Vector-borne transmission of Trypanosoma cruzi among captive Neotropical primates in a Brazilian zoo

Parasites and Viruses in Callithrix in Brazil

PURPOSE

As a result of environmental imbalances of anthropogenic origin, the potential for transmission of parasites and viruses between different primates, including humans, might increase. Thus, parasitic studies have great relevance to primatology, which motivated us to conduct a literature review to synthesize the information available in American primates of the Callithrix genus.

METHODS

We carried out the bibliographic search on the main groups of parasites (protozoa, helminths, arthropods, ectoparasites) and viruses found in Callithrix in Brazil in search platforms and consider all manuscript that appeared in search engines, published between the years 1910 and December 2022. In each selected article, the following information was recorded: the host species; parasite taxa; scientific classification of the parasite; host habitat (free-living, captive); diagnostic technique; state; and bibliographic reference. Data were tabulated and arranged in a parasite-host table.

RESULTS

Some endemic genera, such as Callithrix, are widely distributed geographically across Brazil and have characteristics of adaptation to different habitats due to their flexibility in diet and behavior. These factors can make them subject to a greater diversity of parasites and viruses in the country. Here, we identified 68 parasitic taxa, belonging to the clades protozoa (n = 22), helminths (n = 34), ectoparasites (n = 7), and viruses (n = 5). Out of this total, 19 have zoonotic potential. Of the six existing marmoset species, Callithrix jacchus was the most frequent in studies, and Callithrix flaviceps did not have reports. All regions of the country had occurrences, mainly the Southeast, where 54% of the cases were reported. In 46% of the reported parasites and viruses, it was not possible to identify the corresponding species.

CONCLUSION

We conclude that in part of the works the identification methods are not being specific, which makes it difficult to identify the species that affects Callithrix spp. Furthermore, the studies present geographic disparities, being concentrated in the southeast of the country, making it impossible to have a more uniform analysis of the findings. Thus, it is observed that information about parasites and viruses is incipient in the genus Callithrix in Brazil.

First Molecular Identification of Trypanosomes and Absence of Babesia sp. DNA in Faeces of Non-Human Primates in the Ecuadorian Amazon

Trypanosomes are a group of pathogens distributed in the continents of Africa, America, Asia and Europe, and they affect all vertebrates including the neotropical primate group. Information about the trypanosome's diversity, phylogeny, ecology and pathology in non-human primates (NHPs) from the neotropical region is scarce. The objective of the study was to identify Trypanosoma and Babesia molecularly in NHPs under the phylogenetic species concept. We extracted DNA from a total of 76 faecal samples collected between 2019 and 2021, from a total of 11 non-human primate species of which 46 are from captive NHPs and 30 are free-living NHPs in the Western Amazon region of Ecuador. We did not detect DNA of Babesia sp. by polymerase chain reaction test in any of the faecal samples. However, the nested-PCR-based method revealed Trypanosoma parasites by ITS gene amplification in two faecal samples; one for the species Leontocebus lagonotus (from the captive population) and a second one for Cebus albifrons (from the free-ranging population). Maximum parsimony and likelihood methods with the Kimura2+G+I model inferred the evolutionary history of the two records, which showed an evolutionary relationship with the genus Trypanosoma. Two sequences are monophyletic with Trypanosoma. However, the number of sequences available in GenBank for their species identification is limited. The two samples present different molecular identifications and evolutionary origins in the tree topology. We are most likely referring to two different species, and two different localities of infection. We suggest that health management protocols should be implemented to prevent the transmission of blood-borne pathogens such as Trypanosoma sp. among captive populations. In addition, these protocols also protect the personnel of wildlife rehabilitation centers working in close proximity to NHPs and vice versa.

Discovery of an orally active benzoxaborole prodrug effective in the treatment of Chagas disease in non-human primates

Trypanosoma cruzi, the agent of Chagas disease, probably infects tens of millions of people, primarily in Latin America, causing morbidity and mortality. The options for treatment and prevention of Chagas disease are limited and underutilized. Here we describe the discovery of a series of benzoxaborole compounds with nanomolar activity against extra- and intracellular stages of T. cruzi. Leveraging both ongoing drug discovery efforts in related kinetoplastids, and the exceptional models for rapid drug screening and optimization in T. cruzi, we have identified the prodrug AN15368 that is activated by parasite carboxypeptidases to yield a compound that targets the messenger RNA processing pathway in T. cruzi. AN15368 was found to be active in vitro and in vivo against a range of genetically distinct T. cruzi lineages and was uniformly curative in non-human primates (NHPs) with long-term naturally acquired infections. Treatment in NHPs also revealed no detectable acute toxicity or long-term health or reproductive impact. Thus, AN15368 is an extensively validated and apparently safe, clinically ready candidate with promising potential for prevention and treatment of Chagas disease.

