Phlebotomine sandflies and the spreading of leishmaniases and other diseases of public health concern

Spatio-temporal analysis of American Tegumentary Leishmaniasis incidences in the Brazilian state of Amazonas: 2011 to 2022

This study aimed to conduct a spatio-temporal analysis of tegumentary leishmaniasis occurrences in the Amazonas state, Brazil. An ecological study encompassing time series and spatial analysis was performed, exploring the geographic distribution and temporal trends of American Tegumentary Leishmaniasis (ATL) in Amazonas between 2011 and 2022. Secondary data extracted from the Department of Informatics of the Unified Health System (DATASUS) were utilized for this analysis. The study evaluated the relationship between disease cases and environmental/climatic variables (deforestation, temperature, precipitation, and relative humidity). Over the study period, 19,730 cases of tegumentary leishmaniasis were recorded, averaging an incidence of 41.4/100,000 inhabitants across the 62 municipalities of Amazonas state. Disease intensity varied with seasons. Generally, Amazonas state displayed a declining trend in ATL cases. However, certain municipalities, notably Rio Preto da Eva and Presidente Figueiredo, exhibited high incidence rates, while Canutama, Envira, Eirunepé, and Pauini municipalities demand closer attention due to their demonstrated increasing temporal trend of ATL cases. The analysis indicated a correlation between the number of ATL cases reported and relative humidity as well as precipitation. These findings underscore the significance of tegumentary leishmaniasis as a public health issue in the region and emphasize the necessity for public initiatives aimed at preventing this endemic illness.

Ecological determinants of leishmaniasis vector, Lutzomyia spp.: A scoping review

Leishmania spp. are zoonotic parasites transmitted by phlebotomine sand flies, including those of the Lutzomyia genus, which can cause leishmaniases in both humans and dogs. Lutzomyia spp. are established in many countries in South and Central America and some areas of the southern United States, with suspected potential of these vectors to undergo further range expansion due to climate change. A scoping review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extensions for Scoping Reviews (PRISMA-ScR) guidelines to describe the current state of knowledge on the key ecological factors associated with Lutzomyia spp. survival, reproduction and establishment. The following electronic databases were searched for eligible studies published from 1 January 1990, to the date of search, 26 April 2023: CAB Direct (CABI), MEDLINE (via Ovid), Biological Sciences Database and Environmental Sciences Database. Primary research articles that were available in English and focused on ecological factors associated with Lutzomyia spp., such as climatic and habitat factors, geographic range, seasonality and temporality, and host abundance, were eligible for inclusion in the study. Following de-duplication, a total of 167 studies were included in Level 1 screening, 64 studies were included in Level 2 screening and 31 studies met the criteria for data extraction. Study locations included Argentina, Brazil, Colombia, Peru, Venezuela, the United States, Mexico and Canada, with some studies including multiple regions. A total of 31 different Lutzomyia spp. were assessed across these studies, with most (51.6%) of the studies focused on Lutzomyia longipalpis. Eligible studies investigated factors such as seasonality (n = 5), temperature (n = 19), precipitation (n = 13), humidity (n = 2), vegetation presence or requirements (n = 13), ecotypes (n = 7), and/or community type (i.e., urban, suburban, rural) (n = 5). Lutzomyia spp. activity was found to be higher during the rainy season, and peak when temperatures were between 20 and 25°C. Lutzomyia spp. were also found to preferentially reside in tropical or subtropical forests, which are characterised by their lack of a distinct dry season and high precipitation. This scoping review summarised the current state of the literature on the ecological factors associated with the survival, activity and reproduction of Lutzomyia spp. While there appears to be some consensus in the literature regarding some ecological requirements (such as seasonality, temperature and habitat features), overall, there is a lack of published research in this topic. This poses a significant challenge for future studies, which aim to predict the future distribution of Lutzomyia spp. in the context of climate and land use changes. Additional ecological research is urgently needed on Lutzomyia spp. given their relevance to both human and animal health.

Seasonal dynamics of sand flies in Lençóis Maranhenses National Park: a tourist destination and endemic area for leishmaniasis

Numerous sand fly species have been reported in Lençóis Maranhenses National Park (LMNP) in Northeast Brazil, including important Leishmania vectors, making the park an endemic area for tegumentary and visceral leishmaniasis. We evaluated sand fly abundance monthly over 7 years, correlating it with environmental variables and monthly tourist numbers in LMNP. Sand fly species were observed throughout the year, with Lutzomyia longipalpis Lutz & Neiva and Nyssomyia whitmani Antunes and Coutinho (Diptera: Psychodidae) being the most abundant species, especially from April to June. In addition to seasonal abundance patterns, Lu. longipalpis showed increasing abundance throughout 2013 until April 2014, whereas Ny. whitmani exhibited a consistent increase throughout the study period. Redundancy analysis indicated that monthly sand fly abundances increased with humidity but decreased with mean temperature and wind speed. Ecotourists mainly visit the park from May to September when interdune lagoons are full, coinciding with high-frequency vector activity during the rainy months (May-June). Tourists also visit in January and February during school holidays, when the rains begin and sand fly abundance increases, and in July, when sand fly abundance decreases. To date, no instances of infected tourists have been recorded, likely because visits to LMNP occur during the day when sand flies are inactive. However, there is a potential risk of vector exposure if tourists engage in nighttime cultural visits to villages around the park, where leishmaniasis cases occur annually.

Leishmania spp. in equids and their potential vectors in endemic areas of canine leishmaniasis

Equids may be infected by zoonotic Leishmania spp., including Leishmania infantum, in regions where canine leishmaniasis (CanL) is endemic, and Leishmania martiniquensis, which has been reported in horses from Central Europe. This study was designed to evaluate the occurrence of both Leishmania spp. among equids living in CanL endemic areas of Italy, as well as to identify dipteran vectors from the same habitats. From March to October 2023, blood, serum and tissue samples from skin lesions were collected from equids (n = 98; n = 56 donkeys and n = 42 horses) living in Italy, as well as sand flies and biting midges. Blood samples (n = 98) and skin lesions (n = 56) were tested for Leishmania spp. by conventional and real time PCRs and sera were tested by immunofluorescence antibody tests (IFAT) for both L. infantum and L. martiniquensis. Insects were morphologically identified, and female specimens (n = 268 sand flies, n = 7 biting midges) analyzed for Leishmania DNA, as well as engorged sand flies (n = 16) for blood-meal detection. Two animals with skin lesions (i.e., one donkey and one horse) scored positive for Leishmania spp. DNA, and 19 animals (i.e., 19.4%; n = 13 donkeys and n = 6 horses) were seropositive for L. infantum, with five of them also for L. martiniquensis. Most seropositive animals had no dermatological lesions (i.e., 68.4%) while both animals molecularly positive for Leishmania spp. scored seronegative. Of the 356 sand flies collected, 12 females (i.e., n = 8 Sergentomyia minuta; n = 3 Phlebotomus perniciosus, n = 1 Phlebotomus perfiliewi) were positive for Leishmania spp. DNA, and one out of seven biting midges collected was DNA-positive for L. infantum. Moreover, engorged sand flies scored positive for human and equine DNA. Data suggest that equids living in CanL endemic areas are exposed to Leishmania spp., but their role in the circulation of the parasite needs further investigations.

Leishmania infantum detection in Nyssomyia neivai and dogs in Southern Brazil

BACKGROUND

The sand fly Nyssomyia neivai is one of the most abundant species in Southern Brazil. It is frequently found in areas that are foci of visceral leishmaniasis in the state of Santa Catarina, caused by Leishmania infantum. In this region, the main vector of L. infantum, Lutzomyia longipalpis, has not been detected. In the absence of L. longipalpis, this study aimed to identify the sand fly fauna and diagnose any potential Leishmania spp. infection in sand flies and in dogs in a region of Southern Brazil that experienced a recent canine visceral leishmaniasis outbreak.

METHODS

This report includes a survey of the sand fly fauna at the Zoonosis Control Center of the Municipality of Tubarão (Santa Catarina, Brazil). Molecular tests were conducted to investigate Leishmania spp. natural infection in sand flies using polymerase chain reaction (PCR). In positive females, in addition to morphological identification, molecular analysis through DNA barcoding was performed to determine the sand fly species. Additionally, the dogs were tested for the presence of Leishmania spp. using a non-invasive technique for the collection of biological material, to be assessed by PCR.

RESULTS

A total of 3419 sand flies, belonging to five genera, were collected. Nyssomyia neivai was the most abundant species (85.8%), followed by Migonemyia migonei (13.3%), Pintomyia fischeri (0.8%), Evandromyia edwardsi (< 0.1%), and species of the genus Brumptomyia. (0.1%). Out of the 509 non-engorged females analyzed by PCR, two (0.4%) carried L. infantum DNA. The naturally infected females were identified as Ny. neivai, in both morphological and molecular analysis. In addition, two out of 47 conjunctival swabs from dogs tested positive for L. infantum, yielding an infection rate of 4.2%.

