Spread of Gamma (P.1) Sub-Lineages Carrying Spike Mutations Close to the Furin Cleavage Site and Deletions in the N-Terminal Domain Drives Ongoing Transmission of SARS-CoV-2 in Amazonas, Brazil.

The Amazonas was one of the most heavily affected Brazilian states by the COVID-19 epidemic. Despite a large number of infected people, particularly during the second wave associated with the spread of the Variant of Concern (VOC) Gamma (lineage P.1), SARS-CoV-2 continues to circulate in the Amazonas. To understand how SARS-CoV-2 persisted in a human population with a high immunity barrier, we generated 1,188 SARS-CoV-2 whole-genome sequences from individuals diagnosed in the Amazonas state from 1st January to 6th July 2021, of which 38 were vaccine breakthrough infections. Our study reveals a sharp increase in the relative prevalence of Gamma plus (P.1+) variants, designated Pango Lineages P.1.3 to P.1.6, harboring two types of additional Spike changes: deletions in the N-terminal (NTD) domain (particularly Δ144 or Δ141-144) associated with resistance to anti-NTD neutralizing antibodies or mutations at the S1/S2 junction (N679K or P681H) that probably enhance the binding affinity to the furin cleavage site, as suggested by our molecular dynamics simulations. As lineages P.1.4 (S:N679K) and P.1.6 (S:P681H) expanded (Re > 1) from March to July 2021, the lineage P.1 declined (Re < 1) and the median Ct value of SARS-CoV-2 positive cases in Amazonas significantly decreases. Still, we did not find an increased incidence of P.1+ variants among breakthrough cases of fully vaccinated patients (71%) in comparison to unvaccinated individuals (93%). This evidence supports that the ongoing endemic transmission of SARS-CoV-2 in the Amazonas is driven by the spread of new local Gamma/P.1 sublineages that are more transmissible, although not more efficient to evade vaccine-elicited immunity than the parental VOC. Finally, as SARS-CoV-2 continues to spread in human populations with a declining density of susceptible hosts, the risk of selecting more infectious variants or antibody evasion mutations is expected to increase. IMPORTANCE The continuous evolution of SARS-CoV-2 is an expected phenomenon that will continue to happen due to the high number of cases worldwide. The present study analyzed how a Variant of Concern (VOC) could still circulate in a population hardly affected by two COVID-19 waves and with vaccination in progress. Our results showed that the answer behind that was a new generation of Gamma-like viruses, which emerged locally carrying mutations that made it more transmissible and more capable of spreading, partially evading prior immunity triggered by natural infections or vaccines. With thousands of new cases daily, the current pandemics scenario suggests that SARS-CoV-2 will continue to evolve and efforts to reduce the number of infected subjects, including global equitable access to COVID-19 vaccines, are mandatory. Thus, until the end of pandemics, the SARS-CoV-2 genomic surveillance will be an essential tool to better understand the drivers of the viral evolutionary process.

Reduced competence to arboviruses following the sustainable invasion of Wolbachia into native Aedes aegypti from Southeastern Brazil.

Field release of Wolbachia-infected Aedes aegypti has emerged as a promising solution to manage the transmission of dengue, Zika and chikungunya in endemic areas across the globe. Through an efficient self-dispersing mechanism, and the ability to induce virus-blocking properties, Wolbachia offers an unmatched potential to gradually modify wild Ae. aegypti populations turning them unsuitable disease vectors. Here we describe a proof-of-concept field trial carried out in a small community of Niterói, greater Rio de Janeiro, Brazil. Following the release of Wolbachia-infected eggs, we report here a successful invasion and long-term establishment of the bacterium across the territory, as denoted by stable high-infection indexes (> 80%). We have also demonstrated that refractoriness to dengue and Zika viruses, either thorough oral-feeding or intra-thoracic saliva challenging assays, was maintained over the adaptation to the natural environment of Southeastern Brazil. These findings further support Wolbachia's ability to invade local Ae. aegypti populations and impair disease transmission, and will pave the way for future epidemiological and economic impact assessments.

Large-Scale Deployment and Establishment of Wolbachia Into the Aedes aegypti Population in Rio de Janeiro, Brazil.