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.

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.

Zoonotic Blood-Borne Pathogens in Non-Human Primates in the Neotropical Region: A Systematic Review

Background: Understanding which non-human primates (NHPs) act as a wild reservoir for blood-borne pathogens will allow us to better understand the ecology of diseases and the role of NHPs in the emergence of human diseases in Ecuador, a small country in South America that lacks information on most of these pathogens. Methods and principal findings: A systematic review was carried out using PRISMA guidelines from 1927 until 2019 about blood-borne pathogens present in NHPs of the Neotropical region (i.e., South America and Middle America). Results: A total of 127 publications were found in several databases. We found in 25 genera (132 species) of NHPs a total of 56 blood-borne pathogens in 197 records where Protozoa has the highest number of records in neotropical NHPs (n = 128) compared to bacteria (n = 12) and viruses (n = 57). Plasmodium brasilianum and Trypanosoma cruzi are the most recorded protozoa in NHP. The neotropical primate genus with the highest number of blood-borne pathogens recorded is Alouatta sp. (n = 32). The use of non-invasive samples for neotropical NHPs remains poor in a group where several species are endangered or threatened. A combination of serological and molecular techniques is common when detecting blood-borne pathogens. Socioecological and ecological risk factors facilitate the transmission of these parasites. Finally, a large number of countries remain unsurveyed, such as Ecuador, which can be of public health importance. Conclusions and significance: NHPs are potential reservoirs of a large number of blood-borne pathogens. In Ecuador, research activities should be focused on bacteria and viruses, where there is a gap of information for neotropical NHPs, in order to implement surveillance programs with regular and effective monitoring protocols adapted to NHPs.

Trypanosomatid infections in captive wild mammals and potential vectors at the Brasilia Zoo, Federal District, Brazil

Background

Conservation projects in zoos may involve translocation of captive animals, which may lead to pathogen spread. Neotropical mammals are important hosts of Trypanosoma cruzi and Leishmania spp. the etiological agents of Chagas disease and Leishmaniasis respectively. Studies of trypanosomatid‐infected mammals and vectors (triatomines and sandflies) in zoos are important for the establishment of surveillance and control measures.

Objectives

We investigated trypanosomatid infections in captive wild mammals, triatomines and sandflies at the Brasília Zoo.

Methods

We collected triatomines during active bimonthly surveys, sampled sandflies using light‐traps and obtained blood samples from 74 mammals between 2016 and 2017. We used quantitative PCR to detect trypanosomatids in vectors and mammals.

Results

We found a colony of 19 Panstrongylus megistus in the porcupine unit and detected T. cruzi infections in five bugs. We captured 17 sandflies of four species including Nyssomyia whitmani and Lutzomyia longipalpis, but no Leishmania infection was detected. qPCR detected 50 T. cruzi‐infected mammals belonging to 24 species and five groups of mammals (Carnivora, Cetartiodactyla, Perissodactyla, Pilosa and Primates); Leishmania DNA was detected in 23 mammals from 15 species, mainly carnivores. We detected trypanosomatid infections in 11 mammals born at the Brasília Zoo.

Conclusions

Our results suggest vector‐borne transmission of T. cruzi among maned wolves; measures to reduce the risk of new infections should therefore be taken. We also report sandfly presence and Leishmania‐infected mammals at the Brasília Zoo. Translocation of wild mammals in and out of the Brasília Zoo should consider the risk of T. cruzi and Leishmania spread.

