Ecological patterns of blood-feeding by kissing-bugs (Hemiptera: Reduviidae: Triatominae)

"Mi Casa, Tu Casa": the coati nest as a hub of Trypanosoma cruzi transmission in the southern Pantanal biome revealed by molecular blood meal source identification in triatomines

BACKGROUND

The study of the ecology of Trypanosoma cruzi is challenging due to its extreme adaptive plasticity, resulting in the parasitism of hundreds of mammal species and dozens of triatomine species. The genetic analysis of blood meal sources (BMS) from the triatomine vector is an accurate and practical approach for gathering information on which wild mammal species participate in a local transmission network. South American coatis, Nasua nasua, act as important reservoir host species of T. cruzi in the Pantanal biome because of their high rate of infection and elevated parasitemia, with the main discrete typing unit (DTU) lineages (TcI and TcII). Moreover, the carnivore coati is the only mammal species to build high arboreal nests for breeding and resting that can be shared by various vertebrate and invertebrate species. Herein, we applied the sensitive and specific methodology of DNA barcoding and molecular cloning to study triatomines found in a coati nest to access the diversity of mammal species that explore this structure, and therefore, may be involved in the parasite transmission network.

METHODS

Twenty-three Triatoma sordida were collected in one coati's nest in the subregion of Nhecolândia, Pantanal. The DNA isolated from the gut of insects was subjected to BMS detection by PCR using universal primers that flank variable regions of the cytochrome b (cytb) and 12S rDNA mitochondrial genes from vertebrates. The Trypanosoma spp. diagnosis and DTU genotyping were based on an 18S rDNA molecular marker and also using new cytb gene primers designed in this study. Phylogenetic analyses and chord diagrams were constructed to visualize BMS haplotypes, DTU lineages detected on vectors, and their interconnections.

RESULTS

Twenty of 23 triatomines analyzed were PCR-positive (86.95%) showing lineages T. cruzi DTU TcI (n = 2), TcII (n = 6), and a predominance of TcI/TcII (n = 12) mixed infection. Intra-DTU diversity was observed mainly from different TcI haplotypes. Genetic analyses revealed that the southern anteater, Tamandua tetradactyla, was the unique species detected as the BMS of triatomines collected from the coati's nest. At least three different individuals of T. tetradactyla served as BMS of 21/23 bugs studied, as indicated by the cytb and 12S rDNA haplotypes identified.

CONCLUSIONS

The identification of multiple BMS, and importantly, different individuals of the same species, was achieved by the methodology applied. The study demonstrated that the southern anteaters can occupy the South American coati's nest, serving as the BMS of T. sordida specimens. Since anteaters have an individualist nonsocial behavior, the three individuals detected as BMS stayed at the coati's nest at different times, which added a temporal character to BMS detection. The TcI and TcII infection, and significantly, a predominance of TcI/TcII mixed infection profile with different TcI and TcII haplotypes was observed, due to the discriminatory capacity of the methodology applied. Tamandua tetradactyla, a host which has been little studied, may have an important role in the T. cruzi transmission in that Pantanal subregion. The data from the present study indicate the sharing of coatis' nests by other mammal species, expanding the possibilities for T. cruzi transmission in the canopy strata. We propose that coatis' nests can act as the true hubs of the T. cruzi transmission web in Pantanal, instead of the coatis themselves, as previously suggested.

Opportunistic or selective? Stage-dependent feeding behavior in a wild vector of Chagas disease

The composition and contribution of different host species in the dynamics of vector-borne zoonotic parasites are particularly relevant for public health. Hence, the study of host selection by vectors is fundamental. Developmental stage and infection status are factors that may modulate vector feeding behavior. In the semi-arid Mediterranean ecosystem of South America, the transmission of Trypanosoma cruzi, the protozoan causing Chagas disease, includes the triatomine vector Mepraia spinolai and several vertebrate species. In this field study, we examined whether M. spinolai exhibits an opportunistic feeding behavior dependent upon developmental stage and/or infection status. We found that M. spinolai does not feed according to the relative availability of vertebrate species. In addition, early stage nymphs (first/second instars) fed on twice as many different species as middle (third/fourth instars) and late (fifth instars and adults) M. spinolai, with the former feeding on native rodents and lizards and the latter mostly on rabbits. Infected and uninfected M. spinolai showed similar feeding profiles. Wild triatomine species might be described as stage-dependent selective blood feeders, as a consequence of the temporal and spatial scale at which host-vector interactions occur, highlighting that all developmental stages might be infected and capable of transmitting T. cruzi.

Triatoma costalimai, a neglected vector of Trypanosoma cruzi in the Cerrado savannas of South America: A comprehensive review

Triatoma costalimai is a little-known triatomine-bug species whose role as a vector of Chagas disease remains poorly understood. To address this gap, we conducted a comprehensive review of the literature and assessed the evidence base from a public-health perspective. We found 89 individual documents/resources with information about T. costalimai. DNA-sequence and cytogenetic data indicate that T. costalimai belongs, together with Triatoma jatai, in a distinct clade within the 'pseudomaculata group' of South American Triatoma. Triatoma costalimai is probably a narrow endemic of the Cerrado on the upper Tocantins River Basin and associated ranges/plateaus; there, the species thrives in the sandstone/limestone outcrops typical of the "Cerrado rupestre" (rocky-soil savanna) and "mata seca decídua calcária" (limestone-soil dry forest) phytophysiognomies. Wild T. costalimai appear to feed on whatever vertebrates are available in rocky outcrops, with lizards and rodents being most common. There is persuasive evidence that house invasion/infestation by T. costalimai has increased in frequency since the 1990s. The bugs often carry Trypanosoma cruzi, often defecate while feeding, have high fecundity/fertility, and, under overtly favorable conditions, can produce two generations per year. Current knowledge suggests that T. costalimai can transmit human Chagas disease in the upper Tocantins Basin; control-surveillance systems should 'tag' the species as a potentially important local vector in the Brazilian states of Goiás and Tocantins. Further research is needed to clarify (i) the drivers and dynamics of house invasion, infestation, and reinfestation by T. costalimai and (ii) the genetic structuring and vector capacity of the species, including its wild and non-wild populations.

Distribution patterns of Triatominae (Hemiptera: Reduviidae) in the Americas: an analysis based on networks and endemicity

Triatominae, commonly known as kissing bugs, are a group of approximately 150 species of hematophagous reduviids, some of which are vectors of Trypanosoma cruzi, the etiological agent of the Chagas disease. Distributional patterns of triatomines have been studied based on macroecological and historical biogeographic approaches, but the definition of distributional patterns and areas of endemism are yet to be defined based on objective criteria. We used two methods to identify biogeographic units in the Triatominae: the endemicity analysis based on an optimality criterion (NDM/VNDM software) and a network approach aimed to simplify and highlight the underlying structure in species distributions (Infomap Bioregions). Information on species distributions was obtained from a data paper, comprising 21 815 records for 135 triatomine species occurring in the Americas. The resulting areas of each method were clustered using a meta consensus criterion based on dissimilarities and interpreted as recurrent areas. The NDM areas show a nested structure, presenting greater restrictions to the inclusion of species in a given area, requiring broad sympatry. In contrast, bioregions emphasize spatial patterns with better-delimited areas and species occurrences do not need to be highly congruent. When areas were clustered based on their species composition two clear patterns arose from both methods: (i) areas within the southern Amazon and southeast South America, especially in the Chacoan subregion, formed a cluster, and (ii) areas north of the Amazon, Pacific, Mesoamerica, Mexican transition zone and Nearctic formed another cluster. Moreover, within each of these two clusters, there was a latitudinal gradient of the areas in the Americas showing spatial similarity between the areas found in both methods. Results of both methods show well-bound areas separating the triatomine fauna in the Brazilian subregions, resulting in the recognition of areas corresponding to the biomes Chaco, Pampa, Cerrado, and Caatinga, and, to a lesser extent, the Atlantic Forest.

Identification of blood meal sources in species of genus Rhodnius in four different environments in the Brazilian amazon

Chagas disease is a zoonotic disease caused by the hemoflagellate Trypanosoma cruzi and transmitted primarily by triatomine vectors. Triatomines are hematophagous insects that feed on a variety of vertebrate hosts. The Chagas disease transmission cycle is closely related to the interactions between vectors, parasites, and vertebrate hosts. Knowledge of triatomine food sources is critical to understanding Chagas disease transmission dynamics. The aim of this study was to identify blood meal sources used by triatomines from different environments in the Brazilian Amazon. A total of 25 captures were conducted in four environments. Triatomine specimens were captured on palm trees and were identified by morphological and morphometric characters. Blood meal sources identification was conducted using a traditional PCR followed by Sanger sequencing of mtDNA cytb gene. Sequencing was successful in 167 specimens and a total of 21 blood meal sources were identified: two reptilians, six birds, and 13 mammals. Among these 21 species, three (Tamandua tetradactyla, Didelphis marsupialis and Rattus rattus) are considered reservoir of T. cruzi. Knowledge of the relationship between triatomines and possible reservoirs can help to elucidate the enzootic cycle of T. cruzi in the Amazon region and guide control strategies for Chagas disease transmission in that region.

