Bioecological aspects of triatomines and marsupials as wild Trypanosoma cruzi reservoirs in urban, peri-urban and rural areas in the Western Brazilian Amazon

Coinfection by multiple Trypanosoma cruzi clones: a new perspective on host-parasite relationship with consequences for pathogenesis and management of Chagas disease

SUMMARYChagas disease (CD) is caused by the protozoan parasite Trypanosoma cruzi (Tc), infecting 6-7 million people. It is transmitted by insect vectors, orally, through infected tissues, or congenitally. Tc infection can progress toward chronic cardiac and/or digestive severe and fatal CD in 20%-40% of patients. Tc exhibits an important genetic and phenotypic intraspecies diversity and a preponderant clonal population structure. The impact of multiclonal coinfections has been little studied in CD patients. Relationships between the currently used discrete typing unit (DTU)-based classification of Tc lineages and the occurrence of the different clinical forms of CD, its congenital transmission, as well as the efficacy of trypanocidal molecules (benznidazole and nifurtimox) could not be established. In this review, we revisit the different aspects of Tc diversity and analyze the impact of infections with multiple clones and their variants on the dynamic and pathogenesis of CD and its maternal-fetal transmission. We propose to call "cruziome" all the Tc clones and their variants infecting a given host and provide strong evidence that (i) multiclonal Tc infections are likely the rule rather than the exception; (ii) each "cruziome" is associated with a unique combination of virulence factors, tissular tropisms, and host immune responses; (iii) accordingly, some particularly harmful "cruziomes" likely trigger the occurrence and progression of CD and might also favor the congenital transmission of parasites. We propose that our concept of "cruziome" should be taken into consideration because of its practical consequences in epidemiological studies, laboratory diagnosis, clinical management, and treatment of CD.

Unusual frequency of Trypanosoma cruzi DTU TcI and predominance of hybrid lineages in Triatoma infestans before and after control interventions in the Argentinian Chaco

Transmission of Trypanosoma cruzi involves diverse hosts, vectors and parasitic genotypes, in different environments. In recent decades, the distribution of T. cruzi has altered due to urbanization of affected people and vectors. We implemented a longitudinal intervention program between 2015 and 2022 which aimed to suppress (peri)domestic Triatoma infestans in the municipality of Avia Terai (Chaco Province, Argentina), and found a marginal risk of domestic vector-borne transmission across the rural-to-urban gradient after interventions. Here, we identified the parasite Discrete Typing Units (DTUs) in infected T. infestans collected throughout the intervention program (37 insects pre-intervention and 7 post-intervention). Identification of DTUs was conducted by two methodologies, using DNA extracted from T. infestans rectal ampoules. We also assessed the association between blood-feeding sources and DTUs. Complete DTU identification was achieved in 48 % of samples. The hybrid lineages TcV or TcVI and their combinations predominated (72 %), followed by TcI (16 %) and mixed infections of TcI and hybrid lineages (14 %). Half (50 %) of the houses harbored TcI infected bugs either alone or mixed with TcII/TcV/TcVI. Humans predominated as the bloodmeal sources in all insects with identified DTU. All DTUs (TcI, TcV and TcII/TcV/TcVI) were recorded in both rural and peri-urban environments, with 62 % of the houses having more than one DTU. These results confirm the predominance of hybrid lineages in domestic transmission cycles of the Argentine Chaco. However, the finding of several triatomines infected with TcI both pre- and post-intervention raises the question of which host(s) are involved in its transmission.

Unveiling the overlooked: Current and future distribution dynamics of kissing bugs and palm species linked to oral Chagas disease transmission

Chagas disease, a neglected global health concern primarily transmitted through the bite and feces of kissing bugs, has garnered increasing attention due to recent outbreaks in northern Brazil, highlighting the role of oral transmission facilitated by the kissing bugs species Rhodnius robustus and Rhodnius pictipes. These vectors are associated with palm trees with large crowns, such as the maripa palm (Attalea maripa) and moriche palm (Mauritia flexuosa). In this study, we employ maximum entropy (MaxEnt) ecological niche models to analyze the spatial distribution of these vectors and palm species, predicting current and future climate suitability. Our models indicate broader potential habitats than documented occurrences, with high suitability in northern South America, southern Central America, central Africa, and southeast Asia. Projections suggest increased climate suitability by 2040, followed by a reduction by 2080. This study identifies present and future areas suitable for kissing bugs and palm tree species due to climate change, aiding in the design of prevention and management strategies.

