Marcos Takashi Obara

Molecular phylogeny of Triatomini (Hemiptera: Reduviidae: Triatominae)

BackgroundThe Triatomini and Rhodniini (Hemiptera: Reduviidae) tribes include the most diverse Chagas disease vectors; however, the phylogenetic relationships within the tribes remain obscure. This study provides the most comprehensive phylogeny of Triatomini reported to date.MethodsThe relationships between all of the Triatomini genera and representatives of the three Rhodniini species groups were examined in a novel molecular phylogenetic analysis based on the following six molecular markers: the mitochondrial 16S; Cytochrome Oxidase I and II (COI and COII) and Cytochrome B (Cyt B); and the nuclear 18S and 28S.ResultsOur results show that the Rhodnius prolixus and R. pictipes groups are more closely related to each other than to the R. pallescens group. For Triatomini, we demonstrate that the large complexes within the paraphyletic Triatoma genus are closely associated with their geographical distribution. Additionally, we observe that the divergence within the spinolai and flavida complex clades are higher than in the other Triatoma complexes.ConclusionsWe propose that the spinolai and flavida complexes should be ranked under the genera Mepraia and Nesotriatoma. Finally, we conclude that a thorough morphological investigation of the paraphyletic genera Triatoma and Panstrongylus is required to accurately assign queries to natural genera.

Eratyrus mucronatus Stål, 1859 (Hemiptera: Reduviidae: Triatominae): first report in the State of Acre, Brazil, and updated geographic distribution in South America

A new occurrence record of Eratyrus mucronatus (Hemiptera, Reduviidae, Triatominae) is reported from Rio Branco, Acre, Brazil. The distribution of this triatomine species was updated and a potential geographic distribution map in South America was presented based on ecological niche modeling.

Molecular detection of Trypanosoma sp. and Blastocrithidia sp. (Trypanosomatidae) in phlebotomine sand flies (Psychodidae) in the Federal District of Brazil

INTRODUCTION This study describes the occurrence of trypanosomatids in phlebotomines in Brasília, Brazil. METHODS Two hundred and ten females of 13 sand fly species were analyzed by polymerase chain reaction (PCR) using different molecular markers (D7 24Sα rRNA, kDNA, and ITS1) and sequencing. RESULTS PCR revealed trypanosomatid-positive samples from Nyssomyia whitmani and Evandromyia evandroi, which were negative by kDNA and ITS1 Leishmania-specific PCRs. DNA sequence analysis of D7 24Sα rRNA amplicons indicated the occurrence of Blastocrithidia sp. and Trypanosoma sp. in Nyssomyia whitmani and Evandromyia evandroi, respectively. CONCLUSIONS Two trypanosomatid species other than Leishmania sp. were found to circulate in sand flies in Central Brazil.

Surveillance of vector-borne pathogens under imperfect detection: lessons from Chagas disease risk (mis)measurement

Vector-borne pathogens threaten human health worldwide. Despite their critical role in disease prevention, routine surveillance systems often rely on low-complexity pathogen detection tests of uncertain accuracy. In Chagas disease surveillance, optical microscopy (OM) is routinely used for detecting Trypanosoma cruzi in its vectors. Here, we use replicate T. cruzi detection data and hierarchical site-occupancy models to assess the reliability of OM-based T. cruzi surveillance while explicitly accounting for false-negative and false-positive results. We investigated 841 triatomines with OM slides (1194 fresh, 1192 Giemsa-stained) plus conventional (cPCR, 841 assays) and quantitative PCR (qPCR, 1682 assays). Detections were considered unambiguous only when parasitologists unmistakably identified T. cruzi in Giemsa-stained slides. qPCR was >99% sensitive and specific, whereas cPCR was ~100% specific but only ~55% sensitive. In routine surveillance, examination of a single OM slide per vector missed ~50–75% of infections and wrongly scored as infected ~7% of the bugs. qPCR-based and model-based infection frequency estimates were nearly three times higher, on average, than OM-based indices. We conclude that the risk of vector-borne Chagas disease may be substantially higher than routine surveillance data suggest. The hierarchical modelling approach we illustrate can help enhance vector-borne disease surveillance systems when pathogen detection is imperfect.

