencias Biológicas, Facultad de Ciencias Exactas y Naturales, Pontificia Universidad Católica del Ecuador, Quito, Ecuador
- Infectious and Tropical Disease Institute, Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, USA
| | - Ana L Moncayo
- Centro de Investigación para la Salud en América Latina, Escuela de Ciencias Biológicas, Facultad de Ciencias Exactas y Naturales, Pontificia Universidad Católica del Ecuador, Quito, Ecuador
| | - Cesar A Yumiseva
- Centro de Investigación para la Salud en América Latina, Escuela de Ciencias Biológicas, Facultad de Ciencias Exactas y Naturales, Pontificia Universidad Católica del Ecuador, Quito, Ecuador
| | - Sofia Ocaña-Mayorga
- Centro de Investigación para la Salud en América Latina, Escuela de Ciencias Biológicas, Facultad de Ciencias Exactas y Naturales, Pontificia Universidad Católica del Ecuador, Quito, Ecuador
- Infectious and Tropical Disease Institute, Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, USA
| | - Esteban G Baus
- Centro de Investigación para la Salud en América Latina, Escuela de Ciencias Biológicas, Facultad de Ciencias Exactas y Naturales, Pontificia Universidad Católica del Ecuador, Quito, Ecuador
| | - Anita G Villacís
- Centro de Investigación para la Salud en América Latina, Escuela de Ciencias Biológicas, Facultad de Ciencias Exactas y Naturales, Pontificia Universidad Católica del Ecuador, Quito, Ecuador
- Infectious and Tropical Disease Institute, Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, USA
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Laiño MA, Cardinal MV, Gaspe MS, Enriquez GF, Alvedro A, Macchiaverna NP, Gürtler RE. Control of pyrethroid-resistant populations of Triatoma infestans, the main vector of Trypanosoma cruzi, by treating dogs with fluralaner in the Argentine Chaco. MEDICAL AND VETERINARY ENTOMOLOGY 2022; 36:149-158. [PMID: 34866216 DOI: 10.1111/mve.12561] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 11/12/2021] [Accepted: 11/24/2021] [Indexed: 06/13/2023]
Abstract
We assessed whether fluralaner administered to outbred healthy dogs reduced or supressed site infestation and abundance of pyrethroid-resistant populations of Triatoma infestans Klug (Heteroptera: Reduviidae). We conducted a placebo-controlled before-and-after efficacy trial in 28 infested sites in Castelli (Argentine Chaco) over 10 months. All 72 dogs initially present received either an oral dose of fluralaner (treated group) or placebo (control group) at month 0 posttreatment (MPT). Preliminary results justified treating all 38 control-house dogs with fluralaner 1 month later, and 71 of 78 existing dogs at 7 MPT. Site-level infestation and triatomine abundance were evaluated using timed manual searches with a dislodging aerosol. In the fluralaner-treated group, infestation dropped significantly from 100% at baseline to 19% over 6-10 MPT whereas mean abundance fell highly significantly from 5.5 to 0.8-0.9 triatomines per unit effort. In the placebo group, site infestation and mean abundance remained stable between 0 and 1 MPT, and strongly declined after fluralaner administration from 13.0-14.7 - triatomines at 0-1 MPT to 4.0-4.2 over 6-10 MPT. Only one of 81 noninfested sites before fluralaner treatment became infested subsequently. Fluralaner significantly reduced the site-level infestation and abundance of pyrethroid-resistant T. infestans and should be tested more widely in Phase III efficacy trials.
