Residual foci of Triatoma infestans infestation: Surveillance and control in Rio Grande do Sul, Brazil, 2001-2018

Abstract INTRODUCTION: This retrospective study conducted from 2001 to 2018 investigated the residual foci of Triatoma infestans infestation in Rio Grande do Sul, Brazil. METHODS: The data were obtained via entomological surveillance and the distribution of vector occurrence. The coverage of active research was mapped. RESULTS: The largest coverage rate for active research was observed in the northwest region of the total of 515,081 domiciles researched. Most T. infestans specimens were captured in the peridomicile. CONCLUSIONS: Infestation has decreased significantly since 2008, and T. infestans has not been captured since 2015.

Health education in chagas disease control: making an educational video

Several studies have shown that the population has relatively little information regarding Chagas disease (CD) and its vectors; however, this knowledge is relevant because community participation is vital for success in disease control actions. For this reason, and due to the lack of audiovisual material on this subject in the country, this study focused on making an educational documentary on CD and its vectors, which could be available to the population for free. The video preparation was divided into three phases: Pre-production, Production and Post-production. The site chosen for shooting was northwestern Rio Grande do Sul State due to the Triatoma infestans vector persistence in recent decades in that area. A documentary was obtained which addresses relevant CD aspects, such as its history, transmission, major vectors and biology, phases of the disease and, in particular, how to inspect the intra-domiciliary and peri-domiciliary areas in search of triatomine bugs or "kissing bugs". The use of videos as an educational tool helps broadcast information; therefore, this documentary is a public use tool, which aims to promote the control and prophylaxis of CD and its vectors.

Assessment of the housing improvement program for chagas disease control in the northwestern municipalities of Rio Grande do Sul, Brazil

Abstract INTRODUCTION: The Housing Improvement Program for Chagas Disease Control (HIPCDC) was established in 2001 in Northwestern Rio Grande do Sul State, aiming to improve the conditions of the domiciliary and peridomiciliary environments to make them resistant to triatomine colonization. This study aimed to assess the impact of the HIPCDC on triatomine control by developing local population and authority awareness on the issue. METHODS: The study was conducted by means of questionnaires applied to local authorities and the program beneficiaries. Three municipalities - Ajuricaba, Coronel Barros, and Crissiumal - were visited. RESULTS: A program coordinator from each municipality and 62 individuals from selected households were interviewed. The authorities reported difficulties in the implementation of the program due to differences between the project development period and financial resource availability, in addition to a lack of understanding by the community not included in the program. As for the houses, most improvements were made in the peridomiciliary environments; moreover, construction of 4 new residences, as well as the renovation of others, was also reported. Regarding suggestions to the program, requests for better planning (44.9%) and renovation quality (36.7%) were highlighted. With reference to the presence of triatomine bugs, prior to the HIPCDC adaptations, 12.9% of the respondents reported coming across at least one specimen at home, as compared to 22.6% who found these insects in peridomiciliary areas. CONCLUSIONS: Despite reports of difficulties in carrying out the HIPCDC, there was an improvement in the housing conditions, with no triatomine occurrence reports after the program implementation.

Susceptibility characterization of residual Brazilian populations of Triatoma infestans Klug, 1834 (Hemiptera: Reduviidae) to deltamethrin pyrethroid

INTRODUCTION: Despite years of efforts towards the elimination of Triatoma infestans in Brazil, residual foci still persist in some areas of the States of Bahia and Rio Grande do Sul. The persistence of these T. infestans populations in the country has two different origins of equal concern: operational failures or insecticide resistance. Thus, the objective of this study was to characterize the susceptibility profile of the residual Brazilian populations of T. infestans to deltamethrin. METHODS: The susceptibility reference lineage was derived from Cipein/Argentina. The populations studied were manually collected using a dislodging agent in peridomiciles in the States of Bahia (Novo Horizonte) and of Rio Grande do Sul (Santa Rosa and Doutor Maurício Cardoso). Serial dilutions of deltamethrin were prepared and applied at the dorsal abdomen of first instar nymphs. The control group received only pure acetone. Mortality was evaluated after 72h. Qualitative tests assessed the mortality of a diagnostic dose of 1xLD99 (2.76ng a.i./nymph) determined for the susceptibility reference lineage. RESULTS: The susceptibility profile characterization of the T. infestans populations revealed an RR50 ranging from 1.73 to 3.26. The mortality percentage in response to a diagnostic dose was 100%. The results obtained in the quantitative and qualitative assays corresponded for all populations. CONCLUSIONS: The results of this study indicate that the persistence of residual foci of T. infestans in Bahia and Rio Grande do Sul is not related to insecticide resistance but may be associated with operational failures. In Rio Grande do Sul, we must consider the possibility of continuous reinfestation by Argentinian individuals, which justifies active and efficient epidemiological surveillance. .