Pathogen-associated molecular patterns (PAMPs) derived from Leishmania and bacteria increase gene expression of antimicrobial peptides and gut surface proteins in sand flies

The interaction between pathogens and vectors' physiology can impact parasite transmission. Studying this interaction at the molecular level can help in developing control strategies. We study leishmaniases, diseases caused by Leishmania parasites transmitted by sand fly vectors, posing a significant global public health concern. Lipophosphoglycan (LPG), the major surface glycoconjugate of Leishmania, has been described to have several roles throughout the parasite's life cycle, both in the insect and vertebrate hosts. In addition, the sand fly midgut possesses a rich microbiota expressing lipopolysaccharides (LPS). However, the effect of LPG and LPS on the gene expression of sand fly midgut proteins or immunity effectors has not yet been documented. We experimentally fed Lutzomyia longipalpis and Phlebotomus papatasi sand flies with blood containing purified LPG from Leishmania infantum, Leishmania major, or LPS from Escherichia coli. The effect on the expression of genes encoding gut proteins galectin and mucin, digestive enzymes trypsin and chymotrypsin, and antimicrobial peptides (AMPs) attacin and defensins was assessed by quantitative PCR (qPCR). The gene expression of a mucin-like protein in L. longipalpis was increased by L. infantum LPG and E. coli LPS. The gene expression of a galectin was increased in L. longipalpis by L. major LPG, and in P. papatasi by E. coli LPS. Nevertheless, the gene expression of trypsins and chymotrypsins did not significantly change. On the other hand, both L. infantum and L. major LPG significantly enhanced expression of the AMP attacin in both sand fly species and defensin in L. longipalpis. In addition, E. coli LPS increased the expression of attacin and defensin in L. longipalpis. Our study showed that Leishmania LPG and E. coli LPS differentially modulate the expression of sand fly genes involved in gut maintenance and defence. This suggests that the glycoconjugates from microbiota or Leishmania may increase the vector's immune response and the gene expression of a gut coating protein in a permissive vector.

Effects of host species on microbiota composition in Phlebotomus and Lutzomyia sand flies

BACKGROUND

Blood-sucking phlebotomine sand flies are vectors of the protozoan parasites Leishmania spp. Although the intestinal microbiota is involved in a wide range of biological and physiological processes and has the potential to alter vector competence, little is known about the factors that modify the gut microbiota composition of sand flies. As a key step toward addressing this issue, we investigated the impact of host species on the gut bacterial composition in Phlebotomus and Lutzomyia sand flies reared under the same conditions.

METHODS

Bacterial 16S rRNA gene amplification and Illumina MiSeq sequencing were used to characterize the overall bacterial composition of three laboratory-reared sandflies: Phlebotomus papatasi, Ph. duboscqi, and Lutzomyia longipalpis.

RESULTS

Our results showed that the larvae of the three sand fly species harbored almost the same microbes but had different relative abundances. Adult Ph. papatasi and Ph. duboscqi revealed similar microbiome compositions, which were distinct from that of adult Lu. longipalpis. Furthermore, we showed that Ph. papatasi and Ph. duboscqi are hosts for different bacterial genera. The experiment was repeated twice to improve accuracy and increase reliability of the data, and the same results were obtained even when a distinct composition of the microbiome among the same species was identified probably because of the use of different larvae food batch.

CONCLUSIONS

The present study provides key insights into the role of host species in the gut microbial content of different sand fly species reared under the same conditions, which may influence their susceptibility to Leishmania infection.

Molecular detection of Wolbachia and Bartonella as part of the microbiome of phlebotomine sand flies from Chiapas, Mexico

Phlebotomine sand flies are dipterans of relevance due to their role as vectors of several pathogens worldwide. Bacteria in the gut of sand flies possibly affect their vectorial capacity and competence to transmit parasites. A retrospective study was performed in sand fly specimens that had previously been collected in four localities of the state of Chiapas during the period 2009-2011 to detect Wolbachia and Bartonella and their possible coinfection with Leishmania. For the molecular detection of bacteria, we used primers and conditions that had previously been reported. A total of 531 sand fly specimens of 10 species were analyzed. Four Wolbachia strains were detected in five sand fly species, showing a prevalence of 8.6%. All the Wolbachia strains had previously been reported in other taxa. In one sand fly species, we also detected a new lineage of Bartonella evidenced by a phylogenetic analysis. No sand fly specimens showed coinfections of these bacteria and Leishmania. The bacteria found in the phlebotomine sand flies are possibly transmitted by plant-mediated horizontal transmission and during blood meal feeding.

Effects of anti-Leishmania compounds in the behavior of the sand fly vector Lutzomyia longipalpis

BACKGROUND

Leishmaniasis is an infectious parasitic disease caused by pathogens of the genus Leishmania transmitted through the bite of adult female sand flies. To reduce case numbers, it is necessary to combine different control approaches, especially those aimed at the sand fly vectors. Innovative forms of control with the use of attractive sugar baits explored the fact that adult sand flies need to feed on sugars of plant origin. Leishmania parasites develop in the gut of sand flies, interacting with the sugars in the diet of adults. Recent studies have shown that sugar baits containing plant-derived compounds can reduce sand fly survival, the number of parasites per gut, and the percentage of infected sand flies. Several synthetic compounds produced from naphthoquinones and pterocarpans have anti-parasitic activity on Leishmania amazonensis and/or Leishmania infantum in cell culture. This work aimed to assess the inclusion of these compounds in sugar baits for blocking transmission, targeting the development of the Leishmania parasite inside the sand fly vector.

