Genetic diversity, phylogeography and molecular clock of the Lutzomyia longipalpis complex (Diptera: Psychodidae)

Geographical and Molecular Analysis of Haplotype Variations in Leishmania major Among Infected Iranian Phlebotomus papatasi

PURPOSE

Leishmania major is main causative agent and Phlebotomus papatasi is only proven vector of Zoonotic Cutaneous Leishmaniasis (ZCL) in Iran. Human leishmaniasis is mostly susceptible to climatic conditions and molecular variations of Leishmania parasites within sandflies.

METHODS

L. major was analyzed based on geographical, environmental, climatic changes and haplotype variations within P. papatasi. Molecular tools and different geographical aspects were employed using Arc-GIS software for mapping the geographic distribution of samples and other statistics tests. Fragments of ITS-rDNA, k-DNA, and microsatellite genes of Leishmania were used for PCR, RFLP, sequencing, and phylogenetic analyses.

RESULTS

Totally 81 out of 1083 female P. papatasi were detected with Leishmania parasites: 70 and five were L. major and L. turanica, respectively. Golestan and Fars provinces had the highest (13.64%) and lowest (4.55%) infection rates, respectively. The infection rate among female P. papatasi collected from gerbil burrows was significantly higher (15.15%) than animal shelters, yards, and inside houses (4.48%) (P < 0.0%). Microsatellite was more sensitive (22.72%) than k-DNA (18.8%) and ITS-rDNA (7.48%). More molecular variations of L. major were found in Isfahan province.

CONCLUSIONS

Arc-GIS software and other statistics tests were employed to find Leishmania positive and haplotype variations among sand flies. Geographical situations, altitude, climate, precipitation, humidity, temperature, urbanization, migrations, regional divergences, deforestation, global warming, genome instability, ecology, and biology of the sand flies intrinsically, and the reservoir hosts and neighboring infected locations could be reasons for increasing or decreasing the rate of Leishmania infection and haplotype variations.

High climatic ancestral affinity between the lineages of the Leishmania vector Psathyromyia shannoni sensu stricto (Diptera: Phlebotominae)

Psathyromyia (Psathyromyia) shannoni sensu stricto (Dyar) is a vector of Leishmania parasite and the second sandfly of medical importance with a wide geographical but discontinuous distribution in America. Preliminary genetic structure analysis using a mitochondrial marker shows that the species integrated by at least four lineages could be the result of ecological adaptations to different environmental scenarios, but this hypothesis had never been proven. The aim of the present study was to analyse whether the genetic structure that detected Pa. shannoni ss. is associated with divergence or conservatism niche. Using Ecological Niche Models (ENMs) theory, we estimated the potential distribution for each genetic lineage, and then, we evaluated the equivalency niche for assessing whether climatic niche was more different than expected. The ENMs identify different suitable distribution areas but the same climatic or ecological conditions for the genetic lineages of Pa. shannoni (conservatism niche). Our findings allow us to speculate that other potential processes or events could be related to the genetic differentiation of Pa. shannoni. These studies are important because they allow us to identify the factors that could restrict the potential distribution of the different lineages whose vectorial competence is still unknown.

Cryptic Diversity in Sympatric Migonemyia migonei (Diptera: Psychodidae), Eventual Meaning for Leishmaniasis Transmission

Migonemyia migonei (Franҫa, 1920) (Diptera: Psychodidae) belongs to the subfamily Phlebotominae, of epidemiological importance due to its role as a vector in leishmaniasis transmission cycles and its broad geographic distribution in South America. Few morphometric and genetic studies have demonstrated the existence of variability among geographically distant populations in Brazil. The aim of the study was to estimate the genetic distance within the morphospecies Mg. migonei through the analysis of cytochrome C oxidase subunit I (COI) sequences of specimens captured in Argentina and those available in online databases. The COI sequences from specimens collected in different localities of Argentina and sequences available in online databases were utilized. Genetic distances were analyzed and a median-joining haplotype network was constructed. Finally, phylogenetic reconstruction was performed according to Bayesian inference. The analyses led to the identification of at least two haplogroups: haplogroup I with sequences of specimens from Colombia, Brazil and Argentina, and haplogroup II with sequences of specimens from Argentina. Interestingly, specimens from Argentina whose haplotypes corresponded to both haplogroups, were collected in sympatry. The results suggest that Mg. migonei could be a species complex with at least two distinct members. This hypothesis could explain the known characteristics of adaptability and vector permissiveness of the species, as the putative cryptic species of the complex could differ in traits of epidemiological importance.

