Wild and Domestic Canids and Their Interactions in the Transmission Cycles of Trypanosoma Cruzi and Leishmania spp. in an Area of the Brazilian Cerrado

Enzootic transmission of Leishmania spp. in gallery forests of the Brazilian Cerrado

Gallery forests harbor mammals and sand flies that may be involved in the transmission of Leishmania spp. parasites. Characterizing the enzootic cycles of Leishmania spp. is essential for understanding its transmission dynamics. We analyzed the presence of Leishmania spp. in mammals and sand flies in gallery forests during the dry season in the Cerrado. Four gallery forests were investigated in May and September 2014. Our capture effort included 1,280 HP trap-nights, 16 Shannon trap-nights for sand flies, and 5,120 trap-nights for mammals. After identifying the mammalian and sand fly species, SSU rRNA and ITS-1 polymerase chain reaction (PCR) were used to detect Leishmania spp. A total of 1,209 sand flies belonging to 13 species were captured, mainly Bichromomyia flaviscutellata. Leishmania spp. DNA was not detected in the analyzed sand fly females. PCR analysis of 153 mammals revealed Leishmania spp. in 20 samples (13%) in May (early dry season), when the infection rate was 31% in one gallery forest. The host species were Rhipidomys macrurus, Gracilinanus agilis, and Didelphis albiventris. We observed a low frequency of mammals infected with Leishmania spp., which was not detected in sand flies. Our results indicate that Leishmania spp. infection is higher in mammals during the early dry season in Cerrado gallery forests.

Exploring dietary differences among developmental stages of triatomines infected with Trypanosoma cruzi in different habitats

Chagas disease affects millions of people in Colombia and worldwide, with its transmission influenced by ecological, environmental, and anthropogenic factors. There is a notable correlation between vector transmission cycles and the habitats of insect vectors of the parasite. However, the scale at which these cycles operate remains uncertain. While individual triatomine ecotopes such as palms provide conditions for isolated transmission cycles, recent studies examining triatomine blood sources in various habitats suggest a more intricate network of transmission cycles, linking wild ecotopes with human dwellings. This study aims to provide further evidence on the complexity of the scale of Trypanosoma cruzi transmission cycles, by exploring the different blood sources among developmental stages of infected triatomines in different habitats. We evaluated infection rates, parasite loads, feeding sources, and the distribution of Rhodnius prolixus insects in Attalea butyracea palms across three distinct habitats in Casanare, Colombia: peridomestics, pastures, and woodlands. Our results show that there is no clear independence in transmission cycles in each environment. Analyses of feeding sources suggest the movement of insects and mammals (primarily bats and didelphids) among habitats. A significant association was found between habitat and instar stages in collected R. prolixus. The N1 stage was correlated with pasture and woodland, while the N4 stage was related to pasture. Additionally, adult insects exhibited higher T. cruzi loads than N1, N2, and N3. We observed higher T. cruzi loads in insects captured in dwelling and pasture habitats, compared with those captured in woodland areas. Effective Chagas disease control strategies must consider the complexity of transmission cycles and the interplay between domestic and sylvatic populations of mammals and vectors.

Chagas Disease: A Silent Threat for Dogs and Humans

Chagas disease (CD) is a vector-borne Neglected Zoonotic Disease (NZD) caused by a flagellate protozoan, Trypanosoma cruzi, that affects various mammalian species across America, including humans and domestic animals. However, due to an increase in population movements and new routes of transmission, T. cruzi infection is presently considered a worldwide health concern, no longer restricted to endemic countries. Dogs play a major role in the domestic cycle by acting very efficiently as reservoirs and allowing the perpetuation of parasite transmission in endemic areas. Despite the significant progress made in recent years, still there is no vaccine against human and animal disease, there are few drugs available for the treatment of human CD, and there is no standard protocol for the treatment of canine CD. In this review, we highlight human and canine Chagas Disease in its different dimensions and interconnections. Dogs, which are considered to be the most important peridomestic reservoir and sentinel for the transmission of T. cruzi infection in a community, develop CD that is clinically similar to human CD. Therefore, an integrative approach, based on the One Health concept, bringing together the advances in genomics, immunology, and epidemiology can lead to the effective development of vaccines, new treatments, and innovative control strategies to tackle CD.

