scholarly journals Indoor residual spraying practises against Triatoma infestans in the Bolivian Chaco: contributing factors to suboptimal insecticide delivery to treated households

2020 ◽  
Author(s):  
Raquel Gonçalves ◽  
Rhiannon A.E. Logan ◽  
Hanafy M. Ismail ◽  
Mark J.I. Paine ◽  
Caryn Bern ◽  
...  
Keyword(s):  
Chagas Disease ◽  
Negative Binomial ◽  
Community Education ◽  
Indoor Residual Spraying ◽  
Triatoma Infestans ◽  
Contributing Factors ◽  
Worker Training ◽  
Visual Presence ◽  
Chaco Region ◽  
Filter Papers

AbstractBackgroundIndoor Residual Spraying (IRS) of insecticides is a key method to reduce transmission by Triatoma infestans, vector of Chagas disease in a large part of South America. However, the successes of IRS in the Gran Chaco region straddling Bolivia, Argentina and Paraguay, have not equalled those in other Southern Cone countries.AimsThis study evaluated routine IRS practises and insecticide quality control in a typical endemic community in the Bolivian Chaco.MethodsAlpha-cypermethrin active ingredient (a.i.) concentrations captured onto filter papers fitted to sprayed wall surfaces, and in prepared spray tank solutions, were measured using an adapted Insecticide Quantification Kit (IQK™). The results were analysed by negative binomial GLM regression in relation to the time (minutes) spray teams spent treating houses, spray rates (surface area to spray [m2/minute]), householder compliance to empty houses for IRS delivery, and the visual presence/absence of filter papers. The IQK™ assays developed for these samples were validated against HPLC quantification methods. Results: Substantial variations in the delivered a.i. concentrations were observed; only 10.4% (50/480) of filter papers, and 8.8% (5/57) of houses received the target concentration. The delivered concentrations were not related to those in the matched spray tank solutions. The sedimentation of a.i. in the surface solution of prepared spray tanks was rapid, resulting in a 29% loss of a.i. content within 5 minutes, and 48.5% after 15 minutes. The delivered concentrations were positively associated with the time spent spraying the house, and inversely related to the spray rate, but showed weak correlations in both cases. The influence of householder compliance on spray rates were significant, though associated differences in delivered concentrations were not detected. No differences were observed in spray rates between houses fitted with filter papers and houses without.ConclusionsSuboptimal delivery of IRS is partially attributed to the insecticide physical characteristics, and the need for revision of insecticide delivery methods, which includes training of IRS teams and community education to encourage compliance. The IQK™ is a necessary field-friendly tool to improve IRS quality, and to facilitate health worker training and decision making by the Chagas disease vector control managers.

scholarly journals Indoor residual spraying practices against Triatoma infestans in the Bolivian Chaco: contributing factors to suboptimal insecticide delivery to treated households

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Raquel Gonçalves ◽  
Rhiannon A. E. Logan ◽  
Hanafy M. Ismail ◽  
Mark J. I. Paine ◽  
Caryn Bern ◽  
...  
Keyword(s):  
Chagas Disease ◽  
Negative Binomial ◽  
Community Education ◽  
Health Workers ◽  
Indoor Residual Spraying ◽  
Negative Binomial Regression ◽  
Triatoma Infestans ◽  
Contributing Factors ◽  
Filter Papers ◽  
Coverage Rates

Abstract Background Indoor residual spraying (IRS) of insecticides is a key method to reduce vector transmission of Trypanosoma cruzi, causing Chagas disease in a large part of South America. However, the successes of IRS in the Gran Chaco region straddling Bolivia, Argentina, and Paraguay, have not equalled those in other Southern Cone countries. Aims This study evaluated routine IRS practices and insecticide quality control in a typical endemic community in the Bolivian Chaco. Methods Alpha-cypermethrin active ingredient (a.i.) captured onto filter papers fitted to sprayed wall surfaces, and in prepared spray tank solutions, were measured using an adapted Insecticide Quantification Kit (IQK™) validated against HPLC quantification methods. The data were analysed by mixed-effects negative binomial regression models to examine the delivered insecticide a.i. concentrations on filter papers in relation to the sprayed wall heights, spray coverage rates (surface area / spray time [m2/min]), and observed/expected spray rate ratios. Variations between health workers and householders’ compliance to empty houses for IRS delivery were also evaluated. Sedimentation rates of alpha-cypermethrin a.i. post-mixing of prepared spray tanks were quantified in the laboratory. Results Substantial variations were observed in the alpha-cypermethrin a.i. concentrations delivered; only 10.4% (50/480) of filter papers and 8.8% (5/57) of houses received the target concentration of 50 mg ± 20% a.i./m2. The delivered concentrations were not related to those in the matched spray tank solutions. The sedimentation of alpha-cypermethrin a.i. in the surface solution of prepared spray tanks was rapid post-mixing, resulting in a linear 3.3% loss of a.i. content per minute and 49% loss after 15 min. Only 7.5% (6/80) of houses were sprayed at the WHO recommended rate of 19 m2/min (± 10%), whereas 77.5% (62/80) were sprayed at a lower than expected rate. The median a.i. concentration delivered to houses was not significantly associated with the observed spray coverage rate. Householder compliance did not significantly influence either the spray coverage rates or the median alpha-cypermethrin a.i. concentrations delivered to houses. Conclusions Suboptimal delivery of IRS is partially attributable to the insecticide physical characteristics and the need for revision of insecticide delivery methods, which includes training of IRS teams and community education to encourage compliance. The IQK™ is a necessary field-friendly tool to improve IRS quality and to facilitate health worker training and decision-making by Chagas disease vector control managers. Graphic Abstract