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Affiliation(s)
- Mariano Alberto Laiño
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Laboratory of Eco-Epidemiology, Ciudad Universitaria, Buenos Aires, Argentina
- Instituto de Ecología, Genética y Evolución de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Universitaria, Buenos Aires, Argentina
| | - Marta Victoria Cardinal
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Laboratory of Eco-Epidemiology, Ciudad Universitaria, Buenos Aires, Argentina
- Instituto de Ecología, Genética y Evolución de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Universitaria, Buenos Aires, Argentina
| | - María Sol Gaspe
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Laboratory of Eco-Epidemiology, Ciudad Universitaria, Buenos Aires, Argentina
- Instituto de Ecología, Genética y Evolución de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Universitaria, Buenos Aires, Argentina
| | - Gustavo Fabián Enriquez
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Laboratory of Eco-Epidemiology, Ciudad Universitaria, Buenos Aires, Argentina
- Instituto de Ecología, Genética y Evolución de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Universitaria, Buenos Aires, Argentina
| | - Alejandra Alvedro
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Laboratory of Eco-Epidemiology, Ciudad Universitaria, Buenos Aires, Argentina
- Instituto de Ecología, Genética y Evolución de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Universitaria, Buenos Aires, Argentina
| | - Natalia Paula Macchiaverna
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Laboratory of Eco-Epidemiology, Ciudad Universitaria, Buenos Aires, Argentina
- Instituto de Ecología, Genética y Evolución de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Universitaria, Buenos Aires, Argentina
| | - Ricardo E Gürtler
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Laboratory of Eco-Epidemiology, Ciudad Universitaria, Buenos Aires, Argentina
- Instituto de Ecología, Genética y Evolución de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Universitaria, Buenos Aires, Argentina
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A population model for Triatoma infestans in chicken coops. Ecol Modell 2021. [DOI: 10.1016/j.ecolmodel.2021.109753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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8
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Gaspe MS, Cardinal MV, Fernández MDP, Vassena CV, Santo-Orihuela PL, Enriquez GF, Alvedro A, Laiño MA, Nattero J, Alvarado-Otegui JA, Macchiaverna NP, Cecere MC, Freilij H, Gürtler RE. Improved vector control of Triatoma infestans limited by emerging pyrethroid resistance across an urban-to-rural gradient in the Argentine Chaco. Parasit Vectors 2021; 14:437. [PMID: 34454569 PMCID: PMC8401064 DOI: 10.1186/s13071-021-04942-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 08/10/2021] [Indexed: 11/25/2022] Open
Abstract
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 ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s13071-021-04942-9.
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Affiliation(s)
- María Sol Gaspe
- Laboratorio de Eco-Epidemiología, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina. .,Instituto de Ecología, Genética y Evolución de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina.
| | - Marta Victoria Cardinal
- Laboratorio de Eco-Epidemiología, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina.,Instituto de Ecología, Genética y Evolución de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
| | - María Del Pilar Fernández
- Laboratorio de Eco-Epidemiología, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina.,Washington State University, Paul G. Allen School for Global Animal Health, Allen Center, 1155 College Ave., Pullman, WA, 99164, USA
| | - Claudia Viviana Vassena
- Centro de Investigaciones de Plagas e Insecticidas (CIPEIN, CONICET/UNIDEF/CITEDEF), Juan Bautista La Salle 4397, Villa Martelli, CP 1603, Buenos Aires, Argentina.,Universidad Nacional de San Martín, Buenos Aires, Argentina
| | - Pablo Luis Santo-Orihuela
- Centro de Investigaciones de Plagas e Insecticidas (CIPEIN, CONICET/UNIDEF/CITEDEF), Juan Bautista La Salle 4397, Villa Martelli, CP 1603, Buenos Aires, Argentina.,Cátedra de Química Analítica Instrumental, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Gustavo Fabián Enriquez
- Laboratorio de Eco-Epidemiología, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina.,Instituto de Ecología, Genética y Evolución de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
| | - Alejandra Alvedro
- Laboratorio de Eco-Epidemiología, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina.,Instituto de Ecología, Genética y Evolución de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
| | - Mariano Alberto Laiño
- Laboratorio de Eco-Epidemiología, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina.,Instituto de Ecología, Genética y Evolución de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
| | - Julieta Nattero
- Laboratorio de Eco-Epidemiología, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina.,Instituto de Ecología, Genética y Evolución de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
| | - Julián Antonio Alvarado-Otegui
- Laboratorio de Eco-Epidemiología, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
| | - Natalia Paula Macchiaverna
- Laboratorio de Eco-Epidemiología, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina.,Instituto de Ecología, Genética y Evolución de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
| | - María Carla Cecere
- Laboratorio de Eco-Epidemiología, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina.,Instituto de Ecología, Genética y Evolución de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
| | - Héctor Freilij
- Servicio de Parasitología, Hospital de Niños Ricardo Gutiérrez, Instituto Multidisciplinario de Investigación en Patologías Pediátricas, CONICET-GCBA, Buenos Aires, Argentina
| | - Ricardo Esteban Gürtler
- Laboratorio de Eco-Epidemiología, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina. .,Instituto de Ecología, Genética y Evolución de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina.