Molecular detection of blood meal source up to three months since the last meal: Experimental starvation resistance in triatomines

The identification of Blood Meal Source (BMS) in hematophagous vectors contributes to a better understanding of the ecology of hemoparasite transmission. Those insects can endure long periods without feeding, waiting for a favorable setting. Although this represents an important behavior observed in those groups, such as triatomines, little is known about how time can affect BMS detection, especially considering extended periods. To comprehend to which extent this behavioral phenomenon can impact molecular detection, we submitted two groups of Rhodnius robustus to increasing periods of starvation under experimental conditions. It was possible to recover the BMS until the 12th week of the starvation process. Nymphs were more resistant to prolonged periods of starvation (up to more than 189 days) than adults (maximum of 137 days), with no significant difference between their weights after being fed. The study brought new insights to the understanding of Trypanosoma cruzi transmission by R. robustus in the nature, with a temporal perspective.

Characterization of triatomine bloodmeal sources using direct Sanger sequencing and amplicon deep sequencing methods

Knowledge of host associations of blood-feeding vectors may afford insights into managing disease systems and protecting public health. However, the ability of methods to distinguish bloodmeal sources varies widely. We used two methods—Sanger sequencing and amplicon deep sequencing—to target a 228 bp region of the vertebrate Cytochrome b gene and determine hosts fed upon by triatomines (n = 115) collected primarily in Texas, USA. Direct Sanger sequencing of PCR amplicons was successful for 36 samples (31%). Sanger sequencing revealed 15 distinct host species, which included humans, domestic animals (Canis lupus familiaris, Ovis aries, Gallus gallus, Bos taurus, Felis catus, and Capra hircus), wildlife (Rattus rattus, Incilius nebulifer, Sciurus carolinensis, Sciurus niger, and Odocoileus virginianus), and captive animals (Panthera tigris, Colobus spp., and Chelonoidis carbonaria). Samples sequenced by the Sanger method were also subjected to Illumina MiSeq amplicon deep sequencing. The amplicon deep sequencing results (average of 302,080 usable reads per sample) replicated the host community revealed using Sanger sequencing, and detected additional hosts in five triatomines (13.9%), including two additional blood sources (Procyon lotor and Bassariscus astutus). Up to four bloodmeal sources were detected in a single triatomine (I. nebulifer, Homo sapiens, C. lupus familiaris, and S. carolinensis). Enhanced understanding of vector-host-parasite networks may allow for integrated vector management programs focusing on highly-utilized and highly-infected host species.

Control of pyrethroid-resistant populations of Triatoma infestans, the main vector of Trypanosoma cruzi, by treating dogs with fluralaner in the Argentine Chaco

We assessed whether fluralaner administered to outbred healthy dogs reduced or supressed site infestation and abundance of pyrethroid-resistant populations of Triatoma infestans Klug (Heteroptera: Reduviidae). We conducted a placebo-controlled before-and-after efficacy trial in 28 infested sites in Castelli (Argentine Chaco) over 10 months. All 72 dogs initially present received either an oral dose of fluralaner (treated group) or placebo (control group) at month 0 posttreatment (MPT). Preliminary results justified treating all 38 control-house dogs with fluralaner 1 month later, and 71 of 78 existing dogs at 7 MPT. Site-level infestation and triatomine abundance were evaluated using timed manual searches with a dislodging aerosol. In the fluralaner-treated group, infestation dropped significantly from 100% at baseline to 19% over 6-10 MPT whereas mean abundance fell highly significantly from 5.5 to 0.8-0.9 triatomines per unit effort. In the placebo group, site infestation and mean abundance remained stable between 0 and 1 MPT, and strongly declined after fluralaner administration from 13.0-14.7 - triatomines at 0-1 MPT to 4.0-4.2 over 6-10 MPT. Only one of 81 noninfested sites before fluralaner treatment became infested subsequently. Fluralaner significantly reduced the site-level infestation and abundance of pyrethroid-resistant T. infestans and should be tested more widely in Phase III efficacy trials.

Blood-Meal Sources and Trypanosoma cruzi Infection in Coastal and Insular Triatomine Bugs from the Atacama Desert of Chile

Mepraia parapatrica is one of the lesser known and less abundant sylvatic triatomine species naturally infected by the protozoan Trypanosoma cruzi, the etiological agent of Chagas disease. M. parapatrica lives in sympatry with T. cruzi-infected rodents, but only birds, reptiles, and marine mammals have been reported as blood-meal sources of this vector species by serology. The distribution range of this kissing bug overlaps with fishers’ settlements and tourist areas, and therefore the study of the blood-meal sources of this triatomine species is relevant. Here, we determined the blood-meal sources of M. parapatrica by NGS or standard sequencing from a coastal mainland area and an island in northern Chile, and T. cruzi infection by real-time PCR. The blood-meals of. M parapatrica included 61.3% reptiles, 35.5% mammals (including humans) and 3.2% birds. Feeding on reptiles was more frequent on the mainland, while on the island feeding on mammals was more frequent. The presence of T. cruzi-infected triatomine bugs and humans as part of the diet of M. parapatrica in both areas represents an epidemiological threat and potential risk to the human population visiting or established in these areas. Currently there are no tools to control wild triatomines; these results highlight the potential risk of inhabiting these areas and the necessity of developing information campaigns for the community and surveillance actions.

Signs of Urban Evolution? Morpho-Functional Traits Co-variation Along a Nature-Urban Gradient in a Chagas Disease Vector

Environmental change (i.e., urbanization) impacts species in contrasting ways, with some species experiencing benefits given their way of life (i.e., blood-sucking insects). How these species respond to such change is not well understood and for species involved in human diseases, this “how” question is particularly important. Most Triatominae bug species inhabit tropical and subtropical forests where their vertebrate hosts’ temporal abundance depends on climate seasonality. However, in human encroached landscapes, triatomines can benefit from resource stability which may lead to adaptive phenotypic change to track novel hosts. We tested for an association between different landscapes and morpho-functional traits linked to sensory, motion, and feeding functions in Triatoma dimidiata and compared fecundity (i.e., number of eggs) in each landscape as a proxy of fitness. Using geometric and traditional morphometric tools, we predicted a morphological simplification in bugs inhabiting urbanized areas. While wing morphology or proboscis were not influenced by landscape class, the opposite occurred for thorax morphology and number of sensilla. Wing and thorax morphology did not covary under modified landscape scenarios, yet we detected a morpho-functional convergence for thorax size and antennal phenotype in both sexes, with a simplification trend, from nature to urban settings. Given no fecundity differences across landscapes, there is no potential reproductive costs. Moreover, the convergence of thorax size and antennal phenotype suggests differences in flight/locomotion performance and host/environment perception, as a possible adaptive response to relaxed selective pressures of the bug’s native habitat. These results imply that T. dimidiata could be adapting to urbanized areas.

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

In the Amazon region, Trypanosoma cruzi transmission cycles involve a great diversity of Triatominae vectors and mammal reservoirs. Some Rhodnius spp. mainly inhabit palm trees that act as microhabitats for hosts and vectors. The current study aimed to describe aspects of the bio-ecology of the vectors and reservoirs of T. cruzi in relation to human populations resident near areas with large quantities of palm trees, in rural, peri-urban and urban collection environments, located in the Western Brazilian Amazon. Rhodnius pictipes and Didelphis marsupialis were respectively the most predominant vector and reservoir, with rates of 71% for R. pictipes and 96.5% for D. marsupialis. The vast majority of T. cruzi isolates clustered with TcI. The most prevalent haplotype was TcI COII1 (69.7%). Mauritia flexuosa and Attalea phalerata were the main ecological indicators of infestation by triatomines. Birds were the most common food source (27,71%). T. cruzi isolated from R. robustus has the haplotype HUM-13, previously detected in a chronic Chagas patient living in the same area. Our results demonstrate the relevance of this study, with the occurrence of elevated infection rates in animals, and suggest the importance of the Amazon zones where there is a risk of infection in humans.

Triatomine and Trypanosoma cruzi discrete typing units distribution in a semi-arid area of northeastern Brazil

The occurrence of triatomine species, their bloodmeal sources and the discrete typing units (DTUs) of Trypanosoma cruzi isolated from them were determined in different municipalities of the state of Rio Grande do Norte, Brazil. Triatomine captures were carried out in the rural areas of 23 municipalities. The genotyping of T. cruzi isolates was performed using the mitochondrial cytochrome c oxidase subunit 2 (coii) gene, the D7 region of the 24Sα rDNA, and the spliced leader intergenic region (SL-IR). Five triatomine species were captured, and the most frequent was Triatoma brasiliensis (84.3%; 916/1086), which was found in 16 of the 23 municipalities surveyed, and infested all types of environment investigated. The TcI DTU was found in all mesoregions surveyed in 51.5% (17/33) of the culture-positive samples. In contrast, TcII (9.1%; 3/33) was detected in the Central mesoregion, while TcIII (27.3%; 9/33) was found in all mesoregions. The geographic distribution and spatial overlap of different DTUs was inferred using the superposition of the radius of occurrence of isolates and using ecological niche distribution modelling. Triatoma brasiliensis was found infected in all mesoregions and with all three T. cruzi DTUs, including mixed infections. With regard to bloodmeal sources, the DNA of rodents was found in triatomines infected with either TcI or TcIII, while that of domestic animals and humans was associated with both single and mixed infections. Our findings demonstrate that different DTUs of T. cruzi are widely dispersed among triatomines in our study area. The association of T. brasiliensis with several different mammalian hosts, as well as overlapping areas with different DTUs, suggests that this triatomine species may have an important role as a vector in both anthropic and sylvatic environments.

