Enzootic transmission of Trypanosoma cruzi and T. rangeli in the Federal District of Brazil

Occurrence and spatial distribution of triatomines (Hemiptera: Reduviidae) in the urban area of the municipality of Montes Claros, Northern Minas Gerais, Brazil

The north of the Brazilian state of Minas Gerais is classified as an area of high risk of vectorial transmission of Chagas disease (CD) or of reestablishing transmission in the home, but the Chagas disease control programme is disjointed. The study evaluated the occurrence, natural infection and the spatial distribution of species of triatomines associated with climatic variations in the urban area of Montes Claros, a municipality endemic to CD in the north of Minas Gerais, Brazil. Triatomine data were obtained from passive entomological surveillance actions of the Chagas Disease Control Program (Programa de Controle de Doença de Chagas-PCDCh), registered by the Zoonosis Control Center (Centro de Controle de Zoonoses-CCZ) from 2009 to 2019. A total of 277 triatomines belonging to eight species were collected, and of these, 203 insects were examined. It was found that 46.2% of triatomines were captured inside the home and 8.3% around the home. The natural infection rate was 6.9%; 14 specimens showed natural infection by Trypanosoma cruzi (12 females and 2 males), and of these, 13 were found in the home and one in an uninformed location. The number of triatomine records collected was significantly higher in the month of September (p = .01), and there was an inverse correlation between the number of triatomines and the relative humidity of the air (p < .001). It was verified that the highest triatomine densities are located in transition areas between urban infrastructure (32.12%) and pasture (25.72%). The diversity of species of triatomines infected with T. cruzi in residential units in urban areas in the municipality of Montes Claros is worrying, as it suggests a potential risk of transmission of the parasite to domestic animals and humans.

Trypanosomatid species in Didelphis albiventris from urban forest fragments

Urbanization results in loss of natural habitats and, consequently, reduction of richness and abundance of specialist to the detriment of generalist species. We hypothesized that a greater richness of trypanosomatid in Didelphis albiventris would be found in fragments of urban forests in Campo Grande, Mato Grosso do Sul, Brazil, that presented a larger richness of small mammals. We used parasitological, molecular, and serological methods to detect Trypanosoma spp. infection in D. albiventris (n = 43) from forest fragments. PCR was performed with primers specific for 18S rDNA, 24Sα rDNA, mini-chromosome satellites, and mini-exon genes. IFAT was used to detect anti-Trypanosoma cruzi IgG. All hemoculture was negative. We detected trypanosomatid DNA in blood of 35% of opossum. Two opossums were seropositive for T. cruzi. The trypanosomatid species number infecting D. albiventris was higher in the areas with greater abundance, rather than richness of small mammals. We found D. albiventris parasitized by T. cruzi in single and co-infections with Leishmania spp., recently described molecular operational taxonomic unit (MOTU) named DID, and Trypanosoma lainsoni. We concluded that (i) trypanosome richness may be determined by small mammal abundance, (ii) D. albiventris confirmed to be bio-accumulators of trypanosomatids, and (iii) T. lainsoni demonstrated a higher host range than described up to the present.

Trypanosomatid infections in captive wild mammals and potential vectors at the Brasilia Zoo, Federal District, Brazil

Background

Conservation projects in zoos may involve translocation of captive animals, which may lead to pathogen spread. Neotropical mammals are important hosts of Trypanosoma cruzi and Leishmania spp. the etiological agents of Chagas disease and Leishmaniasis respectively. Studies of trypanosomatid‐infected mammals and vectors (triatomines and sandflies) in zoos are important for the establishment of surveillance and control measures.

Objectives

We investigated trypanosomatid infections in captive wild mammals, triatomines and sandflies at the Brasília Zoo.

Methods

We collected triatomines during active bimonthly surveys, sampled sandflies using light‐traps and obtained blood samples from 74 mammals between 2016 and 2017. We used quantitative PCR to detect trypanosomatids in vectors and mammals.

Results

We found a colony of 19 Panstrongylus megistus in the porcupine unit and detected T. cruzi infections in five bugs. We captured 17 sandflies of four species including Nyssomyia whitmani and Lutzomyia longipalpis, but no Leishmania infection was detected. qPCR detected 50 T. cruzi‐infected mammals belonging to 24 species and five groups of mammals (Carnivora, Cetartiodactyla, Perissodactyla, Pilosa and Primates); Leishmania DNA was detected in 23 mammals from 15 species, mainly carnivores. We detected trypanosomatid infections in 11 mammals born at the Brasília Zoo.

