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Communications Biology Dec 2023Phlebotomine sand flies (Diptera: Phlebotominae) are the principal vectors of Leishmania spp. (Kinetoplastida: Trypanosomatidae). In Central Europe, Phlebotomus...
Phlebotomine sand flies (Diptera: Phlebotominae) are the principal vectors of Leishmania spp. (Kinetoplastida: Trypanosomatidae). In Central Europe, Phlebotomus mascittii is the predominant species, but largely understudied. To better understand factors driving its current distribution, we infer patterns of genetic diversity by testing for signals of population expansion based on two mitochondrial genes and model current and past climate and habitat suitability for seven post-glacial maximum periods, taking 19 climatic variables into account. Consequently, we elucidate their connections by environmental-geographical network analysis. Most analyzed populations share a main haplotype tracing back to a single glacial maximum refuge area on the Mediterranean coasts of South France, which is supported by network analysis. The rapid range expansion of Ph. mascittii likely started in the early mid-Holocene epoch until today and its spread possibly followed two routes. The first one was through northern France to Germany and then Belgium, and the second across the Ligurian coast through present-day Slovenia to Austria, toward the northern Balkans. Here we present a combined approach to reveal glacial refugia and post-glacial spread of Ph. mascittii and observed discrepancies between the modelled and the current known distribution might reveal yet overlooked populations and potential further spread.
Topics: Animals; Phlebotomus; Psychodidae; Insect Vectors; Europe; Leishmania
PubMed: 38066195
DOI: 10.1038/s42003-023-05616-1 -
Anais Da Academia Brasileira de Ciencias 2023The geographical distribution of sand flies in Brazil has been the subject of some studies, yet there is no information about the phlebotomine fauna in João Pessoa,...
The geographical distribution of sand flies in Brazil has been the subject of some studies, yet there is no information about the phlebotomine fauna in João Pessoa, State of Paraíba, Brazil. The aim of this work is to evaluate the occurrence and distribution of sand flies in the Atlantic forest fragments and to evaluate a possible dispersion in 06 nearby districts. Light traps were used during three consecutive nights, supplemented by an aspirator during the dry period and rainy season. A total of 222 sand flies were found, 143 (130 males and 13 females) in the Atlantic forest, and 79 in urban areas. During the entire dry season, three species of phlebotomine sand flies were recorded in 11 forest fragments, Lutzomyia longipalpis, Lu. migonei and Lu. whitmani. During the rainy season, only Lu. longipalpis was found. This was the only species identified in the studied neighborhoods during both seasons. The differences in diversity of sand flies encountered between natural habitats and urban areas may thus be correlated mostly with adaptations to particular habitats and availability of food. One species (Lu. longipalpis) appears to be rapidly adapting to urban areas because of deforestation.
Topics: Male; Animals; Female; Psychodidae; Insect Vectors; Ecosystem; Forests; Brazil; Seasons
PubMed: 38055605
DOI: 10.1590/0001-3765202320191596 -
Scientific Reports Dec 2023Sandflies (Diptera; Psychodidae) are medical and veterinary vectors that transmit diverse parasitic, viral, and bacterial pathogens. Their identification has always been...
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.
Topics: Animals; Psychodidae; Deep Learning; Reproducibility of Results; Phlebotomus; Entomology
PubMed: 38049590
DOI: 10.1038/s41598-023-48685-2 -
PLoS Neglected Tropical Diseases Dec 2023Miranda Municipality of Mato Grosso do Sul, borders the Pantanal wetland, a famous fishing destination visited by tourists from all over the world, and is a location...