RESULTS

We evaluated the attractant or repellent properties of these compounds, as well as of the reference compound N,N'-diethyl-m-toluamide (DEET), in sugar baits. We also observed changes in feeding preference caused by these compounds, looking for anti-feeding or stimulation of ingestion. Pterocarpanquinone L4 and pentamidine showed attractant and repellent properties, respectively.

CONCLUSION

Based on the effects in feeding preference and intake volume, pterocarpanquinone L6, and the pyrazole-derived compound P8 were chosen as the most promising compounds for the future development of anti-Leishmania sugar baits. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Detection of Wolbachia and Leishmania DNA in sand flies (Diptera: Psychodidae, Phlebotominae) from a focus of cutaneous leishmaniasis in Tabasco, Mexico

Phlebotomine sand flies are the main vectors of Leishmania genus species worldwide; therefore, the detection of some reproductive parasites, such as Wolbachia, has been considered a possible strategy for biological control. In Mexico, leishmaniasis cases have been recorded in 25 states, yet only two sand fly species have been related to Wolbachia spp. Although the state of Tabasco has a high number of leishmaniasis cases, only few studies have been done on sand fly species. The aim of this study was to analyze the diversity of sand fly species and to detect Wolbachia spp. and/or Leishmania spp. in the captured specimens. Sand flies were collected at the locality of Huimango, Tabasco, Mexico, during October 2019, using nine light traps (CDC) and two Shannon traps per night. The specimens were identified and females were analyzed by PCR for the DNA detection for pathogens. A total of 193 sand fly specimens belonging to five species were morphologically identified. Pintomyia ovallesi was the most abundant species (76.84%), followed by Micropygomyia cayennensis (6.40%). Furthermore, first records of four sand fly species were established for the state of Tabasco, thereby increasing the species richness in the state from four to eight. We observed a natural infection rate of 9.7% (10/103) for Leishmania and 0.91% (1/103) for Wolbachia. The importance of conducting entomological surveys in endemic areas of leishmaniasis in Mexico is highlighted, to determine whether other sand fly species may be potential vectors of Leishmania spp., and if some Wolbachia strains could be relevant for the control of leishmaniasis.

Revisiting the Phlebotominae subfamily records in Bahia, Brazil

Brazil is one of the countries that concentrates 90% of all tegumentary and visceral leishmaniases cases and Bahia is one of the highly affected states. In the present report, we consolidated secondary data from several complementary databases that allowed us to record the sand fly species identified including areas of Leishmania spp. transmission in the state of Bahia. We then overlayed the geographical distribution data onto maps of vegetational aspects found across the state. Overall, 21 602 records of phlebotomine sand flies occurrence between 1949 and 2016 were analysed, encompassing 85% of Bahia's municipalities. Seventy-six sand fly species under 17 genera were enlisted. Among described species, 27 were proven or putative Leishmania spp. vectors and three were considered exclusively endemic in the state. Lutzomyia longipalpis, Nyssomyia intermedia and Nyssomyia whitmani were found in 74, 29 and 27% of municipalities, respectively. Salvador, the state capital and major city presented records for 21 different sand fly species, including known vectors for leishmaniasis. In particular, a wide distribution of Evandromyia sallesi was detected for this city. This consolidated account on phebotomine fauna and distribution may be explored for improving the planning and deployment of vector-focused leishmaniasis control measures in affected areas of Bahia.

Leishmania mexicana in a central Texas cat: clinical presentation, molecular identification, sandfly vector collection and novel management

Case summary

This case report documents the clinical appearance, diagnosis and novel treatment of a central Texas cat with cutaneous leishmaniosis. The cat presented with a linear erosion on the right pinnal margin, an ulcerated exophytic nodule on the right hock and a swelling in the right nostril. Cytological and histopathological findings were consistent with leishmaniosis. PCR confirmed the presence of Leishmania mexicana, a species endemic to Texas. An epidemiological investigation was conducted by trapping sandflies from the cat’s environment. Sandflies collected were identified as Lutzomyia species, known vectors of Leishmania species. Given the lack of validated medical therapies for L mexicana in cats, treatments typically prescribed for canine leishmaniosis were administered. Allopurinol achieved clinical success but was discontinued due to suspected drug-related neutropenia. Topical imiquimod also improved lesional skin but was not sustainable due to application difficulty. Oral administration of artemisinin resulted in significant clinical improvement of cutaneous lesions without reported adverse events. Nearly 8 months after the initiation of artemisinin therapy, the cat remained systemically healthy with stable lesions.

Relevance and novel information

This case report demonstrates endemic feline leishmaniosis in central Texas and provides the clinician with alternative therapeutic options for medical management.

