Leishmania genetic exchange is mediated by IgM natural antibodies.

Host factors that mediate Leishmania genetic exchange are not well defined. Here we demonstrate that natural IgM (IgMn)1-4 antibodies mediate parasite genetic exchange by inducing the transient formation of a spherical parasite clump that promotes parasite fusion and hybrid formation. We establish that IgMn from Leishmania-free animals binds to the surface of Leishmania parasites to induce significant changes in the expression of parasite transcripts and proteins. Leishmania binding to IgMn is partially lost after glycosidase treatment, although parasite surface phosphoglycans, including lipophosphoglycan, are not required for IgMn-induced parasite clumping. Notably, the transient formation of parasite clumps is essential for Leishmania hybridization in vitro. In vivo, we observed a 12-fold increase in hybrid formation in sand flies provided a second blood meal containing IgMn compared with controls. Furthermore, the generation of recombinant progeny from mating hybrids and parental lines were only observed in sand flies provided with IgMn. Both in vitro and in vivo IgM-induced Leishmania crosses resulted in full genome hybrids that show equal patterns of biparental contribution. Leishmania co-option of a host natural antibody to facilitate mating in the insect vector establishes a new paradigm of parasite-host-vector interdependence that contributes to parasite diversity and fitness by promoting genetic exchange.

A diterpene synthase from the sandfly Lutzomyia longipalpis produces the pheromone sobralene.

The phlebotomine sandfly, Lutzomyia longipalpis, a major vector of the Leishmania parasite, uses terpene pheromones to attract conspecifics for mating. Examination of the L. longipalpis genome revealed a putative terpene synthase (TPS), which-upon heterologous expression in, and purification from, Escherichia coli-yielded a functional enzyme. The TPS, termed LlTPS, converted geranyl diphosphate (GPP) into a mixture of monoterpenes with low efficiency, of which ß-ocimene was the major product. (E,E)-farnesyl diphosphate (FPP) principally produced small amounts of (E)-ß-farnesene, while (Z,E)- and (Z,Z)-FPP yielded a mixture of bisabolene isomers. None of these mono- and sesquiterpenes are known volatiles of L. longipalpis. Notably, however, when provided with (E,E,E)-geranylgeranyl diphosphate (GGPP), LlTPS gave sobralene as its major product. This diterpene pheromone is released by certain chemotypes of L. longipalpis, in particular those found in the Ceará state of Brazil. Minor diterpene components were also seen as products of the enzyme that matched those seen in a sandfly pheromone extract.

Whole cell reconstructions of Leishmania mexicana through the cell cycle.

The unicellular parasite Leishmania has a precisely defined cell architecture that is inherited by each subsequent generation, requiring a highly coordinated pattern of duplication and segregation of organelles and cytoskeletal structures. A framework of nuclear division and morphological changes is known from light microscopy, yet this has limited resolution and the intrinsic organisation of organelles within the cell body and their manner of duplication and inheritance is unknown. Using volume electron microscopy approaches, we have produced three-dimensional reconstructions of different promastigote cell cycle stages to give a spatial and quantitative overview of organelle positioning, division and inheritance. The first morphological indications seen in our dataset that a new cell cycle had begun were the assembly of a new flagellum, the duplication of the contractile vacuole and the increase in volume of the nucleus and kinetoplast. We showed that the progression of the cytokinesis furrow created a specific pattern of membrane indentations, while our analysis of sub-pellicular microtubule organisation indicated that there is likely a preferred site of new microtubule insertion. The daughter cells retained these indentations in their cell body for a period post-abscission. By comparing cultured and sand fly derived promastigotes, we found an increase in the number and overall volume of lipid droplets in the promastigotes from the sand fly, reflecting a change in their metabolism to ensure transmissibility to the mammalian host. Our insights into the cell cycle mechanics of Leishmania will support future molecular cell biology analyses of these parasites.