Unraveling the Morphological Variation of Triatoma infestans in the Peridomestic Habitats of Chuquisaca Bolivia: A Geometric Morphometric Approach

Morphometrics has been used on Triatomines, a well-known phenotypically variable insect, to understand the process of morphological plasticity and infer the changes of this phenomenon. The following research was carried out in two regions of the inter-Andean valleys and two Chaco regions of Chuquisaca-Bolivia. Triatoma infestans adults were collected from the peridomestic (pens and chicken coops) along a geographic gradient in order to evaluate the morphological differentiation between groups and their pattern of sexual shape dimorphism. Geometric morphometric methods were applied on the wings and heads of T. infestans. The main findings include that we proved sexual dimorphism in heads and wings, determined the impact of environmental factors on size and shape and validated the impact of nutrition on head shape variation. These results show that geometric morphometric procedures can be used to provide key insight into the biological adaptation of T. infestans on different biotic (nutrition) and abiotic (environment) conditions, which could serve in understanding and evaluating infestation processes and further vector control programs.

Trypanosoma cruzi infection in Triatoma infestans and high levels of human-vector contact across a rural-to-urban gradient in the Argentine Chaco

Background

Peri-urban and urban settings have recently gained more prominence in studies on vector-borne transmission of Trypanosoma cruzi due to sustained rural-to-urban migrations and reports of urban infestations with triatomines. Prompted by the finding of Triatoma infestans across the rural-to-urban gradient in Avia Terai, an endemic municipality of the Argentine Chaco, we assessed selected components of domestic transmission risk in order to determine its variation across the gradient.

Methods

A baseline vector survey was conducted between October 2015 and March 2016, following which we used multistage random sampling to select a representative sample of T. infestans at the municipal level. We assessed T. cruzi infection and blood-feeding sources of 561 insects collected from 109 houses using kinetoplast DNA-PCR assays and direct enzyme-linked immunosorbent assays, respectively. We stratified triatomines according to their collection site (domestic or peridomestic), and we further categorized peridomestic sites in ecotopes of low- or high-risk for T. cruzi infection.

Results

The overall adjusted prevalence of T. cruzi-infected T. infestans was 1.8% (95% confidence interval [CI] 1.3–2.3) and did not differ between peri-urban (1.7%) and rural (2.2%) environments. No infection was detected in bugs captured in the urban setting; rather, infected triatomines were mainly collected in rural and peri-urban domiciles, occurring in 8% of T. infestans-infested houses. The main blood-feeding sources of domestic and peridomestic triatomines across the gradient were humans and chickens, respectively. The proportion of triatomines that had fed on humans did not differ between peri-urban (62.5%) and rural (65.7%) domiciles, peaking in the few domestic triatomines collected in urban houses and decreasing significantly with an increasing proportion of chicken- and dog- or cat-fed bugs. The relative odds ratio (OR) of having a T. cruzi infection was nearly threefold higher in bugs having a blood meal on humans (OR 3.15), dogs (OR 2.80) or cats (OR: 4.02) in a Firth-penalized multiple logistic model.

Conclusions

Trypanosoma cruzi transmission was likely occurring both in peri-urban and rural houses of Avia Terai. Widespread infestation in a third of urban blocks combined with high levels of human–triatomine contact in the few infested domiciles implies a threat to urban inhabitants. Vector control strategies and surveillance originally conceived for rural areas should be tailored to peri-urban and urban settings in order to achieve sustainable interruption of domestic transmission in the Chaco region.

Triatomine Feeding Profiles and Trypanosoma cruzi Infection, Implications in Domestic and Sylvatic Transmission Cycles in Ecuador

Understanding the blood meal patterns of insects that are vectors of diseases is fundamental in unveiling transmission dynamics and developing strategies to impede or decrease human–vector contact. Chagas disease has a complex transmission cycle that implies interactions between vectors, parasites and vertebrate hosts. In Ecuador, limited data on human infection are available; however, the presence of active transmission in endemic areas has been demonstrated. The aim of this study was to determine the diversity of hosts that serve as sources of blood for triatomines in domestic, peridomestic and sylvatic transmission cycles, in two endemic areas of Ecuador (central coastal and southern highland regions). Using conserved primers and DNA extracted from 507 intestinal content samples from five species of triatomines (60 Panstrongylus chinai, 17 Panstrongylus howardi, 1 Panstrongylus rufotuberculatus, 427 Rhodnius ecuadoriensis and 2 Triatoma carrioni) collected from 2006 to 2013, we amplified fragments of the cytb mitochondrial gene. After sequencing, blood meal sources were identified in 416 individuals (146 from central coastal and 270 from southern highland regions), achieving ≥ 95% identity with GenBank sequences (NCBI-BLAST tool). The results showed that humans are the main source of food for triatomines, indicating that human–vector contact is more frequent than previously thought. Although other groups of mammals, such as rodents, are also an available source of blood, birds (particularly chickens) might have a predominant role in the maintenance of triatomines in these areas. However, the diversity of sources of blood found might indicate a preference driven by triatomine species. Moreover, the presence of more than one source of blood in triatomines collected in the same place indicated that dispersal of vectors occurs regardless the availability of food. Dispersal capacity of triatomines needs to be evaluated to propose an effective strategy that limits human–vector contact and, in consequence, to decrease the risk of T. cruzi transmission.

Beat the heat: Culex quinquefasciatus regulates its body temperature during blood feeding

Mosquitoes are regarded as one of the most dangerous animals on earth. Because they are responsible for the spread of a wide range of both human and animal pathogens, research of the underlying mechanisms of their feeding behavior and physiology is critical. Among disease vector mosquitoes, Culex quinquefasciatus, a known carrier of West Nile virus and Western Equine Encephalitis, remains relatively understudied. As blood-sucking insects, adaptations (either at the molecular or physiological level) while feeding on warm blood are crucial to their survival, as overheating can result in death due to heat stress. Our research aims to determine how Cx. quinquefasciatus copes with the heat associated with warm blood meal ingestion and possibly uncover the adaptations this species uses to avoid thermal stress. Through the use of thermographic imaging, we analyzed the body temperature of Cx. quinquefasciatus while blood feeding. Infrared thermography has allowed us to identify a cooling strategy, evaporative cooling via the production of fluid droplets, and an overall low body temperature in comparison to the blood temperature during feeding. Understanding Cx. quinquefasciatus' adaptations and the strategies they employ to reduce their body temperature while blood feeding constitutes the first step towards discovering potential targets that could be used for their control.

Landscape disturbance impacts on Attalea butyracea palm distribution in central Panama

BACKGROUND

Increased Attalea butyracea palm propagation, notable for its role as key habitat for the primary Chagas disease vector in Panama, has been linked to landscape disturbance in single-palm observations in this region. Close proximity of these palms to human dwellings is proposed to increase risk of Chagas disease transmission from sylvatic transmission cycles to domestic transmission involving human populations. This study examines the relationship between landscape disturbance and mature A. butyracea spatial distribution, density, and proximity to human populations and vector and reservoir species' movement corridors at a regional scale in a 300 km2 heterogeneous tropical landscape in central Panama.

METHODS

We remotely identified the locations of over 50,000 mature A. butyracea palms using high-resolution WorldView2 satellite imagery. A local Getis-Ord Gi* spatial analysis identified significant clusters of aggregated palms. Associations between palm and cluster abundance and a landscape disturbance gradient, derived from official Panama land cover data, were tested using Chi-square tests for Homogeneity and Z-test for proportions. Kruskall-Wallis non-parametric analysis of variance tests were run to assess whether palm cluster area varied by disturbance level, or whether disturbance was associated with proximity of palms and palm clusters to susceptible populations or vector movement corridors.

RESULTS

Our findings indicate a regional relationship between landscape disturbance and A. butyracea occurrence. We observe a significant increase in both individual and clustered A. butyracea in secondary forest, but a reduction of palms in agricultural settings. We do not detect evidence of any reduction in abundance of palms in residential settings. The majority of residential and commercial buildings in our study area are within vector flight distance of potential vector habitat in palm crowns.

CONCLUSIONS

We observe probable anthropogenic elimination of A. butyracea palms in agricultural, but not residential, settings. Even in heavily deforested regions, significant concentrations of mature palms remain in close proximity to human establishments.

