Synanthropic triatomines (Hemiptera: Reduviidae): infestation, colonization, and natural infection by trypanosomatids in the State of Rio Grande do Norte, Brazil

Drastic reduction in the notification of acute cases of Chagas disease in the Northeast region of Brazil. Epidemiological evaluation in the period 2001-2021

Chagas disease (CD), caused by the protozoan Trypanosoma cruzi (T. cruzi), is a neglected disease endemic to some Latin American countries, including Brazil. Soon after infection, individuals develop an acute phase, which in most cases is asymptomatic and may go undetected. However, when CD is detected early, notification in the Notifiable Diseases Information System (SINAN), is mandatory. This study aimed to evaluate the information registered in the SINAN database and to determine the epidemiological profile of acute CD in Northeast Brazil, an endemic region, from 2001 to 2021. According to this survey, 1,444 cases of acute CD were reported in the Northeastern region of Brazil during this period. During the first six years, referred to as period 1, 90.24% of the notifications were registered, while the number of notifications significantly decreased in the subsequent years, referred to as period 2. Most individuals diagnosed with acute CD were Afro-Brazilian adults. All known routes of infection by the parasite were reported. Vector-borne transmission was predominant during period 1 (73.29%) and oral transmission during period 2 (58.87%). All nine states in Northeast Brazil reported cases in both periods. A higher incidence of disease was reported in Rio Grande do Norte (RN) during period 1, and in Maranhão (MA) during period 2. Our results show that CD remains a significant public health challenge.

Temporal assessment of entomological surveillance of Trypanosoma cruzi vectors in an endemic area of northeastern Brazil

Entomological surveillance is essential for the control of triatomines and the prevention of Trypanosoma cruzi infection in humans and domestic animals. Thus, the objective of this study was to evaluate entomological indicators and triatomine control during the period from 2005 to 2015 in an endemic area in the state of Rio Grande do Norte, Brazil. This observational and retrospective study was developed based on data analysis related to active entomological surveillance activities and chemical control of infested housing units (HU) in the Agreste mesoregion of the state of Rio Grande do Norte, Brazil, in the period between 2005 to 2015. The quantitative analysis of housing units surveyed for entomological indicators was performed by linear regression of random effects (p < 0.05). The effect of the number of HU surveyed on the entomological indicators was analyzed by fitting a linear random effects regression model and an increasing intradomiciliary colonization rate was significant. In the period evaluated 92,156 housing units were investigated and the presence of triatomines was reported in 4,639 (5.0%). A total of 4,653 specimens of triatomines were captured and the species recorded were Triatoma pseudomaculata (n = 1,775), Triatoma brasiliensis (n = 1,569), Rhodnius nasutus (n = 741) and Panstrongylus lutzi (n = 568), with an index of natural infection by T. cruzi of 2.2%. Only 53.1% of the infested HU were subjected to chemical control. Moreover, there was a decrease in the total number of HU surveyed over time associated with an increase in the index of intradomiciliary colonization (p = 0.004). These data demonstrated that entomological surveillance and control of vectors in the Agreste mesoregion of the state has been discontinued, emphasizing the need for more effective public policies to effectively control the vectors, in order to avoid the exposure of humans and domestic animals to the risk of T. cruzi infection.

Dichotomous Keys Based on Cytogenetic Data for Triatomines Reported in Brazilian Regions with Outbreaks of Orally Transmitted Chagas Disease (Pernambuco and Rio Grande Do Norte)

Chagas disease (CD) affects about eight million people worldwide. Brazil has the highest number of estimated cases and the largest number of deaths due to CD. Considering the recent outbreaks of oral CD involving at least 27 cases of acute CD in Pernambuco (PE) as well as 18 cases and 2 deaths in the Rio Grande do Norte (RN), we developed dichotomous keys for the identification of triatomine species in these Brazilian states based on cytogenetic data. All triatomine species could be distinguished by cytogenetic characteristics, emphasizing the importance of the newly developed taxonomic keys for the correct identification of triatomes from PE and RN, particularly for species that exhibit morphological similarities, such as Triatoma brasilensis and T. petrocchiae (present in both states) and T. maculata and T. pseudomaculata (as T. pseudomaculata has been misidentified as T. maculata in PE and RN). These alternative keys are expected to provide a useful tool for the scientific community and, above all, health agents, aimed at preventing mistakes from occurring in the identification of the vectors present in PE and RN related to CD outbreaks caused by oral infection.