Methods for detecting insecticide resistance in sand flies: A systematic review

The classification of insecticide resistance in sand flies populations is based on concepts and methodologies used to characterize the susceptibility profile in mosquitoes. This can generate erroneous and subjective interpretations since they are biologically different organisms. In this context, the goal of this review is to analyze the works and/or articles that aimed at characterizing the susceptibility of sand flies and describing the methodological parameters, in order to improve future works to estimate more accurately the resistance of sand flies to insecticides. Using keywords that refer to the purpose of this review, scientific studies in English, Spanish and Portuguese published until December 2019 were analyzed. A total of 3481 articles were found in searches in four databases (Pubmed, Scopus, BVS and ScienceDirect) and 61 were selected. The panorama of sand-fly resistance revealed 47 populations of sand flies, of species Phlebotomus papatasi, Ph. argentipes e Sergentomyia shorttii, with confirmed resistance, and 28 populations of species Ph. papatasi, Ph. argentipes, Ph. sergenti e Lutzomyia longipalpis. Of the 61 selected studies, only three studies performed comparisons between field and colony phlebotomines, and all colony populations were less susceptible than field populations to at least one tested insecticide. The lethal doses and lethal times of sand flies are very varied, revealing that there is no specific protocol for assessing the susceptibility of sand flies to insecticides. For a quick and early detection of sand flies' resistance to insecticides, we suggest the use of CDC bottle tests with an SRL to estimate the local Dose and Diagnostic Time. Males and females can be used in the same proportion, but with only female sand flies in the control group. Females with engorged abdomen or pregnant should be avoided in the experiment and, if possible, use the F1 generation of field sand flies, up to 5 days old, or at least 100 sand flies to reduce the influence of age on the susceptibility of the population.

Characterization of the sand fly fauna in Barbalha, one of the municipalities with the highest leishmaniasis rates in Brazil

Leishmaniases are a complex of sand fly-borne diseases that are considered a public health issue in several countries. Brazil presents high leishmaniases rates. The South of Ceará State, known as Cariri region, shows worrying statistics mainly on American tegumentary leishmaniasis. In Barbalha, which is one of the municipalities in this region, there is still a lack of studies regarding the local phlebotomine (Diptera: Psychodidae) fauna in order to help clarify the high rates. This study aimed to characterize such fauna by capturing sand flies with light traps during a four-year period. A total of 3730 sand flies were captured, of which 37.8% were females. Fourteen species were found: 13 of the Lutzomyia genus and one of the Brumptomyia genus. Of the Lutzomyia species, four were proven and five had potential involvement in leishmaniasis transmission. Lutzomyia longipalpis was the most common species (66.97%). This predominance, especially in the urban area, indicates its epidemiological importance and adaptation to environmental conditions modified by human activity. In fact, further studies are still required to accurately determine the behavioral features of these vectors in order to guide public health measurements towards its control and prevention.

Natural Leishmania (Leishmania) mexicana infection and biting activity of anthropophilic sand fly Lutzomyia ayacuchensis in the Ecuadorian Andes

To elucidate the transmission mode of Andean cutaneous leishmaniasis (Andean-CL), natural Leishmania infection and biting activity of sand flies were tested in a selected sylvatic focus of the endemic area of the Ecuadorian Andes. Monthly sand fly collections and dissections were conducted during 12 months from July 2018 to June 2019. The Leishmania positive specimens/slides with innumerable amounts of actively mobile flagellates made us easy to detect positive sand flies. The promastigotes observed located in the anterior and posterior midgut, without the hindgut localization. The parasite isolated was identified as L. (L.) mexicana by cytochrome b gene analysis. No other Leishmania or flagellate species parasitic in sand flies was observed in the area. Only Lu. ayacuchensis was caught throughout. Monthly microscopic examination of Lu. ayacuchensis revealed 0.75-8.33% of natural L. (L.) mexicana infection rates. Higher Leishmania infection months were present at the end of the wet season of the Andes, while higher sand fly numbers occurred during the dry season. Diurnal biting (blood meal seeking) activity of sand flies started around 17:30 before sunset, increased between 18:00 and 19:30, and thereafter decreased drastically probably because of low temperature (15-18 °C) in the area. The results provide information important for the planning of vector control strategy and management of the disease in the Andean-CL endemic area of Ecuador.

DNA barcoding and fauna of phlebotomine sand flies (Diptera: Psychodidae: Phlebotominae) from Los Tuxtlas, Veracruz, Mexico

Mexico has great diversity of phlebotomine sand flies related to cases of leishmaniasis, yet few studies have dressed the molecular taxonomy of these sand fly species. The use of the cytochrome oxidase subunit 1 (COI) gene, as a DNA Barcode has facilitated the molecular identification of sand flies species worldwide. We use the DNA barcode as a useful tool for the identification of phlebotomine sand flies of the natural reserve Los Tuxtlas from Veracruz, México. A fragment of 536 bp of the COI gene was obtained from 36 individuals belonging to eight species of five genera (Dampfomyia, Lutzomyia, Psathyromyia, Psychodopygus and Brumptomyia) with coverage between 92-100%, and found similarities ranging from 93-98% with other New World phlebotomine sand flies. The NJ dendogram grouped sand flies into eight clusters according to identified species, supported by bootstrap of 97%-100%. In conclusion, all phlebotomine sand flies were correctly identified and agree with the morphological identification, also could separate genetics the isomorphic females of the genus Brumptomyia.

Phlebotomine (Diptera: Psychodidae) fauna in a cavern containing cave paintings and its surrounding environment, Central-West Brazil

The interior of caves usually presents climate, light, soil, flora and fauna that distinguish it from the external environment. Among the sandfly species found in caves, several may act as vectors of Leishmania spp. and others are a nuisance to humans due to their painful bites. This study sought to identify the phlebotomine fauna in a cavern with cave paintings ("Gruta do Pitoco") which attract tourists in Alcinopólis municipality, Mato Grosso do Sul state, Brazil. The sandflies were collected from March 2014 to September 2015, with automatic light traps, installed monthly, in the entrance and interior of the cave and outside it. A total of 7645 specimens belonging to 27 species were collected. Lutzomyia dispar, Martinsmyia oliverai and those of the Lu. longipalpis complex (Lu. cruzi and Lu. longipalpis) were the predominant species. Among the three environments sampled, no great difference between species richness was observed. Comparing these environments, the interior of the cave presented the lowest diversity index due to the high frequency of Lu. dispar (46%). For the first time, specimens (only females) of the genus Deanemyia were collected in Mato Grosso do Sul state. Moreover, the study revealed the sympatric occurrence of Lu. cruzi and Lu. longipalpis, both proven vectors of L. infantum, and also Lu. dispar, a highly anthropophilic species, which often causes annoyance to those who visit the cave.