Domestic host availability modifies human-triatomine contact and host shifts of the Chagas disease vector Triatoma infestans in the humid Argentine Chaco

Domestic animals may affect human-vector contact and parasite transmission rates. We investigated the relationships between host-feeding choices, site-specific host availability, bug nutritional status, stage and abundance of Triatoma infestans Klug (Heteroptera: Reduviidae) in rural houses of Pampa del Indio during spring. We identified the bloodmeal sources of 865 triatomines collected in 70 sites from four main ecotopes. The main sources in domiciles were human (65.9%), chicken (23.4%) and dog (22.4%); dog (64.4%, 35.3%) and chicken (33.1%, 75.4%) in kitchens and storerooms, respectively; and chicken (94.7%) in chicken coops. Using random-intercept logistic regression clustered by domicile, the fraction of human-fed triatomines strongly decreased with increasing proportions of chicken- and dog-fed bugs, dropping from 96.4% when no chicken or dog slept indoors at night to 59.4% when both did. The fraction of dog-fed bugs significantly decreased with increasing human and chicken blood indices, and marginally increased with an indoor-resting dog. Mixed blood meals occurred 3.62 times more often when a chicken or a dog slept indoors. Host blood source did not affect mean body weight adjusted for body length and bug stage. Indoor-resting chickens and dogs greatly modified human-bug contact rates, and may be targeted with long-lasting systemic insecticides to suppress infestation.

Preliminary Characterization of Triatomine Bug Blood Meals on the Island of Trinidad Reveals Opportunistic Feeding Behavior on Both Human and Animal Hosts

Chagas disease is a neglected tropical disease caused by infection with Trypanosoma cruzi. The parasite is endemic to the Americas, including the Caribbean, where it is vectored by triatomine bugs. Although Chagas disease is not considered a public health concern in the Caribbean islands, studies in Trinidad have found T. cruzi-seropositive humans and T. cruzi-infected triatomine bugs. However, little is known about triatomine bug host preferences in Trinidad, making it difficult to evaluate local risk of vector-borne T. cruzi transmission to humans. To investigate this question, we collected triatomine bugs in Trinidad and diagnosed each one for T. cruzi infection (microscopy and PCR). We then carried out a blood meal analysis using DNA extracted from each bug (PCR and sequencing). Fifty-five adult bugs (54 Panstrongylus geniculatus and one Rhodnius pictipes) were collected from five of 21 sample sites. All successful collection sites were residential. Forty-six out of the 55 bugs (83.6%) were infected with T. cruzi. Fifty-three blood meal hosts were successfully analyzed (one per bug), which consisted of wild birds (7% of all blood meals), wild mammals (17%), chickens (19%), and humans (57%). Of the 30 bugs with human blood meals, 26 (87%) were from bugs infected with T. cruzi. Although preliminary, our results align with previous work in which P. geniculatus in Trinidad had high levels of T. cruzi infection. Furthermore, our findings suggest that P. geniculatus moves between human and animal environments in Trinidad, feeding opportunistically on a wide range of species. Our findings highlight a critical need for further studies of Chagas disease in Trinidad in order to estimate the public health risk and implement necessary preventative and control measures.

Chagas bugs and trypanosoma cruzi: Puppets and puppeteer?

A widely accepted idea in parasite-host relationships is that the former manipulates the latter so that it increases its own success. In the case of complex life cycles, this means that the parasite is able to manipulate the first host which allows its transmission to the second host. In this paper, I formalize the idea that this may be the case for the Trypanosoma cruzi parasite and its vectors, bugs of the subfamily Triatominae. I discuss the sources of existing evidence and propose some types of manipulation. This manipulation could also occur in the second host, that is, a vertebrate. Here, I emphasize humans and domesticated animals. I also discuss how global change and insecticide resistance may drive the arms race between both, triatomines and T. cruzi, and host manipulation.

Long-term survey of sea turtles (Caretta caretta) reveals correlations between parasite infection, feeding ecology, reproductive success and population dynamics

Long-term monitoring of host-parasite interactions is important for understanding the consequences of infection on host fitness and population dynamics. In an eight-year survey of the loggerhead sea turtle (Caretta caretta) population nesting in Cabo Verde, we determined the spatiotemporal variation of Ozobranchus margoi, a sanguivorous leech best known as a vector for sea turtle fibropapilloma virus. We quantified O. margoi association with turtles’ δ¹⁵N and δ¹³C stable isotopes to identify where infection occurs. We then measured the influence of infection on reproduction and offspring fitness. We found that parasite prevalence has increased from 10% of the population in 2010, to 33% in 2017. Stable isotope analysis of host skin samples suggests transmission occurs within the host’s feeding grounds. Interestingly, we found a significant interaction between individual size and infection on the reproductive success of turtles. Specifically, small, infected females produced fewer offspring of poorer condition, while in contrast, large, infected turtles produced greater clutch sizes and larger offspring. We interpret this interaction as evidence, upon infection, for a size-dependent shift in reproductive strategy from bet hedging to terminal investment, altering population dynamics. This link between infection and reproduction underscores the importance of using long-term monitoring to quantify the impact of disease dynamics over time.

Dynamics of food sources, ecotypic distribution and Trypanosoma cruzi infection in Triatoma brasiliensis from the northeast of Brazil

Innovative approaches used to combat Chagas disease transmission tend to combine a set of comprehensive efforts to understand the ecology of local vectors. In this work we identified molecularly the blood meal of 181 Triatoma brasiliensis, distributed in 18 populations (8 sylvatic and 10 peridomestic), which were collected across a range of 240 km (East-West) and 95 km (North-South) in the semi-arid region of northeastern, Brazil. We used the vertebrate mitochondrial gene (cytochrome B) sequencing applied to DNA isolated from bug midgut to identify the insect blood meal sources via the BLAST procedure. The peridomestic populations were classified according to two main hypotheses of site-occupancy for T. brasiliensis: the first says that the infestation is mainly driven by structures that resemble its natural habitat (stony-like ecotopes) and the second assumes that it is associated with key-hosts (rodents and goats). Rodents of the Caviidae family (Galea spixii and Kerodon rupestris) were identified as the key-host of T. brasiliensis, but also the potential Trypanosoma cruzi reservoir-able to connect the sylvatic and domestic T. cruzi cycle. Cats also deserve to be studied better, as potential T. cruzi reservoirs. By modeling the food sources + site-occupancy + T. cruzi natural infection, we identified man-made ecotopes suitable for forming dense triatomine infestations with high rates of T. cruzi natural infection, which may be taken into account for vector control measures.

Microsatellite variation revealed panmictic pattern for Triatoma brasiliensis (Triatominae: Reduviidae) in rural northeastern Brazil: the control measures implications

Background

Triatoma brasiliensis Neiva, 1911 is the main vector of Trypanosoma cruzi in the caatinga of Northeastern Brazil. Despite of its epidemiological relevance, there are few studies on its genetic variability. Using microsatellite markers, we characterized the variability and dynamics of infestation and reinfestation of T. brasiliensis after residual insecticide spraying in five surveys conducted in a well-defined rural area located in the municipality of Tauá, Ceará, between 2009 and 2015. We evaluated: (1) general variability among local of captures; (2) variability along the time analysis (2009, 2010 and 2015); (3) and reinfestation process.

Results

On the analysis (1) global and pairwise F_ST values suggested absence of clusters among the area. AMOVA indicated that total variation is mainly represented by individual differences. Absence of clustering indicates a panmitic unit, with free gene flow. For (2), Pairwise F_ST indicated alterations in the genetic profile of the triatomines along the time. (3) Analysis of the reinfestation process showed that the domiciliary units investigated had different sources of infestation despite of its proximity.

Conclusions

Observed homogeneity can be explained by the great dispersal capacity of T. brasiliensis, overlapping the different environments. Persistent house infestation in Tauá may be attributed to the occurrence of postspraying residual foci and the invasion of triatomines from their natural habitats.

Modelling the climatic suitability of Chagas disease vectors on a global scale

The Triatominae are vectors for Trypanosoma cruzi, the aetiological agent of the neglected tropical Chagas disease. Their distribution stretches across Latin America, with some species occurring outside of the Americas. In particular, the cosmopolitan vector, Triatoma rubrofasciata, has already been detected in many Asian and African countries. We applied an ensemble forecasting niche modelling approach to project the climatic suitability of 11 triatomine species under current climate conditions on a global scale. Our results revealed potential hotspots of triatomine species diversity in tropical and subtropical regions between 21°N and 24°S latitude. We also determined the climatic suitability of two temperate species (T. infestans, T. sordida) in Europe, western Australia and New Zealand. Triatoma rubrofasciata has been projected to find climatically suitable conditions in large parts of coastal areas throughout Latin America, Africa and Southeast Asia, emphasising the importance of an international vector surveillance program in these regions.