Miranda Municipality of Mato Grosso do Sul, borders the Pantanal wetland, a famous fishing destination visited by tourists from all over the world, and is a location where visceral leishmaniasis has been reported. To assess the risk of Leishmania infantum transmission, we studied the sandfly community, focusing on known vector and parasite presence. We conducted light trap collections twice per month at nine sites within the city (including two forested areas) for one year. We collected a total of 12,727 sand flies, 10,891 males and 1,836 females belonging to 11 species: Brumptomyia avellari, Evandromyia aldafalcaoae, Ev. evandroi, Ev. lenti, Ev. sallesi, Ev. walkeri, Lu. longipalpis, Nyssomyia whitmani, Psathyromyia bigeniculata, Pa. hermanlenti and Pa. punctigeniculata. Lutzomyia longipalpis, the proven vector of Leishmania infantum, was captured each month, and was the most abundant species observed, accounting for more than 99% of sand flies captured in most sites, especially where chicken coops were present. Evidence of Leishmania infantum infection was detected in 0.40% of Lu. longipalpis tested. We developed a generalized mixed multilevel model for Lu. longipalpis, that includes within-year seasonality, location of capture (indoors vs. outdoors), vector abundance, and sex ratio. The VL vector was abundant both inside and outside houses. Large numbers of Lu. longipalpis were observed in outdoor sites where domestic animals were present but were absent from forest sites. Our findings suggest high vector populations and Le. infantum presence in a city where tourists could be exposed to visceral leishmaniasis, with significant implications for more surveillance and control activities.
Topics: Male; Animals; Female; Leishmaniasis, Visceral; Wetlands; Hunting; Tourism; Insect Vectors; Leishmaniasis; Psychodidae; Leishmania infantum; Brazil
PubMed: 38048353
DOI: 10.1371/journal.pntd.0011809 -
Frontiers in Immunology 2023Sand flies (Diptera: Phlebotominae) belonging to the genus transmit parasites. To understand the complex interaction between the vector and the parasite, we have been...
INTRODUCTION
Sand flies (Diptera: Phlebotominae) belonging to the genus transmit parasites. To understand the complex interaction between the vector and the parasite, we have been investigating the sand fly immune responses during the infection. Our previous studies showed that genes involved in the IMD, Toll, and Jak-STAT immunity pathways are regulated upon and bacterial challenges. Nevertheless, the parasite can thrive in the vectors' gut, indicating the existence of mechanisms capable of modulating the vector defenses, as was already seen in mammalian infections.
METHODS RESULTS AND DISCUSSION
In this study, we investigated the expression of genes involved in regulating the Toll pathway under parasitic infection. infection upregulated the expression of two genes coding for the putative repressors cactus and protein tyrosine phosphatase SHP. These findings suggest that the parasite can modulate the vectors' immune response. In mammalian infections, the surface glycoprotein GP63 is one of the inducers of host immune depression, and one of the known effectors is SHP. In we found a similar effect: a genetically modified strain of over-expressing the metalloprotease GP63 induced a higher expression of the sand fly SHP indicating that the SHP and parasite GP63 increased expressions are connected. Immuno-stained microscopy of LL5 embryonic cells cultured with strains or parasite conditioned medium showed cells internalization of parasite GP63. A similar internalization of GP63 was observed in the sand fly gut tissue after feeding on parasites, parasite exosomes, or parasite conditioned medium, indicating that GP63 can travel through cells or . When the sand fly SHP gene was silenced by RNAi and females infected by , parasite loads decreased in the early phase of infection as expected, although no significant differences were seen in late infections of the stomodeal valve.
CONCLUSIONS
Our findings show the possible role of a pathway repressor involved in regulating the immune response during infections inside the insect. In addition, they point out a conserved immunosuppressive effect of GP63 between mammals and sand flies in the early stage of parasite infection.
Topics: Animals; Female; Culture Media, Conditioned; Psychodidae; Leishmania infantum; Phlebotomus; Leishmaniasis; Mammals; Immunosuppression Therapy
PubMed: 38022562
DOI: 10.3389/fimmu.2023.1162596 -
The American Journal of Tropical... Jan 2024The aim of this study was to explore epidemiological, serological, entomological, and social aspects of visceral leishmaniasis (VL) in new foci in Nepal. The study was...
The aim of this study was to explore epidemiological, serological, entomological, and social aspects of visceral leishmaniasis (VL) in new foci in Nepal. The study was conducted in 11 villages of five districts that had been previously free of VL but that reported new cases between 2019 and 2021. We screened 1,288 inhabitants using rK39 tests and investigated the epidemiological and clinical characteristics of 12 recent VL cases. A total of 182 community members were interviewed about knowledge, attitude, and practices regarding VL. They then underwent an awareness training; 40 of them had a second interview at 6 months to assess the training impact. Vector surveys were conducted in six houses per village to assess sandfly density and infection rates. The prevalence of VL infection was 0.5% and 3.2% among screened populations in Dolpa and Kavre districts, respectively, while the other districts had no rK39-positive cases. No association between travel history and VL infection was found. Phlebotomus argentipes sandflies were collected in three districts at high altitudes (from 1,084 to 4,450 m). None of the sandflies captured had Leishmania donovani DNA. People in new foci were not aware of VL symptoms, vectors, or preventive measures. The training significantly improved their knowledge and practice in seeking medical care in case of illness. The epidemiological, serological, and entomological investigations suggest indigenous focal transmission of VL. An integrated package of strategic interventions should be implemented by the national VL elimination program in districts with new VL foci.
