Molecular detection of Leishmania spp. in road-killed wild mammals in the Central Western area of the State of São Paulo, Brazil

Absence of Leishmania spp. DNA in road-killed wild mammals in Southern Brazil

Leishmaniasis are neglected diseases transmitted by vectors that affect domestic and wild animals, including humans. Due to its incidence and lethality, this zoonosis is a worrying public health problem, making it essential to identify all links in the transmission chain. Infection of wild mammals by Leishmania spp. remains poorly understood, especially in southern Brazil. Therefore, the objective was to research, using the PCR technique, the presence of Leishmania spp. DNA in road-killed wild mammals in Southern Brazil. Carcasses of 96 animals were collected from highways in the Pelotas microregion, Rio Grande do Sul, southern Brazil and subjected to necropsies. Tissue fragments (spleen, skin, liver, kidney, heart, lung, lymph nodes, bone marrow and blood) were collected and genomic DNA was extracted. PCR protocols targeting the ITS1, kDNA and 18S genes were tested. We found no evidence of Leishmania spp. circulation in the studied population. However, epidemiological studies like this one are of great relevance, as they allow monitoring of the occurrence of pathogens and help identify possible risk areas. As these animals act as epidemiological markers for the presence of the microorganism, studies must be carried out continuously to understand whether there are sources of infection in the region.

Canine Parvovirus 2 in Free-Living Wild Mammals from Southern Brazil

Pathogens from domestic canines represent a significant and constant threat to wildlife. This study looked for four common canine pathogens, Babesia vogeli, Ehrlichia canis, Leishmania infantum, and canine parvovirus 2 (CPV-2) in mammals from the Pampa Biome, southern Brazil. Animals killed by vehicular trauma on a road traversing this biome were evaluated over a 1-yr period. Tissues collected from 31 wild mammals and six dogs were further analyzed by specific real-time PCR assays for each pathogen. Babesia vogeli and L. infantum were not detected in any investigated animal. Ehrlichia canis was detected in one dog and CPV-2 in nine animals: four dogs, three white-eared opossums (Didelphis albiventris), one pampas fox (Lycalopex gymnocercus), and one brown rat (Rattus norvegicus). These results demonstrate the occurrence of important carnivore pathogens (E. canis and CPV-2) in domestic dogs and wild mammals from the Pampa Biome in southern Brazil.

Phylogenetic and biogeographical traits predict unrecognized hosts of zoonotic leishmaniasis

The spatio-temporal distribution of leishmaniasis, a parasitic vector-borne zoonotic disease, is significantly impacted by land-use change and climate warming in the Americas. However, predicting and containing outbreaks is challenging as the zoonotic Leishmania system is highly complex: leishmaniasis (visceral, cutaneous and muco-cutaneous) in humans is caused by up to 14 different Leishmania species, and the parasite is transmitted by dozens of sandfly species and is known to infect almost twice as many wildlife species. Despite the already broad known host range, new hosts are discovered almost annually and Leishmania transmission to humans occurs in absence of a known host. As such, the full range of Leishmania hosts is undetermined, inhibiting the use of ecological interventions to limit pathogen spread and the ability to accurately predict the impact of global change on disease risk. Here, we employed a machine learning approach to generate trait profiles of known zoonotic Leishmania wildlife hosts (mammals that are naturally exposed and susceptible to infection) and used trait-profiles of known hosts to identify potentially unrecognized hosts. We found that biogeography, phylogenetic distance, and study effort best predicted Leishmania host status. Traits associated with global change, such as agricultural land-cover, urban land-cover, and climate, were among the top predictors of host status. Most notably, our analysis suggested that zoonotic Leishmania hosts are significantly undersampled, as our model predicted just as many unrecognized hosts as unknown hosts. Overall, our analysis facilitates targeted surveillance strategies and improved understanding of the impact of environmental change on local transmission cycles.