scholarly journals Smoke of Capsicum baccatumL. var. baccatum (Solanaceae) repels nymphs of Triatoma infestans(Klug) (Hemiptera: Reduviidae)

2022 ◽  
Vol 21 (2) ◽  
pp. 215-223
Author(s):  
Jhean-Carla Echalar ◽  
◽  
Romina Cossio-Rodriguez ◽  
David Veliz ◽  
Fabricio Cardozo-Alarcon ◽  
...  
Keyword(s):  
Chemical Analysis ◽  
Native Plants ◽  
Field Work ◽  
Triatoma Infestans ◽  
Repellent Effect ◽  
Disease Vector ◽  
Development Of Resistance ◽  
Chaco Region ◽  
Synthetic Pesticides ◽  
Filter Papers

Control of the Chagas disease vector, Triatoma infestans(Klug) (Hemiptera: Reduviidae) with synthetic pesticides in Bolivia has become increasingly inefficient due to the development of resistance in the insects. In the Chaco region of Bolivia, guaraní populations have approached the problem by fumigating their houses with the smoke of native plants. Through interviews and field work with local guides, the main plant used by the guaraníes was collected and later identified as Capsicum baccatumL. var. baccatum(Solanaceae). In choice bioassays, filter papers exposed to the smoke of the plant repelled nymphs of T. infestans. Activity remained significant after storing the exposed filter papers for 9 days. Chemical analysis of smoke and literature data suggested that capsaicinoids present in the smoke were responsible for the repellent effect. The data presented provide a rationale for the use of C. baccatumvar. baccatumto control the Chagas vector bythe guaraní populations.

scholarly journals Experimental control of Triatoma infestans in poor rural villages of Bolivia through community participation

2015 ◽  
Vol 109 (2) ◽  
pp. 150-158 ◽  
Author(s):  
Frédéric Lardeux ◽  
Stéphanie Depickère ◽  
Claudia Aliaga ◽  
Tamara Chavez ◽  
Lilian Zambrana
Keyword(s):  
Community Participation ◽  
Chagas Disease ◽  
Disease Transmission ◽  
Control Strategies ◽  
Low Cost ◽  
Health Intervention ◽  
Triatoma Infestans ◽  
Human Environment ◽  
Chaco Region ◽  
House Infestation

Abstract Background Triatoma infestans is the main vector of Chagas disease in the southern cone countries. Present control strategies based on indoor and outdoor residual insecticide spraying are not sufficient to control disease transmission, particularly in Bolivia. Techniques based on the management of the human environment may be good alternatives or supplements. Methods Social and entomological surveys were carried out in four villages of Bolivia situated in the dry inter-Andean Valleys and the Chaco region. Risk factors for house infestation by T. infestans were identified, and an eco-health intervention based on education and community participation was carried out to reduce the risks of house infestation. It consisted of implementing simple and low cost vector control techniques such as coating of mud walls, cleaning activities and removal of poultry that enter rooms to lay eggs. Results The eco-health intervention significantly reduced the number of infested bedrooms, the mean abundance of T. infestans in bedrooms and beds, especially in the Chaco region. Mud wall coating was well accepted and could be proposed as a supplementary tool to the National Program of Chagas Disease Control to enhance the effects of insecticide sprayings. Conclusions Even if cleaning activities were still neglected, community participation proved to be effective in reducing house infestation.

scholarly journals Hosts and vectors of Trypanosoma cruzi discrete typing units in the Chagas disease endemic region of the Paraguayan Chaco