TORC1 is an essential regulator of nutrient-controlled proliferation and differentiation in Leishmania.

Leishmania parasites undergo differentiation between various proliferating and non-dividing forms to adapt to changing host environments. The mechanisms that link environmental cues with the parasite's developmental changes remain elusive. Here, we report that Leishmania TORC1 is a key environmental sensor for parasite proliferation and differentiation in the sand fly-stage promastigotes and for replication of mammalian-stage amastigotes. We show that Leishmania RPTOR1, interacts with TOR1 and LST8, and identify new parasite-specific proteins that interact in this complex. We investigate TORC1 function by conditional deletion of RPTOR1, where under nutrient-rich conditions RPTOR1 depletion results in decreased protein synthesis and growth, G1 cell cycle arrest and premature differentiation from proliferative promastigotes to non-dividing mammalian-infective metacyclic forms. These parasites are unable to respond to nutrients to differentiate into proliferative retroleptomonads, which are required for their blood-meal induced amplification in sand flies and enhanced mammalian infectivity. We additionally show that RPTOR1-/- metacyclic promastigotes develop into amastigotes but do not proliferate in the mammalian host to cause pathology. RPTOR1-dependent TORC1 functionality represents a critical mechanism for driving parasite growth and proliferation.

Leishmania allelic selection during experimental sand fly infection correlates with mutational signatures of oxidative DNA damage.

Trypanosomatid pathogens are transmitted by blood-feeding insects, causing devastating human infections. These parasites show important phenotypic shifts that often impact parasite pathogenicity, tissue tropism, or drug susceptibility. The evolutionary mechanisms that allow for the selection of such adaptive phenotypes remain only poorly investigated. Here, we use Leishmania donovani as a trypanosomatid model pathogen to assess parasite evolutionary adaptation during experimental sand fly infection. Comparing the genome of the parasites before and after sand fly infection revealed a strong population bottleneck effect as judged by allele frequency analysis. Apart from random genetic drift caused by the bottleneck effect, our analyses revealed haplotype and allelic changes during sand fly infection that seem under natural selection given their convergence between independent biological replicates. Our analyses further uncovered signature mutations of oxidative DNA damage in the parasite genomes after sand fly infection, suggesting that Leishmania suffers from oxidative stress inside the insect digestive tract. Our results propose a model of Leishmania genomic adaptation during sand fly infection, with oxidative DNA damage and DNA repair processes likely driving haplotype and allelic selection. The experimental and computational framework presented here provides a useful blueprint to assess evolutionary adaptation of other eukaryotic pathogens inside their insect vectors, such as Plasmodium spp, Trypanosoma brucei, and Trypanosoma cruzi.

Characterisation of the antiviral RNA interference response to Toscana virus in sand fly cells.

Toscana virus (TOSV) (Bunyavirales, Phenuiviridae, Phlebovirus, Toscana phlebovirus) and other related human pathogenic arboviruses are transmitted by phlebotomine sand flies. TOSV has been reported in nations bordering the Mediterranean Sea among other regions. Infection can result in febrile illness as well as meningitis and encephalitis. Understanding vector-arbovirus interactions is crucial to improving our knowledge of how arboviruses spread, and in this context, immune responses that control viral replication play a significant role. Extensive research has been conducted on mosquito vector immunity against arboviruses, with RNA interference (RNAi) and specifically the exogenous siRNA (exo-siRNA) pathway playing a critical role. However, the antiviral immunity of phlebotomine sand flies is less well understood. Here we were able to show that the exo-siRNA pathway is active in a Phlebotomus papatasi-derived cell line. Following TOSV infection, distinctive 21 nucleotide virus-derived small interfering RNAs (vsiRNAs) were detected. We also identified the exo-siRNA effector Ago2 in this cell line, and silencing its expression rendered the exo-siRNA pathway largely inactive. Thus, our data show that this pathway is active as an antiviral response against a sand fly transmitted bunyavirus, TOSV.