Genetic diversity and phylogeography of Phlebotomus argentipes (Diptera: Psychodidae, Phlebotominae), using COI and ND4 mitochondrial gene sequences

BACKGROUND

Phlebotomus argentipes complex is the primary vector for cutaneous leishmaniasis, a burgeoning health concern in contemporary Sri Lanka, where effective vector control is important for proper disease management. Understanding the genetic diversity of the P. argentipes population in Sri Lanka is vital before implementing a successful vector control program. Various studies have indicated that genetic divergence, caused by genetic drift or selection, can significantly influence the vector capacity of arthropod species. To devise innovative control strategies for P. argentipes, exploring genetic diversity and phylogeography can offer valuable insights into vector competence, key genetic trait transfer, and impact on disease epidemiology. The primary objective is to analyze the genetic diversity and phylogeography of the P. argentipes complex in Sri Lanka, based on two mitochondrial genomic regions in modern representatives of P. argentipes populations.

METHODOLOGY

A total of 159 P. argentipes specimens were collected from five endemic areas of cutaneous leishmaniasis and identified morphologically. Two mitochondrial regions (Cytochrome c oxidase subunit I (COI) and NADH dehydrogenase subunit 4 (ND4) were amplified using the total DNA and subsequently sequenced. Partial sequences of those mitochondrial genes were utilized to analyze genetic diversity indices and to explore phylogenetic and phylogeographic relationships.

PRINCIPAL FINDINGS

Among five sampling locations, the highest genetic diversity for COI and ND4 was observed in Hambantota (Hd-0.749, π-0.00417) and Medirigiriya (Hd-0.977, π-0.01055), respectively. Phylogeographic analyses conducted using COI sequences and GenBank retrieved sequences demonstrated a significant divergence of P. argentipes haplotypes found in Sri Lanka. Results revealed that they have evolved from the Indian ancestral haplotype due to historical- geographical connections of the Indian subcontinent with Sri Lanka.

CONCLUSIONS

Utilizing high-mutation-rate mitochondrial genes, such as ND4, can enhance the accuracy of genetic variability analysis in P. argentipes populations in Sri Lanka. The phylogeographical analysis of COI gene markers in this study provides insights into the historical geographical relationship between India and P. argentipes in Sri Lanka. Both COI and ND4 genes exhibited consistent genetic homogeneity in P. argentipes in Sri Lanka, suggesting minimal impact on gene flow. This homogeneity also implies the potential for horizontal gene transfer across populations, facilitating the transmission of genes associated with traits like insecticide resistance. This dynamic undermines disease control efforts reliant on vector control strategies.

Genetic variability highlights the invasion route of the Lutzomyia longipalpis complex, the main vector of Visceral Leishmaniasis in Uruguay

In the Americas, the sandfly Lutzomyia longipalpis is the main vector of the parasitic protozoa Leishmania infantum, the etiological agent of visceral leishmaniasis (VL). The Lu. longipalpis species complex is currently discontinuously distributed across the Neotropical region, from Mexico to the north of Argentina and Uruguay. During its continental spreading, it must have adapted to several biomes and temperature amplitudes, when founder events should have contributed to the high genetic divergence and geographical structure currently observed, reinforcing the speciation process. The first report of Lu. longipalpis in Uruguay was in 2010, calling the attention of Public Health authorities. Five years later, the parasite Le. infantum was recorded and in 2015 the first case of VL in canids was reported. Hitherto seven human cases by VL have been reported in Uruguay. Here, we publish the first DNA sequences from the mitochondrial genes ND4 and CYTB of Lu. longipalpis collected in Uruguay, and we used these molecular markers to investigate their genetic variability and population structure. We described four new ND4 haplotypes in a total of 98 (4/98) and one CYTB in a total of 77 (1/77). As expected, we were able to establish that the Lu. longipalpis collected in two localities (i.e. Salto and Bella Unión) from the north of Uruguay are closely related to the populations from neighbouring countries. We also propose that the possible route for the vector arrival to the region may have been through vegetation and forest corridors of the Uruguay River system, as well as it may have benefited from landscape modifications generated by commercial forestation. The ecological-scale processes shaping Lu. longipalpis populations, the identification of genetically homogeneous groups and the gene flow among them must be carefully investigated by using highly sensible molecular markers (i.e. genome wide SNPs) since it will help to the understanding of VL transmission and contribute to the planification of public policies on its control.

