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Parasites & Vectors Oct 2022Phlebotomine sand flies are proven or suspected vectors of several pathogens of importance, including leishmaniasis, bartonellosis and sand fly fevers. Although sand...
Phlebotomine sand flies are proven or suspected vectors of several pathogens of importance, including leishmaniasis, bartonellosis and sand fly fevers. Although sand flies have a worldwide distribution, there has been limited research published on sand flies and sand fly-borne pathogens throughout the Greater Mekong Sub-region (GMS). This review followed the PRISMA guidelines to determine the biodiversity and presence of phlebotomine sand flies and their associated pathogens in the GMS, specifically Cambodia, Thailand, the Lao People's Democratic Republic (Laos), Malaysia and Vietnam. A total of 1472 records were identified by searching electronic databases, scanning reference lists of articles and consulting experts in the field. After screening of title and abstracts, 178 records remained and were further screened for original data (n = 34), not having regional data (n = 14), duplication of data (n = 4), records not available (n = 4) and no language translation available (n = 2). A total of 120 studies were then included for full review, with 41 studies on sand fly-related disease in humans, 33 studies on sand fly-related disease in animals and 54 entomological studies focused on sand flies (5 papers contained data on > 1 category), with a majority of the overall data from Thailand. There were relatively few studies on each country, with the exception of Thailand, and the studies applied different methods to investigate sand flies and sand fly-borne diseases, impacting the ability to conduct meaningful meta-analysis. The findings suggest that leishmaniasis in humans and the presence of sand fly vectors have been reported across several GMS countries over the past 100 years, with local transmission in humans confirmed in Thailand and Vietnam. Additionally, local Mundinia species are likely transmitted by biting midges. Findings from this study provide a framework for future investigations to determine the geographic distribution and risk profiles of leishmaniasis and other associated sand fly-borne disease throughout the GMS. It is recommended that researchers expand surveillance efforts across the GMS, with an emphasis placed on entomological surveys, syndromic and asymptomatic monitoring in both humans and animals and molecular characterization of sand flies and sand fly-borne pathogens, particularly in the understudied countries of Cambodia, Vietnam and Laos.
Topics: Animals; Humans; Insect Vectors; Leishmania; Leishmaniasis; Phlebotomus; Psychodidae
PubMed: 36199150
DOI: 10.1186/s13071-022-05464-8 -
Infectious Diseases of Poverty Feb 2016After the existence of phlebotomine sand flies was first reported in China in 1910, the distribution of different species and their role in the transmission of visceral... (Review)
Review
After the existence of phlebotomine sand flies was first reported in China in 1910, the distribution of different species and their role in the transmission of visceral leishmaniasis (VL) have been extensively studied. Up until 2008, four species have been verified as vectors of VL, namely, Phlebotomus chinensis (Ph. sichuanensis), Ph. longiductus (Ph. chinensis longiductus), Ph. wui (Ph. major wui), and Ph. alexandri. The sand fly species vary greatly depending on the natural environments in the different geographic areas where they are endemic. Ph. chinensis is euryecious and adaptable to different ecologies, and is thus distributed widely in the plain, mountainous, and Loess Plateau regions north of the Yangtze River. Ph. longiductus is mainly distributed in ancient oasis areas south of Mt. Tianshan in the Xinjiang Uygur autonomous region. Ph. wui is the predominant species in deserts with Populus diversifolia and Tamarix vegetation in Xinjiang and the western part of the Inner Mongolia autonomous region. Finally, Ph. alexandri is steroecious and found only in stony desert areas, such as at the foot of the mountains in Xinjiang and the western Hexi Corridor, in Gansu province. This review summarized the relationship between the geographic distribution pattern of the four sand fly species and their geographical landscape in order to foster research on disease distribution and sand fly control planning. Furthermore, some problems that remained to be solved about vectors of VL in China were discussed.
Topics: Animal Distribution; Animals; China; Humans; Insect Vectors; Leishmania; Leishmaniasis, Visceral; Psychodidae
PubMed: 26906187
DOI: 10.1186/s40249-016-0107-z -
PLoS Neglected Tropical Diseases May 2022Insect-vectored Leishmania are responsible for loss of more disability-adjusted life years than any parasite besides malaria. Elucidation of the environmental factors... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Insect-vectored Leishmania are responsible for loss of more disability-adjusted life years than any parasite besides malaria. Elucidation of the environmental factors that affect parasite transmission by vectors is essential to develop sustainable methods of parasite control that do not have off-target effects on beneficial insects or environmental health. Many phytochemicals that inhibit growth of sand fly-vectored Leishmania-which have been exhaustively studied in the search for phytochemical-based drugs-are abundant in nectars, which provide sugar-based meals to infected sand flies.