Topics: Animals; Humans; Leishmaniasis, Visceral; Nepal; Phlebotomus; Psychodidae; Surveys and Questionnaires
PubMed: 38011729
DOI: 10.4269/ajtmh.23-0373 -
Scientific Reports Nov 2023Canine visceral leishmaniasis (CVL) is a significant vector-borne Meta zoonotic disease caused by agents of the L. donovani complex. The disease is transmitted by the...
Canine visceral leishmaniasis (CVL) is a significant vector-borne Meta zoonotic disease caused by agents of the L. donovani complex. The disease is transmitted by the bite of phlebotomine female sandflies of the genera Phlebotomus and Lutzomyia in the old and new worlds, respectively. This study was conducted to assess the knowledge, attitude, and practices of the residents about CVL based on the One Health concept in two towns of the Oromia Region, Ethiopia. A community-based cross-sectional study was conducted between October 2019 and September 2020, using an interview questionnaire as the study instrument. The study participants were selected through a simple random sampling method. Pearson's Chi-square and logistic regression tests were used to evaluate the association between the study participants' knowledge, attitude, and practices toward CVL and possible risk factors. The study included a total of 400 participants, and the results indicated that 77.25% had good knowledge, 60.5% had a favorable attitude, and 59.25% had good practices toward CVL. The town of Ejaji and dog ownership were significantly associated with good knowledge (p = 0.001), and attitude (p = 0.001) towards CVL, while having a dog (p = 0.001), having a diploma (p = 0.019) or degree and above (0.018), being divorced or widowed (0.012), and being Oromo (p = 0.013) were all significantly associated with good CVL practice. Most participants in both study areas had good knowledge but moderate attitudes and practices toward CVL. Therefore, it is crucial to undertake comprehensive community health education and awareness programs of zoonotic visceral leishmaniasis and its vectors based on the One Health concept through various means.
Topics: Humans; Dogs; Animals; Female; Leishmaniasis, Visceral; Cities; Ethiopia; Cross-Sectional Studies; Health Knowledge, Attitudes, Practice; One Health; Psychodidae
PubMed: 38007526
DOI: 10.1038/s41598-023-47340-0 -
PLoS Neglected Tropical Diseases Nov 2023Molecular surveillance of resistance is an increasingly important part of vector borne disease control programmes that utilise insecticides. The visceral leishmaniasis...
Molecular surveillance of resistance is an increasingly important part of vector borne disease control programmes that utilise insecticides. The visceral leishmaniasis (VL) elimination programme in India uses indoor residual spraying (IRS) with the pyrethroid, alpha-cypermethrin to control Phlebotomus argentipes the vector of Leishmania donovani, the causative agent of VL. Prior long-term use of DDT may have selected for knockdown resistance (kdr) mutants (1014F and S) at the shared DDT and pyrethroid target site, which are common in India and can also cause pyrethroid cross-resistance. We monitored the frequency of these marker mutations over five years from 2017-2021 in sentinel sites in eight districts of north-eastern India covered by IRS. Frequencies varied markedly among the districts, though finer scale variation, among villages within districts, was limited. A pronounced and highly significant increase in resistance-associated genotypes occurred between 2017 and 2018, but with relative stability thereafter, and some reversion toward more susceptible genotypes in 2021. Analyses linked IRS with mutant frequencies suggesting an advantage to more resistant genotypes, especially when pyrethroid was under-sprayed in IRS. However, this advantage did not translate into sustained allele frequency changes over the study period, potentially because of a relatively greater net advantage under field conditions for a wild-type/mutant genotype than projected from laboratory studies and/or high costs of the most resistant genotype. Further work is required to improve calibration of each 1014 genotype with resistance, preferably using operationally relevant measures. The lack of change in resistance mechanism over the span of the study period, coupled with available bioassay data suggesting susceptibility, suggests that resistance has yet to emerge despite intensive IRS. Nevertheless, the advantage of resistance-associated genotypes with IRS and under spraying, suggest that measures to continue monitoring and improvement of spray quality are vital, and consideration of future alternatives to pyrethroids for IRS would be advisable.