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9
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Gonçalves R, Landivar D, Grover Sañez Liendo E, Mamani Fernandez J, Ismail HM, Paine MJI, Courtenay O, Bern C. Improving houses in the Bolivian Chaco increases effectiveness of residual insecticide spraying against infestation with Triatoma infestans, vector of Chagas disease. Trop Med Int Health 2021; 26:1127-1138. [PMID: 34114721 DOI: 10.1111/tmi.13640] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Failure to control domestic Triatoma infestans in the Chaco is attributed to vulnerable adobe construction, which provides vector refuges and diminishes insecticide contact. We conducted a pilot to test the impact of housing improvement plus indoor residual spraying (IRS) on house infestation and vector abundance in a rural community in the Bolivian Chaco. METHODS The intervention included three arms: housing improvement + IRS [HI], assisted IRS [AS] in which the team helped to clear the house pre-IRS and routine IRS [RS]. HI used locally available materials, traditional construction techniques and community participation. Vector parameters were assessed by Timed Manual Capture for 2 person-hours per house at baseline and medians of 114, 173, 314, 389 and 445 days post-IRS-1. A second IRS round was applied at a median of 314 days post-IRS-1. RESULTS Post-intervention infestation indices and abundance fell in all three arms. The mean odds of infestation was 0.29 (95% CL 0.124, 0.684) in the HI relative to the RS arm. No difference was observed between AS and RS. Vector abundance was reduced by a mean 44% (24.8, 58.0) in HI compared to RS, with no difference between AS and RS. Median delivered insecticide concentrations per house were lower than the target of 50 mg/m2 in >90% of houses in all arms. CONCLUSION Housing improvement using local materials and community participation is a promising strategy to improve IRS effectiveness in the Bolivian Chaco. A larger trial is needed to quantify the impact on reinfestation over time.
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Affiliation(s)
- Raquel Gonçalves
- Zeeman Institute and School of Life Sciences, University of Warwick, Coventry, UK
| | | | | | | | - Hanafy M Ismail
- Liverpool School of Tropical Medicine, Department of Vector Biology, Liverpool, UK
| | - Mark J I Paine
- Liverpool School of Tropical Medicine, Department of Vector Biology, Liverpool, UK
| | - Orin Courtenay
- Zeeman Institute and School of Life Sciences, University of Warwick, Coventry, UK
| | - Caryn Bern
- Department of Epidemiology and Biostatistics, School of Medicine, University of California San Francisco, San Francisco, CA, USA
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10
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Vian A, Amstad E. Mechano-responsive microcapsules with uniform thin shells. SOFT MATTER 2019; 15:1290-1296. [PMID: 30468441 DOI: 10.1039/c8sm02047g] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Capsules often prolong the shelf-life of active ingredients, such as many types of drugs, food additives, or cosmetic substances, because they delay oxidation of these substances or prevent their reactions with molecules contained in the surrounding. If capsules are appropriately designed, they can offer an additional benefit: they allow close control over the timing and location of the release of active ingredients. To take advantage of these features, capsules must possess shells whose thickness and composition are well-defined. However, the shell thickness of capsules often varies considerably even within a single capsule, thereby hampering good control over the release kinetics of encapsulants. These variations can be reduced, and hence the degree of control over the release kinetics increased, if shells are made thin. Unfortunately, the controlled fabrication of mechanically stable microcapsules with well-defined sub-μm thick shells is difficult. Here, we introduce a method to fabricate capsules with uniform semi-permeable shells with a thickness as low as 400 nm. This is achieved using water-oil-water double emulsions with 800 nm thick shells as templates to fabricate capsules with uniform 400 nm thin shells. These shells occupy less than 2% of the capsule volume, thereby minimizing their footprint. Despite their thin shells, these capsules are mechanically robust: they withstand pressures up to 1.3 MPa without deformation and remain intact if exposed to pressures up to 2.75 MPa. Moreover, while they are permeable towards water, they retain low molecular weight encapsulants even if dried and re-dispersed. The thin shells of the capsules open up new possibilities of their use to functionalize materials with at least one dimension that is small, such as coatings, where thick shells introduce defects, or as building blocks of new types of functional materials.