Infection agents of Didelphidae (Didelphimorphia) of Brazil: an underestimated matter in zoonoses research

Zoonoses are diseases or infections naturally transmissible from vertebrate animals to humans, and can be bacterial, viral or parasitic. The growth of urbanization, industrialization and the advance of agriculture and livestock facilitate the spread of infectious and parasitic agents from wild animals to the human population and to their domestic animals. Among the various reservoirs of zoonotic agents, we find that didelphid species, due to their high capacity for adaptation in urban environments, as an important study case. We reviewed the literature data on the pathogens, including with zoonotic potential of marsupial species occurring in Brazil, accounted for infections by agents that we categorized into Bacteria, Viruses, Protozoa, and Helminths. Aiming identifies possible knowledge gaps, we also surveyed the origin of studied samples and the institutions leading the researches on host didelphids. Among the hosts, the genus Didelphis in the cycles of these agents stands out. Moreover, we found that the majority of reported cases are in the Southeastern Brazil, mean the data from other Brazilian localities and didelphid species could be underestimated. Most studies took place in graduate programs of public research institutions, emphasizing the importance of the funding public research for the Brazilian scientific development.

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.

Evaluation of an active and early surveillance methodology for visceral leishmaniasis by molecular detection in road-killed wild fauna

The present study aimed to evaluate a methodology for active surveillance of visceral leishmaniasis by detecting Leishmania DNA in organs of wild road-killed animals from November 2016 to October 2018 in the North of Paraná, Brazil. The collection points of road-killed wild animals were georeferenced. The animals were autopsied and samples of bone marrow, lymph node, liver, spleen, and ear skin were collected. Genomic DNA was extracted and subjected to PCR for amplification of Leishmania spp. 18S, kinetoplastic DNA (kDNA), HSP70, and ITS1 genes, and DNA sequencing was performed. The primers used for the amplification of kDNA, ITS1, and HSP70 genes presented non-specific results. Of the 66 mammals collected from 24 different municipalities, one Southern Tamandua (Tamandua tetradactyla) presented DNA of Leishmania spp. in lymph nodes by 18S PCR. DNA sequencing confirmed the results of the subgenus, Viannia, identification. We suggest using the methodology showed in the present study in the active and early surveillance of visceral leishmaniasis in a non-endemic area.

One Health Approach to Leishmaniases: Understanding the Disease Dynamics through Diagnostic Tools

Leishmaniases are zoonotic vector-borne diseases caused by protozoan parasites of the genus Leishmania that affect millions of people around the globe. There are various clinical manifestations, ranging from self-healing cutaneous lesions to potentially fatal visceral leishmaniasis, all of which are associated with different Leishmania species. Transmission of these parasites is complex due to the varying ecological relationships between human and/or animal reservoir hosts, parasites, and sand fly vectors. Moreover, vector-borne diseases like leishmaniases are intricately linked to environmental changes and socioeconomic risk factors, advocating the importance of the One Health approach to control these diseases. The development of an accurate, fast, and cost-effective diagnostic tool for leishmaniases is a priority, and the implementation of various control measures such as animal sentinel surveillance systems is needed to better detect, prevent, and respond to the (re-)emergence of leishmaniases.

Epidemiological study of ticks collected from the northern tamandua (Tamandua mexicana) and a literature review of ticks of Myrmecophagidae anteaters

The family Myrmecophagidae contains three anteater species: Tamandua mexicana (Saussure, 1860), Tamandua tetradactyla (Linnaeus, 1758) and Myrmecophaga tridactyla (Linnaeus, 1758). These American anteater species currently face many conservation threats, among which road traffic accidents stand out. Parasitic studies on this family are scarce, and some of them include records of ectoparasites. Specifically for northern tamandua (T. mexicana), there is a lack of studies at population level. The objectives of the present research were to carry out an epidemiological study of tick species and its abundance on road-killed northern anteater specimens and, moreover, to perform a literature review of ticks collected from anteaters of Myrmecophagidae family. Five tick species were identified, including four Amblyomma spp. and Rhipicephalus sanguineus sensu lato, on 23 road-killed anteaters. Tick infestation prevalence was 43% (10/23), with a median tick infestation intensity of 3.5 per anteater (interquartile range 1-13.7). The bibliographic review highlighted the existence of twenty-nine ixodid species recorded on the three anteater species from 14 countries, mainly Brazil. The most common tick species on the Myrmecophagidae family are Amblyomma nodosum, A. calcaratum, A. cajennense sensu lato and A. auricularium. Some of these ixodids were also described as vectors of pathogens. Further studies are needed to evaluate the impact of ticks on anteater fitness, and to assess the role of these mammals as reservoirs of vector-borne diseases.