Psychodid flies and their implicated role in human myiasis and pseudomyiasis.

Several psychodid flies are commonly associated with human-inhabited environments and have been increasingly implicated in cases of human myiasis. However, the basic biology of psychodid larvae is not well-suited for survival in the human intestinal or urogenital tract, making true, prolonged myiasis unlikely. In this review, we performed a systematic literature review of published cases of purported myiasis caused by psychodid flies, their identification, associated clinical findings, and treatment. We also discuss the anatomy and lifecycle of psychodid flies in relation to their purported ability to use human tissue as a nutritive source and survive in the human alimentary or urogenital tracts. Based on the range of non-specific and varied reported clinical manifestations, lack of observed collections, life cycle patterns of psychodid flies, the mechanics of their mouthparts, and breathing requirements, we conclude that most cases likely represent incidental findings, or in rare cases possibly pseudomyiasis, rather than true myiasis, and provide recommendations for clinical evaluation and reporting so that disease misclassification and unnecessary therapy do not occur.

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.

Molecular and morphometric study of Brazilian populations of Psychodopygus davisi.

In this study, we analysed the molecular and morphometric differences of several populations of the putative sand fly vector Psychodopygus davisi (Root, 1934) (Diptera, Psychodidae, Phlebotominae) in Brazil. We amplified the 658 base pair fragments of the DNA barcoding region-cytochrome c oxidase subunit 1 (COI) gene-for 57 specimens of P. davisi and three specimens of Psychodopygus claustrei (Abonnenc, Léger & Fauran, 1979). We merged our data with public sequences of the same species available from GenBank. Then, the combined dataset-87 sequences and 20 localities-was analysed using population structure analysis and different species delimitation approaches. Geometric morphometry of wings was performed for 155 specimens of P. davisi populations from the North, Midwest and Southeast Brazilian regions, analysing the differences in centroid sizes and canonical variates. Molecular analysis indicated high intraspecific genetic distance values for P. davisi (maximum p distance = 5.52%). All algorithms identified P. davisi and P. claustrei as distinct molecular taxonomic units, despite the low interspecific distance (p distance to the nearest neighbour = 4.79%). P. davisi sequences were split into four genetic clusters by population structure analysis and at least five genetic lineages using intermediate scenarios of the species delimitation algorithms. The species validation analysis of BPP strongly supported the five-species model in our dataset. We found high genetic diversity in this taxon, which is in agreement with its wide geographic distribution in Brazil. Furthermore, the wing analysis showed that specimens from the Southeast Region of Brazil are different from those in the North and the Midwest. The evolutionary patterns of P. davisi populations in Brazil suggest the presence of candidate species, which need to be validated in future studies using a more comprehensive approach with both genomic data and morphological characters.

The Phlebotomine sand fly fauna of Switzerland revisited.

Sand flies (Diptera: Psychodidae, Phlebotominae; Newstead, 1911) are widespread in Europe, being particularly common in the Mediterranean region but rare north of the Alps. Thus, Switzerland is an opportune place to investigate the sand fly fauna on both sides of the Alpine crest, in southern sub-Mediterranean climate and northern oceanic temperate climate. We reinvestigated the Swiss sand fly fauna with the aim to assess changes in composition, altitudinal distribution, abundance and seasonality. Thirty-eight sites were investigated with light traps and/or interception sticky traps in 4 years. Ninety and 380 specimens were caught by light traps and sticky traps, respectively, at 15 collecting sites. Four species were identified. Phlebotomus mascittii (Grassi, 1908), Phlebotomus perniciosus (Newstead, 1911) and Sergentomyia minuta (Rondani, 1843) were confirmed in Ticino, and P. mascittii for the first time in neighbouring Grisons. Also, Phlebotomus neglectus (Tonnoir, 1921) is for the first time reported, though at a very low density compared to P. perniciosus at the same site. Its presence in Ticino supports the northward spread observed in Italy. Sand flies were detected north of the Alps at one site only, endorsing a historical report. Overall, the low density of P. perniciosus and very low density of P. neglectus suggest that canine leishmaniosis may not be an important disease risk in Switzerland.