Topics: Animals; Phlebotomus; Leishmaniasis, Visceral; Insecticide Resistance; DDT; Insecticides; Pyrethrins; India
PubMed: 37939123
DOI: 10.1371/journal.pntd.0011734 -
Nature Communications Nov 2023Whole genome analysis of Leishmania hybrids generated experimentally in sand flies supports a meiotic mechanism of genetic exchange, with Mendelian segregation of the...
Whole genome analysis of Leishmania hybrids generated experimentally in sand flies supports a meiotic mechanism of genetic exchange, with Mendelian segregation of the nuclear genome. Here, we perform functional analyses through the generation of double drug-resistant hybrids in vitro and in vivo (during sand fly infections) to assess the importance of conserved meiosis-related genes in recombination and plasmogamy. We report that HOP1 and a HAP2-paralog (HAP2-2) are essential components of the Leishmania meiosis machinery and cell-to-cell fusion mechanism, respectively, since deletion of either gene in one or both parents significantly reduces or completely abrogates mating competence. These findings significantly advance our understanding of sexual reproduction in Leishmania, with likely relevance to other trypanosomatids, by formally demonstrating the involvement of a meiotic protein homolog and a distinct fusogen that mediates non-canonical, bilateral fusion in the hybridizing cells.
Topics: Animals; Leishmania; Psychodidae; Reproduction; Meiosis
PubMed: 37935664
DOI: 10.1038/s41467-023-42789-z -
Parasites & Vectors Nov 2023Visceral leishmaniasis (VL), a life-threatening neglected tropical disease, is targeted for elimination from Nepal by the year 2026. The national VL elimination program...
BACKGROUND
Visceral leishmaniasis (VL), a life-threatening neglected tropical disease, is targeted for elimination from Nepal by the year 2026. The national VL elimination program is still confronted with many challenges including the increasingly widespread distribution of the disease over the country, local resurgence and the questionable efficacy of the key vector control activities. In this study, we assessed the status and risk of Leishmania donovani transmission based on entomological indicators including seasonality, natural Leishmania infection rate and feeding behavior of vector sand flies, Phlebotomus argentipes, in three districts that had received disease control interventions in the past several years in the context of the disease elimination effort.
METHODS
We selected two epidemiologically contrasting settings in each survey district, one village with and one without reported VL cases in recent years. Adult sand flies were collected using CDC light traps and mouth aspirators in each village for 12 consecutive months from July 2017 to June 2018. Leishmania infection was assessed in gravid sand flies targeting the small-subunit ribosomal RNA gene of the parasite (SSU-rRNA) and further sequenced for species identification. A segment (~ 350 bp) of the vertebrate cytochrome b (cytb) gene was amplified from blood-fed P. argentipes from dwellings shared by both humans and cattle and sequenced to identify the preferred host.
RESULTS
Vector abundance varied among districts and village types and peaks were observed in June, July and September to November. The estimated Leishmania infection rate in vector sand flies was 2.2% (1.1%-3.7% at 95% credible interval) and 0.6% (0.2%-1.3% at 95% credible interval) in VL and non-VL villages respectively. The common source of blood meal was humans in both VL (52.7%) and non-VL (74.2%) villages followed by cattle.
CONCLUSIONS
Our findings highlight the risk of ongoing L. donovani transmission not only in villages with VL cases but also in villages not reporting the presence of the disease over the past several years within the districts having disease elimination efforts, emphasize the remaining threats of VL re-emergence and inform the national program for critical evaluation of disease elimination strategies in Nepal.
Topics: Adult; Humans; Animals; Cattle; Leishmania donovani; Nepal; Leishmaniasis, Visceral; Phlebotomus; Psychodidae
PubMed: 37932813
DOI: 10.1186/s13071-023-05986-9