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Affiliation(s)
- A Vian
- Soft Materials Laboratory, Institute of Materials, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland.
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11
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Socioeconomic profile and perceptions of Chagas disease in indigenous communities of the Paraguayan Chaco. J Public Health (Oxf) 2018. [DOI: 10.1007/s10389-018-1001-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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12
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Hamer GL, Bejcek JR, Valdez EA, Curtis-Robles R, Hamer SA. A Pilot Radio Telemetry Field Study of Triatomine Vectors (Hemiptera: Reduviidae) of the Chagas Disease Parasite. JOURNAL OF MEDICAL ENTOMOLOGY 2018; 55:1380-1385. [PMID: 29986045 PMCID: PMC6201830 DOI: 10.1093/jme/tjy094] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Indexed: 06/08/2023]
Abstract
We conducted the first pilot radio telemetry study of hematophagous arthropods by placing transmitters on wild-caught triatomine insects ('kissing bugs'), vectors of the Chagas disease parasite. In Texas-a recognized hotspot for triatomine diversity and locally-acquired human and animal Chagas disease-we tagged five female and four male Triatoma gerstaeckeri (Stål) (Hemiptera: Reduviidae), as well as one female and one male Triatoma sanguisuga (Leconte) (Hemiptera: Reduviidae) in three counties from 2015 to 2017. In comparative trials, placement of the transmitter on the dorsal side of the abdomen underneath the hemelytra wings, with the transmitter antenna shortened to 3 cm, yielded the best results. We tracked the movements of the 11 tagged bugs over an average of 4.8 d (range of 1 to 12 d) and detected 18 movement events with an average distance of 3.8 m (range of 1 to 20 m). This pilot study demonstrates the potential utility for using telemetry as a tool for studying fine-scale non-flight movement of triatomines and the discovery of cryptic resting habitats. Future studies using this or similar technologies to study movement and behavior of triatomines could test for site-fidelity of resting habitats and provide novel insight into aspects of vector biology that could be targeted in disease risk reduction efforts.