Trypanosoma cruzi Transmission Among Captive Nonhuman Primates, Wildlife, and Vectors

Natural infection of captive nonhuman primates (NHPs) with Trypanosoma cruzi (agent of Chagas disease) is an increasingly recognized problem in facilities across the southern USA, with negative consequences for NHP health and biomedical research. We explored a central Texas NHP facility as a nidus of transmission by characterizing parasite discrete typing units (DTU) in seropositive rhesus macaques (Macaca mulatta), identifying the wildlife reservoirs, and characterizing vector infection. In seropositive NHPs, we documented low and intermittent concentrations of circulating T. cruzi DNA, with two DTUs in equal proportions, TcI and TcIV. In contrast, consistently high concentrations of T. cruzi DNA were found in wild mesomammals at the facility, yet rodents were PCR-negative. Strong wildlife host associations were found in which raccoons (Procyon lotor) harbored TcIV and opossums (Didelphis virginiana) harbored TcI, while skunks (Mephitis mephitis) were infected with both DTUs. Active and passive vector surveillance yielded three species of triatomines from the facility and in proximity to the NHP enclosures, with 17% T. cruzi infection prevalence. Interventions to protect NHP and human health must focus on interrupting spillover from the robust sylvatic transmission in the surrounding environment.

Synanthropic triatomines as potential vectors of Trypanosoma cruzi in Central Brazil

INTRODUCTION

Chagas disease surveillance requires current knowledge on synanthropic triatomines. We analyzed the occurrence and Trypanosoma cruzi infection rates of triatomine bugs in central Brazil, during 2012-2014.

METHODS

Triatomines were collected inside or around houses, and T. cruzi infection was determined by optical microscopy and conventional/quantitative polymerase chain reaction.

RESULTS

Of the 2706 triatomines collected, Triatoma sordida was the most frequent species in Goiás State, whereas Panstrongylus megistus predominated in the Federal District. Parasites identified were T. cruzi, T. rangeli, and Blastocrithidia sp.

CONCLUSIONS

P. megistus and T. sordida sustained the risk of T. cruzi transmission to humans in central Brazil.

High frequency of trypanosomatids in gallery forest bats of a Neotropical savanna

Bats are well-known hosts of trypanosomatids, though information about their role as reservoirs of these protozoans in the Brazilian savanna is poorly known. We aimed to analyze the occurrence of trypanosomatid species in bats occurring in remnants of gallery forests of Brasília, Federal District of Brazil. We sampled bats using mist nets in six sites, and we collected blood, wing fragments and oral swab samples from all captured individuals. Trypanosomatids were identified in the captured bats through sequencing of the SSUrRNA region and kDNA qPCR. We found no parasite in blood smears of 146 individuals of 14 species captured, but blood cultures were positive for nine bats. We detected trypanosomatids molecularly in 111 (76%) specimens of all bat species in the studied areas. Most of the infected bats had Leishmania-like DNA detected in blood and swab samples of the oral mucosa. We distinguished three species of Trypanosoma (Trypanosoma dionisii, T. rangeli and T. cruzi) in Carollia perspicillata. SSUrRNA PCR of oral samples is a non-invasive and practical method for identification of trypanosomatid species in bats. Our results support our belief that bats could be potential reservoirs for Trypanosoma and Leishmania-like species in the enzootic cycle of these parasites in gallery forests of the Brazilian Cerrado biome.

Development of conventional and real-time multiplex PCR-based assays for estimation of natural infection rates and Trypanosoma cruzi load in triatomine vectors

BACKGROUND

Chagas disease is a complex anthropozoonosis with distinct domestic and sylvatic mammal species acting as potential reservoirs. The diversity of vector species and their habitats are among the factors that hinder the control of the disease. Control programs periodically monitor the prevalence of T. cruzi infection in insect bugs through microscopical observation of diluted feces. However, microscopy presents limited sensitivity in samples with low parasite numbers, difficulties in examining all evolutionary stages of the insect and may in turn be limited to differentiate T. cruzi from other morphologically similar trypanosomatids. Here, we report two highly sensitive and accurate methodologies to infer T. cruzi infection rates and to quantify parasite load in the gut of field-collected triatomines.

METHODS

Triatomines were manually collected in the period 2011-2012 and 2014-2015, in domestic, peridomestic or sylvatic habitats in rural areas of 26 municipalities, encompassing three distinct Brazilian biomes: Caatinga, Cerrado and Atlantic Rainforest. Following morphological and taxonomical identification, the search for flagellated protozoa was performed by optical microscopy. A conventional PCR targeting T. cruzi kDNA and a TaqMan qPCR directed to the parasite nuclear satellite DNA (SAT) were developed, both in multiplex, with the triatomine 12S subunit ribosomal RNA gene, used as internal amplification control. Both methods were used for detection (kDNA-PCR) and parasite load quantification (SAT-DNA-qPCR), to investigate T. cruzi infection in captured triatomines.