Impacts of residual insecticide spraying on the abundance and habitat occupancy of Triatoma sordida and co-occurrence with Triatoma infestans: A three-year follow-up in northeastern Argentina

Triatoma infestans, the main vector in the Gran Chaco region, may competitively displace other sympatric species such as Triatoma sordida. We conducted a three-year longitudinal study of site- and house-level infestation and abundance of triatomine bugs before and after an area-wide insecticide spraying campaign followed by sustained vector surveillance in a well-defined rural section of the Argentine Chaco encompassing 368-411 houses. Here, we tested whether insecticide applications targeting and virtually suppressing T. infestans reduced the abundance of T. sordida and modified its habitat occupancies, and whether their joint spatial distribution was random, aggregated or uniform, and varied over time. Systematic timed-manual searches of 18,031 sites yielded 2,226 T. sordida over seven postintervention surveys. Triatoma sordida failed to colonize human sleeping quarters after interventions, and its prime and secondary habitats remained virtually unmodified. Residual insecticide spraying and seasonality best described variations in the house-level abundance of T. sordida as determined using a generalized estimating equation model. Two-species foci occurred in 3.2% of sites ever positive for any species. The habitat-adjusted relative odds of catching one species was 10.8 times greater when the other species was present, with no evidence of heterogeneity among ORs, suggesting no antagonistic interactions throughout the follow-up. The spatial occurrence of both species was significantly aggregated within 300-500 m before and after interventions, and was random at broader spatial scales. The habitat occupancies of T. sordida may be used as a proxy for potential infestation with T. infestans and to guide targeted vector control actions.

Leishmania spp. Infection Rate and Feeding Patterns of Sand Flies (Diptera: Psychodidae) from a Hyperendemic Cutaneous Leishmaniasis Community in Panamá

American cutaneous leishmaniasis (ACL) is a common and important vector-borne parasitic zoonosis in Panamá. Here, we study Leishmania spp. infection rates and blood-feeding patterns among common sand flies in Trinidad de Las Minas, a rural community with hyperendemic ACL transmission, and where a deltamethrin fogging trial was performed. Sand flies were collected from April 2010 to June 2011 with light traps installed inside and in the peridomicile of 24 houses. We restricted our analysis to the most abundant species at the study site: Lutzomyia trapidoi, Lutzomyia gomezi, Lutzomyia panamensis, Lutzomyia triramula, and Lutzomyia dysponeta. We detected Leishmania spp. infection in sand flies by polymerase chain reaction (PCR) amplification of the internal transcribed spacer region 1 (ITS-1) in pooled females (1-10 females per pool). Host species of engorged sand flies were identified using a cytochrome b PCR. From 455 sand fly pools analyzed, 255 pools were positive for Leishmania spp., with an estimated infection rate (confidence interval) of 0.096 [0.080-0.115] before the deltamethrin fogging which slightly, but not significantly (P > 0.05), increased to 0.116 [0.098-0.136] after the deltamethrin fogging. Blood meal analysis suggested that pigs, goats, and birds were the most common sand fly blood sources, followed by humans and domestic dogs. DNA sequencing from a subsample of ITS-1 positive pools suggests that Leishmania panamensis, Leishmania naiffi, and other Leishmania spp. were the parasite species infecting the most common vectors at the study site. Our data confirm an association between sand fly species, humans, domestic dogs, and pigs and Leishmania spp. parasites in rural Panamá.

Wide distribution of Trypanosoma cruzi-infected triatomines in the State of Bahia, Brazil

Background

The identification of Trypanosoma cruzi and blood-meal sources in synanthropic triatomines is important to assess the potential risk of Chagas disease transmission. We identified T. cruzi infection and blood-meal sources of triatomines caught in and around houses in the state of Bahia, northeastern Brazil, and mapped the occurrence of infected triatomines that fed on humans and domestic animals.

Methods

Triatominae bugs were manually captured by trained agents from the Epidemiologic Surveillance team of Bahia State Health Service between 2013 and 2014. We applied conventional PCR to detect T. cruzi and blood-meal sources (dog, cat, human and bird) in a randomized sample of triatomines. We mapped triatomine distribution and analyzed vector hotspots with kernel density spatial analysis.

Results

In total, 5906 triatomines comprising 15 species were collected from 127 out of 417 municipalities in Bahia. The molecular analyses of 695 triatomines revealed a ~10% T. cruzi infection rate, which was highest in the T. brasiliensis species complex. Most bugs were found to have fed on birds (74.2%), and other blood-meal sources included dogs (6%), cats (0.6%) and humans (1%). Trypanosoma cruzi-infected triatomines that fed on humans were detected inside houses. Spatial analysis showed a wide distribution of T. cruzi-infected triatomines throughout Bahia; triatomines that fed on dogs, humans, and cats were observed mainly in the northeast region.

Conclusions

Synanthropic triatomines have a wide distribution and maintain the potential risk of T. cruzi transmission to humans and domestic animals in Bahia. Ten species were recorded inside houses, mainly Triatoma sordida, T. pseudomaculata, and the T. brasiliensis species complex. Molecular and spatial analysis are useful to reveal T. cruzi infection and blood-meal sources in synanthropic triatomines, identifying areas with ongoing threat for parasite transmission and improving entomological surveillance strategies.

Trypanosoma cruzi transmission dynamics in a synanthropic and domesticated host community

Trypanosoma cruzi is the causative agent of Chagas disease, a Neglected Tropical Disease affecting 8 million people in the Americas. Triatomine hematophagous vectors feed on a high diversity of vertebrate species that can be reservoirs or dead-end hosts, such as avian species refractory to T. cruzi. To understand its transmission dynamics in synanthropic and domesticated species living within villages is essential to quantify disease risk and assess the potential of zooprophylaxis. We developed a SI model of T. cruzi transmission in a multi-host community where vector reproduction and parasite transmission depend on a triatomine blood-feeding rate accounting for vector host preferences and interference while feeding. The model was parameterized to describe T. cruzi transmission in villages of the Yucatan peninsula, Mexico, using the information about Triatoma dimidiata vectors and host populations accumulated over the past 15 years. Extensive analyses of the model showed that dogs are key reservoirs and contributors to human infection, as compared to synanthropic rodents and cats, while chickens or other domesticated avian hosts dilute T. cruzi transmission despite increasing vector abundance. In this context, reducing the number of dogs or increasing avian hosts abundance decreases incidence in humans by up to 56% and 39%, respectively, while combining such changes reduces incidence by 71%. Although such effects are only reached over >10-years periods, they represent important considerations to be included in the design of cost-effective Integrated Vector Management. The concomitant reduction in T. cruzi vector prevalence estimated by simulating these zooprophylactic interventions could indeed complement the removal of colonies from the peridomiciles or the use of insect screens that lower vector indoor abundance by ~60% and ~80%. These new findings reinforce the idea that education and community empowerment to reduce basic risk factors is a cornerstone to reach and sustain the key objective of interrupting Chagas disease intra-domiciliary transmission.

Comparative Study of the Antennal Phenotype in Species of the Belminus (Hemiptera: Triatominae) Genus Using Optical and Scanning Electron Microscopy

The genus Belminus Stål, 1859 is distinguished by markedly entomophagous species. This genus is a poorly studied group of the Triatominae (Jeannel, 1919), which includes hematophagous species that are vectors of Trypanosoma cruzi (Chagas, 1909), the etiological agent of Chagas disease. This study reports for the first time the description of the antennal sensilla of Belminus corredori (Galvão & Angulo, 2003), Belminus herreri (Lent & Wygodzinsky, 1979), and Belminus ferroae (Sandoval, Pabón, Jurberg & Galvão, 2007) nymphs and adults throughout scanning electron microscopy and optical microscopy. Nine morphological types of sensilla were identified in the three species, including bristles I and II, trichobothria, tapered hairs, thin-walled trichoid, thick-walled trichoid, basiconic, campaniform, and coeloconica sensilla. The analysis of the most abundant types of sensilla and their distribution in nymphs and adults shows similarities with the antennal phenotypes described in other Triatominae. Quantitative differences showed the important phenotypic plasticity of this morphological trait in the genus and allowed for the separation of the species in both sexes. These differences were associated with sexual dimorphism and wing condition (macropterous and brachypterous). The role of the antennal phenotype in sexual behavior, its usefulness as a taxonomic tool, and its relationship with the dispersal capacity of these species are discussed.

Protein mass spectrometry detects multiple bloodmeals for enhanced Chagas disease vector ecology

Chagas disease, a neglected tropical disease endemic in Latin America, is caused by the protozoan parasite Trypanosoma cruzi and is responsible for significant health impacts, especially in rural communities. The parasite is transmitted by insect vectors in the Triatominae subfamily and due to lack of vaccines and limited treatment options, vector control is the main way of controlling the disease. Knowing what vectors are feeding on directly enhances our understanding of the ecology and biology of the different vector species and can potentially aid in engaging communities in active disease control, a concept known as Ecohealth management. We evaluated bloodmeals in rural community, house-caught insect vectors previously evaluated for bloodmeals via DNA analysis as part of a larger collaborative project from three countries in Central America, including Guatemala. In addition to identifying bloodmeals in 100% of all samples using liquid chromatography tandem mass spectrometry (LC-MS/MS) (n = 50), strikingly for 53% of these samples there was no evidence of a recent bloodmeal by DNA-PCR. As individual vectors often feed on multiple sources, we developed an enhanced detection pipeline, and showed the ability to quantify a bloodmeal using stable-isotope-containing synthetic references peptides, a first step in further exploration of species-specific bloodmeal composition. Furthermore, we show that a lower resolution mass spectrometer is sufficient to correctly identify taxa from bloodmeals, an important and strong attribute of our LC-MS/MS-based method, opening the door to using proteomics in countries where Chagas disease is endemic.