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Affiliation(s)
- Gabriel L Hamer
- Department of Entomology, Texas A&M University, College Station, TX
| | - Justin R Bejcek
- Department of Entomology, Texas A&M University, College Station, TX
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX
| | - Edwin A Valdez
- Department of Entomology, Texas A&M University, College Station, TX
| | - Rachel Curtis-Robles
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX
| | - Sarah A Hamer
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX
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13
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Gaspe MS, Provecho YM, Fernández MP, Vassena CV, Santo Orihuela PL, Gürtler RE. Beating the odds: Sustained Chagas disease vector control in remote indigenous communities of the Argentine Chaco over a seven-year period. PLoS Negl Trop Dis 2018; 12:e0006804. [PMID: 30278044 PMCID: PMC6168123 DOI: 10.1371/journal.pntd.0006804] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 08/29/2018] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Rapid reinfestation of insecticide-treated dwellings hamper the sustained elimination of Triatoma infestans, the main vector of Chagas disease in the Gran Chaco region. We conducted a seven-year longitudinal study including community-wide spraying with pyrethroid insecticides combined with periodic vector surveillance to investigate the house reinfestation process in connection with baseline pyrethroid resistance, housing quality and household mobility in a rural section of Pampa del Indio mainly inhabited by deprived indigenous people (Qom). METHODOLOGY/PRINCIPAL FINDINGS Despite evidence of moderate pyrethroid resistance in local T. infestans populations, house infestation dropped from 31.9% at baseline to 0.7% at 10 months post-spraying (MPS), with no triatomine found at 59 and 78 MPS. Household-based surveillance corroborated the rare occurrence of T. infestans and the house invasion of other four triatomine species. The annual rates of loss of initially occupied houses and of household mobility were high (4.6-8.0%). Housing improvements did not translate into a significant reduction of mud-walled houses and refuges for triatomines because most households kept the former dwelling or built new ones with mud walls. CONCLUSIONS/SIGNIFICANCE Our results refute the assumption that vector control actions performed in marginalized communities of the Gran Chaco are doomed to fail. The larger-than-expected impacts of the intervention program were likely associated with the combined effects of high-coverage, professional insecticide spraying followed by systematic vector surveillance-and-response, broad geographic coverage creating a buffer zone, frequent housing replacement and residential mobility. The dynamical interactions among housing quality, mobility and insecticide-based control largely affect the chances of vector elimination.
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Affiliation(s)
- M. Sol Gaspe
- Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales, Laboratorio de Eco-Epidemiología, Ciudad Universitaria, Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas-Universidad de Buenos Aires. Instituto de Ecología, Genética y Evolución de Buenos Aires (IEGEBA), Ciudad Universitaria, Buenos Aires, Argentina
| | - Yael M. Provecho
- Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales, Laboratorio de Eco-Epidemiología, Ciudad Universitaria, Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas-Universidad de Buenos Aires. Instituto de Ecología, Genética y Evolución de Buenos Aires (IEGEBA), Ciudad Universitaria, Buenos Aires, Argentina
- Coordinación de Vectores, Dirección Nacional de Epidemiología y Análisis de la Situación de Salud, Ministerio de Salud de la Nación, Buenos Aires, Argentina
| | - María P. Fernández
- Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales, Laboratorio de Eco-Epidemiología, Ciudad Universitaria, Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas-Universidad de Buenos Aires. Instituto de Ecología, Genética y Evolución de Buenos Aires (IEGEBA), Ciudad Universitaria, Buenos Aires, Argentina
- Earth Institute, Columbia University, New York, New York, United States of America
| | - Claudia V. Vassena
- Centro de Investigaciones de Plagas e Insecticidas (UNIDEF, CITEDEF, CONICET, CIPEIN), Buenos Aires, Argentina
- Cátedra de Química Analítica Instrumental, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Pablo L. Santo Orihuela
- Centro de Investigaciones de Plagas e Insecticidas (UNIDEF, CITEDEF, CONICET, CIPEIN), Buenos Aires, Argentina
- Departamento de Investigación e Ingeniería Ambiental (3iA), Universidad Nacional de San Martín, Buenos Aires, Argentina
| | - Ricardo E. Gürtler
- Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales, Laboratorio de Eco-Epidemiología, Ciudad Universitaria, Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas-Universidad de Buenos Aires. Instituto de Ecología, Genética y Evolución de Buenos Aires (IEGEBA), Ciudad Universitaria, Buenos Aires, Argentina
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15