CONCLUSIONS

These results confirm the presence of Ny. neivai naturally infected with L. infantum in an area where dogs were also infected by the parasite, suggesting its potential role as a vector in Southern Brazil.

Are phlebotomine sand flies (Diptera: Psychodidae) really attracted to UV-light sources?

Phlebotomine sand flies are the sole confirmed vector of leishmaniosis, a group of endemic and re-emerging diseases in southern European countries such as Spain. Light traps are the major surveillance method currently being employed. Nevertheless, color light attraction by sand flies remains mostly unknown. Following prior research, the effect of UV-LED light sources, and its synergic effect with different color lights has been evaluated employing a modified Flebocollect (FC) light trap model. Results suggest that female Phlebotomus perniciosus sand flies are more attracted to a FC trap lured with the combination of blue and UV LED light sources than commercial CDC (Center for Disease Control and prevention) traps (Bonferroni post-hoc test; p < 0.08; blue/UV mean = 0.50; CDC mean = 0.13), while the combination of red and UV modified-traps excel in capturing Sergentomyia minuta sand flies (Bonferroni post-hoc test; p < 0.04; blue/UV mean = 1.19; CDC mean = 0.66). However, based on our prior studies, incorporating UV light sources into sand fly traps does not seem to enhance their attractiveness, as it has not resulted in higher capture rates. These findings contribute to understanding how sand flies' vision and light color detection is. Further research is recommended to standardize trap construction procedures and explore variations in different endemic regions according to different sand fly species.

Phlebotomine sand flies (Diptera: Psychodidae, Phlebotominae): Diversity of potential Leishmania vectors in northern Colombia

Phlebotomine sand flies are critical vectors of Leishmania parasites, impacting public health significantly. This study focused on assessing the diversity of sand flies in a rural area of El Carmen de Bolívar Municipality, northern Colombia, employing rarefaction curves and Hill numbers to understand potential vector communities and inform environmental management. From January 2018 to April 2019 (five samplings), sand flies were collected using CDC light traps with blue LED in domestic/peridomestic/sylvatic ecotopes, identifying species per Young and Duncan (1994) and Galati (2003). Hill numbers provided diversity estimates across samples, while Principal Component Analysis correlated with environmental factors with phlebotomine species presence and abundance. 8,784 phlebotomine individuals were collected; 56.4 % females and 43.6% males (ratio 3:2). These individuals belonged to eight species: Pintomyia evansi, Psychodopygus panamensis, Lutzomyia gomezi, Micropygomyia cayennensis, Evandromyia dubitans, Psathyromyia aclydifera, Pintomyia serrana, and Pintomyia rangeliana; with Pi. evansi being the most abundant species (74.39 %; 6,530 exemplars). The ANOVA showed no significant differences between phlebotomine sand flies abundances across ecotopes (p = 0.018). Species of epidemiological relevance as Pi. evansi and Lu. gomezi not show a positive correlation with environmental variables evaluated, only Ps. panamensis was positively correlated with precipitation. However, the study emphasizes the need for a continuous sand fly monitoring and research to enhance leishmaniasis control strategies, highlighting the necessity to expand knowledge on phlebotomine diversity and environmental interactions to understand vector ecology and disease dynamics better.

A review on potential therapeutic targets for the treatment of leishmaniasis

Leishmania, a protozoan parasite, is responsible for the occurrence of leishmaniasis, a disease that is prevalent in tropical regions. Visceral Leishmaniasis (VL), also known as kala-azar in Asian countries, is one of the most significant forms of VL, along with Cutaneous Leishmaniasis (CL) and Mucocutaneous Leishmaniasis (ML). Management of this condition typically entails the use of chemotherapy as the sole therapeutic option. The current treatments for leishmaniasis present several drawbacks, including a multitude of side effects, prolonged treatment duration, disparate efficacy across different regions, and the emergence of resistance. To address this urgent need, it is imperative to identify alternative treatments that are both safer and more effective. The identification of appropriate pharmacological targets in conjunction with biological pathways constitutes the initial stage of drug discovery. In this review, we have addressed the key metabolic pathways that represent potential pharmacological targets as well as prominent treatment options for leishmaniasis.

Occupational exposure to malaria, leishmaniasis and arbovirus vectors in endemic regions: A systematic review

Vector-borne diseases, including dengue, leishmaniasis and malaria, may be more common among individuals whose occupations or behaviours bring them into frequent contact with these disease vectors outside of their homes. A systematic review was conducted to ascertain at-risk occupations and situations that put individuals at increased risk of exposure to these disease vectors in endemic regions and identify the most suitable interventions for each exposure. The review was conducted in accordance with PRISMA guidelines on articles published between 1945 and October 2021, searched in 16 online databases. The primary outcome was incidence or prevalence of dengue, leishmaniasis or malaria. The review excluded ecological and qualitative studies, abstracts only, letters, commentaries, reviews, and studies of laboratory-acquired infections. Studies were appraised, data extracted, and a descriptive analysis conducted. Bite interventions for each risk group were assessed. A total of 1170 articles were screened and 99 included. Malaria, leishmaniasis and dengue were presented in 47, 41 and 24 articles, respectively; some articles presented multiple conditions. The most represented populations were soldiers, 38% (43 of 112 studies); refugees and travellers, 15% (17) each; migrant workers, 12.5% (14); miners, 9% (10); farmers, 5% (6); rubber tappers and missionaries, 1.8% (2) each; and forest workers, 0.9% (1). Risk of exposure was categorised into round-the-clock or specific times of day/night dependent on occupation. Exposure to these vectors presents a critical and understudied concern for outdoor workers and mobile populations. When devising interventions to provide round-the-clock vector bite protection, two populations are considered. First, mobile populations, characterized by their high mobility, may find potential benefits in insecticide-treated clothing, though more research and optimization are essential. Treated clothing offers personal vector protection and holds promise for economically disadvantaged individuals, especially when enabling them to self-treat their clothing to repel vectors. Secondly, semi-permanent and permanent settlement populations can receive a combination of interventions that offer both personal and community protection, including spatial repellents, suitable for extended stays. Existing research is heavily biased towards tourism and the military, diverting attention and resources from vulnerable populations where these interventions are most required like refugee populations as well as those residing in sub-Saharan Africa.

Smelly interactions: host-borne volatile organic compounds triggering behavioural responses in mosquitoes, sand flies, and ticks

Volatile organic compounds (VOCs) are chemicals emitted as products of cell metabolism, which reflects the physiological and pathological conditions of any living organisms. These compounds play a key role as olfactory cues for arthropod vectors such as mosquitoes, sand flies, and ticks, which act in the transmission of pathogens to many animal species, including humans. Some VOCs may influence arthropod behaviour, e.g., host preference and oviposition site selection for gravid females. Furthermore, deadly vector-borne pathogens such as Plasmodium falciparum and Leishmania infantum are suggested to manipulate the VOCs profile of the host to make them more attractive to mosquitoes and sand fly vectors, respectively. Under the above circumstances, studies on these compounds have demonstrated their potential usefulness for investigating the behavioural response of mosquitoes, sand flies, and ticks toward their vertebrate hosts, as well as potential tools for diagnosis of vector-borne diseases (VBDs). Herein, we provide an account for scientific data available on VOCs to study the host seeking behaviour of arthropod vectors, and their usefulness as attractants, repellents, or tools for an early diagnosis of VBDs.

Canine leishmaniasis in the Americas: etiology, distribution, and clinical and zoonotic importance

Canine leishmaniasis is a widespread disease on the American continent, with cases reported from Uruguay to the USA and Canada. While numerous Leishmania spp. have been reported in dogs in this region, Leishmania infantum and Leishmania braziliensis are the most common etiological agents of canine leishmaniasis from a continental perspective. Nonetheless, other species may predominate locally in some countries. The participation of dogs in the transmission cycle of various Leishmania spp. has long been speculated, but evidence indicates that their role as reservoirs of species other than L. infantum is negligible. Various native wildlife (e.g., small rodents, marsupials, sloths, and monkeys) are, in fact, the primary hosts of Leishmania spp. in the Americas. In this review, an updated list of Leishmania spp. infecting dogs in the Americas is presented, along with their distribution and clinical and zoonotic importance.