Antibodies and Molecular Detection of Leishmania (Leishmania) infantum in Samples of Free-Ranging Marmosets (Primates: Callitrichidae: Callithrix spp.) in an Area of Canine Visceral Leishmaniasis in Southeastern Brazil

Leishmaniasis is a vector-borne parasitic protozoan infection that affects mammals and involves a complex epidemiology. Although dogs are considered the main reservoir in zoonotic visceral leishmaniasis (VL), the possible presence of other mammalian species acting as reservoirs has been associated as a possible cause of lack of success in the control of human VL in many endemic areas. The knowledge about natural infections of some species is still scarce, such as nonhuman primates (NHP), especially from the genus Callithrix (marmosets). We investigated the infection by Leishmania (Leishmania) infantum, the agent of VL in the Americas, in 26 marmosets captured monthly, from April 2014 to March 2015, in an environmentally protected area (EPA) in Southeastern Brazil. The EPA has undergone significant environmental changes and has a transmission focus of canine VL since 2009. Serology was performed through the direct agglutination test, which detected low antibody titers in seven marmosets (7/26; 26.9%, 95% confidence interval 9.9-44.0), being five Callithrix penicillata (black-tufted-ear marmoset) and two Callithrix jacchus (white-tufted-ear marmoset). The presence of the DNA of Leishmania was investigated in blood and skin samples by PCR and genetic sequencing. This is the first report of the detection of L. (L.) infantum in the skin of a marmoset, which was verified in a sample from one C. penicillata. The results demonstrate the natural infection of marmosets by L. (L.) infantum and may suggest the participation of these animals as hosts in the parasite's transmission cycle in the EPA. However, more comprehensive studies are needed to elucidate their role on the VL epidemiology in this area and also in different endemic areas, especially because these NHP are increasingly in contact with humans and domestic animals, particularly due to environmental changes.

A retrospective pathology study of two Neotropical deer species (1995-2015), Brazil: Marsh deer (Blastocerus dichotomus) and brown brocket deer (Mazama gouazoubira)

This retrospective study describes the biological and epidemiological aspects, gross and microscopical findings, and most likely causes of death (CD) in two species of Neotropical deer in Brazil. The animals were collected between 1995 and 2015 and represented 75 marsh deer (MD) and 136 brown brocket deer (BBD). Summarized, pneumonia was diagnosed microscopically in 48 MD and 52 BBD; 76 deer suffered trauma, involving dog attack (14 BBD) and vehicle-collision (14 BBD). Pulmonary edema (50 MD; 55 BBD) and congestion (57 MD; 78 BBD) were the most common findings for both species. Additionally, we diagnosed ruminal and myocardial mycosis in MD and BBD, respectively; ovarian dysgerminoma and pancreatic trematodiasis in BBD; and lesions suggestive of malignant catarrhal fever and orbiviral hemorrhagic disease in both species. The main CD in MD was: respiratory (41/75), alimentary, nutritional, trauma and euthanasia (3/75 each). Correspondingly, in BBD were: trauma (34/131), respiratory (30/131) and euthanasia (9/131). Respiratory disease was often defined by pulmonary edema and pneumonia. We provide evidence that respiratory disease, mainly pneumonia, is a critical pathological process in these Neotropical deer species. Although no etiological agents were identified, there is evidence of bacterial and viral involvement. Our results show trauma, mainly anthropogenic, as a common ailment in BBD. We propose to prioritize respiratory disease in future research focused on South American deer health aspects. We believe anthropogenic trauma may be a primary threat for populations of BBD.

Molecular detection of fungi of public health importance in wild animals from Southern Brazil

Some animals have an important relationship with fungal infections, and searching for pathogens in animal samples may be an opportunity for eco-epidemiological research. Since studies involving wildlife are generally restricted, using samples from road kills is an alternative. The aim of this study was to verify whether pathogenic fungi of public health importance occur in wildlife road kills from Santa Catarina State, Brazil. Organ samples (n = 1063) from 297 animals were analysed according to Polymerase Chain Reaction (PCR) using universal primers to detect fungi in general and, subsequently, using primers specific to Paracoccidioides brasiliensis, Histoplasma capsulatum and Cryptococcus spp. There were 102 samples positive for fungal species. Eight samples were positive for P. brasiliensis, three samples were positive for Cryptococcus spp. and one sample had coinfection by these two fungi. No sample was positive for Histoplasma spp. according to the molecular detection. Genetic sequencing allowed the identification of Fungal sp. in 89 samples, Cryptococcus neoformans in two samples and Aspergillus penicillioides in three samples. This study shows the importance of wild animals in the epidemiology of fungal infections and assists in the mapping of pathogen occurrence in a region that was not previously evaluated.