A phased genome assembly of a Colombian Trypanosoma cruzi TcI strain and the evolution of gene families

Chagas is an endemic disease in tropical regions of Latin America, caused by the parasite Trypanosoma cruzi. High intraspecies variability and genome complexity have been challenges to assemble high quality genomes needed for studies in evolution, population genomics, diagnosis and drug development. Here we present a chromosome-level phased assembly of a TcI T. cruzi strain (Dm25). While 29 chromosomes show a large collinearity with the assembly of the Brazil A4 strain, three chromosomes show both large heterozygosity and large divergence, compared to previous assemblies of TcI T. cruzi strains. Nucleotide and protein evolution statistics indicate that T. cruzi Marinkellei separated before the diversification of T. cruzi in the known DTUs. Interchromosomal paralogs of dispersed gene families and histones appeared before but at the same time have a more strict purifying selection, compared to other repeat families. Previously unreported large tandem arrays of protein kinases and histones were identified in this assembly. Over one million variants obtained from Illumina reads aligned to the primary assembly clearly separate the main DTUs. We expect that this new assembly will be a valuable resource for further studies on evolution and functional genomics of Trypanosomatids.

Neglected zoonotic helminthiases in wild canids: new insights from South America

The global threat of neglected tropical diseases (NTDs) constitutes a public health issue in underdeveloped countries. Zoonotic helminthiases are the most common human NTD agents in developing countries in sub-Saharan Africa, Asia, and the Americas, causing a global burden of disease that exceeds that of more recognized infectious diseases such as malaria and tuberculosis. Wild canids are well-known mammals that act as natural reservoirs of zoonotic-relevant helminthiasis worldwide, thus playing a pivotal role in their epidemiology and transmission to humans. Here we evaluate the occurrence of zoonotic gastrointestinal helminths in two Neotropical wild canid species from the Amazonian and Andean regions of Colombia, i.e., the bush dog (Speothos venaticus) and the crab-eating fox (Cerdocyon thous). We recovered tapeworm proglottids from bush dog fecal samples and identified them molecularly as the canine-specific lineage of Dipylidium caninum by using cytochrome c oxidase subunit I (cox1) gene sequences. Moreover, examination of a crab-eating fox during necropsy revealed the presence of non-embryonated eggs of the neglected nematode Lagochilascaris cf. minor, in addition to eggs and gravid proglottids of the cestode Spirometra mansoni. These findings represent the first report of zoonotic-relevant cestodes, i.e., D. caninum ("canine genotype"), S. mansoni, and the nematode L. cf. minor, in bush dogs and crab-eating foxes as final hosts. The occurrence of these zoonotic helminthiases in wild canid species calls for regular monitoring programs to better understand the epidemiology and transmission routes of neglected dipylidiasis, lagochilascariosis, and sparganosis in South America.

Identification of infection by Leishmania spp. in wild and domestic animals in Brazil: a systematic review with meta-analysis (2001-2021)

Leishmaniasis is a zoonosis caused by protozoan species of the genus Leishmania. It generates different clinical manifestations in humans and animals, and it infects multiple hosts. Leishmania parasites are transmitted by sandfly vectors. The main objective of this systematic review was to identify the host, or reservoir animal species, of Leishmania spp., with the exception of domestic dogs, that were recorded in Brazil. This review included identification of diagnostic methods, and the species of protozoan circulating in the country. For this purpose, a literature search was conducted across index journals. This study covered the period from 2001 to 2021, and 124 studies were selected. Eleven orders possible hosts were identified, including 229 mammalian species. Perissodactyla had the highest number of infected individuals (30.69%, 925/3014), with the highest occurrence in horses. In Brazil, the most commonly infected species were found to be: horses, domestic cats, rodents, and marsupials. Bats, that were infected by one or more protozoan species, were identified as potential reservoirs of Leishmania spp. Molecular tests were the most commonly used diagnostic methods (94 studies). Many studies have detected Leishmania spp. (n = 1422): Leishmania (Leishmania) infantum (n = 705), Leishmania (Viannia) braziliensis (n = 319), and Leishmania (Leishmania) amazonensis (n = 141). Recognizing the species of animals involved in the epidemiology and biological cycle of the protozoan is important, as this allows for the identification of environmental biomarkers, knowledge of Leishmania species can improve the control zoonotic leishmaniasis.