Alternative hosts of Leishmania infantum: a neglected parasite in Europe

Multi-host pathogens that infect various animal species and humans are considered of great importance for public and animal health. Leishmania spp. parasites are a characteristic example of such pathogens. Although leishmaniosis in humans is endemic for about 100 countries around the world it is classified as a neglected tropical disease. There are three main forms of leishmaniosis in humans: cutaneous (CL), visceral (VL) and mucocutaneous leishmaniosis (MCL). Each year, about 30,000 new cases of VL and more than 1 million new cases of CL are recorded. In Europe L. infantum is the dominant species with dogs being reservoir hosts. Apart from dogs, infection has been recorded in various animals, which suggests that other species could play a role in the maintenance of the parasite in nature. Herein we provide an in-depth review of the literature with respect to studies that deal with Leishmania infantum infections in domestic and wild animal species in Europe. Given the fact that domesticated and wild animals could contribute to the incidences of leishmaniosis in humans, the aim of this paper is to provide a comprehensive review which could potentially be used for the development of measures when it comes to the control of the Leishmania infantum parasite.

Epidemiological survey, molecular profiling and phylogenetic analysis of cutaneous leishmaniasis in Khyber Pakhtunkhwa, Pakistan

BACKGROUND

Cutaneous leishmaniasis (CL), an emerging vector-borne ailment in Khyber Pakhtunkhwa (KPK), Pakistan, exhibits diverse spread patterns and outbreaks.

METHODS

To comprehend its epidemiology and identify parasite species, we conducted an active survey on suspected CL cases (n=8845) in KPK.

RESULTS

Microscopy and internal transcribed spacer-1 PCR-restriction fragment length polymorphism (RFLP) molecular techniques detected Leishmania spp. in blood samples. Phylogenetic analysis gauged genetic affinities with other areas. District Bannu displayed the highest CL impact (14.58%), while Swat had the lowest impact (4.33%) among cases. Annual blood examination rate, parasite incidence and slide positivity rate were 4.96 per 1000 people, 0.0233 and 0.047%, respectively. CL infections were prevalent in 1- to 20-y-olds, with males (57.17%) more vulnerable than females (42.82%). Single lesions occurred in 43.73% of patients, while 31.2% people had two lesions, 17.31% had three lesions and 7.74% had more than three lesions. Most had sand-fly exposure but lacked preventive measures like repellents and bed nets. Leishmania tropica was confirmed via RFLP analysis in amplified samples. Phylogenetic analysis unveiled genetic parallels between L. tropica of KPK and isolates from China, Iran, Afghanistan, India, Syria and Morocco.

CONCLUSIONS

Urgent comprehensive control measures are imperative. Early detection, targeted interventions and raising awareness of CL and sand-fly vectors are vital for reducing the disease's impact. International collaboration and monitoring are crucial to tackle Leishmania spp.'s genetic diversity and curtail its cross-border spread.

Hit-to-lead optimization of 2-aminoquinazolines as anti-microbial agents against Leishmania donovani

Visceral leishmaniasis is a potentially fatal disease caused by infection by the intracellular protist pathogens Leishmania donovani or Leishmania infantum. Present therapies are ineffective because of high costs, variable efficacy against different species, the requirement for hospitalization, toxicity and drug resistance. Detailed analysis of previously published hit molecules suggested a crucial role of 'guanidine' linkage for their efficacy against L. donovani. Here we report the design of 2-aminoquinazoline heterocycle as a basic pharmacophore-bearing guanidine linkage. The introduction of various groups and functionality at different positions of the quinazoline scaffold results in enhanced antiparasitic potency with modest host cell cytotoxicity using a physiologically relevant THP-1 transformed macrophage infection model. In terms of the ADME profile, the C7 position of quinazoline was identified as a guiding tool for designing better molecules. The good ADME profile of the compounds suggests that they merit further consideration as lead compounds for treating visceral leishmaniasis.

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.

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.

Molecular monitoring of insecticide resistance in major disease vectors in Armenia

BACKGROUND

Armenia is considered particularly vulnerable to life-threatening vector-borne diseases (VBDs) including malaria, West Nile virus disease and leishmaniasis. However, information relevant for the control of the vectors of these diseases, such as their insecticide resistance profile, is scarce. The present study was conducted to provide the first evidence on insecticide resistance mechanisms circulating in major mosquito and sand fly populations in Armenia.

METHODS

Sampling sites were targeted based mainly on previous historical records of VBD occurrences in humans and vertebrate hosts. Initially, molecular species identification on the collected vector samples was performed. Subsequently, molecular diagnostic assays [polymerase chain reaction (PCR), Sanger sequencing, PCR-restriction fragment length polymorphism (RFLP), quantitative PCR (qPCR)] were performed to profile for major insecticide resistance mechanisms, i.e. target site insensitivity in voltage-gated sodium channel (vgsc) associated with pyrethroid resistance, acetylcholinesterase (ace-1) target site mutations linked to organophosphate (OP) and carbamate (CRB) resistance, chitin synthase (chs-1) target site mutations associated with diflubenzuron (DFB) resistance and gene amplification of carboxylesterases (CCEs) associated with resistance to the OP temephos.

RESULTS

Anopheles mosquitoes were principally represented by Anopheles sacharovi, a well-known malaria vector in Armenia, which showed no signs of resistance mechanisms. Contrarily, the knockdown resistance (kdr) mutations V1016G and L1014F/C in the vgsc gene were detected in the arboviral mosquito vectors Aedes albopictus and Culex pipiens, respectively. The kdr mutation L1014S was also detected in the sand fly, vectors of leishmaniasis, Phlebotomus papatasi and P. tobbi, whereas no mutations were found in the remaining collected sand fly species, P. sergenti, P. perfiliewi and P. caucasicus.

CONCLUSIONS

This is the first study to report on molecular mechanisms of insecticide resistance circulating in major mosquito and sand fly disease vectors in Armenia and highlights the need for the establishment of systematic resistance monitoring practices for the implementation of evidence-based control applications.

New sand fly (Diptera, Psychodidae) records and COI DNA barcodes in the state of Maranhão, Eastern Amazon, Brazil

The sand fly fauna and the usefulness of the DNA barcoding fragment of the cytochrome c oxidase subunit I (COI) gene were accessed in a forest fragment in the municipality of Governador Newton Bello, state of Maranhão, Brazil. We performed entomological collections in three independent campaigns in May and October 2021, and January 2023. Sand flies were morphologically-identified and then DNA barcoded. Sequences were deposited and analyzed in the BOLD System Database, and various species delimitation algorithms, to assess whether DNA sequences merge into taxonomic units in accordance with nominal species. In total, 1,524 sand flies were collected, comprising 32 nominal species. Nyssomyia antunesi was the most abundant species (31.5 %), followed by Psychodopygus davisi (27 %). We reported for the first time in the state of Maranhão, the presence of Lutzomyia evangelistai, Lutzomyia sherlocki, Pressatia equatorialis, and Psathyromyia barrettoi. We amplified and analyzed 67 COI barcodes of 23 species, which were merged with conspecific sequences extracted from GenBank. The maximum intraspecific p distances ranged from 0.0 % to 14.74 %, while the distances to the nearest neighbor varied from 1.67 % to 13.64 %. The phylogenetic gene tree and species delimitation tools clustered sequences into well-supported clades/clusters for each nominal species, except for Pressatia choti/Pr. equatorialis, which have the lowest interspecific genetic distance (1.67 %). We sequenced for the first time COI barcodes of Brumptomyia brumpti, Evandromyia monstruosa, Micropygomyia rorotaensis, Micropygomyia pilosa, Pintomyia christenseni, Pintomyia pacae, Pr. equatorialis, Pa. barrettoi, and Psathyromyia hermanlenti, which will be useful for further molecular identification and classification proposals of Neotropical species. This study updated the current list of the sand fly fauna for the state of Maranhão to 97, and demonstrated that COI barcodes are useful for specific identification.

Sand fly-borne diseases in Europe: epidemiological overview and potential triggers for their emergence and re-emergence

Phlebotomine sand flies (Diptera: Phlebotominae) are vectors of human and animal pathogens, including Leishmania species protozoan parasites and viruses of the genus Phlebovirus. In Europe, visceral zoonotic leishmaniasis caused by Leishmania infantum, a deadly disease when left untreated, is endemic in southern countries, and dogs are the main reservoir hosts for human infection. Most phleboviruses cause asymptomatic infections or flu-like syndromes in humans, but Toscana phlebovirus can cause meningitis and encephalitis. These diseases are likely to re-emerge, posing a growing threat to public and animal health. Potential triggers include the movement of humans and dogs, increasing numbers of immunosuppressive conditions, climate change and other human-mediated environmental changes. An overview of the main epidemiological characteristics of the pathogens transmitted by sand flies in Europe and the potential triggers involved in their emergence and re-emergence are reviewed here. There is a need to implement mandatory notification of human and canine leishmaniases and human phleboviruses and coordinated epidemiological surveillance programmes at a European level, and to raise awareness among healthcare professionals and citizens about sand fly-borne diseases, following a One Health approach.