Sandflies (Diptera: Psychodidae: Phlebotominae), present in an endemic area of cutaneous leishmaniasis in western Boyacá, Colombia

Introduction:

Sandflies are known for having vector species of the tropical disease Leishmaniasis, a disease which is of an endemic nature in Western Boyacá, where the town of Otanche is one of the main source of Cutaneous Leishmaniasis.

Objective:

To identify the species of sandfly present in an endemic area of cutaneous leishmaniasis in West Boyacá.

Methods:

The search and collection of sandflies was carried out using CDC gravid traps, over a period of twelve hours (18:00- 06:00). Identification was carried out by revising the genitalia on both male and female samples under a microscope. The distribution took as reference households with a history of people infected with this disease, locating them intra, peri and extra domicile.

Results:

Were recollected 361 individuals (252 females and 109 male), belonging to 9 genres and 16 species. 60% of all recollected phlebotominae consists of Nyssomyia yuilli and Nyssomyia trapidoi. Other species recollected and relevant, due to vector precedent, are Lutzomyia hartmanni, Psychodopygus panamensis, Lutzomyia gomezi and Psychodopygus carrerai.

Conclusion:

It was established that, due to its abundance and vector precedent for the country and the area under study, Nyssomyia yuilli and Nyssomyia trapidoi constitute the species of phlebotominae which may be involved in the transmission of cutaneous Leishmaniasis in the region.

First Report of Bartonella SP. In Sand Flies (Diptera: Psychodidae: Phlebotominae) From Southern Mexico

The genus Bartonella encompasses several zoonotic species that cause emerging infectious diseases in humans. These species are transmitted to humans by hematophagous arthropods. In South America, sand flies are the most important vectors of Bartonella bacilliformis, the etiological agent of Verruga peruana. Due to the importance of bartonellosis in public health, the aim of this study was to detect Bartonella in wild populations of phlebotomine sand flies in southern Mexico. In total, 29 sand flies belonging to 6 species were collected. Only 2 specimens were positive, representing a prevalence of 8.69% (2/23). This appears to be the first report of Bartonella sp. in phlebotomine sand flies outside the endemic area of Verruga peruana in South America. Further studies are needed to clarify the relation between this bacterium and sand flies in Mexico.

Surveillance of phlebotomine fauna and Didelphis marsupialis (Didelphimorphia: Didelphidae) infection in an area highly endemic for visceral leishmaniasis in Colombia

INTRODUCTION

The study of the interaction between the parasite, the vector and the mammalian hosts, including man, allows to understand the behavior of the leishmaniases.

OBJECTIVE

To determine the presence of Lutzomyia species and to detect the Leishmania infection in Didelphis marsupialis in an endemic area for visceral leishmaniasis.

MATERIALS AND METHODS

Phlebotomine fauna and individuals of D. marsupialis were collected with CDC and Tomahawk™ traps, respectively. The species of Lutzomyia were identified using the Young and Duncan key (1994). Ear and tail biopsies and blood samples from D. marsupialis were taken to identify the Leishmania species by amplifying a fragment of the gene associated with the 70 kD heat shock protein.

RESULTS

Seven Lutzomyia species were identified: Lu. evansi, Lu. gomezi, Lu. panamensis, Lu. dubitans, Lu. cayennensis cayennensis, Lu. rangeliana and Lu. trinidadensis. The first three species have epidemiological importance in Colombia because of their implications in the transmission of the Leishmania parasite. Sixty-five tissue samples from 19 D. marsupialis individuals were negative for Leishmania spp.

CONCLUSIONS

The presence of the Lutzomyia species that have been identified as vectors for Leishmania inside and around houses in the village of El Bledo, in El Carmen de Bolívar represents a risk of infection. Furthermore, the presence of Lu. panamensis is reported for first time in El Carmen de Bolívar in Colombia. Although the lack of detection of Leishmania spp. in D. marsupialis samples may suggest that D. marsupialis does not play an important role in the transmission cycle of Leishmania in this region, it is necessary to carry out further longitudinal studies to confirm this hypothesis.

Optimization of DNA Extraction from Individual Sand Flies for PCR Amplification

Numerous protocols have been published for extracting DNA from phlebotomines. Nevertheless, their small size is generally an issue in terms of yield, efficiency, and purity, for large-scale individual sand fly DNA extractions when using traditional methods. Even though this can be circumvented with commercial kits, these are generally cost-prohibitive for developing countries. We encountered these limitations when analyzing field-collected Lutzomyia spp. by polymerase chain reaction (PCR) and, for this reason, we evaluated various modifications on a previously published protocol, the most significant of which was a different lysis buffer that contained Ca²⁺ (buffer TESCa). This ion protects proteinase K against autolysis, increases its thermal stability, and could have a regulatory function for its substrate-binding site. Individual sand fly DNA extraction success was confirmed by amplification reactions using internal control primers that amplify a fragment of the cacophony gene. To the best of our knowledge, this is the first time a lysis buffer containing Ca²⁺ has been reported for the extraction of DNA from sand flies.