High-throughput sequencing of kDNA amplicons for the analysis of Leishmania minicircles and identification of Neotropical species

Leishmania kinetoplast DNA contains thousands of small circular molecules referred to as kinetoplast DNA (kDNA) minicercles. kDNA minicircles are the preferred targets for sensitive Leishmania detection, because they are present in high copy number and contain conserved sequence blocks in which polymerase chain reaction (PCR) primers can be designed. On the other hand, the heterogenic nature of minicircle networks has hampered the use of this peculiar genomic region for strain typing. The characterization of Leishmania minicirculomes used to require isolation and cloning steps prior to sequencing. Here, we show that high-throughput sequencing of single minicircle PCR products allows bypassing these laborious laboratory tasks. The 120 bp long minicircle conserved region was amplified by PCR from 18 Leishmania strains representative of the major species complexes found in the Neotropics. High-throughput sequencing of PCR products enabled recovering significant numbers of distinct minicircle sequences from each strain, reflecting minicircle class diversity. Minicircle sequence analysis revealed patterns that are congruent with current hypothesis of Leishmania relationships. Then, we show that a barcoding-like approach based on minicircle sequence comparisons may allow reliable identifications of Leishmania spp. This work opens up promising perspectives for the study of kDNA minicercles and a variety of applications in Leishmania research.

Leishmania in synanthropic rodents (Rattus rattus): new evidence for the urbanization of Leishmania (Leishmania) amazonensis

This study aimed to detect parasites from Leishmania genus, to determine the prevalence of anti-Leishmania spp. antibodies, to identify circulating species of the parasite, and to determine epidemiological variables associated with infection in rats caught in urban area of Londrina, Paraná, Brazil. Animal capture was carried out from May to December 2006, serological and molecular methods were performed. DNA was extracted from total blood, and nested-PCR, targeting SSu rRNA from Leishmania genus, was performed in triplicate. The positive samples were sequenced twice by Sanger method to species determination. In total, 181 rodents were captured, all were identified as Rattus rattus and none showed clinical alterations. Forty-one of the 176 (23.3%) animals were positive for Leishmania by ELISA and 6/181 (3.3%) were positive by IFAT. Nine of 127 tested animals (7.1%) were positive by PCR; seven were identified as L. (L.) amazonensis, one as L. (L.) infantum. Four rats were positive using more than one test. This was the first description of synanthropic rodents naturally infected by L. (L.) amazonensis (in the world) and by L. (L.) infantum (in South Brazil). Regarding L. (L.) amazonensis, this finding provides new evidence of the urbanization of this etiological agent.

In vitro infection by Leishmania infantum in the peripheral blood mononuclear cell-derived macrophages from crab-eating foxes (Cerdocyon thous)

Wild canids are natural reservoirs of visceral leishmaniais (VL). In Brazil, only the crab-eating fox (Cerdocyon thous) is a natural reservoir of this zoonotic disease, but there is still a lack of understanding regarding the sylvatic transmission of the Leishmania infantum infection. This is the first study on the isolation, cultivation and infection with L. infantum in the peripheral blood mononuclear cell-derived macrophages from crab-eating foxes. It is also the first to compare macrophages from crab-eating foxes to other canine macrophages under the same conditions. Blood samples collected from crab-eating foxes held at the local zoo were processed to obtain macrophages that were subsequently infected with stationary phase L. infantum promastigotes. The percentage of infected macrophages and intracellular amastigotes per 100 macrophages were similar in both fox and dog blood samples at 2h after infection. Unlike dog macrophages, in fox macrophages there was a significant reduction in the number of infected macrophages after 24 and 48 h. At 72 h after infection, the intracellular amastigotes were practically undetectable. These results indicate that crab-eating foxes have cellular mechanisms of infection control as efficient as the domestic dog. Further study is required to discern the potential epidemiologic role of crab-eating foxes in the visceral leishmaniasis transmission cycle.