Comparative Study of a Novel Lateral Flow Rapid Test with Conventional Serological Test Systems for the Diagnosis of Canine Leishmaniosis in Croatia and Brazil

Control of canine infections with Leishmania infantum (L. infantum), a major zoonotic disease in Brazil and southern Europe, is becoming increasingly important due to its close proximity to humans, the increasing import of dogs from endemic regions and the impact of climate change on vector spreading. Simple, rapid and reliable diagnostic tests are therefore needed to detect infected dogs. Here, we re-evaluated different serological methods for the diagnosis of canine leishmaniosis (CanL) in Croatia and Brazil. The diagnostic performance of the indirect fluorescent antibody test (IFAT) and the VetLine® Leishmania ELISA (GSD Frankfurt, Germany) was compared with three rKLi8.3-based diagnostic test systems, the rKLi8.3 ELISA (GSD Frankfurt, Germany), the INgezim® Leishma CROM (GSD Madrid, Spain) lateral flow test (LFT) and the VetBlot®Leishmania LineBlot (GSD Frankfurt, Germany). CanL symptomatic dogs were efficiently diagnosed by all tests, except the VetLine® Leishmania ELISA, which is based on whole Leishmania antigens. The advantage of rKLi8.3 was also observed in oligo- and asymptomatic dogs from Brazil and Croatia, although with reduced diagnostic efficiency compared to symptomatic dogs. Similar to IFAT and rKLi8.3 ELISA, the LFT did not cross-react with other common canine pathogens; it showed very high specificity for healthy dogs from endemic regions in both countries and did not react with healthy, vaccinated dogs in Brazil. In conclusion, serodiagnostic tests based on the rKLi8.3 antigens are superior to whole parasite antigens, and the LFT has the advantage of providing a laboratory-independent, rapid and specific diagnosis of CanL.

Phlebotomine sand flies in rural Mayan communities of Southern Mexico: The heterogeneity of the ruralscape increases the entomological risk

In the Yucatan Peninsula, tropical preserved forests harbor a high diversity of phlebotomine sand fly species, potential vectors of Leishmania. As a result, a significant risk of contracting localized cutaneous leishmaniasis (LCL) is associated with entry into these forest ecosystems. However, with the current trajectory of land use in the region, communities now live within modified landscapes which could increase their risk of contact with vectors. In this study, we characterized the sand fly fauna and its relationship with the characteristics of peridomestic habitats in two rural communities in Yucatan characterized by contrasting records of leishmaniasis. Five human dwellings in each community were randomly selected and the peridomestic landscape was characterized (i.e., type and percentage of land use). For the collection of sand flies, CDC traps were deployed in both the intra and peridomicile. Differences in alpha and beta diversity between communities and ecotopes were estimated considering three separate groups, all species together, zoophilic species, and anthropophilic species. In total, 1, 241 sand flies represented by eight species were collected from November 2021-March 2022. Both communities registered the presence of sand flies in the intra and peridomicile, and females were more abundant than males. However, the greatest diversity of species was recorded in the peridomicile of the community with the highest composition of land uses. Our study demonstrates that the transformation of the forest around the communities favors the abundance and richness of sand flies in the peridomestic environment. We discuss the limitations and implications of our findings regarding the potential risk of the emergence of peri‑rural cycles of leishmaniasis in the region.

Genetic variation and geographic distribution of Leishmania orientalis and Leishmania martiniquensis among Leishmania/HIV co-infection in Thailand

Since 1999, the number of asymptomatic leishmaniasis cases has increased continuously in Thailand, particularly among patients with HIV who are prone to develop symptoms of cutaneous and visceral leishmaniasis further. The asymptomatic infection could play a key role in Leishmania transmission and distribution. Understanding population structure and phylogeographic patterns could be crucially needed to develop effective diagnoses and appropriate guidelines for therapy. In this study, genetic variation and geographic distribution of the Leishmania/HIV co-infected population were investigated in endemic northern and southern Thailand. Interestingly, Leishmania orientalis was common and predominant in these two regions with common regional haplotype distribution but not for the others. Recent population expansion was estimated, probably due to the movement and migration of asymptomatic individuals; therefore, the transmission and prevalence of Leishmania infection could be underestimated. These findings of imbalanced population structure and phylogeographic distribution patterns provide valuable, insightful population structure and geographic distribution of Leishmania/HIV co-infection to empower prevention and control of transmission and expansion of asymptomatic leishmaniasis.

Interactions between Leishmania parasite and sandfly: a review

Leishmaniasis transmission cycles are maintained and sustained in nature by the complex crosstalk of the Leishmania parasite, sandfly vector, and the mammalian hosts (human, as well as zoonotic reservoirs). Regardless of the vast research on human host-parasite interaction, there persists a substantial knowledge gap on the parasite's development and modulation in the vector component. This review focuses on some of the intriguing aspects of the Leishmania-sandfly interface, beginning with the uptake of the intracellular amastigotes from an infected host to the development of the parasite within the sandfly's alimentary canal, followed by the transmission of infective metacyclic stages to another potential host. Upon ingestion of the parasite, the sandfly hosts an intricate repertoire of immune barriers, either to evade the parasite or to ensure its homeostatic coexistence with the vector gut microbiome. Sandfly salivary polypeptides and Leishmania exosomes are co-egested with the parasite inoculum during the infected vector bite. This has been attributed to the modulation of the parasite infection and subsequent clinical manifestation in the host. While human host-based studies strive to develop effective therapeutics, a greater understanding of the vector-parasite-microbiome and human host interactions could help us to identify the targets and to develop strategies for effectively preventing the transmission of leishmaniasis.

Field evaluation of a new suction light trap for the capture of phlebotomine sand flies (Diptera: Psychodidae: Phlebotominae), vectors of leishmaniasis

Phlebotomine sand flies are crepuscular and nocturnal small dipteran insects in the family Psychodidae. Several disease agents, including Leishmania parasites, are transmitted to humans and other vertebrate hosts by the bite of an infected female sand fly. As part of leishmaniasis surveillance programs, light traps have been routinely used in sand fly collections. In this context, new trapping devices are always being required to improve vector monitoring. Here, the efficiency of a new suction light trap, named Silva suction trap or SS trap, was field evaluated in collecting sand flies. Two SS traps, one with green (520 nm, 15,000 mcd) and the other with white (wide spectrum, 18,000 mcd) LEDs, and one CDC-type trap were deployed in a rural forested environment. A total of 4686 phlebotomine sand flies were captured. The most frequent species were females of the Ps. Chagasi series (77.8%) followed by males of Ps. wellcomei (11.6%), Nyssomyia whitmani (3.3%), and Bichromomyia flaviscutellata (2.4%). The CDC-type light trap collected 101.9 ± 20.89 sand flies and 14 species, followed by the white-baited SS trap (87.78 ± 16.36, 14), and the green-baited SS trap (70.61 ± 14.75, 15), but there were no statistically significant differences among traps. A discussion on the considerable advantages of the use of SS traps over CDC traps is included. In this study, the Silva suction trap proved to be efficient and can be an alternative to CDC traps for monitoring adult phlebotomine sand fly populations.

Species identification of phlebotomine sandflies using deep learning and wing interferential pattern (WIP)

Sandflies (Diptera; Psychodidae) are medical and veterinary vectors that transmit diverse parasitic, viral, and bacterial pathogens. Their identification has always been challenging, particularly at the specific and sub-specific levels, because it relies on examining minute and mostly internal structures. Here, to circumvent such limitations, we have evaluated the accuracy and reliability of Wing Interferential Patterns (WIPs) generated on the surface of sandfly wings in conjunction with deep learning (DL) procedures to assign specimens at various taxonomic levels. Our dataset proves that the method can accurately identify sandflies over other dipteran insects at the family, genus, subgenus, and species level with an accuracy higher than 77.0%, regardless of the taxonomic level challenged. This approach does not require inspection of internal organs to address identification, does not rely on identification keys, and can be implemented under field or near-field conditions, showing promise for sandfly pro-active and passive entomological surveys in an era of scarcity in medical entomologists.

A disfiguring neglected tropical disease sweeps war-torn Yemen: a community-based study of prevalence and risk factors of cutaneous leishmaniasis among rural communities in the western highlands

BACKGROUND

Cutaneous leishmaniasis (CL) is a major health problem in Yemen and is endemic in many rural areas across the country.

METHODS

A community-based cross-sectional survey followed by unmatched case-control comparisons was conducted among 612 participants in Utmah district, western Yemen. A total of 223 participants were included in the case-control analysis to identify the significant risk factors. Skin scrapping samples were examined by microscopy and internal transcribed spacer 1 nested polymerase chain reaction.