RESULTS

The combined methods were assayed on a panel of 205 field-collected triatomine samples. Diagnostic analysis revealed 21% positivity for the kDNA-PCR, whereas microscopic examination enabled identification of T. cruzi in only 7.0% of the PCR-positive samples. Negative PCR results were confirmed by the absence of T. cruzi flagellates using microscopy. Caatinga biome yielded the highest T. cruzi infection rate (60%), followed by the Atlantic Rainforest and Cerrado with 7.1 and 6.1%, respectively. In addition, a wide range distribution of parasite load, varying from 8.05 × 10-2 to 6.31 × 1010 was observed with a median of 2.29 × 103 T. cruzi/intestine units. When parasite load was analyzed by triatomine species, a significantly higher median was found for Panstrongylus lutzi in comparison with Triatoma brasiliensis.

CONCLUSIONS

Our results demonstrate highly sensitive PCR-based methodologies to monitor T. cruzi infection in triatomines. In addition, the qPCR assay offers the possibility of further evaluation parasite load, as a promising biomarker of the vectorial capacity of triatomines in Chagas disease endemic areas.

Lineage-specific serology confirms Brazilian Atlantic forest lion tamarins, Leontopithecus chrysomelas and Leontopithecus rosalia, as reservoir hosts of Trypanosoma cruzi II (TcII)

Background

Trypanosoma cruzi, the agent of Chagas disease in humans, has a vast reservoir of mammalian hosts in the Americas, and is classified into six genetic lineages, TcI-TcVI, with a possible seventh, TcBat. Elucidating enzootic cycles of the different lineages is important for understanding the ecology of this parasite, the emergence of new outbreaks of Chagas disease and for guiding control strategies. Direct lineage identification by genotyping is hampered by limitations of parasite isolation and culture. An indirect method is to identify lineage-specific serological reactions in infected individuals; here we describe its application with sylvatic Brazilian primates.

Methods

Synthetic peptides representing lineage-specific epitopes of the T. cruzi surface protein TSSA were used in ELISA with sera from Atlantic Forest Leontopithecus chrysomelas (golden-headed lion tamarin), L. rosalia (golden lion tamarin), Amazonian Sapajus libidinosus (black-striped capuchin) and Alouatta belzebul (red-handed howler monkey).

Results

The epitope common to lineages TcII, TcV and TcVI was recognised by sera from 15 of 26 L. chrysomelas and 8 of 13 L. rosalia. For 12 of these serologically identified TcII infections, the identity of the lineage infection was confirmed by genotyping T. cruzi isolates. Of the TcII/TcV/TcVI positive sera 12 of the 15 L. chrysomelas and 2 of the 8 L. rosalia also reacted with the specific epitope restricted to TcV and TcVI. Sera from one of six S. libidinous recognised the TcIV/TcIII epitopes.

Conclusions

This lineage-specific serological surveillance has verified that Atlantic Forest primates are reservoir hosts of at least TcII, and probably TcV and TcVI, commonly associated with severe Chagas disease in the southern cone region of South America. With appropriate reagents, this novel methodology is readily applicable to a wide range of mammal species and reservoir host discovery.

First report of Sapajus cay naturally infected by Trypanosoma cruzi in San Pedro Department, Paraguay

To verify the occurrence of natural Trypanosoma cruzi infection in non-human primates from a rural endemic area of the east region of Paraguay, xenodiagnosis was performed in 35 animals belonging to two species. For genotyping and T. cruzi discrete typing unit (DTU) assignment, a combination of four markers was used, including amplification products of the small (18S) and large (24Sα) subunits of ribosomal ribonucleic acid gene, the intergenic region of mini-exon gene and the heat shock protein 60 Eco-RV polymerase chain reaction-restriction fragment length polymorphism (HSP60/EcoRV-PCR-RFLP). One specimen of Sapajus cay was found positive and infected by the DTU TcII. This result constitutes the first record of natural T. cruzi infection in a sylvatic monkey in Paraguay, harbouring a DTU associated with severe Chagas disease in humans.