Molecular taxonomy of phlebotomine sand flies (Diptera, Psychodidae) with emphasis on DNA barcoding: A review

The taxonomy and systematics of sand flies (Diptera, Psychodidae, Phlebotominae) are one of the pillars of research aimed to identifying vector populations and the agents transmitted by these insects. Traditionally, the use of morphological traits has been the main line of evidence for the definition of species, but the use of DNA sequences is useful as an integrative approach for their delimitation. Here, we discuss the current status of the molecular taxonomy of sand flies, including their most sequenced molecular markers and the main results. Only about 37% of all sand fly species have been processed for any molecular marker and are publicly available in the NCBI GenBank or BOLD Systems databases. The genera Phlebotomus, Nyssomyia, Psathyromyia and Psychodopygus are well-sampled, accounting for more than 56% of their sequenced species. However, less than 34% of the species of Sergentomyia, Lutzomyia, Trichopygomyia and Trichophoromyia have been sampled, representing a major gap in the knowledge of these groups. The most sequenced molecular markers are those within mtDNA, especially the DNA barcoding fragment of the cytochrome c oxidase subunit I (coi) gene, which has shown promising results in detecting cryptic diversity within species. Few sequences of conserved genes have been generated, which hampers higher-level phylogenetic inferences. We argue that sand fly species should be sequenced for at least the coi DNA barcoding marker, but multiple markers with different mutation rates should be assessed, whenever possible, to generate multilocus analysis.

Variation in scent amount but not in composition correlates with pollinator visits within populations of deceptive Arum maculatum L. (Araceae)

Floral scent is vital for pollinator attraction and varies among and within plant species. However, little is known about how inter-individual variation in floral scent affects the abundance and composition of floral visitor assemblages within populations. Moreover, for deceptive plants it is predicted that intra-population variation in scent can be maintained by negative frequency-dependent selection, but empirical evidence is still lacking. To investigate the ecological and evolutionary relations between inter-individual scent variation (i.e., total emission and composition) and floral visitors in deceptive plants, we studied floral scent, visitor assemblages, and fruit set in two populations of fly-pollinated (Psychodidae, Sphaeroceridae; Diptera) and deceptive Arum maculatum from Austria (JOS) and northern Italy (DAO). By correlating individual data on floral scent and visitor assemblages, we show that inter-individual variation in floral scent partly explains variation in visitor assemblages. The quantity of floral scent emitted per individual correlated positively with visitor abundance in both populations but explained visitor composition only in DAO, where strongly scented inflorescences attracted more sphaerocerid flies. However, in each population, the composition of floral scent did not correlate with the composition of floral visitors. There was also no evidence of negative frequency-dependent selection on floral scent. Instead, in JOS, more frequent scent phenotypes attracted more pollinators and were more likely to set an infructescence than rarer ones. Our results show that floral scent, despite being key in pollinator attraction in A. maculatum, only partly explains variation in pollinator abundance and composition. Overall, this study is the first to shed light on the importance of inter-individual variation in floral scent in explaining floral visitor assemblages at the population level in a deceptive plant species.

Phlebotomine Sandfly (Diptera: Psychodidae) Fauna and The Association Between Climatic Variables and The Abundance of Lutzomyia longipalpis sensu lato in an Intense Transmission Area for Visceral Leishmaniasis in Central Western Brazil