Traditional methods of vector control have proven insufficient to reduce the alarming incidence of dengue, Zika, and chikungunya in endemic countries. The bacterium symbiont Wolbachia has emerged as an efficient pathogen-blocking and self-dispersing agent that reduces the vectorial potential of Aedes aegypti populations and potentially impairs arboviral disease transmission. In this work, we report the results of a large-scale Wolbachia intervention in Ilha do Governador, Rio de Janeiro, Brazil. wMel-infected adults were released across residential areas between August 2017 and March 2020. Over 131 weeks, including release and post-release phases, we monitored the wMel prevalence in field specimens and analyzed introgression profiles of two assigned intervention areas, RJ1 and RJ2. Our results revealed that wMel successfully invaded both areas, reaching overall infection rates of 50-70% in RJ1 and 30-60% in RJ2 by the end of the monitoring period. At the neighborhood-level, wMel introgression was heterogeneous in both RJ1 and RJ2, with some profiles sustaining a consistent increase in infection rates and others failing to elicit the same. Correlation analysis revealed a weak overall association between RJ1 and RJ2 (r = 0.2849, p = 0.0236), and an association at a higher degree when comparing different deployment strategies, vehicle or backpack-assisted, within RJ1 (r = 0.4676, p < 0.0001) or RJ2 (r = 0.6263, p < 0.0001). The frequency knockdown resistance (kdr) alleles in wMel-infected specimens from both areas were consistently high over this study. Altogether, these findings corroborate that wMel can be successfully deployed at large-scale as part of vector control intervention strategies and provide the basis for imminent disease impact studies in Southeastern Brazil.

Ecological aspects of Rhodnius nasutus Stål, 1859 (Hemiptera: Reduviidae: Triatominae) in palms of the Chapada do Araripe in Ceará, Brazil.

The aim of this work is to present aspects related to the ecology of Rhodnius nasutus Stål, 1859 in palms from Chapada do Araripe in Ceará, Brazil. The following five species of palms were investigated: babaçu (Attalea speciosa), buriti (Mauritia flexuosa), carnaúba (Copernicia prunifera), catolé (Syagrus oleracea) and macaúba-barriguda (Acrocomia intumescens). Fifth palms were dissected (10 specimens for each species). The overall infestation index was 86%, with a total of 521 triatomines collected. The Trypanosoma cruzi Chagas, 1909 Index was 16.8% and two insects presented mixed infection with Trypanosoma rangeli Tejera, 1920. A precipitin test showed that R. nasutus from palms of Chapada do Araripe are associated with opossum and bird although other possible bloodmeals were observed. Our results showing a high index of infestation of the palms as well as T. cruzi infection, the association of R. nasutus with the most diverse species of palms and proximity of these palms to houses demonstrate the importance of this area for sylvatic T. cruzi transmission and suggest the need for epidemiological surveillance in the region of the Chapada do Araripe.

How does competition among wild type mosquitoes influence the performance of Aedes aegypti and dissemination of Wolbachia pipientis?

BACKGROUND: Wolbachia has been deployed in several countries to reduce transmission of dengue, Zika and chikungunya viruses. During releases, Wolbachia-infected females are likely to lay their eggs in local available breeding sites, which might already be colonized by local Aedes sp. mosquitoes. Therefore, there is an urgent need to estimate the deleterious effects of intra and interspecific larval competition on mosquito life history traits, especially on the duration of larval development time, larval mortality and adult size. METHODOLOGY/PRINCIPAL FINDINGS: Three different mosquito populations were used: Ae. aegypti infected with Wolbachia (wMelBr strain), wild Ae. aegypti and wild Ae. albopictus. A total of 21 treatments explored intra and interspecific larval competition with varying larval densities, species proportions and food levels. Each treatment had eight replicates with two distinct food levels: 0.25 or 0.50 g of Chitosan and fallen avocado leaves. Overall, overcrowding reduced fitness correlates of the three populations. Ae. albopictus larvae presented lower larval mortality, shorter development time to adult and smaller wing sizes than Ae. aegypti. The presence of Wolbachia had a slight positive effect on larval biology, since infected individuals had higher survivorship than uninfected Ae. aegypti larvae. CONCLUSIONS/SIGNIFICANCE: In all treatments, Ae. albopictus outperformed both wild Ae. aegypti and the Wolbachia-infected group in larval competition, irrespective of larval density and the amount of food resources. The major force that can slow down Wolbachia invasion is the population density of wild mosquitoes. Given that Ae. aegypti currently dominates in Rio, in comparison with Ae. albopictus frequency, additional attention must be given to the population density of Ae. aegypti during releases to increase the likelihood of Wolbachia invasion.