Flying to the moon: Impactful accounts of triatomines invasion from the 2nd to the 13th floor of an urban residential building in the municipality of Rio Branco, Acre, Brazil

BACKGROUND

Vectorial transmission through hematophagous triatomine insects remains the primary mode of Chagas Disease contagion. These insects have become increasingly common in urban environments. Therefore, this study aimed to report an encounter of triatomines with trypanosomatid infection in a vertical residential condominium in Rio Branco, the capital of the state of Acre, in the western Brazilian Amazon.

METHODS

Triatomines were collected from residents and sent to the municipality's Entomological Surveillance sector. Trypanosomatid positivity was evaluated using optical microscopy, followed by species and genotype identification using molecular biology techniques.

RESULTS

Twenty-five adult triatomine specimens were collected from two of three condominium buildings invading apartments from the 2nd to 13th floors. Six specimens were identified as Rhodnius sp. and 19 as R. montenegrensis. Among these, molecular tests were conducted on seven specimens, with five testing positive for Trypanosoma cruzi, all belonging to genotype TcI.

CONCLUSIONS

These findings underscore the need for further studies to better understand the invasive capacity of these insects in these environments and the mechanisms involved in this process.

Predictor Variables in the Spread of Chagas Disease in Rural Areas

Over a hundred years ago after the discovery of Chagas disease (CD) in Brazil, the World Health Organization estimates a number of 6 to 7 million people infected by Trypanosoma cruzi worldwide. Therefore, the goal of this work was to identify variables related to the spread of infection by T. cruzi in humans living in rural areas, seeking predictor variables. A systematic review of the literature has been conducted, with a search in the Scopus platform, using the search string "Chagas disease" and "rural", resulting in 85 valid and analyzed scientific studies (1977 and 2022). Twenty-seven predictor variables have been acquired, and 19 of them have been grouped, such as: socioeconomic and educational, housing, environmental, sanitary, and cultural; and 8 variables related to T. cruzi seropositive individuals. The predictor variables yielded significant results (p-value < 0.05) in 59.5% of the cases (195/328), with a median of 66.7%. In other words, studies relating to 50% of the 27 variables showed significance equal to or greater than 66.7% of the time. The independent variables with the highest proportion of significant data (p-value < 0.05) were Education (87.6%), Intradomicile building (70%), Domestic animals (69.6%), and Triatomines (69.2%) in the households. Some variables reached 100%; however, few articles were found, indicating the need for further research, especially for Sanitation and Culture. It has been concluded that, in the several contexts found, the social vulnerability and lack of information led the individual to living in environments where inhabitability is inadequate, to perform limited work activity and develop habits and behaviors which impair them in an environmental insalubrity situation, favorable to the access of vectors and pathogens of anthropozoonoses such as CD.

Urban vectors of Chagas disease in the American continent: A systematic review of epidemiological surveys

BACKGROUND

Chagas is a complex and multidimensional socio-environmental health phenomenon, in which different components converge and interact. Historically, this disease was associated with insect vectors found in the rural environment. However, in the Americas, we are currently facing a new paradigm, in which different scenarios allow maintaining the vectorial transmission of the parasite through triatomine populations that either occasionally enter the dwellings or colonize urban environments.

METHODOLOGY/PRINCIPAL FINDINGS

Records of scientific reports available in the PubMed and LILACS search engines were retrieved, using three criteria according to the main triatomine genera of epidemiological importance and to the general scientific production on Chagas disease in urban contexts. Results showed that records on the occurrence of vectors in urban dwellings began to increase in the last three decades. Results also showed that the main species of triatomines collected inside dwellings (18 in total) belong mainly to the genera Triatoma and Panstrongylus, with most species (16/18, 88.8%) infected with the parasite, and that infestation of triatomine species occurs in all types of cities (small, medium and large, including megalopolises), from Argentina to the USA.