Clogmia albipunctata (Williston, 1893) midgut physiology: pH control and functional relationship with Lower Diptera (nematoceran) especially with hematophagous species.

Clogmia albipunctata (Williston, 1893) is a non-hematophagous insect belonging to the order Diptera, suborder Nematocera (Lower Diptera) and family Psychodidae. In the present work, we investigated how C. albipunctata control their midgut pH under different physiological conditions, comparing their midgut physiology with some nematoceran hematophagous species. The C. albipunctata midgut pH was measured after ingestion of sugar, protein and under the effect of the alkalinizing hormone released in the hemolymph of the hematophagous sand fly Lutzomyia longipalpis obtained just after a blood meal. The midgut pH of unfed or sugar-fed C. albipunctata is 5.5-6, and its midgut underwent alkalinization after protein ingestion or under treatment with hemolymph collected from blood fed L. longipalpis. These results suggested that in nematocerans, mechanisms for pH control seem shared between hematophagous and non-hematophagous species. This kind of pH control is convenient for successful blood digestion. The independent evolution of many hematophagous groups from the Lower Diptera suggests that characteristics involved in midgut pH control were already present in non-hematophagous species and represent a readiness for adaptation to this feeding mode.

Leishmania (Leishmania) infantum DNA detection in Nyssomyia neivai in Vale do Ribeira, Paraná, Brazil.

BACKGROUND: The incidence of visceral leishmaniasis (VL) has increased in the Southern region of Brazil in recent years, especially in the State of Paraná. New species have been suggested with potential to act as vector in VL endemic areas. OBJECTIVES: Identify the Leishmania species in sand fly specimens collected from 2016 to 2018 in the municipality of Itaperuçu, Vale do Ribeira, Paraná, Brazil. METHODS: Light traps were used for collections and for the analysis of sand fly were used the multiplex polymerase chain reaction (PCR) methodology and subsequent sequencing. FINDINGS: Among the collected specimens, 88.62% were attributed to the species Nyssomyia neivai, which were grouped into 176 pools. Three positive pools were detected: two with Leishmania (Viannia) braziliensis and one with L. (Leishmania) infantum. The positivity rate for the parasite was 0.25% based on the presence of at least one infected insect in the pool. MAIN CONCLUSIONS: The detection of L. infantum in Ny. neivai draws attention due to its abundance and anthropophily in the State of Paraná. Moreover, this finding is considered as an alert and suggests that the vector competence of Ny. neivai and the criteria for its incrimination should be carried out, given its wide distribution in southern of Brazil.

Identification of Ochrobactrum as a bacteria with transstadial transmission and potential for application in paratransgenic control of leishmaniasis.

Leishmaniasis is a zoonotic vector-borne disease with worldwide distribution. All current approaches in leishmaniasis control or development of vaccines/cures showed only limited success. Recently, paratransgenesis has been marked as a promising strategy for leishmaniasis control. Thus, the investigations of the gut microbial content of sand flies have gained popularity. Gut microbial composition of the laboratory colony of Phlebotomus papatasi was investigated via microbial culturomics approach which refers to the combination of multiple culture conditions and different selective and/or enriched culture mediums, followed by 16S rDNA sequencing. Investigations were conducted on three offspring generations, with six samplings of immature stages (four larval samplings, one pre-pupa, one pupa) and samplings of adults before and after blood feeding. The aim was to determine if microbiome changes during the sand fly development and to identify bacteria with transstadial potential. The presence of 8 bacterial taxa (Bacillus sp., Terribacillus sp., Staphylococcus sp., Alcaligenes sp., Microbacterium sp., Leucobacter sp., Ochrobactrum sp. and Enterobacter sp.), 2 fungi (Fusarium sp. and Acremonium sp.) and 1 yeast (Candida sp.) were recorded. Gram-positive bacteria were more diverse, but gram-negative bacteria were more abundant. All taxa were recorded among immature stage samples, while only one bacterium was detected in adults. Microbial diversity among larval samples was stable, with a steady decrease in pre-pupa and pupa, resulting in the survival of only Ochrobactrum sp. in adults. Abundance of microbes was higher when larvae were actively feeding, with a gradual decrease after larvae stopped feeding and commenced pupation. Ochrobactrum sp. is the bacteria with transstadial potential, worthy of future in-depth analysis for the application in paratransgenic approach for the control of Leishmania sp.