RESULTS

Overall, 33% (202/612) of the participants had active skin lesions and/or scars that met the clinical criteria for CL. A total of 90 (14.7%) participants had suspected active CL lesions; however, a prevalence of 8.7% (53/612) was obtained based on molecular and parasitological examination, with Leishmania tropica being the only causative agent identified. Multivariable logistic regression analyses showed that being ≤10 y old, being female, living in houses with cracked walls, living in the presence of other family members with typical ulcerating skin diseases and sleeping outside were factors significantly associated with an increased likelihood of having CL. Moreover, keeping livestock on the ground floor of the house was significantly associated with a decreased likelihood of having CL.

CONCLUSION

The study reveals an alarmingly high prevalence of CL among the studied population. Therefore there is an urgent need for effective control measures and improved treatment efforts against this devastating disease.

Seroprevalence of Toscana and sandfly fever Sicilian viruses in humans and livestock animals from western Saudi Arabia

High seroprevalence rates of several phleboviruses have been reported in domestic animals and humans in sandfly-infested regions. Sandfly Fever Sicilian virus (SFSV) and Toscana virus (TOSV) are two of these viruses commonly transmitted by Phlebotomus sandflies. While SFSV can cause rapidly resolving mild febrile illness, TOSV could involve the central nervous system (CNS), causing diseases ranging from aseptic meningitis to meningoencephalitis. Sandfly-associated phleboviruses have not been investigated before in Saudi Arabia and are potential causes of infection given the prevalence of sandflies in the country. Here, we investigated the seroprevalence of SFSV and TOSV in the western region of Saudi Arabia in samples collected from blood donors, livestock animals, and animal handlers. An overall seroprevalence of 9.4% and 0.8% was found in humans for SFSV and TOSV, respectively. Seropositivity was significantly higher in non-Saudis compared to Saudis and increased significantly with age especially for SFSV. The highest seropositivity rate was among samples collected from animal handlers. Specifically, in blood donors, 6.4% and 0.7% tested positive for SFSV and TOSV nAbs, respectively. Animal handlers showed higher seroprevalence rates of 16% and 1% for anti-SFSV and anti-TOSV nAbs, respectively, suggesting that contact with livestock animals could be a risk factor. Indeed, sera from livestock animals showed seropositivity of 53.3% and 4.4% in cows, 27.5% and 7.8% in sheep, 2.2% and 0.0% in goats, and 10.0% and 2.3% in camels for SFSV and TOSV, respectively. Together, these results suggest that both SFSV and TOSV are circulating in the western region of Saudi Arabia in humans and livestock animals, albeit at different rates, and that age and contact with livestock animals could represent risk factors for infection with these viruses.

Neutralizing based seroprevalence study of Toscana virus in livestock from Algeria

Toscana virus is a sandfly-borne human pathogen belonging to Phlebovirus genus into Phenuiviridae family. It is emerging in north Africa posing a complex threat to public health. TOSV is heavily affecting sandfly-exposed people in northern Algeria. A larger distribution has recently been stated in Algeria by using dog sera. Dog exposure to TOSV was repeatedly identified in north Algeria, with 4.56% lately detected to possess respective neutralizing antibodies. However, evidence for TOSV has only been observed in dogs among various species of domestic animals. Therefore, we attempted to assess sera from 221 livestock comprising cattle, sheep, goats, rabbits and horses, to identify the presence of TOSV neutralizing antibodies. The study was conducted during 2017, in 11 areas from the governorates of Blida, Medea, Algiers, Tipaza, Ain Defla, Tissemsilt in the north center, and Setif, Mila, Tizi Ouzou, Jijel in the northeast of Algeria. Positive results were obtained in 14.6% (12/82) cattle, 17.18% (11/64) sheep, 15% (3/20) horses and 3.33% (1/30) goats, whereas rabbits remained negative. Positive samples originated mainly from the north centre, with new areas being first-ever detected. The seroprevalence was noticed to be very strongly related to sample origin (p < 0.01). Females (OR=4.09) were observed to be more likely infected. Our findings represent a further proof of TOSV circulation in Algeria. Moreover, they revealed a potential role of livestock (p = 0.00731) in its natural cycle. This fact emphasize how important is to elucidate the exact contribution of livestock to the epidemiology of sandfly-borne phleboviruses, and their impact on public health.

Trichophoromyia auraensis: evidence for cryptic species and first record in the state of Maranhão, Brazil

Trichophoromyia auraensis (Mangabeira, 1942) (Diptera, Psychodidae, Phlebotominae) has a wide geographic distribution in the western region of the Amazon biome, where it is a putative Leishmania vector. Here, we reported for the first time a population of this species in the Brazilian state of Maranhão, in the eastern Amazon, from which we DNA-barcoded and compared with previously processed specimens from Acre State, in the western Amazon. For this, we analyzed the DNA barcoding fragment (658 bp) of the mitochondrial cytochrome c oxidase subunit I (COI) gene and the nuclear internal transcribed spacer 2 (ITS2) of Trichophoromyia species using phylogenetic gene trees, and species delimitation algorithms. The analyses of COI barcodes showed high values of genetic distance (mean K2P = 5.17) and well-supported clades/MOTUs for the eastern and western populations of T. auraensis, which may indicate a possible complex of cryptic species. The western population of this taxon merged with the close-related sand fly Trichophoromyia velezbernali Posada-López, Galvis and Galati, 2018 from Colombia, which may be associated with the recent speciation history and introgression between these populations. These evidences should be evaluated with a more comprehensive sampling in terms of analyzed populations and molecular markers.

Biting rhythms and infection rates of anthropophilic sand fly species (Diptera: Phlebotominae) in sites with different land use in southern Mexico

Could tropical forest conversion shape sand fly (Diptera: Phlebotominae) biting rhythms and Leishmania infection rates? Using a Shannon trap, we estimated the bite rate and infection prevalence among anthropophilic sand flies at sites with different land use in southern Mexico. We estimated the expected monthly infection rate of the Leishmania parasite along the gradient and generated information on the biting rhythm of sand flies in a poorly characterized cutaneous leishmaniasis endemic region. We used generalized mixed linear and mixed additives models to evaluate differences in the biting rate, nocturnal activity, and inoculation rate of female sand flies, as well as their relationship with the loss of forest cover and environmental disparities recorded throughout the study area. Our results show that the loss of forest cover influences the biting rhythm of sand fly species and the potential number of infectious bites with Leishmania, but the greatest entomological and potential epidemiological risk continues to be associated with sylvatic areas (amplification events). Despite this, we detected that the effect of forest cover (%) on the entomological exposure seems to be also dependent on the sand fly species, and that, albeit to a lesser extent, Leishmania parasite is circulating in disturbed landscapes through generalist and competent sand fly vector species. We also found that land use change did not affect the nocturnal activity, however we detected that important vector species were active most of the time. Contrary to our expectation, temperature and humidity did not shape the biting rhythm of sand fly species. We discuss the limitations and epidemiological implications of our findings regarding the risk of contracting leishmaniasis in southern Mexico.

Molecular identification of Leishmania major species in phlebotomine sand flies from Al Ahsa, Eastern KSA

Objectives

Cutaneous leishmaniasis (CL) is considered an overlooked public health threat in KSA. CL is endemic to several Saudi regions, including Al Ahsa City, Eastern KSA. To our knowledge, no prior molecular identification of Leishmania parasites in vectors in Al Ahsa has been published. The aim of this study was to perform molecular identification of Leishmania species in sand flies collected from Al Ahsa.

Methods

This cross-sectional study was conducted in Al Ahsa from July 2020 to May 2021. Sand flies were collected from the three areas with the highest rates of CL cases and sand flies, according to data from the Vector Borne Diseases Prevention Center in Al Ahsa. CDC miniature light traps and sticky traps were used to collect sand flies. Pools of 3-10 female sand flies were subjected to genomic DNA extraction. The extracted DNA was then amplified with a protocol targeting the Leishmania genus and using species-specific primers. For Leishmania species identification, a PCR-restriction fragment length polymorphism (PCR-RFLP) method was used.

Results

Ten of 113 pools of samples tested positive for the Leishmania genus, according to our experimental protocol. Characterization of Leishmania species by PCR-RFLP established Leishmania major as the only species found in the collected sand flies.

Conclusion

This is the first documentation of molecular identification of Leishmania species in phlebotomine sand flies in the Al Ahsa region. L. major was the only species identified in our study. Further comprehensive research investigating the vectors and reservoirs will be crucial to establish the dynamics of transmission of Leishmania in Al Ahsa.