The presence, abundance, and distribution of sandflies are strongly influenced by climate and environmental changes. This study aimed to describe the sandfly fauna in an intense transmission area for visceral leishmaniasis and to evaluate the association between the abundance of Lutzomyia longipalpis sensu lato (Lutz & Neiva 1912) (Diptera: Psychodidae) and climatic variables. Captures were carried out 2 yr (July 2017 to June 2019) with automatic light traps in 16 sites of the urban area of Campo Grande, Mato Grosso do Sul state. The temperature (°C), relative humidity (%), precipitation (mm3), and wind speed (km/h) were obtained by a public domain database. The Wilcoxon test compared the absolute frequencies of the species by sex. The association between climatic variables and the absolute frequency of Lu. longipalpis s.l. was assessed using the Spearman's correlation coefficient. A total of 1,572 sandflies into four species were captured. Lutzomyia longipalpis s.l. was the most abundant species and presented a significant correlation with the average temperature, humidity, and wind speed in different periods. Lutzomyia longipalpis s.l. was captured in all months, showing its plasticity in diverse weather conditions. We emphasize the importance of regular monitoring of vectors and human and canine cases, providing data for surveillance and control actions to continue to be carried out in the municipality.

Genetic structure of allopatric populations of Lutzomyia longipalpis sensu lato in Brazil

Lutzomyia longipalpis sensu lato is a complex of phlebotomine sand fly species, which are widespread in the Neotropics. They have a great medico-veterinary importance due their role as vectors of Leishmania infantum, the causative agent of visceral leishmaniasis. Morphological variations of Lu. longipalpis s.l. males were reported in the late 1960s in Brazil. Male populations can present either one pair of spots on third abdominal tergites or two pairs on third and fourth ones, namely 1S and 2S phenotypes, respectively. Since then, there has been much interest on the taxonomic status of Lu. longipalpis s.l. Thereafter, several lines of evidence have been congruent in suggesting the existence of an uncertain number of cryptic species within Lu. longipalpis s.l. in Brazil. Herein, a 525 bp-fragment of the period gene was used for assessing the genetic structure and phylogenetic relationship of Lu. longipalpis s.l. populations in Brazil. We performed two set of analyses, first we originally sequenced three populations (Passira, Santarém and Teresina) of Lu. longipalpis s.l. and compared them. Thereafter, we performed a global analysis including in our dataset other three pairs of sympatric populations of Lu. longipalpis s.l. from three Brazilian localities available in GenBank. Fixed single nucleotide polymorphisms (SNPs) sharing, maximum likelihood inference, genetic structure and haplotype analyses revealed the presence of two genetic groups, one composed of Teresina population, and the other encompassing Passira and Santarém populations. The global analysis reflected the first of its kind, and two prominent groups were observed: the clade I comprising Teresina 1S, Bodocó 1S, Caririaçu 1S and Sobral 1S; and the clade II encompassing Passira 2S, Santarém 1S, Bodocó 2S, Caririaçu 2S and Sobral 2S. Genetic differentiation data suggested a limited gene flow between populations of the clade I versus clade II. Our results disclosed the presence of two prominent genetic groups, which could reasonably represent populations of Lu. longipalpis s.l. whose males produce the same courtship song.

Beyond taxonomy: species complexes in New World phlebotomine sand flies

A species complex (= species group, species series) is an assemblage of species, which are related morphologically and phylogenetically. Recent research has revealed several arthropod vector species that were believed to be a single nominal species actually representing a group of closely related species, which are sometimes morphologically indistinguishable at one or more developmental stages. In some instances, differences in terms of vector competence, capacity, or both have been recorded. It highlights the importance of detecting and studying species complexes to improve our understanding of pathogen transmission patterns, which may be vectored more or less efficiently by different species within the complex. Considering more than 540 species, about one-third of the phlebotomine sand flies in the New World present males and/or females morphologically indistinguishable to one or more species. Remarkably, several of these species may act in transmission of pathogenic agents. In this article, we review recent research on species complexes in phlebotomine sand flies from the Americas. Possible practical implications of recently acquired knowledge and future research needs are also discussed.

Lutzomyia longipalpis: an update on this sand fly vector

Lutzomyia longipalpis is the most important vector of Leishmania infantum, the etiological agent of visceral leishmaniasis (VL) in the New World. It is a permissive vector susceptible to infection with several Leishmania species. One of the advantages that favors the study of this sand fly is the possibility of colonization in the laboratory. For this reason, several researchers around the world use this species as a model for different subjects including biology, insecticides testing, host-parasite interaction, physiology, genetics, proteomics, molecular biology, and saliva among others. In 2003, we published our first review (Soares & Turco 2003) on this vector covering several aspects of Lu. longipalpis. This current review summarizes what has been published between 2003-2020. During this period, modern approaches were incorporated following the development of more advanced and sensitive techniques to assess this sand fly.