PRINCIPLE FINDINGS
In a quantitative meta-analysis, we compare inhibitory phytochemical concentrations for Leishmania to concentrations present in floral nectar and pollen. We show that nectar concentrations of several flowering plant species exceed those that inhibit growth of Leishmania cell cultures, suggesting an unexplored, landscape ecology-based approach to reduce Leishmania transmission.
SIGNIFICANCE
If nectar compounds are as effective against parasites in the sand fly gut as predicted from experiments in vitro, strategic planting of antiparasitic phytochemical-rich floral resources or phytochemically enriched baits could reduce Leishmania loads in vectors. Such interventions could provide an environmentally friendly complement to existing means of disease control.
Topics: Animals; Insect Vectors; Leishmania; Parasites; Phlebotomus; Phytochemicals; Plant Nectar; Psychodidae
PubMed: 35551517
DOI: 10.1371/journal.pntd.0010373 -
Journal of Vector Borne Diseases 2023Present study was conducted to carry out morphological and molecular confirmation of sandflies collected at the Department of Parasitology, Faculty of Veterinary and...
Present study was conducted to carry out morphological and molecular confirmation of sandflies collected at the Department of Parasitology, Faculty of Veterinary and Animal Sciences, R.S. Pura, Jammu, India. Larva was maggot like with large head, thorax and abdomen with typical black head, 12 abdominal segments and last abdominal segment carried two pairs of caudal bristles with matchstick hairs on each segment. The adult fly possessed head, abdomen and thorax. Head consisted of pair of long, hairy and beaded antenna, proboscis and one pair of prominent black eyes. Thorax possessed a pair of wings and three pairs of legs, wings were hairy and pointed with 2 longitudinal vein branched twice. The abdominal segments were covered with small hairs and last abdominal segment was having a pair of anal recti. These identification characteristics confirmed the fly under study as Phlebotomus argentipes that confirms its occurance in this region. Molecular characterization of identified flies was carried out on positive morophological flies. Confirmation of Phlebotomus species was ascertained by amplifying the 18S ribosomal RNA gene sequence using PCR. Clear amplification was observed for Phlebotomus argentipes (538 bp). After sequencing/genotyping, Phlebotomus argentipes (OP646634) isolate of present study was clustering in same clade with Phlebotomus argentipes sequences obtained from GeneBank from other locations across globe, irrespective of their geographical location, thus providing the molecular evidence of this species present in Jammu region of North India.
Topics: Animals; Phlebotomus; Psychodidae; Insect Vectors; Leishmaniasis; India
PubMed: 37843245
DOI: 10.4103/0972-9062.374037 -
Acta Tropica Feb 2023The taxonomy and systematics of sand flies (Diptera, Psychodidae, Phlebotominae) are one of the pillars of research aimed to identifying vector populations and the... (Review)
Review
The taxonomy and systematics of sand flies (Diptera, Psychodidae, Phlebotominae) are one of the pillars of research aimed to identifying vector populations and the agents transmitted by these insects. Traditionally, the use of morphological traits has been the main line of evidence for the definition of species, but the use of DNA sequences is useful as an integrative approach for their delimitation. Here, we discuss the current status of the molecular taxonomy of sand flies, including their most sequenced molecular markers and the main results. Only about 37% of all sand fly species have been processed for any molecular marker and are publicly available in the NCBI GenBank or BOLD Systems databases. The genera Phlebotomus, Nyssomyia, Psathyromyia and Psychodopygus are well-sampled, accounting for more than 56% of their sequenced species. However, less than 34% of the species of Sergentomyia, Lutzomyia, Trichopygomyia and Trichophoromyia have been sampled, representing a major gap in the knowledge of these groups. The most sequenced molecular markers are those within mtDNA, especially the DNA barcoding fragment of the cytochrome c oxidase subunit I (coi) gene, which has shown promising results in detecting cryptic diversity within species. Few sequences of conserved genes have been generated, which hampers higher-level phylogenetic inferences. We argue that sand fly species should be sequenced for at least the coi DNA barcoding marker, but multiple markers with different mutation rates should be assessed, whenever possible, to generate multilocus analysis.