CONCLUSIONS/SIGNIFICANCE

Urban Chagas represents a new challenge that adds a different dimension to the problem of Chagas disease due to the particular characteristics of the lifestyle in urban agglomerates. The new scenario will require adaptations of the programs of control of vector to this shift from rural to urban settlements.

Surveillance and genotype characterization of zoonotic trypanosomatidae in Didelphis marsupialis in two endemic sites of rural Panama

Didelphis marsupialis has been reported as a competent reservoir for trypanosomatid parasites infections. The aim of this study was to measure Trypanosoma cruzi, T. rangeli, and Leishmania spp. infection rates and to characterize discrete typing units (DTUs) of T. cruzi in D. marsupialis from two Chagas disease endemic sites in Panama. Blood from 57 wild-caught D. marsupialis were examined from two rural communities, Las Pavas (N = 18) and Trinidad de las Minas (N = 39). Twenty-two (38.60%) opossums were positive for flagellates by general hemoculture. T. cruzi infection was confirmed by positive hemoculture and/or kDNA based PCR performed in 31/57 (54.39%) blood samples from opossums. T. rangeli infection was confirmed by hemoculture and/or TrF/R2-Primer PCR assay applied on 12/57 (21.05%) blood samples. Nine (15.79%) D. marsupialis harbored T. cruzi/T. rangeli coinfections. All opossums tested negative for Leishmania spp. by PCR assays based on kDNA and HSP70 gene amplification. There was a significant association between T. cruzi infection and site (Fisher exact test, p = 0.02), with a higher proportion of T. cruzi infected opossums in Las Pavas (77.78%, n = 14/18) compared to Trinidad de las Minas (43.59%, n = 17/39). A significant association was found between habitat type and T. cruzi infection in opossums across both communities, (X² = 6.91, p = 0.01, df = 1), with a higher proportion of T. cruzi infection in opossums captured in forest remnants (76%, 19/25) compared to peridomestic areas (37.5%, 12/32). T. rangeli detection, but not T. cruzi detection, may be improved by culture followed by PCR. TcI was the only DTU detected in 22 T. cruzi samples using conventional and real-time PCR. Eight T. rangeli positive samples were characterized as KP1(-)/lineage C. Trypanosome infection data from this common synanthropic mammal provides important information for improved surveillance and management of Chagas disease in endemic regions of Panama.

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Trypanosoma cruzi infection is common in Didelphis marsupialis from the studied sites.

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T. rangeli infection was confirmed in many opossums.

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All opossums tested negative for Leishmania infection.

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A higher proportion of T. cruzi infected opossums came from forest remnants.

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T. cruzi parasites were characterized as TcI and T. rangeli as KP1(-)/lineage C.

Vector-borne zoonotic blood parasites in wildlife from Ecuador: A report and systematic review

Background and Aim:

Ecuador is a hugely diverse country, but information on infectious diseases in local wild animals is scarce. The aim of this study was to screen the presence of blood parasites in free-ranging wild animals admitted to the Wildlife Hospital at Universidad San Francisco de Quito, from April 2012 to January 2019.

Materials and Methods:

We identified blood parasites by microscopic observation of blood smears from free-ranging wildlife species that attended the Wildlife Hospital of Universidad San Francisco de Quito (Ecuador) from April 2012 to January 2019.

Results:

The microscopic evaluations of animals as potential reservoirs for vector-borne zoonotic blood parasites revealed the presence of Anaplasma spp., Babesia spp., Ehrlichia spp., Hepatozoon spp., microfilaria, Mycoplasma spp., and Trypanosoma spp. in previously unreported wildlife species. In addition, we performed a systematic review to understand the current knowledge gaps in the context of these findings.

Conclusion:

Our data contribute to the knowledge of blood parasites in wildlife from Ecuador. Furthermore, the potential transmission of these parasites to humans and domestic animals, current anthropogenic environmental changes in the region, and the lack of information on this suggest the importance of our results and warrant further investigations on infectious diseases in animals and humans and their relationship with environmental health as key domains of the One Health concept.