Molecular investigation of Leishmania in sandflies (Diptera: Psychodidae) and rodents (Mammalia: Rodentia) in Nahavand, west of Iran.

Cutaneous leishmaniasis caused by different species of Leishmania is transmitted by Phlebotominae sandflies. This disease remains a public health concern in Iran. Therefore, the present study aimed to examine Leishmania infection in sandflies and reservoir rodents in six rural regions of Nahavand, located in western Iran. From May to October 2022, sandflies and rodents were collected and identified at the species level. Additionally, rodents' skin lesions and earlobe specimens were collected separately for microscopic and molecular examination. All specimens were tested for Leishmania DNA by PCRs targeting the parasite's ITS-2 and 18S rRNA gene and positive were Sanger sequenced. A total of 3396 sandflies belonging to seven subgenera and 11 species, i.e., Phlebotomus papatasi (42.7%), P. major (20.6%), P. mascitti (0.3%), P. neglectus (0.2%), P. alexandri (0.2%), P. turanicus (0.3%), Sergentomyia murgabiensis (18.1%), S. dentata (10.5%), S. theodori (5.8%), S. antennata (1.1%), and S. pawlowski (0.1%) were identified. Based on the species population, 29 pools of sandflies were examined for the presence of Leishmania DNA using conventional PCR (cPCR), and individual DNAs were tested when positive. Leishmania major DNA was detected in two P. papatasi and Leishmania sp. in one P. major individual sandfly. This is the first report of Leishmania infection in sandflies from Hamadan province. The captured rodents (n = 61) belonged to four families and seven species, i.e., Arvicola amphibius (37.7%), Mus musculus (29.5%), Microtus socialis (13.1%), Apodemus sylvaticus (11.5%), Talpa davidiana (4.9%), Apodemus witherbyi (1.6%), and Rattus norvegicus (1.6%). Microscopic and molecular examinations of the rodent lesions and earlobes scored negative results. The presence of Leishmania in the Phlebotominae sandflies in Nahavand indicates a potential threat to humans and animals in the region. Regular monitoring and examination of the sandflies' population and timely diagnosis and treatment of new patients are strongly recommended.

Phlebotomine sand fly (Diptera: Phlebotominae) diversity in the foci of cutaneous leishmaniasis in the Surxondaryo Region of Uzbekistan: 50 years on.

In Uzbekistan, the number of reported leishmaniasis cases is rising at the alarming rate. In this work, we studied the phlebotomine sand fly (Diptera: Phlebotominae) diversity in the foci of cutaneous leishmaniasis in the Surxondaryo Region of Uzbekistan and compared it with the data obtained for the same area 50 years ago, when infection prevalence was reportedly low. We found that the implicated vector for zoonotic leishmaniasis, P. papatasi, remained eudominant; the proportion of implicated anthroponotic leishmaniasis vector, P. sergenti, rose significantly from averaged 5.4 to 41.4%; Phlebotomus alexandri, a suspected visceral leishmaniasis vector, was eudominant at two sites, and a second suspected vector for this disease, P. longiductus, was newly recorded in the region. We conclude that the increase in the documented cases of cutaneous leishmaniasis in the Surxondaryo Region of Uzbekistan may be connected to the changes in fauna of sand flies vectoring Leishmania spp.

