Trypanosoma cruzi III from armadillos (Dasypus novemcinctus novemcinctus) from Northeastern Venezuela and its biological behavior in murine model. Risk of emergency of Chagas’ disease

Parasitological and molecular characterization of Trypanosoma cruzi of triatomines and mammals from endemic areas for Chagas disease in Venezuela

It is estimated that 6-7 million people worldwide are infected with Trypanosoma cruzi, the parasite that causes Chagas disease. In Venezuela, Chagas disease remains a public health problem. In this work, T. cruzi isolates from six species of triatomines and mammals of the orders Didelphimorphia and Xenarthra, captured in rural communities of Monagas, underwent parasitological and molecular characterization. A total of 471 triatomines and 17 mammals were captured, with a natural infection rate of 41.4% and 70.6%, respectively. In the male NMRI mouse model used for parasitological characterization (prepatent period, parasitemia curve, mouse mortality, and tissular parasitism), T. cruzi isolates exhibited high lethality due to their pronounced virulence, irrespective of the parasite load in each mouse, resulting in a mortality rate of 75%. Among the vector isolates, in the mouse model, only 2 out of 6 remained alive, while the rest perished during the evaluation. Conversely, the isolates from mammals proved fatal for all the inoculated mice. All isolates were identified as belonging to DTU TcI, based on the molecular markers such as the intergenic region of the miniexon, D7 divergent domain of the 24Sα rDNA, size-variable domain of the 18S rDNA, and hsp60-PCR-RFLP-EcoRV. This study demonstrates the presence of vectors and mammalian reservoirs naturally infected with T. cruzi in communities of Monagas, the 9th largest and 9th most populous state in Venezuela. This situation represents a neglected epidemiological problem demanding urgent attention and imperative health care intervention.

Geographic Distribution of the Genus Panstrongylus Berg, 1879 in the Neotropic with Emphasis on Trypanosoma cruzi Vectors

Panstrongylus is a Neotropical taxa of 16 species, some more widespread than others, that act as vectors of Trypanosoma cruzi, the etiologic agent of Chagas disease (CD). This group is associated with mammalian reservoir niches. There are few studies of the biogeography and niche suitability of these triatomines. Using zoo-epidemiological occurrence databases, the distribution of Panstrongylus was determined based on bioclimatic modelling (DIVA GIS), parsimonious niche distribution (MAXENT), and parsimony analysis of endemic species (PAE). Through 517 records, a wide presence of P. geniculatus, P. rufotuberculatus, P. lignarius, and P. megistus was determined and recorded as frequent vectors of T. cruzi in rainforest habitats of 24-30 °C. These distributions were modeled with AUC >0.80 and <0.90, as well as with the seasonality of temperature, isothermality, and precipitation as relevant bioclimatic variables. Individual traces for each taxon in Panstrongylus-1036 records-showed widely dispersed lines for frequent vectors P. geniculatus, P. lignarius, P. rufotuberculatus, and P. megistus. Other occasional vectors showed more restricted dispersal, such as P. howardi, P. humeralis, P. lenti, P. lutzi, P. tupynambai, P. noireaiui, and P. chinai. Areas of defined environmental variation, geological change, and trans domain fluid fauna, such as the American Transition Zone and the Pacific Domain of Morrone, had the highest Panstrongylus diversity. Pan-biogeographic nodes appear to be areas of the greatest species diversity that act as corridors connecting biotopes and allowing fauna migration. Vicariance events in the geologic history of the continent need to be investigated. The geographical distribution of Panstrongylus overlapped with CD cases and Didelphis marsupialis/Dasypus novemcinctus presence, two important reservoirs in Central and South America. The information derived from the distribution of Panstrongylus provides knowledge for surveillance and vector control programs. It would increase information on the most and less relevant vector species of this zoonotic agent, for monitoring their population behavior.

Trypanosoma cruzi genetic diversity: impact on transmission cycles and Chagas disease

Trypanosoma cruzi, the agent of Chagas disease (ChD), exhibits remarkable biological and genetic diversity, along with eco-epidemiological complexity. In order to facilitate communication among researchers aiming at the characterisation of biological and epidemiological aspects of T. cruzi, parasite isolates and strains were partitioned into seven discrete typing units (DTUs), TcI-TcVI and TcBat, identifiable by reproducible genotyping protocols. Here we present the potential origin of the genetic diversity of T. cruzi and summarise knowledge about eco-epidemiological associations of DTUs with mammalian reservoirs and vectors. Circumstantial evidence of a connection between T. cruzi genotype and ChD manifestations is also discussed emphasising the role of the host’s immune response in clinical ChD progression. We describe genomic aspects of DTUs focusing on polymorphisms in multigene families encoding surface antigens that play essential functions for parasite survival both in the insect vector and the mammalian host. Such antigens most probably contributed to the parasite success in establishing infections in different hosts and exploring several niches. Gaps in the current knowledge and challenges for future research are pointed out.