Wolbachia Blocks Currently Circulating Zika Virus Isolates in Brazilian Aedes aegypti Mosquitoes.

The recent association of Zika virus with cases of microcephaly has sparked a global health crisis and highlighted the need for mechanisms to combat the Zika vector, Aedes aegypti mosquitoes. Wolbachia pipientis, a bacterial endosymbiont of insect, has recently garnered attention as a mechanism for arbovirus control. Here we report that Aedes aegypti harboring Wolbachia are highly resistant to infection with two currently circulating Zika virus isolates from the recent Brazilian epidemic. Wolbachia-harboring mosquitoes displayed lower viral prevalence and intensity and decreased disseminated infection and, critically, did not carry infectious virus in the saliva, suggesting that viral transmission was blocked. Our data indicate that the use of Wolbachia-harboring mosquitoes could represent an effective mechanism to reduce Zika virus transmission and should be included as part of Zika control strategies.

Description and characterization of the melanic morphotype of Rhodnius nasutus Stål, 1859 (Hemiptera: Reduviidae: Triatominae).

INTRODUCTION: For the first time we provide the description of the melanic (dark) morphotype of Rhodnius nasutus and determine the pattern of genetic inheritance for this characteristic. METHODS: Dark morph R. nasutus specimens were crossbred with standard (typically patterned) R. nasutus. RESULTS: We present the first occurrence of the melanic morphotype in the genus Rhodnius. The crossbreeding results demonstrate that the inheritance pattern of this characteristic follows Mendel's simple laws of segregation and an independent assortment of alleles. CONCLUSIONS: Phenotypic variation of R. nasutus reinforces the heterogeneity found in the Triatominae. Descriptions of new species in this subfamily require rigorous validation criteria.

The exotic palm Roystonea oleracea (Jacq.) O.F. Cook as a rural biotype for Rhodnius neglectus Lent, 1954, in Caçu, State of Goiás.

INTRODUCTION: Rhodnius neglectus is a triatomine that colonizes different palm species. In this study, we aimed to describe the presence of this triatomine bug in the royal palms (Roystonea oleracea) in a rural region of the State of Goiás. METHODS: Palm infestation was investigated by dissecting the palms or by using live-bait traps. RESULTS: Two palm trees were infested by R. neglectus negative for Trypanosoma cruzi, the etiological agent for Chagas disease. In the study area, R. neglectus is frequently found in households. CONCLUSIONS: The adaptation of this species to palm trees introduced in Brazil for landscaping purposes poses another challenge for controlling the vectors of Chagas disease.

Ecology of Rhodnius robustus Larrousse, 1927 (Hemiptera, Reduviidae, Triatominae) in Attalea palm trees of the Tapajós River Region (Pará State, Brazilian Amazon).

BACKGROUND: The rising number of acute cases of Chagas disease in the State of Pará, reported in the past two decades, has been associated, in part, with the ingestion of juice of local palm tree fruits, mainly açaí berry and bacaba. Near the study area, in Santarém, Pará State, an outbreak of Chagas disease has been notified and investigations suggest the consumption of bacaba juice as the main source of infection with T. cruzi. The purpose of this study is to assess the aspects associated to the ecology of Rhodnius robustus in palm trees of three communities of the Tapajós region, in the State of Pará, Brazil. METHODS: Palm trees were cut down and dissected to search for triatomines. DNA from triatomines was extracted to investigate natural infection by Trypanosoma cruzi and T. rangeli. For statistical analyzes, data from infestation of palm trees, as well as the rates of natural infection by T. cruzi and T. rangeli were compared by Chi-square test. Triatomine density values were analyzed by the nonparametric Kruskal Wallis test and then comparisons between each pair of variables were made by the Mann-Whitney test assuming a confidence interval of 95%. RESULTS: We dissected 136 palm trees, 60 at the end of the rainy period and 76 at the end of the dry period. Seventy-three of them (53.7%) were infested with triatomines and three species were found, namely: Rhodnius robustus, Rhodnius pictipes and Panstrongylus lignarius. We collected 743 triatomines, and R. robustus was predominant (n = 739). The identification of natural infection of the insects by trypanosomatids revealed that 125 triatomines were infected by T. cruzi, 69 by T. rangeli and 14 presented both parasites, indicating the presence of mixed infection in the same vector. CONCLUSION: The results suggest that São Tomé is the community with greater density of triatomines and infestation of palm trees; also, it demonstrates the existence of an intense sylvatic cycle in the region, which demands intensive surveillance to prevent human transmission.