Experimental Infection of Sand Flies by Massilia Virus and Viral Transmission by Co-Feeding on Sugar Meal

Background: Massilia virus (MASV) is a phlebovirus isolated from Phlebotomus perniciosus in various regions of southwestern Europe. It is closely related to human pathogens such as Toscana virus and sandfly fever Naples virus. The natural cycle of phleboviruses is poorly understood. Indeed, experimental studies demonstrate that transovarial and sexual transmission are not efficient enough for the maintenance of the virus in nature and to date there is no convincing evidence that a species of vertebrates is the reservoir of the virus. Here, we studied various transmission routes of MASV taking advantage of experimental colonies representing different species of sand flies. Methodology/Principal findings: In P. perniciosus, four sources of infection were compared: (i) Virus-seeded larval food to the first instar larvae (L1), or (ii) to the fourth instar larvae (L4), (iii) virus-seeded blood meal to adult females, and (iv) virus-seeded sugar meal to adults of both sexes. From 875 adults emerged from infected L1 and L4, only three were positive. In females infected by bloodmeal the infection rate was high before defecation, then it decreased drastically; MASV RNA was detected in only 5 out of 27 post-defecation. Surprisingly, the most efficient route of infection was observed after intake of virus-seeded sugar meal: 72% of females (79/110) and 52% of males (51/99) were found to be MASV RNA-positive. In addition, MASV-infected sandflies regurgitated virus particules into the sugar drop and MASV RNA was detectable in this drop for at least 24 h after regurgitation. MASV RNA was detected in about one third of the P. perniciosus exposed to this sugar drop contaminated by regurgitation. Sugar meal infection was also tested with six other species of sand flies. In males, there were no significant differences in infection rates when compared to P. perniciosus. In females, most species tested showed high infection rate at the beginning but then significant gradual decrease in infection rate during the experiment. Conclusions/Significance: We present the first description of arboviral infection of a dipteran vector using sugar meal. In all seven sand fly species tested, MASV was detected for two weeks post-infection. Our results showed that MASV can be transmitted between P. perniciosus either through co-feeding or via an infected sugar source such as plant sap. These newly described routes of horizontal transmission may play an important role in the circulation of phleboviruses in nature.

Carrion's disease: more than a neglected disease

Infections with Bartonella bacilliformis result in Carrion's disease in humans. In the first phase of infection, the pathogen causes a hemolytic fever ("Oroya fever") with case-fatality rates as high as ~90% in untreated patients, followed by a chronical phase resulting in angiogenic skin lesions ("verruga peruana"). Bartonella bacilliformis is endemic to South American Andean valleys and is transmitted via sand flies (Lutzomyia spp.). Humans are the only known reservoir for this old disease and therefore no animal infection model is available. In the present review, we provide the current knowledge on B. bacilliformis and its pathogenicity factors, vectors, possible unknown reservoirs, established and potential infection models and immunological aspects of the disease.

Non-invasive visualisation and identification of fluorescent Leishmania tarentolae in infected sand flies

Background: The leishmaniases are neglected diseases that affect some of the most vulnerable populations in the tropical and sub-tropical world. The parasites are transmitted by sand flies and novel strategies to control this neglected vector-borne disease are needed. Blocking transmission by targeting the parasite inside the phlebotomine vector offers potential in this regard. Some experimental approaches can be best performed by longitudinal study of parasites within flies, for which non-destructive methods to identify infected flies and to follow parasite population changes are required. Methods: Lutzomyia longipalpis were reared under standard insectary conditions at the Wellcome Centre for Molecular Parasitology. Flies were artificially infected with L. tarentolae expressing green fluorescent protein (GFP. Parasite counts were carried out 5 days post-infection and the percentage of infected flies and survival of infected females was established up to days 5 post-infection. Whole living females were visualised using an epifluorescence inverted microscope to detect the presence parasites inferred by a localised green fluorescent region in the upper thorax. Confirmation of infection was performed by localised-fluorescence of dissected flies and estimates of the parasite population. Results : Leishmania tarentolae was successfully transfected and expressed GFP in vitro. L. tarentolae-GFP Infected flies showed similar parasite populations when compared to non-transfected parasites ( L. tarentolae-WT). Survival of non-infected females was higher than L. tarentolae-infected groups, (Log-rank (Mantel-Cox) test, p<0.05). L. tarentolae-GFP infected females displayed an intense localised fluorescence in the thorax while other specimens from the same infected group did not. Localised fluorescent flies were dissected and showed higher parasite populations compared to those that did not demonstrate high concentrations in this region (t-test, p<0.005). Conclusion : These results demonstrate the feasibility of establishing a safe non-human infectious fluorescent Leishmania-sand fly infection model by allowing non-destructive imaging to signal the establishment of Leishmania infections in living sand flies.

Entomological surveys of Lutzomyia flaviscutellata and other vectors of cutaneous leishmaniasis in municipalities with records of Leishmania amazonensis within the Bragança region of Pará State, Brazil

In southeast Amazon, Lutzomyia (Nyssomyia) flaviscutellata is the incriminated vector of Leishmania (Leishmania) amazonensis, a causative agent of zoonotic cutaneous leishmaniasis (CL). The optimal methods for surveying Lu. flaviscutellata were investigated in the Bragança region, northeast Pará State, Brazil, selected for the presence of Le. amazonensis. The performances of modified Disney traps and CDC light traps were compared in four ecotopes within and around four village transects during the wet and dry seasons. The physiological age of female sand flies was estimated and natural infection by flagellates was evaluated by dissection. Disney traps were better for detecting the presence of Lu. flaviscutellata, while CDC traps performed well for detecting Lutzomyia (Nyssomyia) antunesi, suspected vector of Leishmania lindenbergi. The former was more abundant during the wet season, when female flies were naturally infected with Le. amazonensis. These findings identified the environments of local transmission. In order to improve surveys of Lu. flaviscutellata as part of integrated epidemiological surveillance of CL, our recommendations include focusing vector surveys with Disney traps on forest fragments where people work, during the seasonal peak of the vector. Further field studies are required to make model-based predictions of seasonal variations in the vectorial capacity of vector populations.

