The role played by different mammal species in the maintenance of Trypanosoma cruzi is not constant and varies in time and place. This study aimed to characterise the importance of domestic, wild and peridomestic hosts in the transmission of T. cruzi in Tauá, state of Ceará, Caatinga area, Brazil, with an emphasis on those environments colonised by Triatoma brasiliensis. Direct parasitological examinations were performed on insects and mammals, serologic tests were performed on household and outdoor mammals and multiplex polymerase chain reaction was used on wild mammals. Cytochrome b was used as a food source for wild insects. The serum prevalence in dogs was 38% (20/53), while in pigs it was 6% (2/34). The percentages of the most abundantly infected wild animals were as follows: Thrichomys laurentius 74% (83/112) and Kerodon rupestris 10% (11/112). Of the 749 triatomines collected in the household research, 49.3% (369/749) were positive for T. brasiliensis, while 6.8% were infected with T. cruzi (25/369). In captured animals, T. brasiliensis shares a natural environment with T. laurentius, K. rupestris, Didelphis albiventris, Monodelphis domestica, Galea spixii, Wiedomys pyrrhorhinos, Conepatus semistriatus and Mus musculus. In animals identified via their food source, T. brasiliensis shares a natural environment with G. spixii, K. rupestris, Capra hircus, Gallus gallus, Tropidurus oreadicus and Tupinambis merianae. The high prevalence of T. cruzi in household and peridomiciliar animals reinforces the narrow relationship between the enzootic cycle and humans in environments with T. brasiliensis and characterises it as ubiquitous.

BackgroundKnowledge of triatomine food sources in different ecotopes enables the estimation of T. cruzi transmission risk in diverse environments, as well as its dynamics of dispersion and ecological niche. For Triatoma brasiliensis in the Caatinga, in the northeast of Brazil, seasonal differences influence feeding eclecticism and rates of T. cruzi infection. The objective of the present study was to monitor food sources and to characterize the populations of T. cruzi associated with T. brasiliensis in wild and domestic environments in the Caatinga of northeast Brazil.MethodsA cross-sectional study based on a search for triatomines in wild and domestic environments, was undertaken at five different time periods from 2009 to 2015. Insects from 2015 were used for identification of food sources. Two universal primers, based on the conserved regions of the 12S rRNA locus, were used to amplify fragments of 215 bp. The content of the intestinal tract of triatomines was identified by a comparison between the sequences obtained and those deposited in the GenBank database, using BLAST. In triatomines with parasitological diagnosis of infection by trypanosomatids, xenoculture was performed for the isolation and characterization of strains, using cox2, the amplification of the SL-IL mini-exon intergenic spacer and the polymorphism of the D7 divergent domain of the gene 24αrDNA-LSU.ResultsFood sources were identified in 76.3% (213/279) T. brasiliensis specimens sampled in 2015. The most frequent sources in a total of 20 vertebrate species were: rodents (58%, 123/213), ruminants (30%, 64/213) and cats (6%, 12/213). A total of 49% (44/89) of the samples of T. cruzi isolated in the period from 2009 to 2015 were characterized: TcII (43%, 19/44), TcI (41%, 18/44) and TcIII (16%, 7/44).ConclusionsThe feeding eclecticism of T. brasiliensis shows its importance in maintaining the transmission dynamics of T. cruzi, with evidence of intense circulation between anthropic and wild environments. Attention should be placed on the association among T. brasiliensis, rodents and ruminants, in addition to the presence of TcIII in the study region.Electronic supplementary materialThe online version of this article (10.1186/s13071-018-3235-4) contains supplementary material, which is available to authorized users.