A reduction in ecological niche for Trypanosoma cruzi-infected triatomine bugs

Background

Theory predicts that parasites can affect and thus drive their hosts’ niche. Testing this prediction is key, especially for vector-borne diseases including Chagas disease. Here, we examined the niche use of seven triatomine species that occur in Mexico, based on whether they are infected or not with Trypanosoma cruzi, the vectors and causative parasites of Chagas disease, respectively. Presence data for seven species of triatomines (Triatoma barberi, T. dimidiata, T. longipennis, T. mazzottii, T. pallidipennis, T. phyllosoma and T. picturata) were used and divided into populations infected and not infected by T. cruzi. Species distribution models were generated with Maxent 3.3.3k. Using distribution models, niche analysis tests of amplitude and distance to centroids were carried out for infected vs non-infected populations within species.

Results

Infected populations of bugs of six out of the seven triatomine species showed a reduced ecological space compared to non-infected populations. In all but one case (T. pallidipennis), the niche used by infected populations was close to the niche centroid of its insect host.

Conclusions

Trypanosoma cruzi may have selected for a restricted niche amplitude in triatomines, although we are unaware of the underlying reasons. Possibly the fact that T. cruzi infection bears a fitness cost for triatomines is what narrows the niche breadth of the insects. Our results imply that Chagas control programmes should consider whether bugs are infected in models of triatomine distribution.

Electronic supplementary material

The online version of this article (10.1186/s13071-019-3489-5) contains supplementary material, which is available to authorized users.

Second-Best Is Better Than Nothing: Cockroaches as a Viable Food Source for the Kissing Bug Triatoma recurva (Hemiptera: Reduviidae)

Kissing bugs in the genus Triatoma are obligate blood feeders that feed mainly on vertebrate blood and have lost the predatory lifestyle found in other reduviid bugs. They occasionally also feed on the hemolymph of arthropods, especially during the first and second instar stages. The largest kissing bug species in the United States, Triatoma recurva (Stål) (Hemiptera: Reduviidae), is poorly known and was chosen to investigate its ability to feed and develop on a diet of cockroach hemolymph. Molting from first instar individuals to second instars readily occurred at approximately the same rate reported for the species feeding on mammalian blood. Subsequent instars also fed on and survived on cockroach hemolymph with some individuals maturing to adults. In the larger instars, development time and survival rates were reduced relative to the results reported in the literature for mammalian-blood-fed individuals. Two other species of kissing bugs, Triatoma protracta (Uhler) and T. rubida (Uhler) failed to survive on cockroach hemolymph with most individuals failing to molt from the first instar stage. Although T. recurva does not thrive on a diet limited to hemolymph of cockroaches, it appears to be an unusual species in which cockroaches might be a primary source of nutrition for smaller individuals and are a viable exclusive source of nutrition for all immatures. At a minimum during times of limited availability of vertebrate blood sources, the presence of cockroaches enhances survival opportunities. Efforts to control populations of this kissing bug species likely will be improved with additional control of cockroach populations in the environment.

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.

An oral dose of Fluralaner administered to dogs kills pyrethroid-resistant and susceptible Chagas disease vectors for at least four months

New vector control tools that can fit into a broader integrated vector management strategy are notably lacking. We conducted a seven-month randomized trial to assess the efficacy of a single oral dose of Fluralaner (Bravecto^®) administered to dogs on the blood-feeding success, engorgement levels and mortality of pyrethroid-resistant and -susceptible Triatoma infestans third- and fifth-instar nymphs. The trial included 10 Fluralaner-treated and 10 placebo-treated (control) outbred healthy dogs residing in rural houses of the Argentine Chaco. Most (92.7%) of the 3017 triatomines exposed were able to blood-feed. Generalized linear models showed that blood-feeding success was not significantly modified by Fluralaner treatment, time posttreatment and their interaction. However, pyrethroid-susceptible fifth instars blood-fed significantly more frequently than susceptible third instars, and no significant differences were observed between the latter and resistant fifth instars. Engorgement levels were not significantly modified by Fluralaner treatment, time posttreatment and their interaction. Nearly all the triatomines that blood-fed on treated dogs up to 60 days posttreatment (DPT) died within 24 h regardless of pyrethroid susceptibility status combined with bug stage. Cumulative bug mortality over 4 days postexposure remained high over 90-120 DPT (70-81% in susceptible third and fifth instars, and 47-49% in resistant fifth instars), and was virtually nil at 210 DPT. Triatomines that fed on control dogs suffered marginal mortality (0-4%) except at 4 and 30 DPT. Fluralaner and xenointoxication are eligible for Phase III efficacy trials alone or combined with other methods in the frame of an integrated vector management strategy in areas with or without pyrethroid resistance.

Triatoma brasiliensis Neiva, 1911: food sources and diversity of Trypanosoma cruzi in wild and artificial environments of the semiarid region of Ceará, northeastern Brazil

Background

Knowledge 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.

Methods

A 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.

Results

Food 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).

Conclusions

The 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 material

The online version of this article (10.1186/s13071-018-3235-4) contains supplementary material, which is available to authorized users.

Toward an Ecological Framework for Assessing Reservoirs of Vector-Borne Pathogens: Wildlife Reservoirs of Trypanosoma cruzi across the Southern United States

Wildlife species are critical for both feeding vectors and serving as reservoirs of zoonotic vector-borne pathogens. Transmission pathways leading to disease in humans or other target taxa might be better understood and managed given a complete understanding of the relative importance of different reservoir species in nature. Using the conceptual framework of “reservoir potential,” which considers elements of both reservoir competence and vector-host contact, we review the wildlife reservoirs of Trypanosoma cruzi in the southern United States, where many species of triatomine vectors occur and wildlife maintain enzootic cycles that create a risk of spillover to humans, domestic dogs, and captive nonhuman primates that may develop Chagas disease. We reviewed 77 published reports of T. cruzi infection in at least 26 wildlife species across 15 southern states. Among the most well-studied and highly infected reservoirs are raccoon (Procyon lotor), woodrat (Neotoma spp.), and opossum (Didelphis virginiana), with aggregate overall infection prevalences of 36.4, 34.7, and 22.9%, respectively. Just over 60% of studies utilized methods from which an infectiousness index could be generated and show that raccoons and striped skunk (Mephitis mephitis) are among the most infectious wildlife hosts. Triatomine-host contact has sparsely been quantified in the southern United States, but 18 of the 24 host species previously identified to have been fed upon by triatomines are wildlife. Future studies to parameterize the reservoir potential model, especially to quantify wildlife infectiousness, vector-host contact, and the epidemiological importance of parasite strains maintained by wildlife, could open new doors for managing enzootic cycles and reducing T. cruzi spillover risk.

Implementation science: Epidemiology and feeding profiles of the Chagas vector Triatoma dimidiata prior to Ecohealth intervention for three locations in Central America

The Ecohealth strategy is a multidisciplinary data-driven approach used to improve the quality of people's lives in Chagas disease endemic areas, such as regions of Central America. Chagas is a vector-borne disease caused by the parasite Trypanosoma cruzi. In Central America, the main vector is Triatoma dimidiata. Because successful implementation of the Ecohealth approach reduced home infestation in Jutiapa department, Guatemala, it was scaled-up to three localities, one in each of three Central American countries (Texistepeque, El Salvador; San Marcos de la Sierra, Honduras and Olopa, Guatemala). As a basis for the house improvement phase of the Ecohealth program, we determined if the localities differ in the role of sylvatic, synanthropic and domestic animals in the Chagas transmission cycle by measuring entomological indices, blood meal sources and parasite infection from vectors collected in and around houses. The Polymerase Chain Reaction (PCR) with taxa specific primers to detect both, blood sources and parasite infection, was used to assess 71 T. dimidiata from Texistepeque, 84 from San Marcos de la Sierra and 568 from Olopa. Our results show that infestation (12.98%) and colonization (8.95%) indices were highest in Olopa; whereas T. cruzi prevalence was higher in Texistepeque and San Marcos de la Sierra (>40%) than Olopa (8%). The blood meal source profiles showed that in Olopa, opossum might be important in linking the sylvatic and domestic Chagas transmission cycle, whereas in San Marcos de la Sierra dogs play a major role in maintaining domestic transmission. For Texistepeque, bird was the major blood meal source followed by human. When examining the different life stages, we found that in Olopa, the proportion bugs infected with T. cruzi is higher in adults than nymphs. These findings highlight the importance of location-based recommendations for decreasing human-vector contact in the control of Chagas disease.

Protein mass spectrometry extends temporal blood meal detection over polymerase chain reaction in mouse-fed Chagas disease vectors

BACKGROUND

Chagas disease is highly prevalent in Latin America, and vector control is the most effective control strategy to date. We have previously shown that liquid chromatography tandem mass spectrometry (LC-MS/MS) is a valuable tool for identifying triatomine vector blood meals.