Adenylate cyclases of Trypanosoma brucei inhibit the innate immune response of the host.

The parasite Trypanosoma brucei possesses a large family of transmembrane receptor-like adenylate cyclases. Activation of these enzymes requires the dimerization of the catalytic domain and typically occurs under stress. Using a dominant-negative strategy, we found that reducing adenylate cyclase activity by about 50% allowed trypanosome growth but reduced the parasite's ability to control the early innate immune defense of the host. Specifically, activation of trypanosome adenylate cyclase resulting from parasite phagocytosis by liver myeloid cells inhibited the synthesis of the trypanosome-controlling cytokine tumor necrosis factor-α through activation of protein kinase A in these cells. Thus, adenylate cyclase activity of lyzed trypanosomes favors early host colonization by live parasites. The role of adenylate cyclases at the host-parasite interface could explain the expansion and polymorphism of this gene family.

Influence of the palm tree species on the variability of Rhodnius nasutus Stål, 1859 (Hemiptera, Reduviidae, Triatominae).

This work evaluated the occurrence and genetic structure of Rhodnius nasutus sampled in two sites using morphometry and microsatellites. These sites, presented distinct abiotic features and palm trees: (i) nine Attalea speciosa palm trees, so called babaçu, were sampled from the Meruoca Mountain Ridge, a sloping region of reminiscent forest in the state of Ceará, Brazil, and (ii) 17 Copernicia prunifera palm trees, so called carnaúba, were sampled in the scrub savanna region (Sobral district) that surrounds the mountain ridge. Of the twenty-six palm trees dissected, 70.6% of carnauba and 88.9% of babaçu were infested by R. nasutus. The micro-climatic data where R. nasutus were sheltered demonstrated that the babaçu and carnaúba palm trees presented significant differences (p < 0.05) in relation to the external environment, except for temperature and relative humidity regulation, suggesting that the architecture of the babaçu crown keeps a more stable micro-environment. The morphometric studies of the F1 generation demonstrated that insects from the babaçu (A. speciosa) were significantly larger (p = 0.000) than those collected in carnaúba (C. prunifera) palm trees. Also, microsatellite analysis demonstrated a high genetic differentiation between the two groups of R. nasutus (R(st) = -0.77). Our results suggest that the difference in size between the populations is probably related to an incipient process of genetic drift in populations associated to each palm tree, probably also driven by the different climatic features observed in these micro-environments.

Tamandua tetradactyla Linnaeus, 1758 (Myrmecophagidae) and Rhodnius robustus Larrousse, 1927 (Triatominae) infection focus by Trypanosoma rangeli Tejera, 1920 (Trypanosomatidae) in Attalea phalerata Mart. ex Spreng (Arecaceae) palm tree in the Brazilian Amazon.

A sylvatic infection focus of Trypanosoma rangeli, whose cycle involves the anteater Tamandua tetradactyla and triatomine insect Rhodnius robustus was observed in a pasture-dominated landscape of the rural riparian community of São Tomé located along the Tapajós river in the municipal district of Aveiro (State of Pará, Brazil), the Brazilian Amazon region. During a field work campaign with the objective of Chagas disease diagnosis in the Tapajós region, an anteater and 31 triatomines were found inhabiting in the same Attalea phalerata palm tree crown. Collected triatomines were identified as R. robustus with morphological and molecular procedures. The analysis of infection by T. rangeli using the repetitive ARN nucleolar Cl1 (sno-RNA-Cl1) gene showed that 25 triatomines of all stages were infected by T. rangeli (total infection rate of 80.6%). Infection by Trypanosoma cruzi using mini-exon markers was not identified. Examination of the digestive content of the triatomines demonstrated that the only feeding source found was the anteater. These results demonstrate that T. tetradactyla can be an important reservoir for T. rangeli and a good vehicle of the parasite within the Brazilian Amazon region.