Molecular signatures of sexual communication in the phlebotomine sand flies

Phlebotomine sand flies employ an elaborate system of pheromone communication wherein males produce pheromones that attract other males to leks (thus acting as an aggregation pheromone) and females to the lekking males (sex pheromone). In addition, the type of pheromone produced varies among populations. Despite the numerous studies on sand fly chemical communication, little is known of their chemosensory genome. Chemoreceptors interact with chemicals in an organism’s environment to elicit essential behaviors such as the identification of suitable mates and food sources. Thus, they play important roles during adaptation and speciation. Major chemoreceptor gene families, odorant receptors (ORs), gustatory receptors (GRs) and ionotropic receptors (IRs) together detect and discriminate the chemical landscape. Here, we annotated the chemoreceptor repertoire in the genomes of Lutzomyia longipalpis and Phlebotomus papatasi, major phlebotomine vectors in the New World and Old World, respectively. Comparison with other sequenced Diptera revealed a large and unique expansion where over 80% of the ~140 ORs belong to a single, taxonomically restricted clade. We next conducted a comprehensive analysis of the chemoreceptors in 63 L. longipalpis individuals from four different locations in Brazil representing allopatric and sympatric populations and three sex-aggregation pheromone types (chemotypes). Population structure based on single nucleotide polymorphisms (SNPs) and gene copy number in the chemoreceptors corresponded with their putative chemotypes, and corroborate previous studies that identified multiple populations. Our work provides genomic insights into the underlying behavioral evolution of sexual communication in the L. longipalpis species complex in Brazil, and highlights the importance of accounting for the ongoing speciation in central and South American Lutzomyia that could have important implications for vectorial capacity.

Phlebotomine sand flies are the primary vectors of Leishmania parasites, the causative agents of cutaneous and visceral leishmaniasis. Due to the lack of vaccines, control of leishmaniasis relies upon reducing human exposure to sand flies. Sand flies produce sex-aggregation pheromones that elicit robust olfactory behaviors, and the molecular targets for pheromone detection remain unknown. We identified chemoreceptors in the genomes of L. longipalpis and P. papatasi, and used these gene models to explore chemoreceptor evolution in 63 L. longipalpis individuals representing different pheromone types. These analyses identified genomic loci underlying chemosensory behavior in sand flies. This paves the way for understanding the sand fly species diversity at the molecular level, and functional characterization of these candidate genes will isolate and identify chemostimuli that can directly be tested as potential attractants for odor-baited traps.

Niche divergence and paleo-distributions of Lutzomyia longipalpis mitochondrial haplogroups (Diptera: Psychodidae)

Lutzomyia longipalpis is a complex of species which has a wide but discontinuous distribution from southeastern Mexico to northern Argentina and Uruguay. To date, eight mitochondrial haplogroups have been identified along its distribution although key environmental tolerances and ecological niche models have been analyzed only at the complex level. The aim of the present study was to analyze whether genetic diversification using three mitochondrial genes of the Lu. longipalpis complex is associated with niche divergence and to explore evolution of distributional projections of all haplogroups between the Last Glacial Maximum (LGM; 21,000 yrs ago) and the present. Current occurrence of all haplogroups was used to develop ecological niche models (ENM) and these were projected in both periods to quantify and identify geographic area shifts. Environmental space was used to estimate niche similarity between major clades and pairwise between individual haplogroups. The two major Lu. longipalpis clades (Mex, CA, Col and Ven vs Arg and Bra) had significantly different environmental space, indicating niche divergence. Environmental space overlap of southern haplogroups was variable, with divergent niche, except between Arg and ArgBra. The most suitable regions for the ArgBra haplogroup were northeastern and southeastern Brazil, and the Gran Chaco region. In contrast, ENM of haplogroups within the northern major clade have significantly similar niche, with highest geographic ENM suitability along both the Caribbean and Pacific coasts. The intensity and coverage of high suitability areas in the LGM decreased for most haplogroups in the present. Integrating ENM and phylogenetic analyses has allowed us to test hypotheses of niche similarity between Lu. longipalpis haplogroups and major clades, and to identify conserved distributional areas of haplogroups since the LGM, with the exception of Arg. Evidence for distributional shifts and overlap of haplogroups is important to analyze Leishmaniasis´ eco-epidemiology and to successfully monitor and control transmission.