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Messenger LA, Rowland M. Insecticide-treated durable wall lining (ITWL): future prospects for control of malaria and other vector-borne diseases. Malar J 2017; 16:213. [PMID: 28532494 PMCID: PMC5441104 DOI: 10.1186/s12936-017-1867-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 05/15/2017] [Indexed: 11/24/2022] Open
Abstract
While long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) are the cornerstones of malaria vector control throughout sub-Saharan Africa, there is an urgent need for the development of novel insecticide delivery mechanisms to sustain and consolidate gains in disease reduction and to transition towards malaria elimination and eradication. Insecticide-treated durable wall lining (ITWL) may represent a new paradigm for malaria control as a potential complementary or alternate longer-lasting intervention to IRS. ITWL can be attached to inner house walls, remain efficacious over multiple years and overcome some of the operational constraints of first-line control strategies, specifically nightly behavioural compliance required of LLINs and re-current costs and user fatigue associated with IRS campaigns. Initial experimental hut trials of insecticide-treated plastic sheeting reported promising results, achieving high levels of vector mortality, deterrence and blood-feeding inhibition, particularly when combined with LLINs. Two generations of commercial ITWL have been manufactured to date containing either pyrethroid or non-pyrethroid formulations. While some Phase III trials of these products have demonstrated reductions in malaria incidence, further large-scale evidence is still required before operational implementation of ITWL can be considered either in a programmatic or more targeted community context. Qualitative studies of ITWL have identified aesthetic value and observable entomological efficacy as key determinants of household acceptability. However, concerns have been raised regarding installation feasibility and anticipated cost-effectiveness. This paper critically reviews ITWL as both a putative mechanism of house improvement or more conventional intervention and discusses its future prospects as a method for controlling malaria and other vector-borne diseases.
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Affiliation(s)
- Louisa A Messenger
- Department of Disease Control, Faculty of Infectious Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.
| | - Mark Rowland
- Department of Disease Control, Faculty of Infectious Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
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16
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Espinoza Echeverria J, Rodriguez AN, Cortez MR, Diotaiuti LG, Gorla DE. Spatial and temporal distribution of house infestation by Triatoma infestans in the Toro Toro municipality, Potosi, Bolivia. Parasit Vectors 2017; 10:58. [PMID: 28148283 PMCID: PMC5288887 DOI: 10.1186/s13071-017-1984-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2016] [Accepted: 01/12/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Triatoma infestans is the main vector of Trypanosoma cruzi in Bolivia. The species is present both in domestic and peridomestic structures of rural areas, and in wild ecotopes of the Andean valleys and the Great Chaco. The identification of areas persistently showing low and high house infestation by the vector is important for the management of vector control programs. This study aimed at analyzing the temporal and spatial distribution of house infestation by T. infestans in the Toro Toro municipality (Potosi, Bolivia) between 2009 and 2014, and its association with environmental variables. METHODS House infestation and T. infestans density were calculated from entomological surveys of houses in the study area, using a fixed-time effort sampling technique. The spatial heterogeneity of house infestation was evaluated using the SatScan statistic. Association between house infestation with Bioclim variables (Worldclim database) and altitude was analyzed using a generalized linear model (GLM) with a logit link. Model selection was based on the Akaike information criteria after eliminating collinearity between variables using the variable inflation factor. The final model was used to create a probability map of house infestation for the Toro Toro municipality. RESULTS A total of 73 communities and 16,489 house evaluation events were analyzed. Presence of T. infestans was recorded on 480 house evaluation events, giving an overall annual infestation of 2.9% during the studied period (range 1.5-5.4% in 2009 and 2012). Vector density remained at about 1.25 insects/ house. Infestation was highly aggregated in five clusters, including 11 communities. Relative risk of infestation within these clusters was 1.7-3.9 times the value for the regional average. Four environmental variables were identified as good descriptors of house infestation, explaining 57% of house infestation variability. The model allowed the estimation of a house infestation surface for the Toro Toro municipality. CONCLUSION This study shows that residual and persistent populations of T. infestans maintain low house infestation, representing a potential risk for the transmission of T. cruzi in these communities, and it is possible to stratify house infestation using EV, and produce a risk map to guide the activities of vector control interventions in the municipality of Toro Toro (Potosi, Bolivia).
