Rural houses infestation by Triatoma infestans in northwestern Argentina: Vector control in a high spatial heterogeneous infestation area

Abstract

Triatoma infestans (Hemiptera: Reduviidae) is a vector of the Trypanosoma cruzi parasite, causative agent of Chagas disease. During the last decade, vector control activities have been systematically carried out in northwestern Argentina, an endemic region for this disease. The general aim of this study to evaluate was spatio-temporal variation of infestation by T. infestans in rural communities of Los Llanos in La Rioja province. We estimated house infestation using two sampling methods: passive and active. Passive collection was conducted with community participation collecting triatomines. Six passive collections were carried out in 397 houses during the warm season between 2014 and 2017. Active collection of T. infestans was thoroughly performed by trained staff for 60 minutes and was carried out once in March 2016. The estimate of intradomestic infestation did not show significant differences between both collection methods (p = 0.39). However, passive collection method had lower sensitivity than active collection method for the estimation of peridomestic infestation and intradomestic colonization (PDI: p< 0.01; ID colonization: p< 0.01). The results obtained with passive collection methods showed that the infestation in the study area was spatially heterogeneous and temporally variable. Intradomiciliary infestation decreased over time (14.4% to 7.9%, p<0.05) although the effect of the chemical treatment application was not associated with the infestation level of T. infestans (p = 0.15) and the Departments had a different response each year (p<0.01). A high infestation cluster was located in the south of our study area during 2016–2017. The vector presence in the houses confirms the importance of to improve entomological surveillance programs. The search for triatomines carried out by the inhabitants might be a useful method to complement the activities of vector control programs in isolated and rural areas.

Impact Involving the Community in Entomological Surveillance of the Triatoma Infestans Vectorial Control

“…In addition to the cost reduction, T. infestans domestic infestation estimated with community participation allowed a spatially heterogeneous infestation detection in the north of La Rioja. These results coincide with those obtained in the south of La Rioja [4,5,11] and in other areas of Gran Chaco [23]. Within of La Rioja Province, T. infestans domestic infestation in CBD was lower than in Los Llanos riojanos (13.8 vs 21.4%) carried out with community participation [11].…”

“…7,8,9,10]. In Los Llanos riojanos, our working group con rmed the importance of incorporating community participation in entomological evaluation of houses [11].…”

“…The low frequency with a vertical program cannot meet demand in areas where infestation risk is known to be low [5], causing the domestic vector persistence to continue and recovering populations among spraying cycles [6]. Incorporating participatory approaches against vector-borne diseases has been shown to be important for control program sustainability [8,10,11,19,20]. However, there is still debate regarding the limitations of incorporating community participation in house surveillance circuit due to T. infestans presence reported in houses where it is not present, as positive false.…”

“…Despite methodological differences, there are many works showing a cost decrease when community collaborates in surveillance phase [8,10,11,19,20,22]. In this work, we recommended that community intervention is only in surveillance phase to guarantee an early triatomines detection but the spraying function is always responsibility of personnel speci cally trained for this task.…”

“…The infestation by T. infestans was evaluated by passive collection method on the selected DUs. This methodology includes the monitor DU infestation carried out for the householders [11]. A total of 434 DU corresponding to nine localities of CBD (Fig.…”