Conclusions

Our results suggest vector‐borne transmission of T. cruzi among maned wolves; measures to reduce the risk of new infections should therefore be taken. We also report sandfly presence and Leishmania‐infected mammals at the Brasília Zoo. Translocation of wild mammals in and out of the Brasília Zoo should consider the risk of T. cruzi and Leishmania spread.

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.

High frequency of trypanosomatids in gallery forest bats of a Neotropical savanna

Bats are well-known hosts of trypanosomatids, though information about their role as reservoirs of these protozoans in the Brazilian savanna is poorly known. We aimed to analyze the occurrence of trypanosomatid species in bats occurring in remnants of gallery forests of Brasília, Federal District of Brazil. We sampled bats using mist nets in six sites, and we collected blood, wing fragments and oral swab samples from all captured individuals. Trypanosomatids were identified in the captured bats through sequencing of the SSUrRNA region and kDNA qPCR. We found no parasite in blood smears of 146 individuals of 14 species captured, but blood cultures were positive for nine bats. We detected trypanosomatids molecularly in 111 (76%) specimens of all bat species in the studied areas. Most of the infected bats had Leishmania-like DNA detected in blood and swab samples of the oral mucosa. We distinguished three species of Trypanosoma (Trypanosoma dionisii, T. rangeli and T. cruzi) in Carollia perspicillata. SSUrRNA PCR of oral samples is a non-invasive and practical method for identification of trypanosomatid species in bats. Our results support our belief that bats could be potential reservoirs for Trypanosoma and Leishmania-like species in the enzootic cycle of these parasites in gallery forests of the Brazilian Cerrado biome.

Exploring the molecular complexity of Triatoma dimidiata sialome

Triatoma dimidiata, a Chagas disease vector widely distributed along Central America, has great capability for domestic adaptation as the majority of specimens caught inside human dwellings or in peridomestic areas fed human blood. Exploring the salivary compounds that overcome host haemostatic and immune responses is of great scientific interest. Here, we provide a deeper insight into its salivary gland molecules. We used high-throughput RNA sequencing to examine in depth the T. dimidiata salivary gland transcriptome. From >51 million reads assembled, 92.21% are related to putative secreted proteins. Lipocalin is the most abundant gene family, confirming it is an expanded family in Triatoma genus salivary repertoire. Other putatively secreted members include phosphatases, odorant binding protein, hemolysin, proteases, protease inhibitors, antigen-5 and antimicrobial peptides. This work expands the previous set of functionally annotated sequences from T. dimidiata salivary glands available in NCBI from 388 to 3815. Additionally, we complemented the salivary analysis through proteomics (available data via ProteomeXchange with identifier PXD008510), disclosing the set complexity of 119 secreted proteins and validating the transcriptomic results. Our large-scale approach enriches the pharmacologically active molecules database and improves our knowledge about the complexity of salivary compounds from haematophagous vectors and their biological interactions.

SIGNIFICANCE

Several haematophagous triatomine species can transmit Trypanosoma cruzi, the etiological agent of Chagas disease. Due to the reemergence of this disease, new drugs for its prevention and treatment are considered priorities. For this reason, the knowledge of vector saliva emerges as relevant biological finding, contributing to the design of different strategies for vector control and disease transmission. Here we report the transcriptomic and proteomic compositions of the salivary glands (sialome) of the reduviid bug Triatoma dimidiata, a relevant Chagas disease vector in Central America. Our results are robust and disclosed unprecedented insights into the notable diversity of its salivary glands content, revealing relevant anti-haemostatic salivary gene families. Our work expands almost ten times the previous set of functionally annotated sequences from T. dimidiata salivary glands available in NCBI. Moreover, using an integrated transcriptomic and proteomic approach, we showed a correlation pattern of transcription and translation processes for the main gene families found, an important contribution to the research of triatomine sialomes. Furthermore, data generated here reinforces the secreted proteins encountered can greatly contribute for haematophagic habit, Trypanosoma cruzi transmission and development of therapeutic agent studies.