Impact of different Leishmania reservoirs on sand fly transmission: Perspectives from xenodiagnosis and other one health observations

Leishmania has biologically adapted to specific phlebotomine sand flies through long co-evolution. The ability of Leishmania spp. to bind to sand fly midgut allows each Leishmania species to propagate and differentiate into infectious promastigotes and be transmitted. Sand fly feeding upon a mammalian host is the first step towards being infected and a host of Leishmania. Once deposited into the skin, host susceptibility to infection vs. ability to mount a sterilizing immune response predicts which hosts could be reservoirs of different Leishmania spp. Materials, in addition to parasites, are expelled during sand fly during feeding, including salivary antigens and other factors that promote local inflammatory responses. These factors aid visceralization of infection increasing the likelihood that systemic infection is established. Any environmental factor that increases sand fly biting of a particular host increases that host's role in Leishmania transmission. First descriptions of reservoir species were based on association with local human disease and ability to observe infected leukocytes on cytology. This approach was one pathogen for one reservoir host. Advances in sensitive molecular tools greatly increased the breadth of mammals found to host Leishmania infection. Visceralizing species of Leishmania, particularly L. infantum, are now known to have multiple mammalian hosts. L. donovani, long been described as an anthroponotic parasite, was recently identified through molecular and serologic surveys to have additional mammalian hosts. The epidemiological role of these animals as a source of parasites to additional hosts via vector transmission is not known. Current evidence suggests that dogs and other domestic animals either control infection or do not have sufficient skin parasitemia to be a source of L. donovani to P. argentipes. Further xenodiagnosis and characterization of skin parasitemia in these different hosts is required to more broadly understand which Leishmania spp. hosts can be a source of parasites to sand flies and which ones are dead-end hosts.

Multiscale environmental determinants of Leishmania vectors in the urban-rural context

Background

In South America, cutaneous leishmaniasis (CL) and visceral leishmaniasis (VL) are emerging diseases, expanding in the border area of Argentina, Brazil and Paraguay. Outbreaks of CL were reported since the 1990s, with Nyssomyia whitmani as the main vector in this region. Regarding VL, urban reports started in 2010 with Lutzomyia longipalpis as the main vector. The aim of this study was to evaluate environmental determinants related to the main vectors of leishmaniasis, to contribute to the prevention and control response to the emergence of VL and CL in the Argentina-Brazil-Paraguay border region.

Methods

The cross-sectional survey includes two cities and two close rural areas in the Argentinean Northeast Region, between November 2014 and January 2015, with a total of 95 sampling sites. REDILA-BL traps were set for three consecutive nights, and a total of 68 meso- and microscale environmental and landscape characteristics were surveyed. The association between vector abundance with different variables was evaluated using a generalized linear model with zero-inflated negative binomial distribution. We analyzed females for detection of Leishmania DNA.

Results

The analysis for Lu. longipalpis indicates an excess of absences when the mean NDWI around the sites were higher. The abundance of Lu. longipalpis at mesoscale level was higher when more urban services were present, and when blood sources such as chickens or dogs at the microscale level were present. For Ny. whitmani, no variable was found to be associated with the absences, while its abundance increased in association with the following variables: percentage of tree cover, presence of garbage collection service, hosted people and, at microscale, the presence of poultry. Leshmania infantum DNA was detected in 2/49 (4%) Lu. longipalpis.

Conclusions

The abundance of both species is influenced by variables at different scales, their influence probably has a hierarchy and they are acting on different aspects of the biology of these vectors. The urban spatial segregation of Lu. longipalpis and the peri-urban and rural segregation of N. whitmani increase the risk of VL and CL. The selection of the better variables for each scale will allow the design of appropriate control strategies depending on species.