Species diversity and detection of pathogens in phlebotomine sand flies collected from forest management areas of Quintana Roo, Mexico

Sand flies have expanded their areas of distribution, thereby increasing the risk of pathogen transmission in non-endemic areas. To establish efficient prevention and control strategies for the transmission of vector-borne pathogens, it is important to understand seasonal dynamics of their vectors. In Mexico, there are several areas where the contact between sand flies, hosts and reservoirs favours the transmission of the pathogen. We compared sand fly communities in a forest management area and a conserved area in Noh-Bec, Quintana Roo, Mexico. The analysis included species diversity, activity peaks and molecular detection of pathogens. Sand flies were collected from November to December 2021 and April to May 2022, during 84 night-traps. The conserved area showed higher numbers and greater species heterogeneity of sand flies as compared with the other sites. The β-diversity analysis revealed that sites disturbed by logging (S1, S2, S3) had greater similarity (90%) in their sand fly species composition than a conserved area (S4) (similarity = 36%). Although none of the specimens were infected with Leishmania, we detected Wolbachia (19.4%) in all four sites, as well as Bartonella (3.25%) only in the disturbed sites. Further studies on the dynamics of sand fly populations and their association with pathogens are necessary.

Human Cutaneous Leishmaniasis in North Africa and Its Threats to Public Health: A Statistical Study Focused on Djelfa (Algeria)

Cutaneous leishmaniasis, the most common form of leishmaniasis, causes long-term skin lesions on exposed areas of the skin. It is caused by a protozoan parasite belonging to the genus Leishmania and is transmitted via infected phlebotomine sand flies. In North Africa, particularly Algeria, the disease represents a major public health problem. This retrospective study, which focuses on the agropastoral region of Djelfa (central Algeria) during a period of 16 years, from 2006 to 2021, is part of the surveillance of cutaneous leishmaniasis to identify the key factors favouring its probable spread. The analyzed data reveal that this disease is more prevalent in male patients (53.60%) and is highly widespread in this vast area of 66,415 km2 with a total of 3864 CL cases, reaching a peak of 1407 cases in 2006. Statistically, the Pearson correlation validated by the p-value shows, in an original and sometimes unexpected way, that certain factors, such as temperature linked to climate change, are playing a significant role in the probable spread of the disease in Djelfa and its surrounding regions. The concentration of the population in some specific rural areas with limited or nonexistent access to public health services is another potential factor in disease transmission. The results were highlighted by a significant correlation coefficient (r=0.66) with a p-value less than 0.01. While there is currently no vaccine or prophylactic drug available, our research represents a preliminary approach that addresses various epidemiological aspects of the disease. This paves the way for a proactive preventive strategy involving the control of vector-borne diseases.

Comprehensive Cross-Sectional Evaluation of Human Sandfly-Borne Phlebovirus Exposure in an Endemic Region

Sandfly-borne phleboviruses are endemic in countries around the Mediterranean Basin and pose a significant health threat for populations, with symptoms spanning from febrile diseases to central nervous system involvement. We carried out a comprehensive cross-sectional screening via microneutralization (MN) assays for a quantitative assessment of neutralizing antibodies (NAs) to seven phleboviruses representing three distinct serocomplexes, using samples previously screened via immunofluorescence assays (IFAs) in Turkey, an endemic region with various phleboviruses in circulation. We detected NAs to three phleboviruses: Toscana virus (TOSV), sandfly fever Naples virus (SFNV), and sandfly fever Sicilian virus (SFSV), while assays utilizing Adana virus, Punique virus, Massilia virus, and Zerdali virus remained negative. The most frequently observed virus exposure was due to TOSV, with a total prevalence of 22.6%, followed by SFNV (15.3%) and SFSV (12.1%). For each virus, IFA reactivity was significantly associated with NA detection, and further correlated with NA titers. TOSV and SFSV seroreactivities were co-detected, suggesting exposure to multiple pathogenic viruses presumably due to shared sandfly vectors. In 9.6% of the samples, multiple virus exposure was documented. In conclusion, our findings demonstrate widespread exposure to distinct pathogenic phleboviruses, for which diagnostic testing and serological screening efforts should be directed.

Molecular Detection of Leishmania in Wild Caught Sand Flies of Larroussius Subgenus in Iran: Combined Use of Internal and External Morphological Characters as a Mean to Differentiate Morphologically Similar Females

OBJECTIVE

Phlebotomine sand flies are the primary vectors of leishmaniasis; visceral form of disease is transmitted mainly by species belonging to Larroussius and Adlerius subgenus. Species identification of some females in Larroussius subgenus is not easy due to the high similarity. Accurate species identification enables control operations to target only main vectors and increase understanding of ecological needs, bionomic characteristics, and behavioral traits. The purpose of current study was to use two approaches based on internal and external morphological characters to identify the wild caught of female specimens belonged to Larroussius subgenus and investigate Leishmania infection.

METHODS

Totally, 128 specimens belonging to Larroussius' subgenus were collected from a VL focus in northwestern Iran, species differentiation was done by two approaches proposed in literature: (1) characters of pharyngeal armature, number of Spermathecal segment, length of spermathecal neck, palpal and ascoid formulae; (2) blindly on the basis of the shape of the base of spermathecal duct. Their potential infection to Leishmania was investigated by kDNA-Nested-PCR.

RESULTS

The results of species identification were consistent based on two methods. Among three identified species, Phlebotomus perfiliewi was found to be the dominant species, followed by Ph. neglectus and Ph. tobbi. Two specimens of Ph. perfiliewi were found to be infected by Leishmania infantum, which emphasizes the role of this species in VL transmission in study area.

CONCLUSION

It is suggested that combination of the characters used here be considered for species identification of female of Larroussius subgenus to take advantage of maximum characters, especially where species present sympatrically.

Molecular identification of phlebotomine sand flies and the harbored Leishmania spp. in Sokoto State, Nigeria

Introduction

Female sand flies are hematophagous, feeding on animals and in the process serve as vectors for Leishmania, the parasites that cause leishmaniasis in humans. Leishmaniasis are a group of parasitic neglected tropical diseases in 98 countries including Nigeria and kills ~60,000 people/year. In Nigeria, Sokoto State is endemic to leishmaniasis but there is a knowledge gap on the identity of the prevalent sand flies and the Leishmania species they transmit. Hence, this cross-sectional study was designed to take inventory of the species of sand flies in Sokoto using genetic methods.

Methods

1,260 (310 females) sand flies were collected from three Local Government Areas (L.G.A) of Sokoto State- Wamakko, Sokoto South and Kware. Genomic DNA was extracted from each fly and DNA amplification by polymerase chain reaction (PCR) was carried out on the DNA samples using primers targeting the arthropods mitochondrial cytochrome oxidase subunit 1 (mt-coI) gene, and nested PCR with primers targeting the gene for Leishmania internal transcribed spacer-1 (its-1) of ribosomal RNA its-1rRNA. The PCR products were sequenced.

Results

Gene sequence analysis revealed five species of sand flies belonging to the old-world genera namely Phlebotomus and Sergentomyia. The identified species were P. papatasi (6.45%), S. adleri (6.45%), S. affinis (9.7%), S. distincta (9.7%), S. schwetzi (67.7%). Within the sampling period, sand flies were most abundant in the rainy months of August (104/33.5%) and September (116/37.4%) with all the five identified species occurring. Sequence analysis of its-1 gene identified Leishmania infantum in two sand flies (2/310)- P. papatasi (from Sokoto South) and S. affinis (from Wamakko). BLAST search in NCBI and phylogenetic analysis revealed that the sand fly species are related to the species reported in different parts of Africa, while the L. infantum is identical to strain reported in Brazil (KY379083.1).

Discussion

Phlebotomus papatasi and four species belonging to the genus Sergentomyia are the most prevalent sand flies in Sokoto State, Nigeria and they harbor L. infantum solely. The results shed light on why visceral leishmaniasis is the most predominant form of the disease. Therefore, we recommend that adequate care for dogs must be instituted as dogs are the major animal reservoir for L. infantum.

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.

Morphological and DNA-based description of Trichophoromyia peixotoi n. sp. (Diptera: Psychodidae), a new sand fly species from the Brazilian Amazon

BACKGROUND

Phlebotomine sand flies of the genus Trichophoromyia Barretto, 1962 are of great relevance to public health as vectors of Leishmania protozoans. A new phlebotomine species named Trichophoromyia peixotoi n. sp. is here described based on both male morphology and COI DNA barcodes.

METHODS

The sand fly specimens were collected in the Parque Nacional da Amazônia (PNA), situated in the municipality of Itaituba, state of Pará, Brazil. Morphological description was done based on 10 male specimens. Five specimens were DNA barcoded for the COI gene.

RESULTS

The morphological and molecular analyses allowed the delimitation of this new species from others of Trichophoromyia. Trichophoromyia peixotoi n. sp. is closely related to other species with aedeagal ducts > 4 times the length of the sperm pump, from which it may be distinguished by the gonocoxite bristles and paramere shape.