New Trypanosoma species, Trypanosoma gennarii sp. nov., from South American marsupial in Brazilian Cerrado

Hundreds of trypanosome species have been described in all mammalian orders, on every continent, including with mixed infections. Trypanosomes circulate in the form of sylvatic enzootic infections transmitted by blood-sucking insects that are associated with the host mammals. Small wild mammals were caught in a fragment of Cerrado terrain on an island in the hydroelectric reservoir of Três Marias, in the central region of the state of Minas Gerais, using pitfall and Sherman traps with different means of attraction. DNA samples from these mammals were subjected to the conventional polymerase chain reaction (PCR) for the full-length genes SSU rDNA and gGAPDH. A total of 232 animals of the orders Didelphimorphia, Rodentia, Chiroptera and Cingulata were caught (total of 17 species). There were also four species of marsupials: Monodelphis domestica, Didelphis albiventris, Gralicinanus agilis and Micoureus paraguaianus. Among these, there were eight positive individuals of Monodelphis domestica. However, nine cultures were established, because one of them was parasitized by two species of trypanosomes: Trypanosoma cruzi and a new trypanosome species. The new species have a large epimastigote forms, and with a well-developed undulating membrane in trypomastigote forms. The new species Trypanosoma gennarii was described in Monodelphis domestica.

A Deep Insight into the Sialome of Rhodnius neglectus, a Vector of Chagas Disease

BACKGROUND

Triatomines are hematophagous insects that act as vectors of Chagas disease. Rhodnius neglectus is one of these kissing bugs found, contributing to the transmission of this American trypanosomiasis. The saliva of hematophagous arthropods contains bioactive molecules responsible for counteracting host haemostatic, inflammatory, and immune responses.

METHODS/PRINCIPAL FINDINGS

Next generation sequencing and mass spectrometry-based protein identification were performed to investigate the content of triatomine R. neglectus saliva. We deposited 4,230 coding DNA sequences (CDS) in GenBank. A set of 636 CDS of proteins of putative secretory nature was extracted from the assembled reads, 73 of them confirmed by proteomic analysis. The sialome of R. neglectus was characterized and serine protease transcripts detected. The presence of ubiquitous protein families was revealed, including lipocalins, serine protease inhibitors, and antigen-5. Metalloproteases, disintegrins, and odorant binding protein families were less abundant.

CONCLUSIONS/SIGNIFICANCE

The data presented improve our understanding of hematophagous arthropod sialomes, and aid in understanding hematophagy and the complex interplay among vectors and their vertebrate hosts.

Vector-borne transmission of Trypanosoma cruzi among captive Neotropical primates in a Brazilian zoo

BACKGROUND

Neotropical primates are important sylvatic hosts of Trypanosoma cruzi, the etiological agent of Chagas disease. Infection is often subclinical, but severe disease has been described in both free-ranging and captive primates. Panstrongylus megistus, a major T. cruzi vector, was found infesting a small-primate unit at Brasília zoo (ZooB), Brazil. ZooB lies close to a gallery-forest patch where T. cruzi circulates naturally. Here, we combine parasitological and molecular methods to investigate a focus of T. cruzi infection involving triatomine bugs and Neotropical primates at a zoo located in the Brazilian Savannah.

METHODS

We assessed T. cruzi infection in vectors using optical microscopy (n = 34) and nested PCR (n = 50). We used quantitative PCR (qPCR) to examine blood samples from 26 primates and necropsy samples from two primates that died during the study. We determined parasite lineages in five vectors and two primates by comparing glucose-6-phosphate isomerase (G6pi) gene sequences.

RESULTS

Trypanosoma cruzi was found in 44 vectors and 17 primates (six genera and eight species); one Mico chrysoleucus and one Saguinus niger had high parasitaemias. Trypanosoma cruzi DNA was detected in three primates born to qPCR-negative mothers at ZooB and in the two dead specimens. One Callithrix geoffroyi became qPCR-positive over a two-year follow-up. All G6pi sequences matched T. cruzi lineage TcI.

CONCLUSIONS

Our findings strongly suggest vector-borne T. cruzi transmission within a small-primate unit at ZooB - with vectors, and perhaps also parasites, presumably coming from nearby gallery forest. Periodic checks for vectors and parasites would help eliminate T. cruzi transmission foci in captive-animal facilities. This should be of special importance for captive-breeding programs involving endangered mammals, and would reduce the risk of accidental T. cruzi transmission to keepers and veterinarians.