OBJECTIVES

The purpose of this study was to determine blood meal detection ability as a function of method [polymerase chain reaction (PCR) vs. LC-MS/MS], time since feeding, and the effect of molting in mouse-fed triatomine insect vectors targeting hemoglobin and albumin proteins with LC-MS/MS and short interspersed nuclear elements (SINE)-based PCR.

METHODS

We experimentally fed Triatoma protracta on mice and used LC-MS/MS to detect hemoglobin and albumin peptides over time post-feeding and post-molting (≤ 12 weeks). We compared LC-MS/MS results with those of a standard PCR method based on SINEs.

FINDINGS

Hemoglobin-based LC-MS/MS detected blood meals most robustly at all time points post-feeding. Post-molting, no blood meals were detected with PCR, whereas LC-MS/MS detected mouse hemoglobin and albumin up to 12 weeks.

MAIN CONCLUSIONS

In our study, the hemoglobin signature in the insect abdomen lasted longer than that of albumin and DNA. LC-MS/MS using hemoglobin shows promise for identifying triatomine blood meals over long temporal scales and even post-molting. Clarifying the frequency of blood-feeding on different hosts can foster our understanding of vector behavior and may help devise sounder disease-control strategies, including Ecohealth (community based ecosystem management) approaches.

Trypanosoma cruzi Infection in Rhodnius pallescens (Heteroptera: Reduviidae) Infesting Coyol Palms in the Dry Arch of Panamá

Ecoepidemiological scenarios for Trypanosoma cruzi Chagas transmission are partially shaped by kissing bug vector ecology. The presence of Attalea butyracea Kunth, the 'royal palm', is a major risk factor for Chagas disease transmission in Panamá given their frequent infestations by Rhodnius pallescens Barber, a major neotropical T. cruzi vector. It was assumed that in Panamá this relationship was very close and unique, limiting the niche of R. pallescens to that of Att. butyracea. However, here we present observations about T. cruzi-infected R. pallescens infesting coyol palms, Acrocomia aculeata Jacquin, in Pedasí district, Los Santos Province, Panamá. Between May 2015 and August 2016, we sampled kissing bugs from 83 coyol palms using mice-baited traps placed at the crown of each palm during the dry and wet season. We collected 62 R. pallescens and one Eratyrus cuspidatus Stål kissing bugs. Using logistic regression, we found that the probability of kissing bug infestation in coyol palms increased during the rainy season, with infructescence number and palm height. We examined adult R. pallescens bugs (n = 30) and found T. cruzi in 67% of the samples. We were able to isolate and characterize T. cruzi from parasites present in the feces from R. pallescens, all parasites belonging to the TC I lineage. We found that green fronds number and house proximity increased T. cruzi infection probability in kissing bugs collected in coyol palms. These results highlight coyol palms as a potential risk factor for Chagas disease transmission in the dry arch of Panamá.

Habitat-Specific Occupancy and a Metapopulation Model of Triatoma sordida (Hemiptera: Reduviidae), a Secondary Vector of Chagas Disease, in Northeastern Argentina

Triatoma sordida Stål (Hemiptera: Reduviidae), a secondary vector of Trypanosoma cruzi Chagas (Kinetoplastida: Trypanosomatidae), occasionally colonizes human sleeping quarters in Paraguay, Bolivia, and Brazil, whereas only sylvatic and peridomestic populations are found in Argentina. We carried out a cross-sectional survey of house infestation in a well-defined rural area of northeastern Argentina to identify the key habitats of T. sordida; describe its spatial distribution in an apparently undisturbed setting under no recent insecticide treatment and use metapopulation theory to investigate these spatially structured populations. Timed-manual searches in 2,177 georeferenced sites from 368 houses yielded T. sordida in 78 sites (house infestation prevalence, 19.9%). Most triatomines occurred in chicken nests, chicken coops, and trees where chickens roosted (prime habitats). Goat or sheep corrals and pig corrals had a lower fraction of occupied sites (occupancies) and abundance. Both occupancy and catch increased with increasing refuge availability according to multimodel inference with model averaging. The majority of suitable habitats were unoccupied despite their proximity to occupied sites. The site-specific occurrence of T. sordida and Triatoma infestans Klug (Hemiptera: Reduviidae) was positively and homogeneously associated over ecotopes, showing no evidence of interspecific interference. An incidence function metapopulation model (including intersite distances and vector carrying capacity) predicted a fivefold greater occupancy relative to the observed pattern, suggesting the latter represented a transient state. T. sordida failed to colonize human sleeping quarters, thrived in peridomestic habitats occupied by chickens, and had a limited occupancy likely related to a poor colonizing ability and the relative instability of its prime habitats.

Evolutionary ecology of Chagas disease; what do we know and what do we need?

The aetiological agent of Chagas disease, Trypanosoma cruzi, is a key human pathogen afflicting most populations of Latin America. This vectorborne parasite is transmitted by haematophageous triatomines, whose control by large‐scale insecticide spraying has been the main strategy to limit the impact of the disease for over 25 years. While those international initiatives have been successful in highly endemic areas, this systematic approach is now challenged by the emergence of insecticide resistance and by its low efficacy in controlling species that are only partially adapted to human habitat. In this contribution, we review evidences that Chagas disease control shall now be entering a second stage that will rely on a better understanding of triatomines adaptive potential, which requires promoting microevolutionary studies and –omic approaches. Concomitantly, we show that our knowledge of the determinants of the evolution of T. cruzi high diversity and low virulence remains too limiting to design evolution‐proof strategies, while such attributes may be part of the future of Chagas disease control after the 2020 WHO's target of regional elimination of intradomiciliary transmission has been reached. We should then aim at developing a theory of T. cruzi virulence evolution that we anticipate to provide an interesting enrichment of the general theory according to the specificities of transmission of this very generalist stercorarian trypanosome. We stress that many ecological data required to better understand selective pressures acting on vector and parasite populations are already available as they have been meticulously accumulated in the last century of field research. Although more specific information will surely be needed, an effective research strategy would be to integrate data into the conceptual and theoretical framework of evolutionary ecology and life‐history evolution that provide the quantitative backgrounds necessary to understand and possibly anticipate adaptive responses to public health interventions.

Body size and hosts of Triatoma infestans populations affect the size of bloodmeal contents and female fecundity in rural northwestern Argentina

Human sleeping quarters (domiciles) and chicken coops are key source habitats of Triatoma infestans—the principal vector of the infection that causes Chagas disease—in rural communities in northern Argentina. Here we investigated the links among individual bug bloodmeal contents (BMC, mg), female fecundity, body length (L, mm), host blood sources and habitats. We tested whether L, habitat and host blood conferred relative fitness advantages using generalized linear mixed-effects models and a multimodel inference approach with model averaging. The data analyzed include 769 late-stage triatomines collected in 120 sites from six habitats in 87 houses in Figueroa, Santiago del Estero, during austral spring. L correlated positively with other body-size surrogates and was modified by habitat type, bug stage and recent feeding. Bugs from chicken coops were significantly larger than pig-corral and kitchen bugs. The best-fitting model of log BMC included habitat, a recent feeding, bug stage, log L_c (mean-centered log L) and all two-way interactions including log L_c. Human- and chicken-fed bugs had significantly larger BMC than bugs fed on other hosts whereas goat-fed bugs ranked last, in consistency with average blood-feeding rates. Fecundity was maximal in chicken-fed bugs from chicken coops, submaximal in human- and pig-fed bugs, and minimal in goat-fed bugs. This study is the first to reveal the allometric effects of body-size surrogates on BMC and female fecundity in a large set of triatomine populations occupying multiple habitats, and discloses the links between body size, microsite temperatures and various fitness components that affect the risks of transmission of Trypanosoma cruzi.

The few bug species of Triatominae that have become domesticated are the most important vectors of human Trypanosoma cruzi infection, which causes Chagas disease. Evolutionary theory predicts that the fitness of hematophagous species closely adapted to human habitations should increase with feeding on human hosts and insect body length (L). Testing these hypotheses is important for a better understanding of triatomine population dynamics, identifying key productive habitats, modeling parasite transmission and designing innovative vector control strategies. This study is the first to describe the distributions of L and total individual bloodmeal contents (BMC) of triatomines over bug stages and habitats in rural villages where Chagas disease is endemic, and provides a direct link between individual BMC and female fecundity, host-feeding choices and L. L positively and significantly correlated with other body-size surrogates and was modified by habitat and host associations. Feeding on humans was associated with larger BMC and maximal female fecundity in domestic triatomine populations. Human- and chicken-fed bugs had significantly larger BMC than bugs fed on other hosts. Goat-fed bugs ranked last over all habitats, in agreement with other evidence. This study demonstrates that identifiable habitat-host associations provide nearly optimal resources and conditions for T. infestans.