Ecology, evolution, and the long-term surveillance of vector-borne Chagas disease: a multi-scale appraisal of the tribe Rhodniini (Triatominae).

Chagas disease incidence has sharply declined over the last decade. Long-term disease control will, however, require extensive, longitudinal surveillance systems capable of detecting (and dealing with) reinvasion-reinfestation of insecticide-treated dwellings by non-domiciliated triatomines. Sound surveillance design calls for reliable data on vector ecology, and these data must cover different spatial scales. We conducted a multi-scale assessment of ecological and evolutionary trends in members of the tribe Rhodniini, including (i) a macroscale analysis of Rhodniini species richness and composition patterns across the Americas, and (ii) a detailed, mesoscale case-study of ecological and behavioural trends in Rhodnius neglectus and R. nasutus. Our macroscale overview provides some comprehensive insights about key mechanisms/processes probably underlying ecological and genetic diversification in the Rhodniini. These insights translate into a series of testable hypotheses about current species distributions and their likely causes. At the landscape scale, we used geometric morphometrics to identify dubious specimens as either R. neglectus or R. nasutus (two near-sibling species), and studied palm tree populations of these two vector taxa in five geographical areas. The data suggest that deforestation and the associated loss of habitat and host diversity might increase the frequency of vector-human contact (and perhaps Trypanosoma cruzi infection rates in vectors). Surveillance in central-northeastern Brazil should prioritise deforested landscapes where large palm trees (e.g., Attalea, Mauritia, Copernicia, Acrocomia or Syagrus) occur near houses. We anticipate that, by helping define the distribution patterns and ecological preferences of each species, multi-scale research will significantly strengthen vector surveillance systems across Latin America.

The exotic palm Roystonea oleracea (Jacq.) O.F. Cook as a rural biotype for Rhodnius neglectus Lent, 1954, in Caçu, State of Goiás

Introduction Rhodnius neglectus is a triatomine that colonizes different palm species. In this study, we aimed to describe the presence of this triatomine bug in the royal palms (Roystonea oleracea) in a rural region of the State of Goiás. Methods Palm infestation was investigated by dissecting the palms or by using live-bait traps. Results Two palm trees were infested by R. neglectus negative for Trypanosoma cruzi, the etiological agent for Chagas disease. In the study area, R. neglectus is frequently found in households. Conclusions The adaptation of this species to palm trees introduced in Brazil for landscaping purposes poses another challenge for controlling the vectors of Chagas disease. .

First report on the occurrence of Trypanosoma rangeli Tejera, 1920 in the state of Ceará, Brazil, in naturally infected triatomine Rhodnius nasutus Stål, 1859 (Hemiptera, Reduviidae, Triatominae).

The aim of this work was to identify and report the occurrence of Trypanosoma rangeli and Trypanosoma cruzi in naturally infected Rhodnius nasutus (Hemiptera, Reduviidae, Triatominae) in the state of Ceará, Brazil. Triatomines feces, salivary glands, and hemolymph were collected for fresh examination, and specific detection of T. rangeli and T. cruzi DNA by polymerase chain reaction was carried out. The specific characterization of these two parasites showed the simultaneous presence of both parasites in two (7.7%) of the 26 positive insects. Our results provide further knowledge on the geographical distribution of T. rangeli in Brazil.

Ecological aspects of Rhodnius nasutus Stål, 1859 (Hemiptera: Reduviidae: Triatominae) in palms of the Chapada do Araripe in Ceará, Brazil

The aim of this work is to present aspects related to the ecology of Rhodnius nasutus Stål, 1859 in palms from Chapada do Araripe in Ceará, Brazil. The following five species of palms were investigated: babaçu (Attalea speciosa), buriti (Mauritia flexuosa), carnaúba (Copernicia prunifera), catolé (Syagrus oleracea) and macaúba-barriguda (Acrocomia intumescens). Fifth palms were dissected (10 specimens for each species). The overall infestation index was 86 percent, with a total of 521 triatomines collected. The Trypanosoma cruzi Chagas, 1909 Index was 16.8 percent and two insects presented mixed infection with Trypanosoma rangeli Tejera, 1920. A precipitin test showed that R. nasutus from palms of Chapada do Araripe are associated with opossum and bird although other possible bloodmeals were observed. Our results showing a high index of infestation of the palms as well as T. cruzi infection, the association of R. nasutus with the most diverse species of palms and proximity of these palms to houses demonstrate the importance of this area for sylvatic T. cruzi transmission and suggest the need for epidemiological surveillance in the region of the Chapada do Araripe.