Topics: Animals; Psychodidae; DNA Barcoding, Taxonomic; Phylogeny; Phlebotomus; DNA, Mitochondrial
PubMed: 36435214
DOI: 10.1016/j.actatropica.2022.106778 -
PLoS Neglected Tropical Diseases Feb 2023The incidence of vector-borne diseases is rising as deforestation, climate change, and globalization bring humans in contact with arthropods that can transmit pathogens....
The incidence of vector-borne diseases is rising as deforestation, climate change, and globalization bring humans in contact with arthropods that can transmit pathogens. In particular, incidence of American Cutaneous Leishmaniasis (ACL), a disease caused by parasites transmitted by sandflies, is increasing as previously intact habitats are cleared for agriculture and urban areas, potentially bringing people into contact with vectors and reservoir hosts. Previous evidence has identified dozens of sandfly species that have been infected with and/or transmit Leishmania parasites. However, there is an incomplete understanding of which sandfly species transmit the parasite, complicating efforts to limit disease spread. Here, we apply machine learning models (boosted regression trees) to leverage biological and geographical traits of known sandfly vectors to predict potential vectors. Additionally, we generate trait profiles of confirmed vectors and identify important factors in transmission. Our model performed well with an average out of sample accuracy of 86%. The models predict that synanthropic sandflies living in areas with greater canopy height, less human modification, and within an optimal range of rainfall are more likely to be Leishmania vectors. We also observed that generalist sandflies that are able to inhabit many different ecoregions are more likely to transmit the parasites. Our results suggest that Psychodopygus amazonensis and Nyssomia antunesi are unidentified potential vectors, and should be the focus of sampling and research efforts. Overall, we found that our machine learning approach provides valuable information for Leishmania surveillance and management in an otherwise complex and data sparse system.
Topics: Animals; Humans; Leishmania; Insect Vectors; Leishmaniasis, Cutaneous; Phlebotomus; Psychodidae; Americas
PubMed: 36809249
DOI: 10.1371/journal.pntd.0010749 -
Acta Tropica Nov 2022Leishmaniases are neglected tropical diseases with a broad clinical spectrum. Tegumentary leishmaniasis (TL) is a disease caused by different Leishmania species,... (Review)
Review
Leishmaniases are neglected tropical diseases with a broad clinical spectrum. Tegumentary leishmaniasis (TL) is a disease caused by different Leishmania species, transmitted by phlebotomine sand flies and distributed worldwide. TL can present a cutaneous (CL) or mucocutaneous (MCL) clinical form depending on factors inherent to the parasite, the host and the vector. Polymorphisms in the immune response genes are host genetic factors that influence the pathogenesis or control of leishmaniasis. Single nucleotide polymorphisms (SNPs) in immune genes have been evaluated in several countries where leishmaniasis is endemic. In this review, we report studies on SNPs in several immune genes that might be associated with susceptibility or resistance to TL. We summarize studies from around the world and in Brazil, highlight the difficulties of these studies and future analyses needed to enhance our knowledge regarding host genetic factors in TL. Understanding the genetic characteristics of the host that facilitate resistance or susceptibility to leishmaniasis can contribute to the development of immunotherapy schedules for this disease. The current treatment methods are toxic, and no human vaccine is available.
Topics: Animals; Immunity; Leishmania; Leishmaniasis; Leishmaniasis, Cutaneous; Neglected Diseases; Polymorphism, Single Nucleotide; Psychodidae
PubMed: 35988820
DOI: 10.1016/j.actatropica.2022.106660 -
PLoS Neglected Tropical Diseases Aug 2022The trypanosomatid protist Leishmania tarentolae is a saurian-associated parasite vectored by the Sergentomyia minuta sand fly. This study aimed to confirm the...
The trypanosomatid protist Leishmania tarentolae is a saurian-associated parasite vectored by the Sergentomyia minuta sand fly. This study aimed to confirm the circulation of L. infantum and L. tarentolae in sand flies, reptiles and dogs and to isolate new strains of these protists. Reptilian and sheltered dog blood samples were collected, and sand flies were captured. Samples were tested for Leishmania spp. using duplex real-time PCR (dqPCR) and real-time PCR (qPCR); the origin of blood meal was identified in engorged sand flies by conventional PCR. The reptilian blood and intestinal content of sand fly females were cultured. Dog sera were tested by IFAT using both Leishmania species. Four Tarentola mauritanica geckoes were molecularly positive for L. infantum or L. tarentolae, with no co-infections; moreover, amastigote-like forms of L. infantum were observed in the bone marrow. 24/294 sand flies scored positive for Leishmania spp. by dqPCR, 21 S. minuta and two Phlebotomus perniciosus were positive for L. tarentolae, while only a single Ph. perniciosus was positive for L. infantum. Blood meal analysis confirmed reptile and dog in S. minuta, dog and human in Ph. perniciosus and dog in Phlebotomus neglectus. Two axenic strains of L. tarentolae were obtained. Twelve of 19 dogs scored positive for L. infantum and L. tarentolae by IFAT and three of them also for L. infantum by dqPCR, and six by qPCR. These data confirm the sympatric circulation of L. infantum and L. tarentolae in geckoes, sand flies, and dogs, and suggest that geckoes may be infected with L. infantum.