The role of sigmodontine rodents as sylvatic hosts of Trypanosoma cruzi in the Argentinean Chaco

The role of rodents in the sylvatic transmission of Trypanosoma cruzi has seldom been investigated using parasitological and molecular methods. We assessed the occurrence of T. cruzi in wild small rodents from Pampa del Indio, in the Argentinean Chaco, and identified the taxonomic status of positive rodents by sequencing a fragment of cytochrome b gene (cytb) and performing BLAST searches and phylogenetic analyses. A total of 176 Sigmodontinae rodents was captured in six surveys using 5425 trap-nights in a wide range of sylvatic habitats between 2009 and 2011. Host infection was determined by xenodiagnosis and by polymerase chain reaction amplification of the hyper-variable region of kinetoplast DNA minicircles of T. cruzi (kDNA-PCR) from blood samples. None of the 176 rodents examined was xenodiagnosis-positive. The prevalence of infection determined by kDNA-PCR from blood samples was 16.2% (95% confidence interval, 10.1-21.9%). Half of the infections detected by kDNA-PCR were confirmed by nuclear satellite DNA-PCR or by kDNA-PCR of the rectal contents of xenodiagnostic bugs. The 24 positive specimens were assigned to eight species, providing the first records of T. cruzi in Akodon montensis, Akodon toba, Graomys chacoensis, and Oligoryzomys chacoensis. The occurrence of T. cruzi infection in Oligoryzomys nigripes, Calomys callosus, Necromys lasiurus and Oecomys sp. (most probably Oecomys mamorae) from the Gran Chaco is also reported for the first time. Although sigmodontine rodents were frequently infected, the intensity of bug rectal infection with T. cruzi was below the detection limit of xenodiagnosis (subpatent infectiousness to bugs), indicating they had a low reservoir host competence.

Occurrence of synanthropic triatomines (Hemiptera: Reduviidae) in the Federal District of Brazil

INTRODUCTION

Entomological surveillance of Chagas disease in the Federal District of Brazil (DF), has recorded the following triatomine species: Panstrongylus megistus, P. geniculatus, P. diasi, Rhodnius neglectus, Triatoma pseudomaculata, and T. sordida. We aimed to analyze the spatial and temporal occurrence of triatomine species collected in DF, and their indices of natural infection with trypanosomes.

METHODS

The Health State Secretariat of DF recorded triatomines between 2002 and 2010 in 20 administrative regions. This retrospective analysis considered the number of adults and nymphs of each species collected and infected in both intradomicile and peridomicile.

RESULTS

A total of 754 triatomines were collected in 252 reported domiciles. Panstrongylus megistus was the most frequent species (65%), followed by T. pseudomaculata (14%). Of the 309 examined insects, only 3 (1%) specimens of P. megistus were infected with flagellates morphologically similar to Trypanosoma cruzi. The spatial occurrence indicated a higher diversity of triatomines and frequency of T. sordida in rural areas. Moreover, there was a predominance of P. megistus in urban areas. The number of records of P. megistus in the rainy season was two times higher than that during the dry season. The largest number of triatomines was collected in November.

CONCLUSIONS

The presence of P. megistus specimens infected with trypanosomes in domiciles, shows the potential risk of human infection in DF. Thus, it is essential to continue entomological surveillance, intensifying it in the rainy season and in regions of greater occurrence.

Geographic distribution of chagas disease vectors in Brazil based on ecological niche modeling

Although Brazil was declared free from Chagas disease transmission by the domestic vector Triatoma infestans, human acute cases are still being registered based on transmission by native triatomine species. For a better understanding of transmission risk, the geographic distribution of Brazilian triatomines was analyzed. Sixteen out of 62 Brazilian species that both occur in >20 municipalities and present synanthropic tendencies were modeled based on their ecological niches. Panstrongylus geniculatus and P. megistus showed broad ecological ranges, but most of the species sort out by the biome in which they are distributed: Rhodnius pictipes and R. robustus in the Amazon; R. neglectus, Triatoma sordida, and T. costalimai in the Cerrado; R. nasutus, P. lutzi, T. brasiliensis, T. pseudomaculata, T. melanocephala, and T. petrocchiae in the Caatinga; T. rubrovaria in the southern pampas; T. tibiamaculata and T. vitticeps in the Atlantic Forest. Although most occurrences were recorded in open areas (Cerrado and Caatinga), our results show that all environmental conditions in the country are favorable to one or more of the species analyzed, such that almost nowhere is Chagas transmission risk negligible.