Molecular detection of Wolbachia pipientis in natural populations of sandfly vectors of Leishmania infantum in endemic areas: first detection in Lutzomyia longipalpis

A polymerase chain reaction-based method was used to screen sandflies for infection with Wolbachia (Rickettsiales: Rickettsiaceae), an intracellular bacterial endosymbiont found in many arthropods and filarial hosts. Positive results were obtained in five of 200 field-collected sandflies and were confirmed by sequencing. All sandflies were Lutzomyia longipalpis (Diptera: Psychodidae) captured in a region endemic for visceral leishmaniasis in Brazil. This is the first study to identify Wolbachia infection in this Lutzomyia species, which is the main vector of leishmaniasis in the study area. The low infection rate found in this study (2.5%), together with the lack of detection of Wolbachia in previous studies and the diversity found in the sequences analysed, suggests horizontal transmission to these sandflies.

A new whole mitochondrial genome qPCR (WMG-qPCR) with SYBR Green® to identify phlebotomine sand fly blood meals

Phlebotomine sand flies are blood-feeding insects of marked medical and veterinary significance. Investigations on the biology of these insects hold great importance for both ecological and epidemiological purposes. The present work describes a new approach for real-time PCR (qPCR) with SYBR Green^®, named WMG-qPCR, to identify phlebotomine blood meals. The novelty of the assay was to design primers based on the Whole Mitochondrial Genome (WMG) of the potential hosts (human, dog, cat, brown rat and chicken) aiming to amplify through qPCR the regions of mitochondrial DNA (mtDNA) which are less conserved among all species. Initially, the best method for mtDNA extraction to be applied in WMG-qPCR was determined. Afterwards, amplification specificities were accessed by cross-reaction assays with mtDNA samples from all animal species, besides phlebotomine DNA. Finally, the selected primers were also tested for their limit of DNA detection through standard curves constructed by serial dilution of blood DNA obtained for each target animal species. The WMG-qPCR was able to detect as low as 10pL of blood, equivalent to 26, 84, 130, and 320fg DNA of cat, human, dog and rat, respectively. The assay was also capable to amplify as low as 5pL of chicken blood (5pg DNA). In conclusion, WMG-qPCR seems to be a promising tool to identify phlebotomine blood meals, with high species-specificity and sensitivity. Furthermore, as no supplementary techniques are required, this new approach presents minimized costs and simplified technical-training requirements for execution.

Molecular detection and identification of Wolbachia in three species of the genus Lutzomyia on the Colombian Caribbean coast

Background

The hematophagous habits of insects belonging to the genus Lutzomyia (Diptera: Psychodidae), as well as their role as biological vectors of Leishmania species, make their presence an indication of infection risk. In the present study, seven species of Lutzomyia were identified and screened for natural infections with Wolbachia.

Methods

Collection of sand flies was done in an endemic focus of leishmaniasis on the Colombian Caribbean coast (Department of Sucre, Ovejas municipality). DNA collected from Lutzomyia species was evaluated with PCR for wsp gene amplification to screen for bacterial infection.

Results

Endosymbiotic Wolbachia was found in three species: Lutzomyia c. cayennensis, Lutzomyia dubitans and Lutzomyia evansi. Two Wolbachia strains (genotypes) were found in Lutzomyia spp. These genotypes were previously unknown in dipteran insects. The wLev strain was found in Lutzomyia dubitans, L. c. cayennensis and L. evansi and the wLcy strain was found only in L. c. cayennensis.

Conclusions

Genetic analysis indicated that the Wolbachia strains wLcy and wLev belong to the B Supergroup. This study provides evidence of infections of more than one strain of Wolbachia in L. c. cayennensis.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-017-2031-x) contains supplementary material, which is available to authorized users.

Genetic differentiation over a small spatial scale of the sand fly Lutzomyia vexator (Diptera: Psychodidae)

Background

The geographic scale and degree of genetic differentiation for arthropod vectors that transmit parasites play an important role in the distribution, prevalence and coevolution of pathogens of human and wildlife significance. We determined the genetic diversity and population structure of the sand fly Lutzomyia vexator over spatial scales from 0.56 to 3.79 km at a study region in northern California. The study was provoked by observations of differentiation at fine spatial scales of a lizard malaria parasite vectored by Lu. vexator.

Methods

A microsatellite enrichment/next-generation sequencing protocol was used to identify variable microsatellite loci within the genome of Lu. vexator. Alleles present at these loci were examined in four populations of Lu. vexator in Hopland, CA. Population differentiation was assessed using Fst and D (of Cavalli-Sforza and Edwards), and the program Structure was used to determine the degree of subdivision present. The effective population size for the sand fly populations was also calculated.

Results

Eight microsatellite markers were characterized and revealed high genetic diversity (uHe = 0.79–0.92, Na = 12–24) and slight but significant differentiation across the fine spatial scale examined (average pairwise D = 0.327; F_ST = 0.0185 (95 % bootstrapped CI: 0.0102–0.0264). Even though the insects are difficult to capture using standard methods, the estimated population size was thousands per local site.