Chagas disease was described by Carlos Chagas, who first identified the parasite Trypanosoma cruzi from a 2-year-old girl called Berenice. Many T. cruzi sequencing projects based on short reads have demonstrated that genome assembly and downstream comparative analyses are extremely challenging in this species, given that half of its genome is composed of repetitive sequences. Here, we report de novo assemblies, annotation, and comparative analyses of the Berenice strain using a combination of Illumina short reads and MinION long reads. Our work demonstrates that Nanopore sequencing improves T. cruzi assembly contiguity and increases the assembly size in ∼16 Mb. Specifically, we found that assembly improvement also refines the completeness of coding regions for both single-copy genes and repetitive transposable elements. Beyond its historical and epidemiological importance, Berenice constitutes a fundamental resource because it now constitutes a high-quality assembly available for TcII (clade C), a prevalent lineage causing human infections in South America. The availability of Berenice genome expands the known genetic diversity of these parasites and reinforces the idea that T. cruzi is intraspecifically divided in three main clades. Finally, this work represents the introduction of Nanopore technology to resolve complex protozoan genomes, supporting its subsequent application for improving trypanosomatid and other highly repetitive genomes.

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(Galvão et al. 2003, Galvão & Angulo 2006, Costa et al. 2006, Costa & Felix 2007, Sandoval et al. 2007, Bérenger & Blanchet 2007, Martinez et al. 2007) and is a vector of Trypanosoma cruzi. Its geographical distribution is limited to the Brazilian states of Bahia, Espírito Santo, Minas Gerais (MG), and Rio de Janeiro (Galvão et al. 2003). Although considered to be of secondary importance in T. cruzi transmission to man, this species shows high rates of trypanosome infection (Santos et al. 1969a,c, Pinto et al. 1969, Barros et al. 1975, Sessa & Carias 1986, Dias et al. 1989, Gonçalves et al. 1998, Santos et al. 2005 and is often captured in man-made habitats, with frequent reports of adult bugs invading houses (Santos et al. 1969b, Ferreira et al. 1986, Sessa & Carias 1986, Dias et al. 1989, Gonçalves et al. 1998, possibly attracted by light (Ferreira et al. 1986 to T. cruzi are very high, especially in adult bugs captured indoors in Itahomi. However, Chagas disease is rare in the area, a prevalence of only 0.4% has been recorded as part of a national serological survey (Camargo et al. 1984). It is not known whether the low transmission of T. cruzi to man is due to characteristics of the vector (the long interval between feeding and defecation) or the strain of parasite involved.Among the available taxonomic marker techniques, morphometry of the head, random amplified polymorphism of DNA (RAPD) and isoenzyme analysis have been most used in triatomine population studies (Costa et al. 1997, Dujardin et al. 1998, Borges et al. 2000, Soares et al. 2001, Barbosa et al 2003. We used these three techniques to investigate T. vitticeps population dynamics in the Itanhomi district. MATERIALS AND METHODSStudy area -Itanhomi (19°11'15"S, 41°48'45"W) has an estimated population of 11,012 inhabitants. The urban and rural area comprise 93 localities. In 11 of the rural sites (Adão Daniel, Cabeceira do Guido, Francisco Inácio, Jesus Julião, Jose Horta, Jose Noberto, João Caboclo, Júlio Carlos, Liés Alves, Orides I, and Valico) the search for T. vitticeps was intensively performed in 2002 in domestic and peridomestic environments. The following year, sylvatic sampling was attempted in Cabeceira do Guido, particularly in a wooded area 100 m from a house where adult triatomines are periodically detected.Houses in Itanhomi in which T. vitticeps was sampled conform to a distinct pattern of construction, being built on stilts.The floors of these dwellings are wooden 15 Mem Inst Oswaldo Cruz, Rio de Janeiro, Vol. 103(1), February 2008 and often have cracks that allow triatomines to pass in and out; the floor is a kind of roof for the open basement (classified as the peridomicile). Houses are built on stilt, providing shelter for domestic animals and storage of materials. Furthermore, 100-500 m from the houses there are remnants of Atlantic forest and rocks, constituting sylvatic habitat for the bugs. This peculiar characteristic of the locality is the proximity of the habitats.Insects -A pool of T. vitticeps captured in Itanhomi ...