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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. 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. 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.

Reactivation of Trypanosoma cruzi transmission by native vectors with different domiciliation capabilities is a major concern for Chagas disease control programs . T. cruzi transmission via intra-domestic Rhodnius prolixus was certified as interrupted by the Pan American Health Organization in Miraflores municipality (Boyacá, Colombia) in 2019. However, Triatoma venosa, a native vector infected with T. cruzi has been increasingly found inside human dwellings across rural areas. In this study, the aim was to describe the eco-epidemiological aspects of T. cruzi transmission in the rural area of Miraflores. For this, we designed a comprehensive, multi-faceted study in 6 rural villages and performed: ( i ) A cross-sectional serological and molecular study enrolling 155 people and 58 domestic dogs living within 80 households, (ii) a domestic entomological survey, (iii) a determination of the natural infection and blood meal source in collected triatomine bugs, and ( iv ) an evaluation of synanthropic mammal infection by parasitological and molecular tools. The T. cruzi seroprevalence rates in humans and dogs were 9.03% (14/155) and 22.4% (13/58), respectively. Most infected humans were adults between the ages of 55 and 85 years old. No evidence of T. cruzi DNA was found using qPCR in human blood samples, but we found high parasitemia levels in the infected dogs. In total, 38 triatomine bugs were collected inside dwellings and peridomestic areas: 68.4% (26/38) Triatoma venosa, 29% (11/38) Panstrongylus geniculatus, and 2.6% (1/38) P. rufotuberculatus. Natural infection prevalence was 88% (22/25) for T. venosa , 100% (12/12) for P. geniculatus, and 100% (1/1) P. rufotuberculatus : only TcI was found. No evidence of R. prolixus was found in the area. Two feeding sources were identified in T. venosa (humans and cats), while P. geniculatus fed on cows and bats. Lastly, seven D. marsupialis were captured in peridomestic areas, three were infected with T. cruzi (TcI). The results suggest the existence of T. cruzi transmission cycle between triatomines, dogs, and opossums representing a risk of infection for the human population in rural areas of Miraflores. Despite PAHO declaring Miraflores municipality, Colombia an area of T. cruzi transmission interruption in 2019, this study documents evidence of a secondary vector establishing in domestic settings. T. venosa entomological surveillance is warranted to evaluate prospective human transmission risk in an otherwise ‘no-risk’ perceived Chagas disease region.

Background Triatomines are hematophagous insects that play an important role as vectors of Trypanosoma cruzi , the causative agent of Chagas disease. These insects have adapted to multiple blood-feeding sources that can affect relevant aspects of their life-cycle and interactions, thereby influencing parasitic transmission dynamics. We conducted a characterization of the feeding sources of individuals from the primary circulating triatomine genera in Colombia using amplicon-based next-generation sequencing (NGS). Methods We used 42 triatomines collected in different departments of Colombia. DNA was extracted from the gut. The presence of T. cruzi was identified using real-time PCR, and discrete typing units (DTUs) were determined by conventional PCR. For blood-feeding source identification, PCR products of the vertebrate 12S rRNA gene were obtained and sequenced by next-generation sequencing (NGS). Blood-meal sources were inferred using blastn against a curated reference dataset containing the 12S rRNA sequences belonging to vertebrates with a distribution in South America that represent a potential feeding source for triatomine bugs. Mean and median comparison tests were performed to evaluate differences in triatomine blood-feeding sources, infection state, and geographical regions. Lastly, the inverse Simpsonʼs diversity index was calculated. Results The overall frequency of T. cruzi infection was 83.3%. TcI was found as the most predominant DTU (65.7%). A total of 67 feeding sources were detected from the analyses of approximately 7 million reads. The predominant feeding source found was Homo sapiens (76.8%), followed by birds (10.5%), artiodactyls (4.4%), and non-human primates (3.9%). There were differences among numerous feeding sources of triatomines of different species. The diversity of feeding sources also differed depending on the presence of T. cruzi . Conclusions To the best of our knowledge, this is the first study to employ amplicon-based NGS of the 12S rRNA gene to depict blood-feeding sources of multiple triatomine species collected in different regions of Colombia. Our findings report a striking read diversity that has not been reported previously. This is a powerful approach to unravel transmission dynamics at microgeographical levels.

