João Victor Leite Dias

Spatial distribution of triatomines in domiciles of an urban area of the Brazilian Southeast Region

Reports of triatomine infestation in urban areas have increased. We analysed the spatial distribution of infestation by triatomines in the urban area of Diamantina, in the state of Minas Gerais, Brazil. Triatomines were obtained by community-based entomological surveillance. Spatial patterns of infestation were analysed by Ripley’s K function and Kernel density estimator. Normalised difference vegetation index (NDVI) and land cover derived from satellite imagery were compared between infested and uninfested areas. A total of 140 adults of four species were captured (100 Triatoma vitticeps, 25Panstrongylus geniculatus, 8 Panstrongylus megistus, and 7 Triatoma arthurneivai specimens). In total, 87.9% were captured within domiciles. Infection by trypanosomes was observed in 19.6% of 107 examined insects. The spatial distributions ofT. vitticeps, P. geniculatus, T. arthurneivai, and trypanosome-positive triatomines were clustered, occurring mainly in peripheral areas. NDVI values were statistically higher in areas infested by T. vitticeps and P. geniculatus. Buildings infested by these species were located closer to open fields, whereas infestations of P. megistus andT. arthurneivai were closer to bare soil. Human occupation and modification of natural areas may be involved in triatomine invasion, exposing the population to these vectors.

Human and canine visceral leishmaniasis in an emerging focus in Araçuaí, Minas Gerais: spatial distribution and socio-environmental factors

This study aimed to analyse the spatial distribution of human (2007-2013) and canine (2013) visceral leishmaniasis (VL) in the city of Araçuaí, Minas Gerais, Brazil, and identify the socio-environmental factors related to their occurrence. The spatial distribution of human and canine cases was analysed by kernel density estimation (KDE) and the K function. The KDE values were analysed for correlation between human and canine LV and for normalised difference vegetation index (NDVI). Socio-environmental aspects of household structures and surroundings were evaluated. The spatial distribution of human and canine VL cases exhibited a significant aggregated pattern in distances greater than 350 and 75 m, respectively. The higher occurrence of human and canine infection occurred in the central area of the city. A positive correlation between the densities of human and canine cases was observed, as well as a negative correlation between NDVI and densities of human and canine cases. Socio-environmental analysis revealed that the large amount of animals, organic material from trees and deficiencies in environmental sanitation are possibly contributing to the continuation of the transmission cycle of Leishmania infantum in Araçuaí. These results can contribute to the planning by competent agencies to reduce the incidence of infection in the city.

Profile of the Trypanosoma cruzi vector infestation in Jaboticatubas, State of Minas Gerais, Brazil

INTRODUCTION This work aimed to analyze the triatomine infestation scenario in Jaboticatubas after 30 years of the uninterrupted actions of the Program of Chagas Disease Control. METHODS From 2007 to 2010, household unit infestation was researched, and an exploratory analysis of the localities infested with Panstrongylus megistus was performed. RESULTS In total, 613 triatomines were captured in 78 households, the majority of which were Panstrongylus megistus and were captured mainly in chicken houses, but they were also found to be colonizing human houses. CONCLUSIONS The epidemiological importance of Panstrongylus megistus was confirmed in Jaboticatubas, and capability to colonize indoors has been demonstrated, as has its proximity to humans. Its distribution is aggregated in the northern and in central-eastern regions of the municipality.

High seroprevalence and peripheral spatial distribution of visceral leishmaniasis among domestic dogs in an emerging urban focus in Central Brazil: a cross-sectional study

Abstract The Brazilian municipality of Rondonópolis is an emerging urban focus of intense transmission of visceral leishmaniasis (VL), where few investigations have addressed canine reservoirs. This study assessed the seroprevalence and spatial distribution of canine visceral leishmaniasis (CVL) in the urban area of Rondonópolis. A CVL serosurvey was conducted between October 2016 and February 2017 using an immunochromatographic rapid test and enzyme-linked immunosorbent assay. Domestic dogs were sampled from 25 heterogeneous regions previously defined by the Spatial ‘K’luster Analysis by Tree Edge Removal algorithm, which considered the socioeconomic and environmental features from the last demographic census. The CVL spatial distribution was analyzed by kernel density estimation (KDE) and spatial scan statistic. All the autochthonous human VL cases reported between 2014 and 2016 were georeferenced. Of the 600 dogs tested, 115 were seropositive in both tests. The overall CVL prevalence was 19.2% (95%CI: 16.1–22.3%), which varied widely among the evaluated regions (0.0–35.1%). Almost 25% of the sampled households (n = 405) had at least one infected dog. KDE demonstrated that positive CVL households were concentrated in the peripheral areas of the city. Spatial scan statistics detected a spatial cluster with significantly low CVL prevalence in the central region (relative risk = 0.37; p = 0.04), where only one human VL case was reported. Thus, we demonstrated a high prevalence of CVL in domestic dogs from diverse socioeconomic and environmental urban contexts in Rondonópolis. The CVL cases were peripherally distributed and occurred more frequently in areas that had reported human VL.