Genotypic Trypanosoma cruzi distribution and parasite load differ ecotypically and according to parasite genotypes in Triatoma brasiliensis from endemic and outbreak areas in Northeastern Brazil

This study aimed to identify the Trypanosoma cruzi genotypes and their relationship with parasitic load in distinct geographic and ecotypic populations of Triatoma brasiliensis in two sites, including one where a Chagas disease (ChD) outbreak occurred in Rio Grande do Norte state, Brazil. Triatomine captures were performed in peridomestic and sylvatic ecotopes in two municipalities: Marcelino Vieira - affected by the outbreak; and Currais Novos - where high pressure of peridomestic triatomine infestation after insecticide spraying have been reported. The kDNA-PCR was used to select 124 T. cruzi positive triatomine samples, of which 117 were successfully genotyped by fluorescent fragment length barcoding (FFLB). Moreover, the T. cruzi load quantification was performed using a multiplex TaqMan qPCR. Our findings showed a clear ecotypic segregation between TcI and TcII harboured by T. brasiliensis (p<0.001). Although no genotypes were ecotypically exclusive, TcI was predominant in peridomestic ecotopes (86%). In general, T. brasiliensis from Rio Grande do Norte had a higher T. cruzi load varying from 3.94 to 7.66 x 10⁶T. cruzi per insect. Additionally, TcII (median value=299,504 T. cruzi/intestine unit equivalents) had more than twice (p=0.1) the parasite load of TcI (median value=149,077 T. cruzi/intestine unit equivalents), which can be attributed to a more ancient co-evolution with T. brasiliensis. The higher prevalence of TcII in the sylvatic T. brasiliensis (70%) could be associated with a more diversified source of bloodmeals for wild insect populations. Either TcI or TcII may have been responsible for the ChD outbreak that occurred in the city of Marcelino Vieira. On the other hand, a smaller portion of T. brasiliensis was infected by TcIII (3%) in the peridomicile, in addition to T. rangeli genotype A (1%), often found in mixed infections. Our results highlight the need of understanding the patterns of T. cruzi genotype´s development and circulation in insect vectors and reservoirs as a mode of tracking situations of epidemiologic importance, as the ChD outbreak recently recorded for Northeastern Brazil.

Understanding the oral transmission of Trypanosoma cruzi as a veterinary and medical foodborne zoonosis

Chagas disease is a neglected tropical disease transmitted by the protozoan Trypanosoma cruzi that lately has been highlighted because several outbreaks attributed to oral transmission of the parasite have occurred. These outbreaks are characterized by high mortality rates and massive infections that cannot be related to other types of transmission such as the vectorial route. Oral transmission of Chagas disease has been reported in Brazil, Colombia, Venezuela, Bolivia, Ecuador, Argentina and French Guiana, most of them are massive oral outbreaks caused by the ingestion of beverages and food contaminated with triatomine feces or parasites' reservoirs secretions and considered since 2012 as a foodborne disease. In this review, we present the current status and all available data regarding oral transmission of Chagas disease, highlighting its relevance as a veterinary and medical foodborne zoonosis.

Update on Chagas disease in Venezuela during the period 2003-2018. A review

The present article reviews the status of Chagas disease in Venezuela during the period 2003-2018, based on the detection of Trypanosoma cruzi-infection in 3,343 blood samples of individuals from rural localities and 182 patients referred from health centers to confirm presumptive clinical diagnostic. The study involved samples from 81 rural localities of 17 states located at different regions and ecological life zones of the country. Analysis by parasitological (fresh microscopic observation, hemoculture and Giemsa stained blood smears), serological (DAT, IFAT-polyvalent, IgM, IgG tests) and molecular (PCR) tests, revealed 10.7% seroprevalence and 42.8% T. cruzi-infection, in individuals from rural localities and referred patients, respectively. In both groups T. cruzi-infection was detected at any age, revealing active transmission in children under 10-years-old. Clinical profile detected in referred patients, showed significantly major number of symptoms in orally infected patients than in infected by vectorial route (P<0.01). Genetic characterization of T. cruzi isolates obtained from orally and vectorial transmitted acute Chagas disease in western Venezuela, revealed the circulation of DTUI and DTUIII in the former, and DTUI, DTUII and DTUIII in patients infected by vectorial route. DTUI predominated in both cases, and haplotype Ib was the most frequently found in this genotype. Statistical analysis of clinical profile - T. cruzi DTUs - transmission route relationships did not show association among these variables and, consequently, chagasic patient's clinical condition did not depend of T. cruzi genotype or its route of transmission. In addition, differences in clinical severity may be associated with host susceptibility and/or parasite load received by the human receptor in spite of the T. cruzi genotype itself. The epidemiological implications of the present findings are discussed, and the need for developing efficient tools as well as implementation of urgent and radical changes in the public health policy to control Chagas disease transmission in the Venezuelan territory are suggested.