Conclusions

The results argue that Lu. vexator at the study sites are abundant and not highly mobile, which may influence the overall transmission dynamics of the lizard malaria parasite, Plasmodium mexicanum, and other parasites transmitted by this species.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-016-1826-5) contains supplementary material, which is available to authorized users.

DNA barcoding to identify species of phlebotomine sand fly (Diptera: Psychodidae) in the mixed leishmaniasis focus of the Colombian Caribbean

Identification of the species of phlebotomine sand flies present in each focus of leishmaniasis is necessary to incriminate vectors and implement vector control strategies. Although the cytochrome oxidase I (COI) gene has been proposed as a barcode for the identification of animal species, less than 20% of New World phlebotomines have been characterized to date. In this study DNA barcoding was used to identify phlebotomine species of the mixed leishmaniasis focus in the Colombian Caribbean by means of three evolutionary models: Kimura's two parameter (K2P) nucleotide substitution model, that of (Tamura and Nei, 1993) (TN93) and proportional sequence divergence (p-distances). A 681bp sequence of the COI gene was obtained from 66 individuals belonging to 19 species of the genus Lutzomyia (Lu. abonnenci, Lu. atroclavata, Lu. bicolor, Lu. carpenteri, Lu. cayennensis cayennensis, Lu. dubitans, Lu. evansi, Lu. gomezi, Lu. gorbitzi, Lu. longipalpis, Lu. micropyga, Lu. migonei, Lu. panamensis, Lu. (Psathyromyia) sp., Lu. rangeliana, Lu. serrana, Lu. shannoni, Lu. trinidadensis and Lu. venezuelensis) and one of Brumptomyia (B. mesai). The genetic divergence values for TN93 among individuals of the same species fluctuated up to 3.2% (vs. 2.9% for K2P and 2.8% for p-distances), while the values between species ranged from 8.8-43.7% (vs. 6.8-19.6% for K2P and 6.6-17.4% for p-distances). A dendrogram constructed by means of the Neighbor-Joining method grouped phlebotomines into 20 clusters according to species, with bootstrap values of up to 100% in those with more than one individual. However, loss of the phylogenetic signal of the gene COI was observed at the supraspecific level as a consequence of substitutional saturation. In conclusion, irrespective of the evolutionary model selected, all phlebotomines were correctly assigned to species, showing 100% concordance with morphological identification.

Intradomiciliary and peridomiciliary captures of sand flies (Diptera: Psychodidae) in the leishmaniasis endemic area of Chapare province, tropic of Cochabamba, Bolivia

In South America, cutaneous leishmaniasis is the most frequent clinical form of leishmaniasis. Bolivia is one of the countries with higher incidence, with 33 cases per 100,000 individuals, and the disease is endemic in 70% of the territory. In the last decade, the number of cases has increased, the age range has expanded, affecting children under 5 years old, and a similar frequency between men and women is found. An entomological study with CDC light traps was conducted in three localities (Chipiriri, Santa Elena and Pedro Domingo Murillo) of the municipality of Villa Tunari, one of the main towns in the Chapare province (Department of Cochabamba, Bolivia). A total of 16 specimens belonging to 6 species of the genus Lutzomyia were captured: Lu. aragaoi, Lu. andersoni, Lu. antunesi, Lu. shawi, Lu. yuilli yuilli and Lu. auraensis. Our results showed the presence of two incriminated vectors of leishmaniasis in an urbanized area and in the intradomicile. More entomological studies are required in the Chapare province to confirm the role of vector sand flies, the intradomiciliary transmission of the disease and the presence of autochthonous cases of cutaneous leishmaniasis.

Evidence for anthropophily in five species of phlebotomine sand flies (Diptera: Psychodidae) from northern Colombia, revealed by molecular identification of bloodmeals

Identification of the bloodmeal sources of phlebotomine sand flies is fundamental to determining which species are anthropophilic and understanding the transmission of Leishmania parasites in natural epidemiological settings. The objective of this study was to identify sand fly bloodmeals in the mixed leishmaniasis focus of the department of Sucre, northern Colombia. In all 141 engorged female sand flies were analyzed, after being captured in intradomiciliary, peridomiciliary and extradomiciliary habitats with Shannon and CDC traps and by active searching in diurnal resting sites. Bloodmeals were identified by sequencing and analysis of a 358bp fragment of the mitochondrial gene Cytochrome b (CYB) and a 330bp fragment of the nuclear gene prepronociceptin (PNOC). Using both genes 105 vertebrate bloodmeals were identified, with an efficiency of 72% for CYB but only 7% for PNOC. Ten species of vertebrates were identified as providing bloodmeal sources for 8 sand fly species: Homo sapiens (Lutzomyia evansi, Lutzomyia panamensis, Lutzomyia micropyga, Lutzomyia shannoni and Lutzomyia atroclavata), Equus caballus (L. evansi, L. panamensis and Lutzomyia cayennensis cayennensis), Equus asinus (L. evansi and L. panamensis), Bos taurus (L. evansi, L. panamensis and L. c. cayennensis), Tamandua mexicana (L. shannoni and Lutzomyia trinidadensis), Proechimys guyanensis (L. evansi, L. panamensis and L. c. cayennensis), Mabuya sp. (Lutzomyia micropyga), Anolissp. (L. micropyga), Sus scrofa (L. evansi and Lutzomyia gomezi) and Gallus gallus (L. evansi). Cattle, donkeys, humans and pigs were significantly more important than other animals (P=0.0001) as hosts of L. evansi, this being the most abundant sand fly species. The five Lutzomyia species in which blood samples of human origin were detected included L. micropyga and L. atroclavata, constituting the first evidence of anthropophily in both species.