CONCLUSIONS

The description of T. peixotoi n. sp. brings the number of species of Trichophoromyia to 45, including 24 for Brazil. The integrative taxonomy effort through the analysis of COI barcodes proved to be effective in the species delimitation of some Trichophoromyia spp.

Improving the COI DNA barcoding library for Neotropical phlebotomine sand flies (Diptera: Psychodidae)

Sand fly species are traditionally identified using morphological traits, though this method is hampered by the presence of cryptic species. DNA barcoding is a widely used tool in the case of insects of medical importance, where it is necessary to know quickly which species are present in a transmission area. Here, we assess the usefulness of mitochondrial cytochrome c oxidase subunit I (COI) DNA barcoding as a practical tool for species identification, correct assignment of isomorphic females, and to evaluate the detection of cryptic diversity that occurs in the same species. A fragment of the COI gene was used to generate 156 new barcode sequences for sand flies from different countries of the Neotropical region, mainly Colombia, which had been identified morphologically as 43 species. The sequencing of the COI gene allowed the detection of cryptic diversity within species and correctly associated isomorphic females with males identified by morphology. The maximum intraspecific genetic distances ranged from 0 to 8.32% and 0 to 8.92% using uncorrected p distances and the Kimura 2-parameter (K2P) model, respectively. The minimum interspecific distance (nearest neighbor) for each species ranged from 1.5 to 14.14% and 1.51 to 15.7% using p and K2P distances, respectively. Three species had more than 3% maximum intraspecific distance: Psychodopygus panamensis, Micropygomyia cayennensis cayennensis, and Pintomyia evansi. They also were split into at least two molecular operational taxonomic units (MOTUs) each, using different species delimitation algorithms. Regarding interspecific genetic distances, the species of the genera Nyssomyia and Trichophoromyia generated values lower than 3% (except Nyssomyia ylephiletor and Ny. trapidoi). However, the maximum intraspecific distances did not exceed these values, indicating the presence of a barcode gap despite their proximity. Also, nine sand fly species were DNA barcoded for the first time: Evandromyia georgii, Lutzomyia sherlocki, Ny. ylephiletor, Ny. yuilli pajoti, Psathyromyia punctigeniculata, Sciopemyia preclara, Trichopygomyia triramula, Trichophoromyia howardi, and Th. velezbernali. The COI DNA barcode analysis enabled the correct delimitation of several Neotropical sand fly species from South and Central America and raised questions about the presence of cryptic species for some taxa, which should be further assessed.

Species diversity of phlebotomine sand flies and sympatric occurrence of Leishmania (Mundinia) martiniquensis, Leishmania (Leishmania) donovani complex, and Trypanosoma spp. in the visceral leishmaniasis focus of southern Thailand

Autochthonous leishmaniasis in Thailand has recently been a public health concern due to an increasing number of new clinical cases. Most indigenous cases were diagnosed with Leishmania (Mundinia) martiniquensis, and Leishmania (Mundinia) orientalis. However, some doubts regarding vector misidentification have arisen and need to be elucidated. Accordingly, we aimed to assess the species composition of sand flies and determine the molecular prevalence of trypanosomatids in the transmission area of leishmaniasis in southern Thailand. In the present study, a total of 569 sand flies were caught from the vicinity of a visceral leishmaniasis patient's house in Na Thawi District, Songkhla Province. Of these, 229 parous and gravid females consisted of Sergentomyia khawi, Se. barraudi, Phlebotomus stantoni, Grassomyia indica, and Se. hivernus, accounting for 31.4%, 30.6%, 29.7%, 7.9%, and 0.4%, respectively. However, Se. gemmea, which has previously been proposed as the most abundant species and putative vector of visceral leishmaniasis, was not found in the present study. Based on ITS1-PCR and sequence analysis, two specimens of Gr. indica and Ph. stantoni showed positive amplification of L. martiniquensis and L. donovani complex, respectively, the first one being presumed indigenous and the second one being not. Anuran Trypanosoma was also molecularly detected using SSU rRNA-PCR and ubiquitously found in sixteen specimens of four dominant sand fly species except for Se. hivernus. The obtained sequences could be phylogenetically categorized into the two major amphibian clades (An04/Frog1 and An01+An02/Frog2). The existence of the monophyletic subgroup and distinct lineage suggests them as novel Trypanosoma species. The TCS network analysis of these anuran Trypanosoma sequences also revealed high haplotype diversity (Hd = 0.925 ± 0.050), but low nucleotide diversity (π = 0.019 ± 0.009). Furthermore, the living anuran trypanosomes were microscopically demonstrated in a single specimen of Gr. indica, supporting the vectorial capacity. Importantly, our data confirmed the scarcity of Se. gemmea and also uncovered, for the first time, the co-circulation of L. martiniquensis, L. donovani complex, and suspected novel anuran Trypanosoma spp. in phlebotomine sand files, implicating their potential role as vectors of trypanosomatid parasites. Therefore, the novel data from this study would greatly facilitate the comprehension of the complexity of trypanosomatid transmission and the establishment of prevention and control measures for this neglected disease more effectively.

Vanadium compounds as antiparasitic agents: An approach to their mechanisms of action

BACKGROUND

Parasitic infections are a public health problem since they have high morbidity and mortality worldwide. In parasitosis such as malaria, leishmaniasis and trypanosomiasis it is necessary to develop new compounds for their treatment since an increase in drug resistance and toxic effects have been observed. Therefore, the use of different compounds that couple vanadium in their structure and that have a broad spectrum against different parasites have been proposed experimentally.

OBJECTIVE

Report the mechanisms of action exerted by vanadium in different parasites.

CONCLUSION

In this review, some of the targets that vanadium compounds have were identified and it was observed that they have a broad spectrum against different parasites, which represents an advance to continue investigating therapeutic options.

Leishmaniasis: Immune Cells Crosstalk in Macrophage Polarization

Leishmaniasis is a complex infectious parasitic disease caused by protozoa of the genus Leishmania, belonging to a group of neglected tropical diseases. It establishes significant global health challenges, particularly in socio-economically disadvantaged regions. Macrophages, as innate immune cells, play a crucial role in initiating the inflammatory response against the pathogens responsible for this disease. Macrophage polarization, the process of differentiating macrophages into pro-inflammatory (M1) or anti-inflammatory (M2) phenotypes, is essential for the immune response in leishmaniasis. The M1 phenotype is associated with resistance to Leishmania infection, while the M2 phenotype is predominant in susceptible environments. Notably, various immune cells, including T cells, play a significant role in modulating macrophage polarization by releasing cytokines that influence macrophage maturation and function. Furthermore, other immune cells can also impact macrophage polarization in a T-cell-independent manner. Therefore, this review comprehensively examines macrophage polarization's role in leishmaniasis and other immune cells' potential involvement in this intricate process.

Ecological interactions of sand flies, hosts, and Leishmania panamensis in an endemic area of cutaneous leishmaniasis in Colombia

BACKGROUND

The transmission dynamics of leishmaniasis are complex. There is also a lack of information about the ecological relationships between the vector/host/parasite at a more local and specific level. The Andean region concentrates more than 50% of Colombia's cutaneous leishmaniasis (CL) cases. The study of the ecological interactions of sand flies through the identification of blood sources has provided information on the female's opportunistic behavior, feeding on various hosts. Therefore, this study aimed to determine sand flies' ecological interactions with Leishmania parasites and their blood sources in an endemic area of CL.

RESULTS

A total of 4,621 sand flies were collected, comprising 20 species, in which the most abundant were Nyssomyia yuilli yuilli (55.4%), Psychodopygus ayrozai (14.5%) and Ps. panamensis (13.4%). Sequences of 12S gene fragment were analyzed using the BLASTn search tool. Blood-meal source identification was successfully performed for 47 sand flies, detecting seven vertebrate species, human and armadillo being the most frequent. Leishmania DNA was amplified in four female pools, constituted by Ny. yuilli yuilli and Ps. ayrozai, and the identification through RFLP detected Leishmania (Viannia) panamensis in the positive pools.

CONCLUSIONS

The interactions between the sand fly species, local mammalian fauna and the Leishmania parasite in this active focus of CL, provide evidence of the potential role of two different species in the maintenance of the parasite transmission, important information for the understanding of the ecoepidemiology and transmission dynamics of the disease in Andean endemic areas. However its necessary further evaluations of the vector and host competence in the transmission and maintenance of Leishmania spp, in these complex and diverse areas.