Antibodies to Toxoplasma gondii, Leishmania spp., and Leptospira spp. in Free-Ranging Six-Banded Armadillos (Euphractus sexcinctus) from Northeastern Brazil

Antibodies to pathogens of public health importance were investigated in 33 free-ranging six-banded armadillos (Euphractus sexcinctus) from Brazil. The frequency of seropositive animals for Toxoplasma gondii, Leishmania spp., and Leptospira spp. were two, three, and two, respectively.

Trypanosoma cruzi infection, discrete typing units and feeding sources among Psammolestes arthuri (Reduviidae: Triatominae) collected in eastern Colombia

BACKGROUND

Chagas disease (CD) is caused by the protozoan parasite Trypanosoma cruzi, and is transmitted by hematophagous insects of the family Reduviidae. Psammolestes arthuri is a sylvatic triatomine distributed in Colombia and Venezuela which feeds on birds and there are a few studies that have reported Ps. arthuri naturally infected with T. cruzi. In Colombia, Ps. arthuri has been found in dwellings, making it important to evaluate its possible role in the T. cruzi transmission cycle. We aimed to evaluate the presence of T. cruzi and feeding sources of Ps. arthuri to elucidate new possible scenarios of T. cruzi transmission in the country.

METHODS

A total of 60 Ps. arthuri were collected in Arauca and Casanare, Colombia. We detected and genotyped T. cruzi and identified feeding sources. The frequency of the presence of T. cruzi was obtained and compared with different eco-epidemiological variables. Multiple correspondence analysis was conducted to explore associations between eco-epidemiological variables and the presence of T. cruzi; with these results, a logistic regression was used to determine statistical associations.

RESULTS

The infection rate of T. cruzi was 70.7% and was mostly associated with insect stage, sex, bird nest and feeding source. Regarding discrete typing units (DTUs), TcI was found in 54.7% samples, of which 21.7% (5/23) were TcI_Dom, 52.1% (12/23) had mixed infection (TcI_Dom-TcI_Sylv), and single infection with TcI_Sylv was not detected. Mixed infections (TcI/TcII-TcVI) were found in 9.52% (4/42) of the samples; of these, 14.2% (6/42) were TcII-TcVI. A total of 15 feeding sources were identified and the most frequent were: Cranioleuca baroni (35.85%), Homo sapiens (26.42%), Thraupis episcopus (11.32%) and Serinus albogularis (3.77%).

CONCLUSIONS

Although Ps. arthuri is mainly ornithophilic, this species may be feeding on other animals that can be infected with T. cruzi, possibly playing a role maintaining the zoonotic cycle of the parasite. Further studies with molecular techniques and wider sampling are needed to improve information regarding infection rates, ecotopes and habits with the aim of evaluating whether Ps. arthuri could be a potential T. cruzi vector.

Phylogeny and molecular species delimitation of long-nosed armadillos (Dasypus: Cingulata) supports morphology-based taxonomy

The armadillo genus Dasypus is the most species-rich and widely distributed genus of the order Cingulata and it has a dynamic taxonomic history. Recent morphology-based studies have proposed new taxonomic arrangements, but these were not yet assessed with molecular data. The two comprehensive phylogenetic hypotheses available for the genus are conflicting and were each based on a subset of taxa, hampering a proper evaluation of species boundaries. Using a multilocus molecular dataset, based on the broadest geographic sampling of Dasypus to date, we inferred the phylogenetic relationships of all species of the genus, including the recently reinstated D. beniensis and D. pastasae. We tested recent taxonomic hypotheses using several species-delimitation approaches. Our phylogeny recovered three main lineages of long-nosed armadillos that we treat as subgenera (Hyperoambon, Muletia and Dasypus) and identified the majority of its diversification as having occurred during the Pliocene. Molecular species delimitation supported morphological evidence in assigning D. hybridus as a subspecies of D. septemcinctus and confirming the split of the D. kappleri complex into three species. Our results strongly support the recognition of Guiana Shield populations formerly assigned to D. novemcinctus as a distinct species. The phylogenetic positions of D. mazzai and D. sabanicola remain uncertain. Further investigation using faster-evolving genes and additional samples may help to clarify the relationships of these young species.