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Affiliation(s)
- Jorge Espinoza Echeverria
- Laboratório de Referência Triatomíneos e Epidemiologia da Doença de Chagas, Centro de Pesquisas René Rachou, FIOCRUZ- MG, Belo Horizonte, Brazil
| | | | | | - Liléia Gonçalves Diotaiuti
- Laboratório de Referência Triatomíneos e Epidemiologia da Doença de Chagas, Centro de Pesquisas René Rachou, FIOCRUZ- MG, Belo Horizonte, Brazil
| | - David E. Gorla
- Instituto Multidisciplinario de Biología Vegetal (IMBIV-CONICET), Córdoba, Argentina
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17
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Santo-Orihuela PL, Vassena CV, Carvajal G, Clark E, Menacho S, Bozo R, Gilman RH, Bern C, Marcet PL. Toxicological, Enzymatic, and Molecular Assessment of the Insecticide Susceptibility Profile of Triatoma infestans (Hemiptera: Reduviidae, Triatominae) Populations From Rural Communities of Santa Cruz, Bolivia. JOURNAL OF MEDICAL ENTOMOLOGY 2017; 54:187-195. [PMID: 28011736 PMCID: PMC5388572 DOI: 10.1093/jme/tjw163] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Accepted: 09/08/2016] [Indexed: 05/09/2023]
Abstract
A wide range of insecticide resistance profiles has been reported across Bolivian domestic and sylvatic populations of Triatoma infestans (Klug, 1834) (Hemiptera, Reduviidae), including some with levels proven to be a threat for vector control. In this work, the insecticide profile of domestic T. infestans was studied with standardized toxicological bioassays, in an area that has not undergone consistent vector control. F1 first-instar nymphs hatched in laboratory from bugs captured in three communities from the Santa Cruz Department were evaluated with different insecticides. Moreover, the enzymatic activity of esterases and cytochrome P450 monooxygenases was measured in individual insects to evaluate the possible mechanism of metabolic resistance to pyrethroids. In addition, the DNA sequence of sodium channel gene (kdr) was screened for two point mutations associated with pyrethroid resistance previously reported in T. infestans.All populations showed reduced susceptibility to deltamethrin and α-cypermethrin, albeit the RR50 values varied significantly among them. Increased P450 monooxygenases and permethrate esterases suggest the contribution, as detoxifying mechanisms, to the observed resistance to deltamethrin in all studied populations. No individuals presented either mutation associated to resistance in the kdr gene. The level of susceptibility to α-cypermethrin, the insecticide used by the local vector control program, falls within an acceptable range to continue its use in these populations. However, the observed RR50 values evidence the possibility of selection for resistance to pyrethroids, especially to deltamethrin. Consequently, the use of pyrethroid insecticides should be closely monitored in these communities, which should be kept under entomological surveillance and sustained interventions.