Although the central coast of the Ecuador is considered endemic for Chagas disease, few studies have focused on determining the risk of transmission in this region. In this study we describe the triatomine household infestation in Manabí province (Central Coast region), determine the rate of Trypanosoma cruzi infection and study the risk factors associated with infestation by Rhodnius ecuadoriensis. An entomological survey found three triatomine species (Rhodnius ecuadoriensis, Panstrongylus rufotuberculatus and P. howardi) infesting domiciles in 47.4% of the 78 communities visited (total infestation rate of 4.5%). Four percent of domiciles were infested, and nymphs were observed in 77% of those domiciles. The three species were found in altitudes below 500 masl and in all ecological zones except cloud forest. Within the domicile, we found the three species mostly in bedrooms. Rhodnius ecuadoriensis and P. rufotuberculatus were abundant in bird nests, including chicken coops and P. howardi associated with rats in piles of bricks, in the peridomicile. Triatomine infestation was characterized by high rates of colonization, especially in peridomicile. Flagelates infection was detected in only 12% of the samples by microscopy and Trypanosoma cruzi infection in 42% of the examined triatomines by PCR (n = 372). The most important risk factors for house infestation by R. ecuadoriensis were ecological zone (w = 0.99) and presence of chickens (w = 0.96). Determinants of secondary importance were reporting no insecticide applications over the last twelve months (w = 0.86) and dirt floor (w = 0.70). On the other hand, wood as wall material was a protective factor (w = 0.85). According the results, approximately 571,000 people would be at high risk for T. cruzi infection in Manabí province. A multidisciplinary approximation and the adhesion to a periodic integrated vector management (IVM) program are essential to guarantee sustainable preventive and control strategies for Chagas disease in this region.

Trypanosoma cruzi is a multi-host parasite that infects dozens of mammalian species in the most variable wild environments in Americas. Between 2013 and 2018, autochthonous infections by T. cruzi were suspected in three European wolves (Canis lupus) and an orange dwarf porcupine (Coendou spinosus) from Fundação Parque Zoológico de São Paulo (FPZSP), Brazil, current Coordenadoria de Fauna Silvestre (CFS), which is inserted in a remnant of the Atlantic rainforest inside one of the biggest and most populous municipality of the world. This study aims to detect T. cruzi infections in captive mammals, triatomines and free-living opossums from surrounding areas of FPZSP/CFS. Blood samples from captive and free-living mammals from surrounding areas were collected for parasitological (direct examination and culture), serological (IFAT) and molecular diagnosis using Nested-PCR 18SrDNA followed by DNA sequence analysis. Triatomines (Panstrongylus megistus) found in FPZSP/CFS were also examined by culture of the digestive tract and PCR. Trypanosoma cruzi infection was detected in 35.7% (n = 60/168 - 106 captive and 62 free-living) of the mammals that belonged to nine different families. From captive mammals, positive T. cruzi serology was observed in 29.6% (n = 27/91). Twenty-six positive hemocultures were obtained, from which parasite isolation was achieved in 69.2%, while positive PCR was observed in 40% of them, including nine free-living individuals that were also positive in hemoculture. Of 28 individuals in which T. cruzi characterization was successful, 89.3% were genotyped as DTU TcI, 7.2% as TcII and 3.5% as TcI/TcII mixed infection. Besides, 29 of 30 collected triatomines were infected, and infection by T. cruzi DTU TcI was confirmed in 16 of them. The confirmed autochthonicity of at least 68.9% of cases demonstrates that captive mammals from FPZSP are immersed in the T. cruzi enzootic cycle that involves the vector species P. megistus, and the reservoir hosts C. spinosus and Didelphis aurita from the wild surrounding areas.