Ecological aspects of sand fly fauna (Diptera: Psychodidae, Phlebotominae) of Sumidouro District, State of Rio de Janeiro, Brazil.

Aiming to compare and update the sand fly fauna of Portão de Pedra site, Sumidouro District, Rio de Janeiro State, Brazil, and considering the environmental changes occurred, the biology and ecology of the local sandfly species were examined five years later as a complementary study carried. Captures were made in the cave, surroundings of cave and forest of the region, from 6 p.m. to 6 a.m. Among the 2323 sandflies of eigth species of the Lutzomyia were captured: L. gasparviannai, L. edwardsi, L. tupynambai, L. hirsuta, L. whitmani, L. migonei, L. intermedia, Lutzomyia. sp and one species of the Brumptomyia Kind: B. brumpti. In 2009 and 2010 were collected 1756 samples from ten species of the former genus and two of the second. L. gasparviannai was predominant, in the three collection sites, in both periods. Five species implicated as vectors of Leishmania: L. intermedia, L. whitmani, L. migonei, L. hirsuta and L. davisi have been collected in the area. Poisson regression and ANOVA were used to perform statistical analysis of species most relevant. The record of L. intermedia and a case of American tegumentary leishmaniasis are relevant to the public health of municipality and of state of Rio de Janeiro.

Re-emergence of human leishmaniasis in northern Italy, 2004 to 2022: a retrospective analysis.

BackgroundHuman leishmaniasis is a protozoan disease transmitted by sand flies and endemic in the Mediterranean region. In Italy, leishmaniasis is present in the south and the western coastal regions, with an epidemic peak detected in northern Italy in the early 1970s.AimTo examine temporal trends, and demographic, clinical, geographical and environmental features of human leishmaniasis cases recorded by the local health unit (LHU) of Bologna, northern Italy.MethodsIn this retrospective observational study, we analysed human leishmaniasis cases recorded from 2004 to 2022 within the Bologna LHU. We also conducted serological investigations for canine leishmaniasis in owned dogs living near the place of infection of human cases.ResultsIn total, 173 cases of human leishmaniasis were detected, and 154 cases were considered autochthonous. An increase of human cases was observed since 2004, with incidence peaks above 2 cases/100,000 inhabitants in 2013, 2018 and 2022; epidemic peaks were preceded by dry summers. Most cases lived in the plain and hilly areas less than 400 m above sea level and many resided in isolated housing, in city outskirts, and/or near uncultivated areas, watercourses and railway sections. The incidence of canine leishmaniasis did not increase in the study period.ConclusionAn epidemic of human leishmaniasis with fluctuating annual numbers of cases, probably related to environmental and climatic factors, was identified in the Bologna LHU. Understanding the risk factors and the environmental characteristics related to places of infection is crucial to evaluate the public health implications of leishmaniasis.

Indicators sandflies and environment associated to spatial landscaping change in Chocó Biosphere Reserve UNESCO.

BACKGROUND OBJECTIVES: Sandflies are vector insects associated with terrestrial forest ecosystems; in the Ecuadorian Andes, they participate in the transmission of human cutaneous leishmaniasis. This geographical area represents an opportunity to evaluate the role of sandflies as bioindicators of the degree of intervention of tropical humid forest ecosystems (THF) associated with changes in the ecology of the local landscape. METHODS: CDC-light traps were used for collecting adult sandflies in February 2020 in a humid tropical forest within the Chocó Biosphere Reserve. All species were identified using morphological keys. Analysis data about abundance, richness, species accumulation, diversity index, species composition communities, species sex proportion, spatial sandflies environmental, Renyi's Diversity Profile were performed to compare six spatial habitats in Mashpi locality, Ecuador. RESULTS: Sandflies were collected (n-1435); the main species are represented by Trichophoromyia reburra, Nyssomyia trapidoi, Psathyromyia aclydifera, Psychodopygus panamensis and Lutzomyia hartmanni. Only Th. reburra is associated with not intervened forest, while the other three species are associated with intervened forest within Mashpi in the Choco Biosphere Reserve. The secondary forest has major sandflies' richness, while the primary forest exhibits major abundance. INTERPRETATION CONCLUSION: Th. reburra is a sandfly restricted to the Andean Forest and is a bioindicator of the high environmental health quality of the forest, while Ny. trapidoi and Pa. aclydifera are bioindicators of environmental disturbances in the forest. Additionally, Ps. panamensis, Lu. hartmanni and Ny. trapidoi are bioindicators of human impact and the risk of leishmaniasis.