Capture of Triatoma arthurneivai (Hemiptera: Reduviidae) using a new luminous trap in Southeast Brazil

INTRODUCTION Triatomine bug captures in the wild are laborious and time-consuming. Some traps may assist in this task. We report a new trap design and the capture of a specimen of a triatomine rarely found. METHODS Two luminous traps were installed in the city of Diamantina, State of Minas Gerais, and surveyed weekly for a year. RESULTS A Triatoma arthurneivai female and other triatomine bugs were caught. CONCLUSIONS A new trap design may be used in triatomine bugs field captures, mainly in low density areas. We assume the center of endemism of Triatoma arthurneivai is the Espinhaço Mountain range.

Contamination by intestinal parasites in vegetables marketed in an area of Jequitinhonha Valley, Minas Gerais, Brazil

Objetivo: O presente estudo teve como objetivo avaliar a presenca de helmintos e protozoarios intestinais em hortalicas comercializados em Diamantina, um municipio localizado no Vale do Jequitinhonha, uma das regioes mais pobres do mundo. Metodos: Cento e oito exemplares, incluindo alface, cebolinha e rucula, foram mensalmente coletados em uma feira livre, uma quitanda e um supermercado do municipio. As amostras foram processadas por um metodo de concentracao e avaliadas por microscopia optica para pesquisa de estruturas parasitarias. Resultados: O percentual global de contaminacao foi de 50,9% (55/108), com predominância de larvas de nematodeos (36,5%), cistos de Entamoeba coli e ovos de ancilostomideos/Strongyloides spp. (12,9%). A alface demonstrou a maior taxa de contaminacao (61,1%) e as amostras da feira livre foram as mais contaminadas (77,8%). Informacoes coletadas em cada ponto de venda apontaram o cultivo em campo como a etapa critica para a contaminacao. Conclusao: Hortalicas comercializadas em Diamantina apresentam uma ampla variedade de parasitas intestinais, o que representa um risco potencial a saude dos consumidores da area.

Occurrence and distribution of triatomines (Hemiptera: Reduviidae) in municipalities of the Northeastern region of Minas Gerais State, Brazil.

INTRODUCTION Triatomines are targeted for the control of Chagas disease in endemic areas of Brazil. METHODS Data regarding triatomines captured during 2001-2008 in 34 municipalities in the Northeast of Minas Gerais were analyzed. RESULTS In total, 11,187 triatomines from eight species were captured, mostly in henhouses and bedrooms. Trypanosomes were found in 203 samples. Main species were Triatoma sordida, Panstrongylus megistus, and Triatoma vitticeps. The number of P. megistus adults was positively correlated with temperature and precipitation, whereas the number of nymphs followed the inverse pattern. CONCLUSIONS Occurrence of triatomines in domiciles indicates the need for sustained entomological surveillance.

The effect of Ageratum fastigiatum extract on Rhodnius nasutus, vector of Chagas disease

Control of Chagas disease is based on insecticide spraying in domiciles in order to exterminate triatomine populations. However, since the vectors differ in susceptibility to currently used insecticides, the screening of the toxic potential of Brazilian flora may identify new molecules lethal to triatomines. This study evaluated the toxicity of ethanolic extract of Ageratum fastigiatum (Gardner) R.M. King & H. Rob., Asteraceae, on Rhodnius nasutus, a known vector of Chagas disease. Ethanolic extracts of the aerial parts of A. fastigiatum were prepared at 25 and 50 mg/mL concentrations, and 5 µL was applied to fifth-instar nymphs of R. nasutus (n=30). Controls included nymphs that were treated with 5 µL ethanol (n=30) or left untreated (n=30). The percentage of dead insects in each group was observed at 24, 48, 72, 96 and 120 h after application. The extracts of A. fastigiatum showed a mortality rate of about 37% and 77% after 120 h, at concentrations of 25 and 50 mg/mL, respectively. In control groups, the mortality rate remained under 7%. The extract of A. fastigiatum contains a coumarin, a molecule with recognized toxicity in insects, and which may be responsible for killing the triatomines.

Conhecimentos sobre triatomíneos e sobre a doença de Chagas em localidades com diferentes níveis de infestação vetorial

Community participation is the main strategy to sustainability of Chagas disease entomological surveillance. The purpose of this study was to evaluate the level of knowledge on triatomine insects and Chagas disease among the residents from eight localities of Diamantina, in Minas Gerais, with a view to observing any associations between their knowledge and infestations by triatomines. In order to evaluate this knowledge, questionnaires were used containing both closed and open questions. They were applied to 583 residents who were ten years old or over. To establish if they could recognize the triatomine insect, they were given samples to look at. The responses to the closed questions were analyzed with reference to any frequencies of and associations with infestations involving this insect. The responses to the questions were organized into different thematic areas and were descriptively analyzed. Although the residents ability to recognize the triatomine insect was not associated with the infestation of the localities, the residents in the areas that had higher infestations showed that they had a good knowledge of the available support services and the need to send the insects to them. We did not observe any associations between triatomine infestations and knowledge of Chagas disease. The results of this study can provide guidance on education that can be given by the health services to the community in order to encourage them to provide notifications of the triatomine insects.