Topics: Animals; Dogs; Female; Humans; Leishmania infantum; Lizards; Phlebotomus; Polymerase Chain Reaction; Psychodidae
PubMed: 35943980
DOI: 10.1371/journal.pntd.0010650 -
Journal of Medical Entomology Sep 2020The species composition, distribution, and bionomics of sand flies was investigated from January to December 2017 in four tehsils (20 villages) of district Bajaur...
The species composition, distribution, and bionomics of sand flies was investigated from January to December 2017 in four tehsils (20 villages) of district Bajaur (formally Bajaur agency), Khyber Pakhtunkhwa, Pakistan. In total, 4,173 adult specimens comprising of seven species of Phlebotomus (Diptera: Psychodidae) and three species of Sergentomyia (Diptera: Psychodidae) were collected by oral aspirator, insecticide spray, and sticky traps from June to October. Highest numbers of flies were collected indoors in July and August when relative humidity and temperature were highest. Phlebotomus sergenti Parrot (Diptera: Psychodidae) was the most abundant species from all the collection sites, making approximately 70% of the total capture. Combined dwellings and chicken cages harbored the highest number of adult and immature flies (unrotated external genitalia). Abundance of P. sergenti had a significant (P ≤ 0.05) positive correlation with monthly average temperature, relative humidity, and average rainfall in indoor collections. On the other hand, P. papatasi Scopoli displayed similar correlation in the indoor and nighttime collections. Both the species were apparently abundant in the elevation range ≤ 419 m above sea level and on rangelands. Phlebotomus papatasi, however, also occurred on agricultural lands. The number of cutaneous leishmaniasis (CL) cases did not significantly correlate with the abundance of sand fly vectors across the villages surveyed. The results reported herein can serve as a baseline for an all-extensive future work in Bajaur. Our investigations will benefit the public health experts and medical entomologists for improved control and surveillance vectors of leishmaniasis.
Topics: Animal Distribution; Animals; Biodiversity; Ecosystem; Female; Insect Vectors; Leishmaniasis, Cutaneous; Male; Pakistan; Psychodidae
PubMed: 32221548
DOI: 10.1093/jme/tjaa050 -
Acta Tropica Sep 2022Sandflies are vector species of Leishmania, among many other pathogens, with a global distribution and a variety of ecological niches. Previous samplings have found that...
Sandflies are vector species of Leishmania, among many other pathogens, with a global distribution and a variety of ecological niches. Previous samplings have found that karstic formations (i.e., caves, grottos, and folds formed by the erosion of limestone) serve as a natural habitat to sandfly species. The majority of samplings of cave sandfly diversity have occurred in Brazil and to date none have studied the species composition in a cave in the Northern Andes. We collected sandflies in the Cave "Los Guácharos", in the state of Antioquia, Colombia. The sampling was carried out during two consecutive nights in September 2019. CDC-type light traps were installed inside the cavern and in other surrounding karst systems (caves, rock-breaks, and folds). In total, we identified 17 species of sandfly from the cave and surrounding karst systems, including a new record for Colombia (Bichromomyia olmeca), and provide the first karstic reports for four other species (Lutzomyia gomezi, Lutzomyia hartmanni, Pintomyia ovallesi, and Psychodopygus panamensis). We then used the results of our survey and published literature to test two hypotheses. First, that sandfly diversity in Neotropical caves is richest nearer to the equator, and second that there is a phylogenetic signal of karstic habitat use in sandflies. Counter to our predictions, we found no evidence that diversity follows a latitudinal gradient. Further, we find no evidence of a phylogenetic signal of karstic habitat use, instead finding that the use of caves likely evolved multiple times across several genera. Our results highlight the importance of a wide sampling to understand the natural habitat of sandflies and other disease vectors.
Topics: Animals; Colombia; Insect Vectors; Phlebotomus; Phylogeny; Psychodidae
PubMed: 35605671
DOI: 10.1016/j.actatropica.2022.106515