[Comparative biology and feeding behavior of Rhodnius neglectus and Rhodnius robustus (Triatominae) under laboratory conditions]

INTRODUCTION

The vector competence of triatomine insects is determined by studying their biology and feeding behavior under field and/or laboratory conditions. Factors including the number of bites, the amount of blood ingested and defecation time have implications for trypanosome transmission. The biological and behavioral parameters of Rhodnius neglectus and R. robustus were compared under experimental conditions to estimate differences in the potential transmission of trypanosomes.

METHODS

The insects were observed daily to determine the period of nymphal development, mortality, detection of food source, number of bites, time of blood meal intake, amount of blood ingested, time elapsed between the end of the meal and the first defecation and the frequency of defecation.

RESULTS

Although the nymphal development of R. neglectus (156.4 ± 25.05d) was lower than that of R. robustus (204.7 ± 13.22d), the mortality between species was similar (63.8 and 65% respectively).R. robustus and R. neglectus quickly located the food source, especially in the first instar (2.5 and 1.6 min, respectively). Although the time of blood meal intake was similar between the species, R. robustus ingested a larger amount of blood on average at all stages and exhibited higher values for the fifth instar. Nymphs of R. neglectus bit more frequently, and they defecated faster and more often than those of R. robustus.

CONCLUSIONS

Under laboratory conditions, R. neglectus has a greater potential for transmission of Trypanosoma cruzi and T. rangeli than does R. robustus, an attribute that should be further evaluated in experimental infections.

Infestation of Mauritia flexuosa palms by triatomines (Hemiptera: Reduviidae), vectors of Trypanosoma cruzi and Trypanosoma rangeli in the Brazilian savanna

To determine the infestation and trypanosome infection of triatomines captured in Mauritia flexuosa palm trees across its geographic distribution in the Brazilian savanna (Cerrado), we sampled 42 localities in eight states and in the Federal District, Brazil, between July 2005 and January 2010. Overall, 2154 specimens of the species Rhodnius neglectus, Psammolestes tertius, Triatoma sordida, and Microtriatoma borbai, were collected. Among the 341 palms sampled, 182 (53.3%) were infested with R. neglectus, which resulted in the capture of 1639 specimens (9.0 insects per infested palm). P. tertius occurred in 26 palms (8%), which resulted in the capture of 484 specimens (19 insects per infested palm). T. sordida (n=30) and M. borbai (n=1) occurred in only one location. From 537 R. neglectus examined, 44 were infected (8%) with Trypanosoma rangeli and/or Trypanosoma cruzi (Tc Id). M. flexuosa was previously recognized as a suitable breeding ecotope for R. neglectus in the Brazilian states of Minas Gerais, Goiás, Tocantins and the Federal District. Our results expand this distribution to other states (São Paulo, Bahia, Mato Grosso, Maranhão and Piauí), and also show that this particular palm tree harbors other triatomine species. Finally, we show that R. neglectus plays an important role in maintaining the enzootic circulation of T. cruzi and T. rangeli in the Brazilian savanna.

Genetic Variability and Phylogenetic Relationships within Trypanosoma cruzi I Isolated in Colombia Based on Miniexon Gene Sequences

Phylogenetic studies of Trypanosoma cruzi have identified the existence of two groups: T. cruzi I and T. cruzi II. There are aspects that still remain unknown about the genetic variability within the T. cruzi I group. Given its epidemiological importance, it is necessary to have a better understanding of T. cruzi transmission cycles. Our purpose was to corroborate the existence of haplotypes within the T. cruzi I group and to describe the genetic variability and phylogenetic relationships, based on single nucleotide polymorphisms (SNPs) found in the miniexon gene intergenic region, for the isolates from different hosts and epidemiological transmission cycles in Colombian regions. 31 T. cruzi isolates were molecularly characterized. Phylogenetic relationships within T. cruzi I isolates showed four haplotype groups (Ia-Id), associated with their transmission cycle. In previous studies, we reported that haplotype Ia is mainly associated with the domestic cycle and domiciliated Rhodnius prolixus. Haplotype Ib is associated with the domestic cycle and peridomestic cycle, haplotype Ic is closely related with the peridomestic cycle, and haplotype Id is strongly associated with the sylvatic cycle. The phylogenetic methodologies applied in this study are tools that bolster the associations among isolates and thus shed light on Chagas disease epidemiology.