Synanthropic triatomines as potential vectors of Trypanosoma cruzi in Central Brazil

INTRODUCTION Chagas disease surveillance requires current knowledge on synanthropic triatomines. We analyzed the occurrence and Trypanosoma cruzi infection rates of triatomine bugs in central Brazil, during 2012-2014. METHODS Triatomines were collected inside or around houses, and T. cruzi infection was determined by optical microscopy and conventional/quantitative polymerase chain reaction. RESULTS Of the 2706 triatomines collected, Triatoma sordida was the most frequent species in Goiás State, whereas Panstrongylus megistus predominated in the Federal District. Parasites identified were T. cruzi, T. rangeli, and Blastocrithidia sp. CONCLUSIONS P. megistus and T. sordida sustained the risk of T. cruzi transmission to humans in central Brazil.

Wing geometry of Triatoma sordida (Hemiptera: Reduviidae) populations from Brazil

Triatoma sordida has a widespread distribution in Argentina, Bolivia, Brazil, Paraguay, and Uruguay and is frequently found in peridomestic environments. We investigated size and shape variability of T. sordida wings across Brazil. Field-collected adults from twelve populations were studied. For each individual female, seven landmarks on the right wing were digitalized. Shape variables derived from Procrustes superimposition were used in Principal Component Analysis (PCA). Wing size and shape variations among populations was explored by means of ANOVA. Wing centroid size was significantly different among T. sordida populations; specimens from Bahia (East) were larger than those of Mato Grosso do Sul (West). PCA based on wing shape variables showed low wing shape variability. These results reinforce previous data showing low genetic variability among T. sordida populations from Brazil.

The role of gallery forests in maintaining Phlebotominae populations: potential Leishmania spp. vectors in the Brazilian savanna

BACKGROUND Knowledge on synanthropic phlebotomines and their natural infection by Leishmania is necessary for the identification of potential areas for leishmaniasis occurrence. OBJECTIVE To analyse the occurrence of Phlebotominae in gallery forests and household units (HUs) in the city of Palmas and to determine the rate of natural infection by trypanosomatids. METHODS Gallery forests and adjacent household areas were sampled on July (dry season) and November (rainy season) in 2014. The total sampling effort was 960 HP light traps and eight Shannon traps. Trypanosomatids were detected in Phlebotominae females through the amplification of the SSU rDNA region, and the positive samples were used in ITS1-PCR. Trypanosomatid species were identified using sequencing. FINDINGS A total of 1,527 sand flies representing 30 species were captured in which 949 (28 spp.) and 578 (22 spp.) were registered in July and November, respectively. In July, more specimens were captured in the gallery forests than in the HUs, and Nyssomyia whitmani was particularly frequent. In November, most of the specimens were found in the HUs, and again, Ny. whitmani was the predominant species. Lutzomyia longipalpis was commonly found in domestic areas, while Bichromomyia flaviscutellata was most frequent in gallery forests. Molecular analysis of 154 pools of females (752 specimens) identified Leishmania amazonensis, L. infantum, and Crithidia fasciculata in Ny. whitmani, as well as L. amazonensis in Lu. longipalpis, Trypanosoma sp. and L. amazonensis in Pintomyia christenseni, and L. amazonensis in both Psathyromyia hermanlenti and Evandromyia walkeri. MAIN CONCLUSIONS These results show the importance of gallery forests in maintaining Phlebotominae populations in the dry month, as well as their frequent occurrence in household units in the rainy month. This is the first study to identify Leishmania, Trypanosoma, and Crithidia species in Phlebotominae collected in Palmas, Tocantins, Brazil.

Mitochondrial PCR-RFLP Assay to Distinguish Triatoma brasiliensis macromelasoma from Triatoma brasiliensis brasiliensis Subspecies (Hemiptera: Reduviidae).