Parasitology ◽  
2017 ◽  
Vol 144 (7) ◽  
pp. 884-898 ◽  
Author(s):  
NIDIA ACOSTA ◽  
ELSA LÓPEZ ◽  
MICHAEL D. LEWIS ◽  
MARTIN S. LLEWELLYN ◽  
ANA GÓMEZ ◽  
...  
Keyword(s):  
Trypanosoma Cruzi ◽  
Chagas Disease ◽  
Control Strategies ◽  
Triatoma Infestans ◽  
Effective Control ◽  
Primary Role ◽  
Endemic Region ◽  
Triatomine Bugs ◽  
Chaco Region ◽  
Euphractus Sexcinctus

SUMMARYActive Trypanosoma cruzi transmission persists in the Gran Chaco region, which is considered hyperendemic for Chagas disease. Understanding domestic and sylvatic transmission cycles and therefore the relationship between vectors and mammalian hosts is crucial to designing and implementing improved effective control strategies. Here we describe the species of triatomine vectors and the sylvatic mammal reservoirs of T. cruzi, in different localities of the Paraguayan and Bolivian Chaco. We identify the T. cruzi genotypes discrete typing units (DTUs) and provide a map of their geographical distribution. A total of 1044 triatomines and 138 sylvatic mammals were captured. Five per cent of the triatomines were microscopically positive for T. cruzi (55 Triatoma infestans from Paraguay and one sylvatic Triatoma guasayana from Bolivia) and 17 animals (12·3%) comprising eight of 28 (28·5%) Dasypus novemcinctus, four of 27 (14·8%) Euphractus sexcinctus, three of 64 (4·7%) Chaetophractus spp. and two of 14 (14·3%) Didelphis albiventris. The most common DTU infecting domestic triatomine bugs was TcV (64%), followed by TcVI (28%), TcII (6·5%) and TcIII (1·5%). TcIII was overwhelmingly associated with armadillo species. We confirm the primary role of T. infestans in domestic transmission, armadillo species as the principal sylvatic hosts of TcIII, and consider the potential risk of TcIII as an agent of Chagas disease in the Chaco.

Improving houses in the Bolivian Chaco increases effectiveness of residual insecticide spraying against infestation with Triatoma infestans, vector of Chagas disease

2021 ◽  
Author(s):  
Raquel Gonçalves ◽  
Daniel Landivar ◽  
Edson Grover Sañez Liendo ◽  
Janet Mamani Fernandez ◽  
Hanafy M. Ismail ◽  
...  
Keyword(s):  
Chagas Disease ◽  
Triatoma Infestans

scholarly journals Molecular Population Genetics and Evolution of the Chagas’ Disease Vector Triatoma infestans (Hemiptera: Reduviidae)

2013 ◽  
Vol 14 (5) ◽  
pp. 316-323 ◽  
Author(s):  
Beatriz García ◽  
Alicia R. Pérez Rosas ◽  
María Blariza ◽  
Carla Grosso ◽  
Cintia Fernández ◽  
...  
Keyword(s):  
Population Genetics ◽  
Chagas Disease ◽  
Triatoma Infestans ◽  
Disease Vector ◽  
Molecular Population Genetics

scholarly journals Intensified Surveillance and Insecticide-based Control of the Chagas Disease Vector Triatoma infestans in the Argentinean Chaco

2013 ◽  
Vol 7 (4) ◽  
pp. e2158 ◽  
Author(s):  
Juan M. Gurevitz ◽  
María Sol Gaspe ◽  
Gustavo F. Enriquez ◽  
Yael M. Provecho ◽  
Uriel Kitron ◽  
...  
Keyword(s):  
Chagas Disease ◽  
Triatoma Infestans ◽  
Disease Vector

scholarly journals The initial success of the Chagas' Disease Control Program: factors contributing to Triatomine infestation

1992 ◽  
Vol 8 (4) ◽  
pp. 391-403 ◽  
Author(s):  
Millicent Fleming-Moran
Keyword(s):  
Chagas Disease ◽  
Control Program ◽  
Triatoma Infestans ◽  
Linear Regression Models ◽  
Disease Vector ◽  
Disease Control Program ◽  
Household Crowding ◽  
Favorable Conditions ◽  
House Infestation ◽  
Regional Comparisons

While the control of the major Chagas' disease vector Triatoma infestans has been achieved in many endemic areas of Brazil, data from the inception of the control program in the Triângulo Mineiro (1976-79) suggest that re-infestation by triatomines occurs under certain favorable conditions. The percentage of houses infested in 500 communities of the Triângulo Mineiro region is compared for two years: 1976 and 1979, using linear regression models. Controlling for three major triatomine vectors, household crowding, house demolition and construction, and infested out-buildings are all independent covariates of house infestation in these communities. While several household factors have been suggested as correlates of infestation, the control program focuses on community-level reductions in infestation, but intra-community or regional comparisons have heretofore been unfeasible. Computerized data are becoming available to identify communities at high risk for re-infestation, and for targeting control-program activities.

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