Predicting the potential geographical distribution of Rhodnius neglectus (Hemiptera, Reduviidae) based on ecological niche modeling

Rhodnius neglectus is frequently found in palm trees and bird nests in sylvatic environments. However, adult specimens infected by Trypanosoma cruzi have been invading houses in central Brazil. Analyzing and predicting the geographical distribution of this species may improve vector surveillance strategies for Chagas disease. Ecological niche modeling using the genetic algorithm for rule-set production (GARP) was applied to predict the geographical distribution of R. neglectus from occurrence records and a set of 23 predictor variables (e.g., temperature, precipitation, altitude, and vegetation). Additionally, the geographical distribution of R. neglectus was compared with the geographical distribution of four species of palm trees and two species of birds from the study region. The models were able to predict, with high probability, the occurrence of R. neglectus as a regular (although nonendemic) species of the Cerrado biome in central Brazil. Caatinga, Amazonian savanna, Pantanal, and the Bolivian Chaco appear as areas with lower probabilities of potential occurrence for the species. A great overlap was observed between the distribution of R. neglectus, palm trees (Acrocomia aculeata and Syagrus oleracea), and birds (Phacellodomus ruber and Pseudoseisura cristata). By including new records for R. neglectus (from both sylvatic and domestic environments), our study showed a distribution increase toward the west and northeast areas of Brazil in the "diagonal of open/dry ecoregions of South America". These results should aid Chagas disease vector surveillance programs, given that household invasion by Rhodnius species maintains the risk of disease transmission and limits control strategies.

Triatominae-Trypanosoma cruzi/T. rangeli: Vector-parasite interactions

Of the currently known 140 species in the family Reduviidae, subfamily Triatominae, those which are most important as vectors of the aetiologic agent of Chagas disease, Trypanosoma cruzi, belong to the tribes Triatomini and Rhodniini. The latter not only transmit T. cruzi but also Trypanosoma rangeli, which is considered apathogenic for the mammalian host but can be pathogenic for the vectors. Using different molecular methods, two main lineages of T. cruzi have been classified, T. cruzi I and T. cruzi II. Within T. cruzi II, five subdivisions are recognized, T. cruzi IIa-IIe, according to the variability of the ribosomal subunits 24Salpha rRNA and 18S rRNA. In T. rangeli, differences in the organization of the kinetoplast DNA separate two forms denoted T. rangeli KP1+ and KP1-, although differences in the intergenic mini-exon gene and of the small subunit rRNA (SSU rRNA) suggest four subpopulations denoted T. rangeli A, B, C and D. The interactions of these subpopulations of the trypanosomes with different species and populations of Triatominae determine the epidemiology of the human-infecting trypanosomes in Latin America. Often, specific subpopulations of the trypanosomes are transmitted by specific vectors in a particular geographic area. Studies centered on trypanosome-triatomine interaction may allow identification of co-evolutionary processes, which, in turn, could consolidate hypotheses of the evolution and the distribution of T. cruzi/T. rangeli-vectors in America, and they may help to identify the mechanisms that either facilitate or impede the transmission of the parasites in different vector species. Such mechanisms seem to involve intestinal bacteria, especially the symbionts which are needed by the triatomines to complete nymphal development and to produce eggs. Development of the symbionts is regulated by the vector. T. cruzi and T. rangeli interfere with this system and induce the production of antibacterial substances. Whereas T. cruzi is only subpathogenic for the insect host, T. rangeli strongly affects species of the genus Rhodnius and this pathogenicity seems based on a reduction of the number of symbionts.