Molecular identification of Trypanosoma cruzi in domestic animals in municipalities of the State of Rio Grande do Norte, Brazil

Trypanosoma cruzi, the etiologic agent of American trypanosomiasis, is a vector-borne zoonotic parasite which has been little studied regarding its infection in domestic animals. In this study, we evaluated the occurrence of natural infection by T. cruzi in farm animals using molecular markers and phylogenetic analysis in blood clot samples of 60 sheep (Ovis aires), 22 goats (Capra hircus), and 14 horses (Equus caballus) in eight municipalities located in an infection risk area in the state of Rio Grande do Norte (RN), Northeast Region of Brazil. Trypanosoma spp. infection was identified by amplifying the rRNA 18S SSU gene in 48.9% of the samples. The SH022 sample showed 99.8% similarity with the Y strain of T. cruzi in phylogeny, grouped in the DTU II clade. Blood clots of sheep, goats, and horses detected T. cruzi kDNA in 28.3% (17/60), 22.7% (5/22), and 15.4% (2/14) of the samples, respectively. These animals were distributed in the three studied mesoregions throughout the state of RN. The identification of natural infection in domestic animals contributes to expand the epidemiological transmission scenario in an area where T. brasiliensis is the main vector.

The connection between Trypanosoma cruzi transmission cycles by Triatoma brasiliensis brasiliensis: A threat to human health in an area susceptible to desertification in the Seridó, Rio Grande do Norte, Brazil

An outbreak of Chagas disease, possibly involving its vector Triatoma brasiliensis brasiliensis, was identified in the state of Rio Grande do Norte (RN). Given the historical significance of this vector in public health, the study aimed to evaluate its role in the transmission dynamics of the protozoan Trypanosoma cruzi in an area undergoing desertification in the Seridó region, RN, Brazil. We captured triatomines in sylvatic and anthropic ecotopes. Natural vector infection was determined using parasitological and molecular methods and we identified discrete typing units (DTUs) of T. cruzi by analyzing the COII gene of mtDNA, 24Sα rDNA, and mini-exon gene. Their blood meals sources were identified by amplification and sequencing of the mtDNA cytochrome b gene. A total of 952 T. b. brasiliensis were captured in peridomestic (69.9%) and sylvatic ecotopes (30.4%). A wide range of natural infection rates were observed in peridomestic (36.0% - 71.1%) and sylvatic populations (28.6% - 100.0%). We observed the circulation of TcI and TcII DTUs with a predominance of Tcl in sylvatic and peridomestic environments. Kerodon rupestris, rocky cavy (13/39), Homo sapiens, human (8/39), and Bos taurus, ox (6/39) were the most frequently detected blood meals sources. Thus, Triatoma b. brasiliensis is invading and colonizing the human dwellings. Furthermore, high levels of natural infection, coupled with the detection of TcI and TcII DTUs, and also the detection of K. rupestris and H. sapiens as blood meals sources of infected T. b. brasiliensis indicate a risk of T. cruzi transmission to human populations in areas undergoing desertification.

Chagas disease currently affects about six to seven million people worldwide, resulting in high morbidity, mortality, and economic burden in endemic countries of Latin America. Its etiological agent, Trypanosoma cruzi, circulates among a wide variety of mammalian and insect vectors. Triatoma brasiliensis brasiliensis is adapted to the dry and warm climate of the Caatinga biome, and is considered the main vector in the semi-arid areas of northeastern Brazil. Information on the infestation, natural infection rates, T. cruzi strains, and blood meals sources of this vector is crucial for understanding the dynamics of T. cruzi transmission in areas susceptible to desertification. Triatoma b. brasiliensis colonizes peridomestic structures, particularly in the stone walls of cattle corrals that emerge as a refuge for sylvatic populations where they access a variety of blood meals sources. The predominance of the TcI strain in the sylvatic and peridomestic environments shows an overlap of transmission cycles by T. cruzi mediated by T. b. brasiliensis. The high rates of natural infection and the evidence of their feeding on humans and the rodent K. rupestris are worrisome and indicate the threat this vector poses to human health in the area studied.