Could age and aging change the host response to systemic parasitic infections? A systematic review of preclinical evidence

The impact of age and aging in the evolution of systemic parasitic infections remains poorly understood. We conducted a systematic review from preclinical models of Chagas disease, leishmaniasis, malaria, sleeping sickness and toxoplasmosis. From a structured and comprehensive search in electronic databases, 29 studies were recovered and included in the review. Beyond the characteristics of the experimental models, parasitological and immunological outcomes, we also discussed the quality of current evidence. Our findings indicated that throughout aging, parasitemia and mortality were consistently reduced in Chagas disease and malaria, but were similar or increased in leishmaniasis and highly variable in toxoplasmosis. While a marked humoral response in older animals was related to the anti-T. cruzi protective phenotype, cellular responses mediated by a polarized Th1 phenotype were associated with a more effective defense against Plasmodium infection. Conversely, in leishmaniasis, severe infections and high mortality rates were potentially related to attenuation of humoral response and an imbalance between Th1 and Th2 phenotypes. Due to the heterogeneous parasitological outcomes and limited immunological data, the role of aging on toxoplasmosis evolution remains unclear. From a detailed description of the methodological bias, more controlled researches could avoid the systematic reproduction of inconsistent and poorly reproducible experimental designs.

Hosts and vectors of Trypanosoma cruzi discrete typing units in the Chagas disease endemic region of the Paraguayan Chaco

Active Trypanosoma cruzi transmission persists in the Gran Chaco region, which is considered hyperendemic for Chagas disease. Understanding domestic and sylvatic transmission cycles and therefore the relationship between vectors and mammalian hosts is crucial to designing and implementing improved effective control strategies. Here we describe the species of triatomine vectors and the sylvatic mammal reservoirs of T. cruzi, in different localities of the Paraguayan and Bolivian Chaco. We identify the T. cruzi genotypes discrete typing units (DTUs) and provide a map of their geographical distribution. A total of 1044 triatomines and 138 sylvatic mammals were captured. Five per cent of the triatomines were microscopically positive for T. cruzi (55 Triatoma infestans from Paraguay and one sylvatic Triatoma guasayana from Bolivia) and 17 animals (12·3%) comprising eight of 28 (28·5%) Dasypus novemcinctus, four of 27 (14·8%) Euphractus sexcinctus, three of 64 (4·7%) Chaetophractus spp. and two of 14 (14·3%) Didelphis albiventris. The most common DTU infecting domestic triatomine bugs was TcV (64%), followed by TcVI (28%), TcII (6·5%) and TcIII (1·5%). TcIII was overwhelmingly associated with armadillo species. We confirm the primary role of T. infestans in domestic transmission, armadillo species as the principal sylvatic hosts of TcIII, and consider the potential risk of TcIII as an agent of Chagas disease in the Chaco.

Between a bug and a hard place: Trypanosoma cruzi genetic diversity and the clinical outcomes of Chagas disease

Over the last 30 years, concomitant with successful transnational disease control programs across Latin America, Chagas disease has expanded from a neglected, endemic parasitic infection of the rural poor to an urbanized chronic disease, and now a potentially emergent global health problem. Trypanosoma cruzi infection has a highly variable clinical course, ranging from complete absence of symptoms to severe and often fatal cardiovascular and/or gastrointestinal manifestations. To date, few correlates of clinical disease progression have been identified. Elucidating a putative role for T. cruzi strain diversity in Chagas disease pathogenesis is complicated by the scarcity of parasites in clinical specimens and the limitations of our contemporary genotyping techniques. This article systematically reviews the historical literature, given our current understanding of parasite genetic diversity, to evaluate the evidence for any association between T. cruzi genotype and chronic clinical outcome, risk of congenital transmission or reactivation and orally transmitted outbreaks.

Trypanosoma cruzi, the Causal Agent of Chagas Disease: Boundaries between Wild and Domestic Cycles in Venezuela

Trypanosoma cruzi the etiological agent of American Trypanosomiasis or Chagas disease (ChD) is transmitted by triatomines vectors between mammals including man. T. cruzi has existed for circa 150 Ma in the Americas and nearly 10 million people are currently infected. The overlap between wild and domestic ecotopes where T. cruzi circulates is increasing. Host–parasite interactions have been determined by infection patterns in these cycles, all under natural or laboratorial conditions. This mini-review describes specific parasite niches, such as plant communities or biological corridors between domestic and wild landscapes, in order to help identify risk factors for ChD and define the boundaries between wild and domestic transmission cycles, with an emphasis on research undertaken in Venezuela.