Toxicity of Trixis vauthieri DC essential oil on Lutzomyia longipalpis (Diptera, Psychodidae, Phlebotominae), a proven vector of visceral leishmaniasis in Brazil.

BACKGROUND OBJECTIVES: In Brazil, one of the visceral leishmaniasis control measures in urban environments is the elimination of Lutzomyia longipalpis, which occurs through the application of pyrethroid insecticides with residual action in homes and outbuildings. Due to the loss of sensitivity of this vector to these insecticides, the search for more efficient insecticide compounds against L. longipalpis has been intensified. The objective of this work was to evaluate the toxicity of Trixis vauthieri essential oil on adult sandflies of the species L. longipalpis, and identify the phytochemical composition of these essential oils. METHODS: Essential oils from leaves collected from T. vauthieri at different times were obtained at concentrations of 5, 10 and 20 mg/mL. Twenty sandflies were exposed to the essential oils and the mortality was evaluated after 1, 2, 4, 16, 24, 48 and 72 h. The chemical constituents of the essential oil were also identified. RESULTS: The essential oils of T. vauthieri at a concentration of 20 mg/mL were the most toxic to sandflies, reaching a mortality rate of 98.33% and 95%, respectively, after 72 h of exposure. The analysis of chemical constituents revealed the presence of triterpenes and/or steroids, tannins, flavonoids, alkaloids, saponins and coumarins. INTERPRETATION CONCLUSION: The results obtained suggest that T. vauthieri essential oil is fairly promising as an insecticidal potential against L. longipalpis. A more detailed analysis of the oil's phytochemical composition is necessary to identify active and pure compounds that can be used in vector control of visceral leishmaniasis.

Distribution changes of cutaneous leishmaniasis: A postulated risk of disease transmission in Hambantota, Sri Lanka.

BACKGROUND OBJECTIVES: Leishmaniasis is caused by various species of parasite Leishmania. Approximately twenty of them are pathogenic to mammals. In Sri Lanka, cutaneous leishmaniasis (CL) is an established vector-borne disease. CL originates and spreads mainly through sandfly bite in many endemic countries. The aim of the present study was to compare the geographical distribution and demographic features of CL cases in Hambantota district, Sri Lanka in 2014 and 2016. METHODS: The patients who were presented to the Tangalle Base Hospital from June to December in 2014 and 2016 were examined and a descriptive study was carried out using a structured-questionnaire. Slit-skin smears were collected from each patient, Giemsa-stained and examined under the light microscope to identify Leishmania amastigotes. RESULTS: Out of 256 and 314 suspected CL patients, 156 and 155 were identified positive for the year 2014 and 2016, respectively. Out of 12 District Secretary Divisions (DSD) in Hambantota district, the highest number of CL cases, 85 and 86 was reported from Tangalle DSD in 2014 and 2016 respectively. Number of identified CL patients in Beliatta DSD had increased from 50 to 67 during the study period. In both years, majority of CL patients were ≥50 years old with males more infected than females. Although CL association with occupations were insignificant, housewives were the highly (23%) infected occupants in this area. INTERPRETATION CONCLUSION: Based on the present findings, geographical distribution within DSDs in Hambantota district had changed. This emphasizes the importance of CL as a health problem in Hambantota district.