First report on the occurrence of Trypanosoma rangeli Tejera, 1920 in the state of Ceará, Brazil, in naturally infected triatomine Rhodnius nasutus Stål, 1859 (Hemiptera, Reduviidae, Triatominae)

The aim of this work was to identify and report the occurrence of Trypanosoma rangeli and Trypanosoma cruzi in naturally infected Rhodnius nasutus (Hemiptera, Reduviidae, Triatominae) in the state of Ceará, Brazil. Triatomines feces, salivary glands, and hemolymph were collected for fresh examination, and specific detection of T. rangeli and T. cruzi DNA by polymerase chain reaction was carried out. The specific characterization of these two parasites showed the simultaneous presence of both parasites in two (7.7 percent) of the 26 positive insects. Our results provide further knowledge on the geographical distribution of T. rangeli in Brazil.

Aspectos ecológicos da Tripanossomíase Americana em comunidades do médio Tapajós, Pará, Brasil, e riscos de transmissão do Trypanosoma cruzi às populações humanas da região / Ecological aspects of American trypanosomiasis in communities of the middle Tapajós, Pará, Brazil, and risks of transmission of Trypanosoma cruzi to human populations in the region

O número crecente de casos agudos da doença de Chagas no estado do Pará, notificados nas últimas duas décadas, tem sido associados, em parte, a ingestão de suco de frutos de palmeiras locais, principalmente açaí e bacaba. O objetivo do presente trabalho foi avaliar os aspectos ecológicos da Tripanossomíase Americana em comunidades do médio Tapajós, Pará, Brasil, e riscos de transmissão do Trypanosoma cruzi às populações humanas da região. Para isto, foram dissecadas 136 palmeiras, sendo 60 no final do período chuvoso e 76 no final do período de seca. Destas, 73 (53,7%) estavam infestadas por triatomíneos e foram encontradas três espécies, a saber: Rhodnius robustus, Rhodnius pictipes e Panstrongylus lignarius. Foram coletados 743 triatomíneos, sendo predominante a presença de R. robustus (n=739). A identificação da infecção natural dos insetos por tripanosomatídeos revelou que 125 triatomíneos estavam infectados pelo T. cruzi, 69 por T. rangeli e 14 apresentaram ambos os parasitas, indicando a presença de infecção mista no mesmo vetor. Foi realizada a tipagem molecular de T. cruzi de acordo com a nova nomenclatura e os resultados demonstraram predominância do grupo TCI (n=29). Além disso, foi constatada a ocorrência de TCII, a presença de TCI e TCII no mesmo triatomíneo e 12 isolados de TCI apresentaram uma variante, sugerindo a existência de um subgrupo dentro de TCI. A análise das fontes alimentares revelou que R. robustus, espécie predominante de triatomíneo coletada nas palmeiras investigadas, alimentou-se na sua grande maioria em mamíferos silvestres. Foram também identificados “sangue” de outras fontes alimentares, como aves e répteis no conteúdo digestivo dos espécies investigados. As análises cartográficas de Kernel e do Interpolador de Médias demonstraram que a comunidade São Tomé apresenta maiores aglomerados (hotspots) tanto em infestação das palmeiras, quanto na densidade triatomínica e número de insetos infectados. Desta forma, os resultados sugerem que São Tomé é a comunidade com maior risco de infecção à população e demonstram a existência de um ciclo silvestre intenso na região que demanda vigilância para prevenção da transmissão.