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Affiliation(s)
- Pablo L Santo-Orihuela
- Centro de Investigaciones de Plagas e Insecticidas (UNIDEF, CITEDEF, CONICET, CIPEIN) Juan B. De La Salle 4397 Buenos Aires (B1603ALO), Argentina (; ; )
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Química Analítica Instrumental, Buenos Aires, (C1113AAD), Argentina
| | - Claudia V Vassena
- Centro de Investigaciones de Plagas e Insecticidas (UNIDEF, CITEDEF, CONICET, CIPEIN) Juan B. De La Salle 4397 Buenos Aires (B1603ALO), Argentina (; ; )
- 3iA, Universidad Nacional de San Martín, Buenos Aires (CP 1650), Argentina
| | - Guillermo Carvajal
- Centro de Investigaciones de Plagas e Insecticidas (UNIDEF, CITEDEF, CONICET, CIPEIN) Juan B. De La Salle 4397 Buenos Aires (B1603ALO), Argentina (; ; )
| | - Eva Clark
- University of Alabama at Birmingham, Birmingham, Alabama
- Currently adress: Baylor College of Medicine in Houston, Texas, 77030
| | | | | | - Robert H Gilman
- Bloomberg School of Public Health. Johns Hopkins University, Baltimore, 21205
| | - Caryn Bern
- University of California San Francisco, San Francisco, 94105, California
| | - Paula L Marcet
- Centro de Investigaciones de Plagas e Insecticidas (UNIDEF, CITEDEF, CONICET, CIPEIN) Juan B. De La Salle 4397 Buenos Aires (B1603ALO), Argentina (; ; )
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18
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Schiøler KL, Alifrangis M, Kitron U, Konradsen F. Insecticidal Paints: A Realistic Approach to Vector Control? PLoS Negl Trop Dis 2016; 10:e0004518. [PMID: 27101473 PMCID: PMC4839634 DOI: 10.1371/journal.pntd.0004518] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Karin L. Schiøler
- Global Health Section, Department of Public Health, University of Copenhagen, Copenhagen, Denmark
- * E-mail:
| | - Michael Alifrangis
- Centre for Medical Parasitology, Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
- Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark
| | - Uriel Kitron
- Department of Environmental Sciences, Emory University, Atlanta, Georgia, United States of America
- Fogarty International Center, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Flemming Konradsen
- Global Health Section, Department of Public Health, University of Copenhagen, Copenhagen, Denmark
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Flores-Villegas AL, Cabrera-Bravo M, Toriello C, Bucio-Torres MI, Salazar-Schettino PM, Córdoba-Aguilar A. Survival and immune response of the Chagas vector Meccus pallidipennis (Hemiptera: Reduviidae) against two entomopathogenic fungi, Metarhizium anisopliae and Isaria fumosorosea. Parasit Vectors 2016; 9:176. [PMID: 27012246 PMCID: PMC4806461 DOI: 10.1186/s13071-016-1453-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 03/15/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Chagas disease is a key health problem in Latin America and is caused and transmitted by Trypanosoma cruzi and triatomine bugs, respectively. Control of triatomines has largely relied on the use pyrethroids, which has proved to be ineffective in the long term. Alternatively, the use of entomopathogenic fungi has been implemented to control triatomine bugs. These fungi are highly efficient as they induce a reduction in immune response on insects. Meccus pallidipennis is the main triatomine vector of Chagas disease in Mexico. In this work we investigated the effects of two entomopathogenic fungi, Metarhizium anisopliae and Isaria fumosorosea, on M. pallidipennis nymphs in terms of insect survival and immune response. METHODS We had an infected and a control group for each fungal species and assessed: a) insect survival during 30 days; and, b) phenoloxidase (PO) and prophenoloxidase (proPO; two key traits in insect immune response) at 24, 48, 96 and 144 h. For survival we used Kaplan-Meier survival analysis while for immune response we used factorial, repeated-measures ANOVA for each fungal species. RESULTS Animals treated with M. anisopliae died sooner than animals treated with I. fumosorosea. Infected animals showed lower PO and proPO values than sham individuals, with a clear decrease in these parameters at 24 h with no further changes after this time. CONCLUSIONS Our study widens the possibility of entomopathogenic fungi being used for triatomine control. The negative effect on PO and proPO seems mediated by a down-regulation of the triatomine immune response.
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Affiliation(s)
- A Laura Flores-Villegas
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, México, DF, Mexico
| | - Margarita Cabrera-Bravo
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, México, DF, Mexico
| | - Conchita Toriello
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, México, DF, Mexico
| | - Martha I Bucio-Torres
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, México, DF, Mexico
| | - Paz María Salazar-Schettino
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, México, DF, Mexico.
| | - Alex Córdoba-Aguilar
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Apdo. P. 70-275, Circuito Exterior, Ciudad Universitaria, 04510, Coyoacán, Distrito Federal, Mexico.
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