ABSTRACT Panstrongylus megistus is the most important autochthonous vector of Trypanosom cruzi, the etiological agent of Chagas disease, in the midwest region of the Minas Gerais State, Brazil. This study investigates the vectorial roles of Triatoma infestans and P. megistus in Chagas disease in this geographical area during the late 1970s. A retrospective analysis of entomological and serological surveys from 1975–1983 was conducted, comparing the presence of T. infestans and P. megistus with the seroprevalence of T. cruzi infection in the human population within the Divinopolis Regional Health Superintendency. Panstrongylus megistus was recorded in all surveyed municipalities (52/52), whereas T. infestans co-occurrence with P. megistus was recorded in only 19.2% (10/52) of them. In the 41 municipalities where only P. megistus was found and relevant data were available, the mean seroprevalence of human T. cruzi infection was 17.8% ranging from 1.0% to 41.9%. In the municipalities where T. infestans occurred, the mean seroprevalence was higher, at 25.8%, ranging from 9.8% to 40.8%. Among the municipalities where only P. megistus was present, 19.5% had a low, 29.3% an intermediate, and 51.2% a high seroprevalence of human T. cruzi infection. In the ten municipalities where both T. infestans and P. megitus were found, 80% showed high seroprevalence, whereas only one municipality each showed low or intermediate levels. The findings highlight the significant role of P. megistus in T. cruzi transmission, even in the absence of T. infestans. The wide distribution of P. megistus increased the risk of transmission. P. megistus was the main household vector in the region in the 1970s. Nowadays, continuous surveillance remains essential for monitoring triatomine infestations and evaluating the current risk of T. cruzi transmission.

Background Chagas disease is a parasitic infection transmitted by “kissing bugs” (Hemiptera: Reduviidae: Triatominae) that has a huge economic impact in Latin American countries. The vector species with the upmost epidemiological importance in Ecuador are Rhodnius ecuadoriensis (Lent & Leon, 1958) and Triatoma dimidiata (Latreille, 1811). However, other species such as Panstrongylus howardi (Neiva, 1911) and Panstrongylus chinai (Del Ponte, 1929) act as secondary vectors due to their growing adaptation to domestic structures and their ability to transmit the parasite to humans. The latter two taxa are distributed in two different regions, they are allopatric and differ mainly by their general color. Their relative morphological similarity led some authors to suspect that P. chinai is a melanic form of P. howardi . Methods The present study explored this question using different approaches: antennal phenotype; geometric morphometrics of heads, wings and eggs; cytogenetics; molecular genetics; experimental crosses; and ecological niche modeling. Results The antennal morphology, geometric morphometrics of head and wing shape and cytogenetic analysis were unable to show distinct differences between the two taxa. However, geometric morphometrics of the eggs, molecular genetics, ecological niche modeling and experimental crosses including chromosomal analyses of the F1 hybrids, in addition to their coloration and current distribution support the hypothesis that P. chinai and P. howardi are separate species. Conclusions Based on the evidence provided here, P. howardi and P. chinai should not be synonymized. They represent two valid, closely related species.

Chagas disease is endemic to the southern Andean region of Ecuador, an area with one of the highest poverty rates in the country. However, few studies have looked into the epidemiology, vectors and transmission risks in this region. In this study we describe the triatomine household infestation in Loja province, determine the rate of Trypanosoma cruzi infection in triatomines and study the risk factors associated with infestation. An entomological survey found four triatomine species (Rhodnius ecuadoriensis, Triatoma carrioni, Panstrongylus chinai, and P. rufotuberculatus) infesting domiciles in 68% of the 92 rural communities examined. Nine percent of domiciles were infested, and nymphs were observed in 80% of the infested domiciles. Triatomines were found in all ecological regions below 2,200 masl. We found R. ecuadoriensis (275 to 1948 masl) and T. carrioni (831 to 2242 masl) mostly in bedrooms within the domicile, and they were abundant in chicken coops near the domicile. Established colonies of P. chinai (175 to 2003 masl) and P. rufotuberculatus (404 to 1613 masl) also were found in the domicile. Triatomine infestation was associated with surrogate poverty indicators, such as poor sanitary infrastructure (lack of latrine/toilet [w = 0.95], sewage to environment [w = 1.0]). Vegetation type was a determinant of infestation [w = 1.0] and vector control program insecticide spraying was a protective factor [w = 1.0]. Of the 754 triatomines analyzed, 11% were infected with Trypanosoma cruzi and 2% were infected with T. rangeli. To date, only limited vector control efforts have been implemented. Together with recent reports of widespread sylvatic triatomine infestation and frequent post-intervention reinfestation, these results show that an estimated 100,000 people living in rural areas of southern Ecuador are at high risk for T. cruzi infection. Therefore, there is a need for a systematic, sustained, and monitored vector control intervention that is coupled with improvement of socio-economic conditions.