Trypanosoma rangeli isolates of bats from Central Brazil: genotyping and phylogenetic analysis enable description of a new lineage using spliced-leader gene sequences

Trypanosoma rangeli infects several mammalian orders but has never confidently been described in Chiroptera, which are commonly parasitized by many trypanosome species. Here, we described trypanosomes from bats captured in Central Brazil identified as T. rangeli, T. dionisii, T. cruzimarinkellei and T. cruzi. Two isolates, Tra643 from Platyrrhinus lineatus and Tra1719 from Artibeus planirostris were identified as T. rangeli by morphological, biological and molecular methods, and confirmed by phylogenetic analyses. Analysis using SSU rDNA sequences clustered these bat trypanosomes together with T. rangeli from other hosts, and separated them from other trypanosomes from bats. Genotyping based on length and sequence polymorphism of PCR-amplified intergenic spliced-leader gene sequences assigned Tra1719 to the lineage A whereas Tra643 was shown to be a new genotype and was assigned to the new lineage E. To our knowledge, these two isolates are the earliest T. rangeli from bats and the first isolates from Central Brazil molecularly characterized. Rhodnius stali captured for this study was found infected by T. rangeli and T. cruzi.

Canine vector-borne diseases in Brazil

Canine vector-borne diseases (CVBDs) are highly prevalent in Brazil and represent a challenge to veterinarians and public health workers, since some diseases are of great zoonotic potential. Dogs are affected by many protozoa (e.g., Babesia vogeli, Leishmania infantum, and Trypanosoma cruzi), bacteria (e.g., Anaplasma platys and Ehrlichia canis), and helminths (e.g., Dirofilaria immitis and Dipylidium caninum) that are transmitted by a diverse range of arthropod vectors, including ticks, fleas, lice, triatomines, mosquitoes, tabanids, and phlebotomine sand flies. This article focuses on several aspects (etiology, transmission, distribution, prevalence, risk factors, diagnosis, control, prevention, and public health significance) of CVBDs in Brazil and discusses research gaps to be addressed in future studies.

Trypanosoma rangeli Tejera, 1920, in chronic Chagas' disease patients under ambulatory care at the Evandro Chagas Clinical Research Institute (IPEC-Fiocruz, Brazil)

We report the finding, the isolation by hemoculture, and the characterization of Trypanosoma rangeli stocks from two chronic Chagas' disease patients who received ambulatory care at the Evandro Chagas Clinical Research Institute (IPEC, FIOCRUZ). Both patients proceeded from Bahia State (Brazil). One of them presented the cardiac form of the disease and the other indeterminate symptomalogy. Giemsa-stained smears of the hemocultures from these patients evidenced that they were coinfected with T. rangeli and Trypanosoma cruzi, with predominance of the former species. These isolates could only be successfully grown in Novy-MacNeal-Nicolle + liver infusion-tryptose supplemented with 20-30% fetal calf serum. After 6 months of serial maintenance, rich and apparently pure cultures of T. rangeli were obtained. Both stocks were analyzed with different approaches and compared with two T. cruzi isolates also from chagasic patients under care at IPEC, besides T. rangeli and T. cruzi reference strains. All stocks were characterized by morphology, biometry, electrophoresis of isoenzymes, and products of kDNA minicircle amplified by polymerase chain reaction. The identification of T. rangeli was largely confirmed by all techniques. Taken together, these data represent the third report on T. rangeli in human hosts in Brazil.

Trypanosoma rangeli: RAPD-PCR and LSSP-PCR analyses of isolates from southeast Brazil and Colombia and their relation with KPI minicircles

This study presents the first genetic characterization of five Trypanosoma rangeli isolates from Minas Gerais, in the southeast of Brazil and their comparison with Colombian populations by minicircle classification, RAPD-PCR and LSSP-PCR analyses. Our results demonstrated a homogenous T. rangeli population circulating among Didelphis albiventris as reservoir host in Brazil while heterogeneous populations were found in different regions of Colombia. KP1(+) minicircles were found in 100% isolates from Brazil and in 36.4% of the Colombian samples, whereas the KP2 and KP3 minicircles were detected in both groups. RAPD-PCR and LSSP-PCR profiles revealed a polymorphism within KP1(+) and KP1(-) T. rangeli populations and allowed the division of T. rangeli in two branches. The Brazilian KP1(+) isolates were more homogenous than the KP1(+) isolates from Colombia. The RAPD-PCR were entirely consistent with the distribution of KP1 minicircles while those obtained by LSSP-PCR were associated in 88.9% and 71.4% with KP1(+) and KP1(-) populations, respectively.