Molecular identification of Leishmania in free-ranging black and gold howler monkeys (Alouatta caraya) in northeastern Argentina

Parasitological surveys of non-human primates provides an important opportunity to better understand the epidemiology, transmission dynamics and emergence risk of anthropozoonoses such as leishmaniasis, which affect human populations in several regions accross South America. Our study area, in northeastern Argentina, can be considered a southern marginal region for the presence of leishmaniases and includes the habitat of black and gold howler monkeys, Alouatta caraya. To evaluate if A. caraya serve as potential hosts in the Leishmania cycle, we used molecular methods to examine infection by Leishmania spp. in 109 howler monkeys of different ages captured between July and August 2010. External ear tissue samples were subjected to PCR amplification for the Leishmania ribosomal internal transcribed spacer (ITS-1) and a RFLP assay with the Hae III restriction enzyme, and finally confirmed by sequencing. Nine howler monkeys (8.3%) were infected with Le. braziliensis (2.8%), Le. amazonensis (2.8%) and/or Le. infantum (3.7%). The results also suggest a case of co-infection between Le. braziliensis and Le. amazonensis. Further, we report the first observation of Le. amazonensis in the northeastern region of Argentina. The detection of Leishmania spp. in free-ranging howler monkeys gives rise to questions about the actual prevalence of the parasite in the wild, as well as if the number of infected wild monkeys detected may present a risk of leishmaniasis emergence in surronding human populations. Anyway, the presence of Leishmania spp. in A. caraya suggests the possible importance of these monkeys in the sylvatic and periurban transmission.

Assessing geographic and climatic variables to predict the potential distribution of the visceral leishmaniasis vector Lutzomyia longipalpis in the state of Espírito Santo, Brazil

Visceral leishmaniasis (VL) is an infectious disease caused by the protozoa Leishmania chagasi, whose main vector in South America is Lutzomyia longipalpis. The disease was diagnosed in the Brazilian state of Espírito Santo (ES) for the first time in 1968. Currently, this disease has been considered endemic in 10 municipalities. Furthermore, the presence of L. longipalpis has been detected in eight other municipalities where the transmission has not been reported thus far. In this study, we performed species distribution modeling (SDM) to identify new and most likely receptive areas for VL transmission in ES. The sandflies were both actively and passively collected in various rural area of ES between 1986 and 2017. The collection points were georeferenced using a global positioning system device. Climatic data were retrieved from the WorldClim database, whereas geographic data were obtained from the National Institute for Space Research and the Integrated System of Geospatial Bases of the State of Espírito Santo. The maximum entropy algorithm was used through the MIAmaxent R package to train and test the distribution models for L. longipalpis. The major contributor to model generation was rocky outcrops, followed by temperature seasonality. The SDM predicted the expansion of the L. longipalpis-prone area in the Doce River Valley and limited the probability of expanding outside its watershed. Once the areas predicted suitable for L. longipalpis occurrence are determined, we can avoid the inefficient use of public resources in conducting canine serological surveys where the vector insect does not occur.

Leishmaniasis en Bolivia, revisión y estado actual en Tarija, frontera con Argentina

Introducción.

En 1997, en el departamento de Tarija, Bolivia, situado en la frontera con Argentina, se notificó por primera vez la presencia de pacientes con úlceras en las partes descubiertas de la piel, cuyas características clínicas y epidemiológicas correspondían a leishmaniasis.

Objetivo.

Describir y comprobar la presencia de leishmaniasis en Tarija, sexto departamento endémico en Bolivia.

Materiales y métodos.

Se hizo un estudio del brote (noviembre de 1998 a diciembre de 2002) y un estudio longitudinal (1997 a 2018) en humanos; además, se capturaron Phlebotominae y potenciales reservorios.

Resultados.

Se registraron 1.250 pacientes de leishmaniasis; 190 y 249 casos, en los brotes de 1998 y 2002, respectivamente, con periodos interepidémicos de 37 casos como promedio anual. El 68 % de los enfermos eran pobladores migrantes del altiplano asentados en viviendas precarias cercanas al bosque residual; el sexo predominante fue el masculino (2/1). El grupo etario económicamente activo (15 a 49 años) fue el más afectado (363/584, 62 %). Hubo 124/584 (21 %) menores de 15 años, 33/584 de menos de cuatro años. En 51/584 (8,7 %) pacientes se presentaron lesiones mucosas. Se aisló y caracterizó Leishmania (V.) braziliensis de úlceras mucosas de perros enfermos y se capturó abundantemente la especie antropofílica Nyssomyia neivai, incriminada como probable vector.