Infections by trypanosomatid (Kinetoplastida: Trypanosomatidae) in triatomines (Hemiptera: Triatominae): A spatiotemporal assessment in an endemic area for Chagas disease

This research analysed the spatiotemporal distribution of triatomines infected by trypanosomatid parasites in an endemic region for Chagas disease, in the state of Pernambuco, Northeastern Brazil. The database included the total number of triatomines captured from intradomicile and peridomicile areas, as well as the infection rate (IR) by trypanosomatid. The G i ∗ by Getis-Ord method was used to statistically identify significant concentration clusters and the IR of triatomines by trypanosomatids. A generalized linear regression model with a binomial distribution was used to evaluate the probability of finding an IR by trypanosomatids. Overall, of 4,800 triatomines examined, trypanosomatid forms similar to Trypanosoma cruzi were detected in 10.29% of them, and the majority of positive specimens (98.17%) were collected at intradomicile. The geospatial analyses identified triatomines clusters in intradomicile and peridomicile environments. According to the logistic regression data for species (Panstrongylus lutzi, P. megistus, Triatoma brasiliensis and T. pseudomaculata), the probability of detection of T. cruzi infection remains constant in up to 50 specimens examined or more. The findings of this research revealed a scenario never studied in this area through this type of spatiotemporal analysis, which is essential to identify areas of vulnerability for the occurrence of these vectors and consequently for Chagas disease.

Healthcare Workers' Knowledge about Chagas Disease: A Systematic Review

Transmission of Chagas disease (CD) has decreased in recent decades, but the disease remains an important problem in endemic areas. There was an increase in the proportion of nonvector transmission, mainly in non-endemic countries. The aim of this study was to gather evidence concerning healthcare professional's knowledge about CD. Searches were performed through Medline/PubMed, Lilacs, Web of Science databases, and Scielo archives, from which 13/97 articles were selected for a qualitative analysis after full-text reading. Most of the studies were from the United States, the oldest published in 2007 and the most recent in 2020, and most of them used surveys as the evaluation method. Each article used different methods, according to the epidemiological status of vector transmission. Two studies targeted specialty-related questions, and two used focus groups as methods for data gathering. Despite differences between the studies, all of them presented knowledge deficits among healthcare workers, regarding at least one of the evaluated aspects. In comparison with population surveys, healthcare professionals demonstrated higher results related to clinical aspects and awareness of the disease's importance. Most of the articles showed a low perception of CD's knowledge by the participants and a low probability of considering CD in the diagnosis of their patients. A previous contact with the subject was pointed by some studies as capable of improving knowledge of the participants. This study emphasizes the importance of continuing education to address deficits of healthcare professionals' knowledge.

Didelphis spp. opossums and their parasites in the Americas: A One Health perspective

Medium sized opossums (Didelphis spp.) are among the most fascinating mammals of the Americas, playing important ecological roles (e.g., dispersal of seeds and control of insect populations) in the environment they inhabit. Nevertheless, as synanthropic animals, they are well adapted to human dwellings, occupying shelters within the cities, peripheral areas, and rural settings. These marsupials can harbor numerous pathogens, which may affect people, pets, and livestock. Among those, some protozoa (e.g., Leishmania infantum, Trypanosoma cruzi, Toxoplasma gondii), helminths (e.g., Ancylostoma caninum, Trichinella spiralis, Alaria marcianae, Paragonimus spp.) and arthropods (e.g., ticks, fleas) present substantial public health and veterinary importance, due to their capacity to cause disease in humans, domestic animals, and wildlife. Here, we reviewed the role played by opossums on the spreading of zoonotic parasites, vectors, and vector-borne pathogens, highlighting the risks of pathogens transmission due to the direct and indirect interaction of humans and domestic animals with Didelphis spp. in the Americas.