Kinetoplastid Species Maintained by a Small Mammal Community in the Pantanal Biome

Kinetoplastids include species economically important in agriculture, livestock, and human health. We evaluated the richness of kinetoplastids that infect small mammals in patches of unflooded forests in the Pantanal biome, an area where we hypothesize that its diversity is higher than currently recognized. Hemocultures (HC) and Next Generation Sequencing (NGS) targeting the 18S rDNA gene were employed for the detection of kinetoplastids. We grouped the positive samples into pools for each small mammal species (Monodelphis domestica, Thylamys macrurus, Oecomys mamorae, Thrichomys fosteri, Clyomys laticeps, and Holochilus chacarius). Eight parasite species were identified: Leishmania amazonensis, L. infantum; Trypanosoma cascavelli (HC + NGS), T. cruzi, T. lainsoni, T. rangeli (HC + NGS), Trypanosoma sp. DID, and Neobodo sp. The use of a tool as sensitive as NGS has increased our awareness of the diversity of kinetoplastids, as well as their host range, with emphasis on the species O. mamorae (seven kinetoplastid species, excepting T. cascavelli in a pool of nine individuals) and T. macrurus (four kinetoplastid species in a single individual). Furthermore, L. infantum and L. amazonensis infections were described in small mammals from this region for the first time. These findings make it mandatory to revisit the kinetoplastids/host associations proposed so far.

Chagas Immunochromatographic Rapid Test in the Serological Diagnosis of Trypanosoma cruzi Infection in Wild and Domestic Canids

Canis lupus familiaris (domestic dog) represents a reliable sentinel for the occurrence of a well-established transmission cycle of Trypanosoma cruzi among wild mammals in the surroundings and, consequently, where the risk of human infection exists. Serological diagnosis is the chosen method to identify T. cruzi infection in dogs that, in Brazil, rarely present positive parasitological tests. The use of recombinant chimeric parasitic antigens results in a sensitive and specific serological diagnostic test in contrast to the use of crude T. cruzi antigens. Our objective was to evaluate the Chagas/Bio-Manguinhos Lateral Flow Immunochromatographic Rapid Test (Chagas-LFRT) for the diagnosis of T. cruzi infection in domestic dogs and the potential of application of this diagnostic platform to wild canid species. Two recombinant proteins (IBMP-8.1 and IBMP-8.4) that displayed the best performance in the enzyme immunoassay (ELISA) in previous studies were tested in a platform with two diagnostic bands. A panel of 281 dog serum samples was evaluated: 133 positive for T. cruzi by serological diagnosis, including 20 samples with positive blood cultures belonging to different discrete typing units (DTUs); 129 negative samples; and 19 samples from dogs infected by other trypanosomatids: Leishmania infantum, Trypanosoma rangeli, Trypanosoma caninum and Crithidia mellificae, in addition to samples infected by Anaplasma platys, Dirofilaria immitis and Erlichia sp. that were employed to evaluate eventual cross-reactions. We also evaluated the Chagas-LFRT to detect T. cruzi infection in 9 serum samples from six wild canid species. We observed that the intensity pattern of the bands was directly proportional to the serological titer observed in IFAT. The sensitivity was 94%, the specificity was 91% according to the ROC curve, and the defined cutoff was an optical density of 4.8. The agreement obtained was considered substantial by the kappa analysis (84%). From T. cruzi positive hemoculture samples, 88.9% were positive by Chagas-LFRT. The test was efficient in recognizing infections by five of the six T. cruzi DTUs. Cross-reactions were not observed in infections by L. infantum, T. rangeli, T. caninum and D. immitis; however, they were observed in sera of dogs infected by Crithidia mellificae, Anaplasma sp. and Erlichia sp. A strong reaction was observed when serum samples from wild canids were submitted to the Protein A affinity test, confirming its applicability for these species. This test will allow rapid preventive actions in areas with high risk to the emergence of Chagas disease in a safer, reliable, low-cost and immediate manner, without the need for more complex laboratory tests.

Trypanosomatid Richness in Wild and Synanthropic Small Mammals from a Biological Station in Rio de Janeiro, Brazil

Trypanosomatids are diverse and can infect several host species, including small mammals (rodents and marsupials). Between 2012 and 2014, 91 small mammals were surveyed for trypanosomatid infection in the Estação Biológica FIOCRUZ Mata Atlântica (EFMA), an Atlantic Forest area in Rio de Janeiro that presents different levels of conserved and degraded areas. Blood, skin, liver, and spleen samples were submitted to parasitological, serological, and molecular assays to detect the infection and determine the taxonomic status of their parasites. Sixty-eight individuals (74.7%; n = 91) were infected by trypanosomatids, including fourteen mixed infected by different trypanosomatid parasites. These hosts were infected by: T. cruzi DTU TcI (n = 12), T. cruzi DTU TcIV (n = 2), T. janseni (n = 15), T. dionisii (n = 1), and T. rangeli A (n = 1) detected in blood or tissue cultures, in addition to T. cruzi DTU TcI (n = 9) and Leishmania sp. (n = 1) only by the molecular diagnosis. Serological diagnosis was positive in 38 (71.6%) individuals for T. cruzi, the same amount for Leishmania spp., and 23 (43.3%) individuals were mixed infected. These data indicate a remarkable richness of trypanosomatid species/genotypes infecting small mammals, even in a disturbed area with low mammal species diversity—as is the case of the EFMA—reinforcing the generalist aspect of these parasites.