Triatoma brasiliensis sensu lato (s.l.), the main vector of Chagas disease in northeastern Brazil, is a species complex comprising four species, one with two subspecies (T. brasiliensis brasiliensis, T. brasiliensis macromelasoma, T. juazeirensis, T. sherlocki, and T. melanica), and each taxon displaying distinct ecological requirements. In order to evaluate the genetic relationships among nine T. brasiliensis s.l. populations from northeastern Brazil, we analyzed their mitochondrial cytochrome c oxidase subunit 1 sequences and suggested a PCR-RFLP assay to distinguish between T. b. macromelasoma and T. b. brasiliensis subspecies. All the specimens were morphologically identified as T. b. brasiliensis. The resulting phylogenies identified two major clades that are congruent with the geographical populations studied. Based on collection sites and in accordance with type-location, one clade was identified as the subspecies T. b. macromelasoma. The second clade grouped T. b. brasiliensis populations. Restriction endonuclease sites were observed in the sequences and used in PCR-RFLP assays, producing distinct fingerprints for T. b. macromelasoma and T. b. brasiliensis populations. The results suggest that these are different species and that gene flow occurs only among T. b. brasiliensis populations, possibly associated with human activity in the area.

Ocorrência de flebotomíneos (Diptera: Psychodidae) em matas de galeria no Distrito Federal, Brasil

O objetivo deste estudo foi analisar a ocorrencia de flebotomineos em matas de galeria do Distrito Federal (DF), em diferentes estacoes climaticas, estratos verticais e condicoes de preservacao das matas. As capturas foram realizadas em tres areas na Fazenda Agua Limpa da Universidade de Brasilia. Em cada area foi analisada a ocorrencia de flebotomineos em 20 pontos visitados em dois meses, novembro de 2012 (estacao chuvosa) e maio de 2013 (estacao seca). Armadilhas luminosas HP foram instaladas a 1,5 m e a 10 m de altura do solo, operando entre 17:00 e 07:00 h, por tres dias consecutivos. Foram instaladas 359 armadilhas-noite na estacao chuvosa e 291 na seca. Nenhum flebotomineo foi capturado na estacao chuvosa. Na estacao seca foram capturados 250 exemplares. As especies identificadas foram Psathyromyia runoides (Fairchild & Hertig) (79,9%), Pintomyia monticola (Costa Lima) (9,7%), Micropygomyia quinquefer (Dyar) (3,7%), Psathyromyia shannoni (Dyar) (3%), Bichromomyia flaviscutellata (Mangabeira) (0,7%), Brumptomyia sp. (0,7%), Pintomyia kuscheli (Le Pont, Martinez, Torrez-Espejo & Dujardin) (0,7%), Psathyromyia lutziana (Costa Lima) (0.7%) e Sciopemyia sordellii (Shannon & Del Ponte) (0,7%). Os resultados indicam que em matas de galeria do DF ha uma maior ocorrencia de flebotomineos na estacao seca, no nivel do solo e em areas preservadas. Registra-se pela primeira vez Pa. runoides , Pi. kuscheli e Mi. quinquefer no DF. Occurrence of Phlebotomine Sand Flies (Diptera: Psychodidae) in the Gallery Forests of the Federal District, Brazil Abstract. We analyzed the occurrence of phlebotomine sand flies in the gallery forests of the Federal District (FD), in different seasons, forest strata and conservation status. The samples were collected in three areas in the Agua Limpa Farm, University of Brasilia. In each area the occurrence data were analyzed in 20 collection sites visited on two months, November 2012 (rainy season) and May 2013 (dry season). HP light traps were installed at 1.5 m and 10 m above the ground operating from 17:00 to 7:00 h, during three consecutive days. We set 359 trap-nights during the rainy season and 291 during the dry season. None sand fly was caught during the rainy season. In the dry season 250 sand flies were captured. The identified species were Psathyromyia runoides (Fairchild & Hertig) (79.9%), Pintomyia monticola (Costa Lima) (9.7%), Micropygomyia quinquefer (Dyar) (3.7%), Psathyromyia shannoni (Dyar) (3%), Bichromomyia flaviscutellata (Mangabeira) (0.7%), Brumptomyia sp. (0.7%), Pintomyia kuscheli (Le Pont, Martinez, Torrez-Espejo & Dujardin) (0.7%), Psathyromyia lutziana (Costa Lima) (0.7%), and Sciopemyia sordellii (Shannon & Del Ponte) (0.7%). The results indicated that in the gallery forests of the FD there is a higher occurrence of sand flies in the dry season, at ground level and in preserved areas. Pa runoides , Pi. kuscheli and Mi. quinquefer were recorded for the first time in the FD.