Intracellular persistence of Leishmania tarentolae in primary canine macrophage cells

Leishmania tarentolae is a non-pathogenic species first isolated from geckoes in the Mediterranean basin. The finding that dogs test positive against both Leishmania infantum and L. tarentolae raises questions regarding the ability of the latter species to persist and adapt to new hosts. This study aimed to evaluate in vitro the capability of L. tarentolae to colonize, survive and persist in canine primary monocyte-derived mononuclear cells. Monocytes were isolated from dog whole blood samples and placed in 24-well plates for differentiation into macrophages and for incubation with L. tarentolae field-isolated strains (RI-325 and SF-178) and laboratory (LEM-124) strain; the parasite burden was assessed at different time points post-infection. The L. infantum laboratory strain (MON-1) was used as control. Infection parameters were evaluated by microscopy, counting the number of amastigotes/200 infected cells, and by duplex real-time PCR from supernatants and detached cells. Similar to L. infantum, L. tarentolae strains developed into round-shaped amastigote-like forms, with higher infection rates detected at 4 h followed by an overall decrease until 48 h. RI-325 presented also a higher infection rate at 72 h. Data showed that L. tarentolae strains infect and persist inside in vitro primary canine mononuclear cells, opening new perspectives for further laboratory studies.

Investigating potential sand fly vectors after the first reported outbreak of cutaneous leishmaniasis in Ghana

BACKGROUND

Leishmaniasis is a parasitic disease caused by species of the genus Leishmania, which are transmitted through the bite of infected female sand flies. Since the first reported outbreak of cutaneous leishmaniasis in Ghana, in 1999, there has been limited published information on its vectors and reservoir hosts there. Previous studies have shown strong dominance of the sand fly genus Sergentomyia over the genus Phlebotomus in Ghana. Thus the aim of this study was to determine the possible sand fly vector species in Ghana, as well as their human-feeding behavior, from the time of the first reported outbreak of CL in the country.

METHODS

Sand flies were collected from randomly selected houses in three communities. They were identified and used for blood meal source identification and the detection of Leishmania infection using molecular methods.  RESULTS: A total of 1051 female sand flies were morphologically identified, of which Sergentomyia africana africana (29%) was the predominant species. Among the 275 female sand flies that had blood-fed, the identified blood meal sources included chicken (33.8%) and goat (12.4%); the percentage of human blood meals was 32%. Single-source and mixed-source blood meals were identified in Sergentomyia africana africana (11.6%), Sergentomyia ingrami (14.9%) and Sergentomyia simillima (20%), with S. simillima having the highest proportion of blood meals that included human blood (14.6%). Using molecular methods, unfed sand flies and identified human-feeding species were examined for the presence of Leishmania DNA. Pool screening analysis revealed three pools of S. ingrami positive for Leishmania major DNA, with an infection rate of 1.27% (95% confidence interval 2.467-3.647).

CONCLUSIONS

The findings suggest that some Sergentomyia species may be involved in the transmission of cutaneous leishmaniasis in Ghana. However, the role of S. ingrami as a vector of leishmaniasis in Ghana needs to be conclusively validated by isolating the parasite from this species and through experimental transmission studies.

Experimental feeding of Sergentomyia minuta on reptiles and mammals: comparison with Phlebotomus papatasi

BACKGROUND

Sergentomyia minuta (Diptera: Phlebotominae) is an abundant sand fly species in the Mediterranean basin and a proven vector of reptile parasite Leishmania (Sauroleishmania) tarentolae. Although it feeds preferentially on reptiles, blood meal analyses and detection of Leishmania (Leishmania) infantum DNA in wild-caught S. minuta suggest that occasional feeding may occur on mammals, including humans. Therefore, it is currently suspected as a potential vector of human pathogens.

METHODS

A recently established S. minuta colony was allowed to feed on three reptile species (i.e. lizard Podarcis siculus and geckos Tarentola mauritanica and Hemidactylus turcicus) and three mammal species (i.e. mouse, rabbit and human). Sand fly mortality and fecundity were studied in blood-fed females, and the results were compared with Phlebotomus papatasi, vector of Leishmania (L.) major. Blood meal volumes were measured by haemoglobinometry.

RESULTS

Sergentomyia minuta fed readily on three reptile species tested, neglected the mouse and the rabbit but took a blood meal on human. However, the percentage of females engorged on human volunteer was low in cage (3%) and feeding on human blood resulted in extended defecation times, higher post-feeding mortality and lower fecundity. The average volumes of blood ingested by females fed on human and gecko were 0.97 µl and 1.02 µl, respectively. Phlebotomus papatasi females readily fed on mouse, rabbit and human volunteer; a lower percentage of females (23%) took blood meal on the T. mauritanica gecko; reptilian blood increased mortality post-feeding but did not affect P. papatasi fecundity.

CONCLUSIONS

Anthropophilic behaviour of S. minuta was experimentally demonstrated; although sand fly females prefer reptiles as hosts, they were attracted to the human volunteer and took a relatively high volume of blood. Their feeding times were longer than in sand fly species regularly feeding on mammals and their physiological parameters suggest that S. minuta is not adapted well for digestion of mammalian blood. Nevertheless, the ability to bite humans highlights the necessity of further studies on S. minuta vector competence to elucidate its potential role in circulation of Leishmania and phleboviruses pathogenic to humans.

Genomic analysis of two phlebotomine sand fly vectors of Leishmania from the New and Old World

Phlebotomine sand flies are of global significance as important vectors of human disease, transmitting bacterial, viral, and protozoan pathogens, including the kinetoplastid parasites of the genus Leishmania, the causative agents of devastating diseases collectively termed leishmaniasis. More than 40 pathogenic Leishmania species are transmitted to humans by approximately 35 sand fly species in 98 countries with hundreds of millions of people at risk around the world. No approved efficacious vaccine exists for leishmaniasis and available therapeutic drugs are either toxic and/or expensive, or the parasites are becoming resistant to the more recently developed drugs. Therefore, sand fly and/or reservoir control are currently the most effective strategies to break transmission. To better understand the biology of sand flies, including the mechanisms involved in their vectorial capacity, insecticide resistance, and population structures we sequenced the genomes of two geographically widespread and important sand fly vector species: Phlebotomus papatasi, a vector of Leishmania parasites that cause cutaneous leishmaniasis, (distributed in Europe, the Middle East and North Africa) and Lutzomyia longipalpis, a vector of Leishmania parasites that cause visceral leishmaniasis (distributed across Central and South America). We categorized and curated genes involved in processes important to their roles as disease vectors, including chemosensation, blood feeding, circadian rhythm, immunity, and detoxification, as well as mobile genetic elements. We also defined gene orthology and observed micro-synteny among the genomes. Finally, we present the genetic diversity and population structure of these species in their respective geographical areas. These genomes will be a foundation on which to base future efforts to prevent vector-borne transmission of Leishmania parasites.

Evaluation of a novel severe combined immunodeficiency mouse model for antiviral drug evaluation against Chandipura virus infection

Chandipura virus (CHPV) is a negative-sense single-stranded RNA virus known to cause fatal encephalitis outbreaks in the Indian subcontinent. The virus displays tropism towards the pediatric population and holds significant public health concerns. Currently, there is no specific, effective therapy for CHPV encephalitis. In this study, we evaluated a novel C.B-17 severe combined immunodeficiency (SCID) mouse model which can be used for pre-clinical antiviral evaluation. Inoculation of CHPV developed a lethal infection in our model. Plaque assay and immunohistochemistry detected increased viral loads and antigens in various organs, including the brain, spinal cord, adrenal glands, and whole blood. We further conducted a proof-of-concept evaluation of favipiravir in the SCID mouse model. Favipiravir treatment improved survival with pre-symptomatic (days 5-14) and post-symptomatic (days 9-18) treatment. Reduced viral loads were observed in whole blood, kidney/adrenal gland, and brain tissue with favipiravir treatment. The findings in this study demonstrate the utility of SCID mouse for in vivo drug efficacy evaluation and the potential efficacy of favipiravir against CHPV infection.

A Review of Historical Phlebotominae Taxonomy (Diptera: Psychodidae)

Psychodidae is a group constituted by ca. 3400 species distributed in six existing and one extinct subfamily. Among them, Phlebotominae is of relevant medical and veterinary interest as vectors of pathogens, such as viruses, bacteria, and trypanosomatides, to vertebrates. The taxonomy of Phlebotominae, begun in 1786, received a great boost at the beginning of the twentieth century, when some of its species began to be implicated as vectors of leishmaniasis agents. Currently, the group consists of 1060 species/subspecies described for both hemispheres. Its taxonomy and systematics have been largely based on the morphological characters of adults in view of the limited number of species known in their immature forms, as well as by molecular approaches. This review focuses on the evolution of the phlebotomine systematics, with information regarding when the descriptions of the sand fly species/subspecies occurred, where their type localities are, the number of authors involved in their descriptions, and the researchers who have most contributed to the description of these taxa and their respective institutions. The morphological characters of adult forms used in the taxonomy of groups, in an evolutionary approach, and the current state of knowledge based on immature forms is also presented.