Comparative phylogeography of Trypanosoma rangeli and Rhodnius (Hemiptera: Reduviidae) supports a long coexistence of parasite lineages and their sympatric vectors

To make reliable interpretations about evolutionary relationships between Trypanosoma rangeli lineages and their insect vectors (triatomine bugs of the genus Rhodnius) and, thus, about the determinant factors of lineage segregation within T. rangeli, we compared phylogenies of parasite isolates and vector species. Sixty-one T. rangeli isolates from invertebrate and vertebrate hosts were initially evaluated in terms of polymorphism of the spliced-leader gene (SL). Further analysis based on SL and SSUrRNA sequences from 33 selected isolates, representative of the overall phylogenetic diversity and geographical range of T. rangeli, supported four phylogenetic lineages within this species. By comparing the phylogeny of Rhodnius species with that inferred for T. rangeli isolates and through analysis of the geographical range of the isolates, we showed that there is a very significant overlap in the distribution of Rhodnius species and T. rangeli lineages. Congruence between phylogeographical analysis of both T. rangeli lineages and complexes of Rhodnius species are consistent with the hypothesis of a long coexistence of parasites and their vectors, with lineage divergence associated with sympatric species of Rhodnius apparently without association with particular vertebrate hosts. Separation of T. rangeli isolates from vectors of distinct complexes living in sympatry favours the absence of gene flow between the lineages and suggests evolution of T. rangeli lineages in independent transmission cycles, probably associated to specific Rhodnius spp. ecotopes. A polymerase chain reaction assay based on SL intergenic sequences was developed for simultaneous identification and lineage genotyping of T. rangeli in epidemiological surveys.

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.

Susceptibility of different triatomine species to Trypanosoma rangeli experimental infection

Trypanosoma rangeli is a kinetoplastid protozoan parasite that has been found in the majority of Latin American countries, overlapping its distribution area with that of Trypanosoma cruzi, the causative agent of Chagas disease. This parasite shares the same reservoirs and vectors as T. cruzi. Triatomines from genus Rhodnius are considered the most susceptible hosts to infection. In this work, we report the susceptibility of different triatomine species (Rhodnius neglectus, Panstrongylus megistus, Triatoma infestans, T. sordida, T. braziliensis, and T. vitticeps) to experimental infection by T. rangeli isolated from Didelphis albiventris in a highly endemic region for Chagas disease. An intense parasitism was evidenced in feces (56% to 81%) of the majority of the species studied on the 10th day after infection, decreasing during the period of the experiment (30 days). T. vitticeps did not present parasites in feces at any time. All triatomine species presented parasites in the hemolymph. In T. vitticeps and P. megistus, this parasitism was scarce (6.3% and 6.6%, respectively). In the other species, the parasitism was variable (62.5% to 100%). Triatomine mortality varied between 3% to 40%, increasing during the infection in all species studied. The lowest mortality was observed for T. infestans. Also, we showed that only trypomastigotes forms from salivary glands, and hemolymph were infective for mice. We conclude that all triatomine species used were susceptible to infection by T. rangeli at different levels. There was no direct correlation between intensity of parasitism and mortality.

Trypanosoma cruzi (Kinetoplastida Trypanosomatidae): ecology of the transmission cycle in the wild environment of the Andean valley of Cochabamba, Bolivia

An active Trypanosoma cruzi transmission cycle maintained by wild rodents in the Andean valleys of Cochabamba Bolivia is described. Wild and domestic Triatoma infestans with 60% infection with T. cruzi were found and was evidenced in 47.5% (rodents) and 26.7% (marsupial) by parasitological and/or serologycal methods. Phyllotis ocilae and the marsupial species Thylamys elegans, are the most important reservoirs followed by Bolomys lactens and Akodon boliviensis. In spite of both genotypes (TCI and TCII) being prevalent in Bolivia, in our study area only T. cruzi I is being transmitted. Our data suggest that wild T. infestans and wild small mammals play an important role in the maintenance of the transmission cycle of T. cruzi. Furthermore, the finding of high prevalence of T. cruzi infection in wild T. infestans point to the risk of the dispersion of Chagas' disease.