Sylvatic host associations of Triatominae and implications for Chagas disease reservoirs: a review and new host records based on archival specimens

BACKGROUND

The 152 extant species of kissing bug include important vectors of the debilitating, chronic, and often fatal Chagas disease, which affects several million people mainly in Central and South America. An understanding of the natural hosts of this speciose group of blood-feeding insects has and will continue to aid ongoing efforts to impede the spread of Chagas disease. However, information on kissing bug biology is piecemeal and scattered, developed using methods with varying levels of accuracy over more than 100 years. Existing host records are heavily biased towards well-studied primary vector species and are derived from primarily three different types of observations, associational, immunological or DNA-based, with varying reliability.

METHODS

We gather a comprehensive and unparalleled number of sources reporting host associations via rigorous targeted searches of publication databases to review all known natural, or sylvatic, host records including information on how each record was collected. We integrate this information with novel host records obtained via attempted amplification and sequencing of a ∼160 base pair (bp) region of the vertebrate 12S mitochondrial gene from the gastrointestinal tract of 64 archival specimens of Triatominae representing 19 species collected primarily in sylvatic habitats throughout the southern United States and Central and South America during the past 10 years. We show the utility of this method for uncovering novel and under-studied groups of Triatominae hosts, as well as detecting the presence of the Chagas disease pathogen via Polymerase Chain Reaction (PCR) of a ∼400 bp sequence of the trypanosome 18S gene.

RESULTS

New host associations for several groups of arboreal mammals were determined including sloths, New World monkeys, coatis, arboreal porcupines and, for the first time as a host of any Triatominae, tayras. A thorough review of previously documented sylvatic hosts, organized by triatomine species and the type of observation (associational, antibody-based, or DNA-based), is presented in a phylogenetic context and highlights large gaps in our knowledge of Triatominae biology.

CONCLUSION

The application of DNA-based methods of host identification towards additional species of Triatominae, including rarely collected species that may require use of archival specimens, is the most efficient and promising way to resolve recognized shortfalls.

Trypanosoma cruzi reservoir-triatomine vector co-occurrence networks reveal meta-community effects by synanthropic mammals on geographic dispersal

Contemporary patterns of land use and global climate change are modifying regional pools of parasite host species. The impact of host community changes on human disease risk, however, is difficult to assess due to a lack of information about zoonotic parasite host assemblages. We have used a recently developed method to infer parasite-host interactions for Chagas Disease (CD) from vector-host co-occurrence networks. Vector-host networks were constructed to analyze topological characteristics of the network and ecological traits of species’ nodes, which could provide information regarding parasite regional dispersal in Mexico. Twenty-eight triatomine species (vectors) and 396 mammal species (potential hosts) were included using a data-mining approach to develop models to infer most-likely interactions. The final network contained 1,576 links which were analyzed to calculate centrality, connectivity, and modularity. The model predicted links of independently registered Trypanosoma cruzi hosts, which correlated with the degree of parasite-vector co-occurrence. Wiring patterns differed according to node location, while edge density was greater in Neotropical as compared to Nearctic regions. Vectors with greatest public health importance (i.e., Triatoma dimidiata, T. barberi, T. pallidipennis, T. longipennis, etc), did not have stronger links with particular host species, although they had a greater frequency of significant links. In contrast, hosts classified as important based on network properties were synanthropic mammals. The latter were the most common parasite hosts and are likely bridge species between these communities, thereby integrating meta-community scenarios beneficial for long-range parasite dispersal. This was particularly true for rodents, >50% of species are synanthropic and more than 20% have been identified as T. cruzi hosts. In addition to predicting potential host species using the co-occurrence networks, they reveal regions with greater expected parasite mobility. The Neotropical region, which includes the Mexican south and southeast, and the Transvolcanic belt, had greatest potential active T. cruzi dispersal, as well as greatest edge density. This information could be directly applied for stratification of transmission risk and to design and analyze human-infected vector contact intervention efficacy.

Bats in urban areas of Brazil: roosts, food resources and parasites in disturbed environments

Urbanization is a widespread intense land use that generally results in biodiversity decline. Among the taxa capable to adapt to urban landscapes, bats are particularly ubiquitous. Brazil has one of the world's largest diversity of bat species and one of the highest urbanization rates of the world. Yet, few studies have synthesized the biology of bats in urban environments, especially in Brazil. To fill this gap, we systematically reviewed the published scientific literature on the bat fauna found in urban areas of Brazil. The knowledge of urban bats is still incipient and heterogeneously spatially distributed, mostly concentrated in the southeastern region of the country. The assembled list of 84 urban species, of which nineteen are new species records for urban areas (including one new family), represents 47% of the bat richness registered in the country. Thirty-one bat species (37%) were captured exclusively inside forest fragments. Moreover, we provide information on the resources used within the urban matrix by summarizing the roosting sites for 38 bat species, as well as 31 plants consumed by at least twelve bat species. Regarding parasitological aspects, we listed eleven zoonotic parasites hosted by 27 bat species and discussed their potential to become a public health threat. Likewise, we considered the different features linked to urbanization, including impacts on immunity, body condition and susceptibility to acquiring parasites, as possible bat conservation issues. Finally, we defined an agenda for bat studies in urban areas of Brazil.

How do biting disease vectors behaviourally respond to host availability?

BACKGROUND

Ecological theory predicts a diverse range of functional responses of species to resource availability; but in the context of human blood consumption by disease vectors, a simplistic, linear response is ubiquitously assumed. A simple and flexible model formulation is presented that extends the Holling's Types to account for a wider range of qualitatively distinct behaviours, and used to examine the impact of different vector responses to the relative availability of multiple blood-host species.

RESULTS

Epidemiological models of falciparum malaria, Chagas disease and Lyme disease demonstrate that the standard, often implicit, assumption of a linear functional response can lead to spurious under- or over-estimates in disease transmission potential, across a full range of pathogen life-cycles. It is shown how the functional response in vector biting can augment disease intervention outcomes. Interactions between vector biting behaviour and uneven pathogen transmission probabilities between alternative hosts, as is the case for Chagas disease, can render infection more resilient to control.

CONCLUSIONS

Both the novel response formula and the nested vector-borne disease structure offer a flexible framework that can be applied to other vector-borne diseases in assessing the role of this newly identified aspect of biting behavioural ecology.

Molecular characterization of trypanosomatid infections in wild howler monkeys (Alouatta caraya) in northeastern Argentina

The transmission of Trypanosoma cruzi by vectors is confined to the Americas, and the infection circulates in at least two broadly defined transmission cycles occurring in domestic and sylvatic habitats. This study sought to detect and characterize infection by T. cruzi and other trypanosomes using PCR strategies in blood samples from free-ranging howler monkeys, Alouatta caraya, in the northeastern Argentina. Blood samples were collected at four sites with variable levels of habitat modification by human activity. PCR was conducted using primers for kinetoplast DNA, satellite DNA and ribosomal DNA of the trypanosomatid parasites. Ribosomal and satellite DNA fragments were sequenced to identify the trypanosomatid species and to characterize the discrete typing units (DTUs) of T. cruzi. Overall, 46% (50/109) of the howlers were positive according to the kDNA-PCR assay, but only 7 of the howlers were positive according to the SatDNA-PCR protocol. We sequenced the amplicons of the satellite DNA obtained from five specimens, and the sequences were 99% and 100% similar to T. cruzi. A sequence typical of DTU T. cruzi I was found in one howler monkey from the "remote" site, while sequences compatible with DTUs II, V, and VI were found in howlers from the "remote", "rural" and "village" sites. We detected 96% positive samples for RibDNA-PCR, 9 of which were sequenced and displayed 99% identity with Trypanosoma minasense, while none showed identity with T. cruzi. The results demonstrated the presence of T. cruzi and a species closely related to T. minasense in blood samples from free-ranging A. caraya, belonging to different T. cruzi DTUs circulating in these howler monkey populations. The results obtained in this study could help evaluate the role of A. caraya as a reservoir of T. cruzi in regions where Chagas disease is hyper-endemic and where the human-wildlife interface is increasing.

Risk factors associated with Trypanosoma cruzi exposure in domestic dogs from a rural community in Panama

Chagas disease, caused by Trypanosoma cruzi infection, is a zoonosis of humans, wild and domestic mammals, including dogs. In Panama, the main T. cruzi vector is Rhodnius pallescens, a triatomine bug whose main natural habitat is the royal palm, Attalea butyracea. In this paper, we present results from three T. cruzi serological tests (immunochromatographic dipstick, indirect immunofluorescence and ELISA) performed in 51 dogs from 24 houses in Trinidad de Las Minas, western Panama. We found that nine dogs were seropositive (17.6% prevalence). Dogs were 1.6 times more likely to become T. cruzi seropositive with each year of age and 11.6 times if royal palms where present in the peridomiciliary area of the dog's household or its two nearest neighbours. Mouse-baited-adhesive traps were employed to evaluate 12 peridomestic royal palms. All palms were found infested with R. pallescens with an average of 25.50 triatomines captured per palm. Of 35 adult bugs analysed, 88.6% showed protozoa flagellates in their intestinal contents. In addition, dogs were five times more likely to be infected by the presence of an additional domestic animal species in the dog's peridomiciliary environment. Our results suggest that interventions focused on royal palms might reduce the exposure to T. cruzi infection.