Shelter dogs as indicators for Trypanosoma cruzi infection in an urban area of Aracaju, Brazil

Shelters are places that receive certain species of domestic animals, mostly dogs and cats, that are normally abandoned. These animals are easy to handle because they are crowded and have limited movement. Dogs, due to the close relationship with humans, are considered the main domestic reservoirs in the peridomiciliary cycle of American trypanosomiasis infection in humans. Therefore, in several countries studies are carried out to assess the occurrence of infection in these animals. This work evaluated the occurrence of Trypanosoma cruzi in dogs from shelters in the city of Aracaju, Sergipe. This was an observational and cross-sectional study to detect the occurrence of T. cruzi in blood samples from shelter dogs using polymerase chain reaction (PCR) with the TcZ1/TcZ2 primers. A total of 168 blood samples from dogs (104 females and 64 males) were collected and subjected to DNA and PCR extraction, and seventeen (10.1%) samples showed amplification of the product of the expected size. The TcZ1/TcZ2 primer pair used is considered specific for T. cruzi, and it is capable of amplifying all strains without amplifying other Trypanosoma species. The shelters evaluated had different physical infrastructure; animals positive for T. cruzi were found in all of them, as confirmed by sequencing. It is concluded that shelter dogs, as well as other domestic animals, can function as indicators of the occurrence of T. cruzi in Aracaju-SE, providing relevant epidemiological information for health surveillance and monitoring of Trypanosomatid infections.

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.

Triatoma petrocchiae (Hemiptera, Reduviidae, Triatominae): A Chagas disease vector of T. brasiliensis species complex associated to reptiles

In semi-arid areas of northeastern Brazil, Chagas disease vectors of Triatoma brasiliensis species complex comprise a monophyletic group of kissing bugs that inhabit rock outcrops. Most of them exhibit allopatric or parapatric distribution; the exception is T. petrocchiae, which is found in cohabitation with T. brasiliensis in rock outcrops. We used vertebrate mitochondrial gene sequencing applied to DNA isolated from bug midgut to identify the insect blood meal sources via BLAST procedure. Fourteen sylvatic insects from four geographic districts in the states of Rio Grande do Norte and Paraíba had their blood meal sources detected. While T. brasiliensis is recorded to be associated mainly (52-71%) with rodents, T. petrocchiae samples were strongly associated (86%) with reptiles of Tropidurus and Hemidactylus genera. We suggest that T. petrocchiae is the single member within this complex to be associated with reptiles, indicating a distinct niche occupation related to the trophic resources.

Molecular eco-epidemiology on the sympatric Chagas disease vectors Triatoma brasiliensis and Triatoma petrocchiae: Ecotopes, genetic variation, natural infection prevalence by trypanosomatids and parasite genotyping

Triatoma petrocchiae is the newly member of the Triatoma brasiliensis species complex. This species overlaps with T. brasiliensis in geographic and ecotypic occupation in the sylvatic habitat because both inhabit rocky outcrops in the semi-arid portion of Brazilian northeast. In this region T. brasiliensis is the most important Chagas disease vector because it constantly colonizes domiciles. In contrast, T. petrocchiae is rarely found in peri or intradomiciliary habitats - reason why little is known about this species. Therefore, Here, we present information for the first time on. the T. petrocchiae ecotopes, genetic diversity, Trypanosoma cruzi prevalence/genotyping in comparison to T. brasiliensis. We found T. brasilensis (N = 223) and T. petrocchiae (N = 69) in co-habitation in rocky outcrops in three Districts of Paraíba and Rio Grande do Norte states. Forty-tree T. petrocchiae insects of eleven sampling spots (composing three geographic populations) were genotyped for the mitochondrial Cyt B gene and little geographic structure was observed. Tajima's D test suggested that species is evolving toward a mutation-drift equilibrium in our collection range. Sylvatic T. petrocchiae had 4% (3/68) of infected insects by T. cruzi, whereas T. brasiliensis had 26% (59/223). Fluorescent Fragment Length Barcoding demonstrated that all three T. petrocchiae harbored TcI whereas T. brasiliensis had TcI, but also TcIII, TcII/TcVI and T. rangeli genotype A, sometimes under mixed infections. None of infected T. petrocchiae were carrying mixed infections. However, this result should be confirmed using a larger pool of infected bugs. We here presented the first documentation of T. rangeli infecting T. brasiliensis. The finding of infected T. petrocchiae calls for constant vector monitoring because the epidemiologic scenario is dynamic and sylvatic vectors are progressively found in adaptation to anthropic environments.