Rotation of male genitalia in various species of phlebotomine sandfly

Phlebotomine sandflies, vectors of Leishmania (Kinetoplastida: Trypanosomatidae) parasites that affect millions of people worldwide, breed in terrestrial biotopes. As immature stages are rarely accessible, the detection of their natural breeding sites is primarily based on findings of juvenile males with unrotated external genitalia. In males, permanent 180° rotation on the longitudinal body axis occurs soon after eclosion; however, no study has as yet addressed this aspect in detail. The present study describes the timing and duration of the rotation of male external genitalia in eight highly medically important sandfly species belonging to the genera Sergentomyia, Lutzomyia and Phlebotomus (all: Diptera: Psychodidae), kept under controlled laboratory conditions. The average duration of rotation was species-specific and varied from 12 h in Sergentomyia schwetzi to 33 h in Phlebotomus sergenti. Significant differences in rotation times were found among species, even between two closely related species of the subgenus Larroussius, Phlebotomus orientalis and Phlebotomus tobbi. The rotation of genitalia in all three studied genera was randomly oriented and similar numbers of clockwise and counter-clockwise events were observed. The study also addresses the effects of some external factors. In all species studied, rotation was not affected by the time of day of eclosion. Similarly, no differences in total rotation time were found between Phlebotomus papatasi males maintained at 25 and 20 °C, respectively. The present findings will assist in the search for natural breeding sites and in studies aimed at elucidating strategies for integrated sandfly and leishmaniasis control.

Mosquito Vector Biology and Control in Latin America-A 25TH Symposium

The 25th Annual Latin American Symposium presented by the American Mosquito Control Association (AMCA) was held as part of the 81st Annual Meeting in New Orleans, LA, in March 2015. The principal objective, as for the previous 24 symposia, was to promote participation in the AMCA by vector control specialists, public health workers, and academicians from Latin America. This publication includes summaries of 24 presentations that were given orally in Spanish by participants from Colombia, Mexico, and the USA. Topics addressed in the symposium included: surveillance, operations, ecology, chemical control, studies of dengue viruses, and insecticide resistance. Insect vectors included Aedes, Culex, and Anopheles mosquitoes in addition to phlebotomine sand flies and triatomine bugs.

The characterization of the fat bodies and oenocytes in the adult females of the sand fly vectors Lutzomyia longipalpis and Phlebotomus papatasi

The fat body (FB) is responsible for the storage and synthesis of the majority of proteins and metabolites secreted into the hemolymph. Oenocytes are responsible for lipid processing and detoxification. The FB is distributed throughout the insect body cavity and organized as peripheral and perivisceral portions in the abdomen, with trophocytes and oenocytes attached to the peripheral portion. Here, we investigated the morphology and the subcellular changes in the peripheral and perivisceral FBs and in oenocytes of the sand flies Lutzomyia longipalpis and Phlebotomus papatasi after blood feeding. In L. longipalpis two-sized oenocytes (small and large) were identified, with both cell types displaying well-developed reticular system and smooth endoplasmic reticulum, whereas in P. papatasi, only small cells were observed. Detailed features of FBs of L. longipalpis and P. papatasi are shared either prior to or after blood feeding. The peripheral and perivisceral FBs responded to blood feeding with the development of glycogen zones and rough endoplasmic reticulum. This study provides the first detailed description of the FBs and oenocytes in sand flies, contributing significantly towards are better understanding of the biology of such important disease vectors.

Environmental factors associated with American cutaneous leishmaniasis in a new Andean focus in Colombia

OBJECTIVE

To evaluate the environmental and ecological factors associated with Leishmania transmission and vector abundance in Chaparral, Tolima-Colombia.

METHODS

First, we compared the ecological characteristics, abundance of phlebotomies and potential reservoir hosts in the peridomestic environment (100 m radius) of randomly selected houses, between two townships with high and low cutaneous leishmaniasis incidence. Second, we examined peridomestic correlates of phlebotomine abundance in all 43 houses in the higher risk township.

RESULTS

The high transmission township had higher coverage of forest (23%vs. 8.4%) and shade coffee (30.7%vs. 11%), and less coffee monoculture (16.8%vs. 26.2%) and pasture (6.3%vs. 12.3%), compared to the low transmission township. Lutzomyia were more abundant in the high transmission township 2.5 vs. 0.2/trap/night. Lutzomyia longiflocosa was the most common species in both townships: 1021/1450 (70%) and 39/80 (49%). Numbers of potential wild mammal reservoirs were small, although four species were found to be infected with Leishmania (Viannia) spp. In the high transmission township, the overall peridomiciliary capture rate of L. longiflocosa was 1.5/trap/night, and the abundance was higher in houses located nearer to forest (ρ = -0.30, P = 0.05).

CONCLUSION

The findings are consistent with a domestic transmission cycle with the phlebotomies dependent on dense vegetation near the house.

The biology and control of leishmaniasis vectors

Vector control remains a key component of many anti-leishmaniasis programs and probably will remain so until an effective vaccine becomes available. Technologies similar to those used for control of adult mosquitoes, specifically interior residual sprays and insecticide-treated nets, are currently at the forefront as disease control measures. This article provides a review of literature on the biology and control of sand fly vectors of leishmaniasis in the context of changing disease risks and the realities of modern vector control. The Literature Retrieval System of the Armed Forces Pest Management Board, Washington, DC, was the primary search engine used to review the literature.