Conclusiones.

En 1997 se comprobó por primera vez la presencia de leishmaniasis tegumentaria en el municipio de Bermejo y, en el 2018, ya se había extendido a cuatro municipios: Padcaya, Caraparí, Entre Ríos y Yacuiba, en dirección noreste del departamento de Tarija.

Lutzomyia longipalpis (Diptera: Psychodidae) Argentina-Bolivia border: new report and genetic diversity

American visceral leishmaniasis (AVL) has two main scenarios of transmission as follows: scattered cases in rural areas and urban outbreaks. Urban AVL is in active dispersion from the northeastern border of Argentina-Paraguay-Brazil to the South. The presence of Lutzomyia longipalpis was initially reported in urban environments in the northwestern border of the country. The presence of Lu. longipalpis, environmental variables associated with its distribution, and its genetic diversity were assessed in Salvador Mazza, Argentina, on the border with Bolivia. The genetic analysis showed high haplotype diversity, low nucleotide diversity, and low nucleotide polymorphism index. We discuss the hypothesis of an expanding urban population with introgressive hybridisation of older haplogroups found in their path in natural forest or rural environments, acquiring a new adaptability to urban environments, and the possibility of changes in vector capacity.

Twice upon a time: The progression of canine visceral leishmaniasis in an Argentinean city

Canine Visceral Leishmaniasis (CVL) prevalence, spatial distribution and associated factors were assessed in four locations in Iguazú department in 2014 and in Puerto Iguazú city again in 2018. The city areas were divided into a grid of 400x400m cells. All cells were sampled in 2014 and a random subsampling was developed in 2018. In each cell, five dogs clustered in a 'critical scenario' (prone to have vectors) were sampled. A rapid immunochromatographic dipstick was used to detect antibodies against Leishmania infantum, confirming by lymph node smears observation and PCR. For Puerto Iguazú, Generalized Linear Models (GLMs) were constructed considering environmental, dog and clinical variables. Pearson's Chi square and Fisher's exact tests were employed to evaluate the association between CVL, dog clinical signs and infestation with other parasites. Cartographic outputs were made and Moran's I indices were calculated as spatial autocorrelation indicators. CVL prevalence rates were 26.18% in 2014 and 17.50% in 2018. No associations were established in environmental models, but dog age and repellent use were significant when running 2014 dog models. Clinical models showed significant associations between seropositive dogs and ophthalmological, dermal signs and onychogryphosis in 2014. In 2018, only adenomegaly was associated. The results of global Moran´s I were not significant but regarding local analysis, six sites in 2014 and one in 2018 presented autocorrelation with neighboring sites. The decrease in CVL prevalence may be associated to transmission stabilization, which could explain the lack of associations with dog-related variables. Further, spatial distribution of CVL is a poor evidence for design of transmission control measures but could be important in case of intensive parasite circulation or when the first autochthonous cases appear. For control success, sensitivity of diagnostic methods, political will and adequate material resources remain critical. Modeling of multiple variables will be required to identify factors that drive disease stabilization/destabilization.

Inferring distributional shifts of epidemiologically important North and Central American sandflies from Pleistocene to future scenarios

Nine sandfly species (Diptera: Psychodidae) are suspected or proven vectors of Leishmania spp. in the North and Central America region. The ecological niches for these nine species were modelled in three time periods and the overlaps for all time periods of the geographic predictions (G space), and of ecological dimensions using pairwise comparisons of equivalent niches (E space), were calculated. Two Nearctic, six Neotropical and one species in both bioregions occupied a reduced number of distribution areas. The ecological niche projections for most sandfly species other than Lutzomyia shannoni and Lutzomyia ovallesi have not expanded significantly since the Pleistocene. Only three species increase significantly to 2050, whereas all others remain stable. Lutzomyia longipalpis shared a similar ecological niche with more species than any other, although both L. longipalpis and Lutzomyia olmeca olmeca had conserved distributions over time. Climate change, at both regional and local levels, will play a significant role in the temporal and spatial distributions of sandfly species.