Identification of Leishmania infantum and Leishmania braziliensis in captive primates from a zoo in Brazil

Using iDNA to determine impacts of Amazonian deforestation on Leishmania hosts, vectors, and their interactions

BACKGROUND

There is debate concerning whether there exists a generalizable effect of land-use change on zoonotic disease risk. Strong data informing this debate are sparse because it is challenging to establish direct links between hosts, vectors, and pathogens. However, molecular methods using invertebrate-derived DNA (iDNA) can now measure species composition and interactions from vector samples at landscape scales, which has the potential to improve mechanistic understanding of the effects of land-use change on zoonotic disease risk.

METHODOLOGY/PRINCIPAL FINDINGS

We used iDNA metabarcoding of sandflies to disentangle the relationships between Leishmania parasites, sandfly vectors, and vertebrate hosts. We paired these samples with iDNA metabarcoding of carrion flies to survey vertebrates independent of sandfly feeding preferences. We collected sandflies and carrion flies at forest sites across a deforestation gradient in the southern Amazon 'Arc of Deforestation', which exemplifies global patterns of deforestation due to agricultural expansion. We used a series of models to test whether sandflies and the vertebrate they feed upon were influenced by deforestation, which we measured using percent forest cover, percent pasture cover, and distance to the major urban center. We found that vectors were encountered less frequently in forests surrounded by pasture. We also found that the probability of a Leishmania host/reservoir being detected in sandfly bloodmeals was quadratically related to local forest cover, with the highest probability found at sites with intermediate levels of deforestation. Hosts were also detected most often with carrion flies at sites with intermediate forest cover, suggesting that increased host availability rather than feeding preferences was responsible for this result. Domestic dogs and the nine-banded armadillo, Dasypus novemcinctus, were the most prevalent hosts found in the sandfly iDNA data.

CONCLUSIONS/SIGNIFICANCE

Our results did not support the generality of the 'dilution effect' hypothesis. However, important vectors and hosts showed consistent responses to deforestation and our findings suggest that interactions between domestic dogs and sylvatic hosts are a pathway for zoonotic disease transmission in human impacted tropical forests.

Non-human primates as indicators of Kinetoplastida diversity in an urban environment in Midwest Brazil

Introduction

Trypanosomatids are parasites widely distributed in nature, parasitizing several host species in single or co-infections. Campo Grande (CG), capital of Mato Grosso do Sul State, is characterized by several green areas and forest fragments where wild mammals have been reported infected by diverse trypanosomatid species. In this study, we evaluated the parasitism by trypanosomatids in the non-human primates (NHP) Sapajus cay and Alouatta caraya sampled in three different areas of CG.

Material and methods

For the detection of infections and identification of trypanosomatid species, we made hemoculture, blood smears, molecular and serological tests.

Results

We detected trypanosomatids in 37/55 (67.3%) of sampled animals, all by the molecular test. DNA sequencing analyzes were performed on 32 samples, resulting in the following species identification: Trypanosoma cruzi, T. minasense, T. rangeli, Leishmania (L.) infantum and L. (L.) amazonensis (species already recorded in primates in Latin America), and for the first time T. lainsoni, a parasite related to small mammals, and Trypanosoma sp. DID, originally reported in marsupials Didelphis sp.

Discussion

The detection of trypanosomatids of public health importance as L. infantum, L. amazonensis and T. cruzi (genotypes TcI, TcII/TcVI and TcIV) indicates the enzootic character of these species in the studied area. Also, the presence of T. cruzi TcIV and T. minasense in the conservation area supports previous studies that these parasites would be associated with the arboreal stratum. We conclude that (i) the NHP at CG participate in a complex reservoir system for parasites of great importance for Public Health in the studied area, such as L. infantum, L. amazonensis and T. cruzi, and (ii) there is a great diversity of trypanosomatids circulating in the urban area of this city located in the Brazilian Midwest.

Monitoring of Leishmania infantum in captive non-human primates in Spain

Cases of Leishmania infantum infection have recently been reported in non-human primates (NHPs) in Spain causing severe clinical disease in critically endangered orangutans (Pongo pygmaeus pygmaeus). The aim of this study was to determine exposure and risk factors associated with L. infantum infection in NHPs housed in zoos and wildlife rescue centers (WRC) in Spain. Between 2007 and 2023, sera from 252 NHPs belonging to 47 different species were collected at 15 centers. Indirect immunofluorescence was used to detect the presence of antibodies against L. infantum (cut-off ≥1:80). In addition, hair samples from 78 individuals were tested for Leishmania kDNA by real-time quantitative PCR (qPCR). Anti-Leishmania antibodies were detected in 4.0 % (10/252; 95 %CI: 1.6-6.4) of the NHPs tested at 26.7 % (4/15) of the centers sampled. Twenty-two NHPs were longitudinally sampled between 2010 and 2023: one ring-tailed lemur (Lemur catta) seroconverted and a seropositive orangutan increased antibody titers during the study period. Leishmania infantum kDNA was found in 62.8 % (49/78; 95 %CI: 52.1-73.6) of animals and at all centers sampled (100 %; 7/7). Phylogenetic analysis revealed high homology between the sequence obtained and strains previously isolated in humans, dogs and captive and free-living wildlife species in Spain. To the authors´ knowledge, this is the first report of Leishmania kDNA detection in NHP hair samples. The results indicate that hair samples could be a useful, non-invasive method of detection of L. infantum infection in these species. This is also the first large-scale survey of L. infantum conducted in NHP species in Europe. We report for the first time the presence of Leishmania kDNA in nine different NHP species belonging to the families Cercopithecidae, Lemuridae, and Hylobatidae, expanding the host range for this parasite. The main risk factors associated with L. infantum infection were: age (≥5 years old) and body size (large). Our results demonstrate widespread circulation of this parasite among NHPs housed in Spain, which could be of conservation and public health concern. Monitoring and control programs should be implemented in zoos and WRCs to minimize the risk of NHP exposure to L. infantum in endemic areas worldwide.

Is leishmaniasis the new emerging zoonosis in the world?

Leishmania is a genus of parasitic protozoa that causes a disease called leishmaniasis. Leishmaniasis is transmitted to humans through the bites of infected female sandflies. There are several different species of Leishmania that can cause various forms of the disease, and the symptoms can range from mild to severe, depending on species of Leishmania involved and the immune response of the host. Leishmania parasites have a variety of reservoirs, including humans, domestic animals, horses, rodents, wild animals, birds, and reptiles. Leishmaniasis is endemic of 90 countries, mainly in South American, East and West Africa, Mediterranean region, Indian subcontinent, and Central Asia. In recent years, cases have been detected in other countries, and it is already an infection present throughout the world. The increase in temperatures due to climate change makes it possible for sandflies to appear in countries with traditionally colder regions, and the easy movement of people and animals today, facilitate the appearance of Leishmania species in new countries. These data mean that leishmaniasis will probably become an emerging zoonosis and a public health problem in the coming years, which we must consider controlling it from a One Health point of view. This review summarizes the prevalence of Leishmania spp. around the world and the current knowledge regarding the animals that could be reservoirs of the parasite.