Aspectos ecológicos da Tripanossomíase Americana em comunidades do médio Tapajós, Pará, Brasil, e riscos de transmissão do Trypanosoma cruzi às populações humanas da região

O número crecente de casos agudos da doença de Chagas no estado do Pará, notificados nas últimas duas décadas, tem sido associados, em parte, a ingestão de suco de frutos de palmeiras locais, principalmente açaí e bacaba. O objetivo do presente trabalho foi avaliar os aspectos ecológicos da Tripanossomíase Americana em comunidades do médio Tapajós, Pará, Brasil, e riscos de transmissão do Trypanosoma cruzi às populações humanas da região. Para isto, foram dissecadas 136 palmeiras, sendo 60 no final do período chuvoso e 76 no final do período de seca. Destas, 73 (53,7%) estavam infestadas por triatomíneos e foram encontradas três espécies, a saber: Rhodnius robustus, Rhodnius pictipes e Panstrongylus lignarius. Foram coletados 743 triatomíneos, sendo predominante a presença de R. robustus (n=739). A identificação da infecção natural dos insetos por tripanosomatídeos revelou que 125 triatomíneos estavam infectados pelo T. cruzi, 69 por T. rangeli e 14 apresentaram ambos os parasitas, indicando a presença de infecção mista no mesmo vetor. Foi realizada a tipagem molecular de T. cruzi de acordo com a nova nomenclatura e os resultados demonstraram predominância do grupo TCI (n=29). Além disso, foi constatada a ocorrência de TCII, a presença de TCI e TCII no mesmo triatomíneo e 12 isolados de TCI apresentaram uma variante, sugerindo a existência de um subgrupo dentro de TCI. A análise das fontes alimentares revelou que R. robustus, espécie predominante de triatomíneo coletada nas palmeiras investigadas, alimentou-se na sua grande maioria em mamíferos silvestres

Foram também identificados “sangue” de outras fontes alimentares, como aves e répteis no conteúdo digestivo dos espécies investigados. As análises cartográficas de Kernel e do Interpolador de Médias demonstraram que a comunidade São Tomé apresenta maiores aglomerados (hotspots) tanto em infestação das palmeiras, quanto na densidade triatomínica e número de insetos infectados. Desta forma, os resultados sugerem que São Tomé é a comunidade com maior risco de infecção à população e demonstram a existência de um ciclo silvestre intenso na região que demanda vigilância para prevenção da transmissão

Ecologia de Rhodnius nasutus Stal 1859 (Hemiptera: Reduviidae: Triatominae) em palmeiras da Chapada do Araripe, Ceará, Brasil

Considera-se que Rhodnius nasutus Stal, 1859 seja um triatomíneo restrito aodomínio da caatinga. Entretanto, seus limites não estão bem reconhecidos. Oobjetivo do presente trabalho foi identificar qual espécie de triatomíneo ocorreao sul do estado do Ceará, nas palmeiras da Chapada do Araripe, Brasil e suaimportância na transmissão local pelo Trypanosoma cruzi e Trypanosomarangeli. Embora esteja incluída no contexto da caatinga, esta região éconsiderada uma área com vegetação mista de cerrado e Mata Atlântica.Sendo as diversas espécies de palmeiras relatadas como ecótopo paratriatomíneos do gênero Rhodnius, foram trabalhadas cinco espécies depalmeiras, num total de 10 exemplares para cada espécie, a saber: babaçu(Attalea speciosa), buriti (Mauritia flexuosa), carnaúba (Copernicia prunifera),catolé (Syagrus oleracea) e macaúba-barriguda (Acrocomia intumescens). Aúnica espécie de triatomíneo encontrada foi R. nasutus, e o índice deinfestação global foi de 86 por cento. No Ceará, esta espécie tem sido encontradafreqüentemente no peridomicílio e intradomicílio, demonstrando significativaimportância na DC. O índice de infecção encontrado pelo Trypanosoma cruzifoi de 16,8 por cento e, pela primeira vez na literatura, relatamos a ocorrência doTrypanosoma rangeli no estado do Ceará, com índice de infecção natural de7,7 por cento, nos insetos analisados. Os tripanosomatídeos foram caracterizadosmolecularmente, confirmando os achados microscópicos, sendo as cepas de T.cruzi pertencentes ao grupo I, característico de cepas circulantes do ambientesilvestre. Estudos da reação de precipitina sugerem que as principais fontesalimentares do R. nasutus são ave e gambá. As árvores UPGMA geradas pelaanálise morfométrica apontam o grupo de insetos dos buritis como o maisdistante geneticamente, o que pode estar relacionado ao isolamento geográficodeste grupo de insetos aos demais. Nossos resultados associados aosenormes palmeirais encontrados na região da Chapada do Araripe fazem ...