After obtaining certification of the absence of transmission of the Trypanosoma cruzi by Triatoma infestans in 2006, other native species of protozoan vectors have been found in human dwellings within municipalities of the State of Paraná, Southern Brazil. However, the spatial distribution of T. cruzi vectors and how climatic and landscape combined variables explain the distribution are still poorly understood. The goal of this study was to predict the potential distribution of T. cruzi vectors as a proxy for Chagas disease transmission risk using Ecological Niche Models (ENMs) based on climatic and landscape variables. We hypothesize that ENM based on both climate and landscape variables are more powerful than climate-only or landscape-only models, and that this will be true independent of vector species. A total of 2,662 records of triatomines of five species were obtained by community-based entomological surveillance from 2007 to 2013. The species with the highest number of specimens was Panstrongylus megistus (73%; n = 1,943), followed by Panstrongylus geniculatus (15.4%; 411), Rhodnius neglectus (6.0%; 159), Triatoma sordida (4.5%; 119) and Rhodnius prolixus (1.1%; 30). Of the total, 71.9% were captured at the intradomicile. T. cruzi infection was observed in 19.7% of the 2,472 examined insects. ENMs were generated based on selected climate and landscape variables with 1 km2 spatial resolution. Zonal statistics were used for classifying the municipalities as to the risk of occurrence of synanthropic triatomines. The integrated analysis of the climate and landscape suitability on triatomines geographical distribution was powerful on generating good predictive models. Moreover, this showed that some municipalities in the northwest, north and northeast of the Paraná state have a higher risk of T. cruzi vector transmission. This occurs because those regions present high climatic and landscape suitability values for occurrence of their vectors. The frequent invasion of houses by infected triatomines clearly indicates a greater risk of transmission of T. cruzi to the inhabitants. More public health attention should be given in the northern areas of the State of Paraná, which presents high climate and landscape suitabilities for the disease vectors. In conclusion, our results-through spatial analysis and predictive maps-showed to be effective in identifying areas of potential distribution and, consequently, in the definition of strategic areas and actions to prevent new cases of Chagas' disease, reinforcing the need for continuous and robust surveillance in these areas.

The aim of this work was to explore the potential risk of vector-borne Chagas disease in urban districts in northeastern Brazil, by analyzing the spatiotemporal distributions and natural infection rates with Trypanosoma cruzi of triatomine species captured in recent years. The main motivation of this work was an acute human case of Chagas disease reported in 2008 in the municipality of Sobral. We analyzed data from community-based entomological surveillance carried out from 2010 to 2014. Triatomine natural T. cruzi infection was assessed by examination of insect feces by optical microscopy. Sites of triatomine capture were georeferenced through Google Earth and analyzed with ArcGIS. A total of 191 triatomines were collected, consisting of 82.2% Triatoma pseudomaculata, 7.9% Rhodnius nasutus, 5.8% T. brasiliensis, 3.7% Panstrongylus lutzi, and 0.5% P. megistus, with an overall natural infection index of 17.8%. Most infestations were reported in the districts of Dom José (36.2%), Padre Palhano (24.7%), and Alto do Cristo (10.6%). The overwhelming majority of insects (185/96.9%) were captured inside houses, and most insects tended to be collected in intermittent peaks. Moreover, captured triatomines tended to constitute colonies. The acute case reported in 2008 was found to be situated within a T. pseudomaculata hotspot. The triatomine collection events carried out by dwellers were aggregated in time and space into distinct foci, suggesting that insects are intermittently and artificially introduced into the city, possibly via accidental migration from their natural reservoirs. The relatively high T. cruzi infection rate indicates considerable circulation of the parasite in these areas, increasing the risk of vector-borne Chagas disease infection. These data suggest a need to strengthen epidemiological surveillance and integrate appropriate control actions targeting triatomines, T. cruzi reservoirs, and human populations. Our data also identify Chagas disease transmission as a hazard in urban areas of Sobral.