Development of an Amplicon-Based Next-Generation Sequencing Protocol to Identify Leishmania Species and Other Trypanosomatids in Leishmaniasis Endemic Areas

Trypanosomatid infections are an important public health threat affecting many low-income countries across the tropics, particularly in the Americas. Trypanosomatids can infect many vertebrate, invertebrate, and plant species and play an important role as human pathogens. Among these clinically relevant pathogens are species from the genera Leishmania and Trypanosoma. Mixed trypanosomatid infections remain a largely unexplored phenomenon. Herein, we describe the application of an amplicon-based next-generation sequencing (NGS) assay to detect and identify trypanosomatid species in mammalian reservoirs, human patients, and sand fly vectors throughout regions of Leishmania endemicity. Sixty-five samples from different departments of Colombia, including two samples from Venezuela, were analyzed: 49 samples from cutaneous leishmaniasis (CL) patients, 8 from sand flies, 2 from domestic reservoirs (Canis familiaris), and 6 from wild reservoirs (Phyllostomus hastatus). DNA from each sample served to identify the presence of trypanosomatids through conventional PCR using heat shock protein 70 (HSP70) gene as the target. PCR products underwent sequencing by Sanger sequencing and NGS, and trypanosomatid species were identified by using BLASTn against a reference database built from trypanosomatid-derived HSP70 sequences. The alpha and beta diversity indexes of amplicon sequence variants were calculated for each group. The results revealed the presence of mixed infections with more than two Leishmania species in 34% of CL samples analyzed. Trypanosoma cruzi was identified in samples from wild reservoirs, as well as in sand fly vectors. Coinfection events with three different Leishmania species were identified in domestic reservoirs. These findings depose the traditional paradigm of leishmaniasis as being a single-species-driven infection and redraw the choreography of host-pathogen interaction in the context of multiparasitism. Further research is needed to decipher how coinfections may influence disease progression. This knowledge is key to developing an integrated approach for diagnosis and treatment.

IMPORTANCE Traditionally, there has been a frequent, yet incorrect assumption that phlebotomine vectors, animal reservoirs, and human hosts are susceptible to Leishmania infection by a single parasite species. However, current evidence supports that these new vector-parasite-reservoir associations lend vectors and reservoirs greater permissiveness to certain Leishmania species, thus promoting the appearance of coinfection events, particularly in disease-endemic regions. The present study describes the application of an amplicon-based next-generation sequencing (NGS) assay to detect and identify trypanosomatid species in mammalian reservoirs, human patients, and sand fly vectors from regions of endemicity for leishmaniasis. This changes our understanding of the clinical course of leishmaniasis in areas of endemicity.

A Systematic Review (1990-2021) of Wild Animals Infected with Zoonotic Leishmania

Leishmaniasis are neglected diseases caused by several species of Leishmania that affect humans and many domestic and wild animals with a worldwide distribution. The objectives of this review are to identify wild animals naturally infected with zoonotic Leishmania species as well as the organs infected, methods employed for detection and percentage of infection. A literature search starting from 1990 was performed following the PRISMA methodology and 161 reports were included. One hundred and eighty-nine species from ten orders (i.e., Carnivora, Chiroptera, Cingulata, Didelphimorphia, Diprotodontia, Lagomorpha, Eulipotyphla, Pilosa, Primates and Rodentia) were reported to be infected, and a few animals were classified only at the genus level. An exhaustive list of species; diagnostic techniques, including PCR targets; infected organs; number of animals explored and percentage of positives are presented. L. infantum infection was described in 98 wild species and L. (Viania) spp. in 52 wild animals, while L. mexicana, L. amazonensis, L. major and L. tropica were described in fewer than 32 animals each. During the last decade, intense research revealed new hosts within Chiroptera and Lagomorpha. Carnivores and rodents were the most relevant hosts for L. infantum and L. (Viannia) spp., with some species showing lesions, although in most of the studies clinical signs were not reported.