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PLoS Neglected Tropical Diseases May 2024
Topics: Leishmania tropica; Animals; Phlebotomus; Salivary Proteins and Peptides; Plasmids; Insect Proteins; Mice; Humans; Leishmaniasis, Cutaneous; Female
PubMed: 38814961
DOI: 10.1371/journal.pntd.0012218 -
Acta Tropica May 2024This study updates knowledge on historical geographic distribution of sand fly species through identifying altitudinal and bioclimatic patterns in leishmaniasis endemic...
Surveillance of sand flies (Psychodidae, Phlebotominae) from Mexico: Altitudinal and climatic patterns after historical and new geographic records in endemic areas of leishmaniasis.
This study updates knowledge on historical geographic distribution of sand fly species through identifying altitudinal and bioclimatic patterns in leishmaniasis endemic areas in Mexico. We analyze and identify sand fly specimens obtained through national efforts by the Instituto de Diagnóstico y Referencia Epidemiológicos (InDRE, Mexico), collected between 1995 and 2001, 2008-2012, and 2017-2023, and add bibliographic information (427 additional records). After a principal components analysis of WorldClim variables and altitudinal ranges, variables that better explain the distribution of sand fly species were chosen (BIO6, BIO12, and BIO16, explaining 72 % of variation). A total of 1,187 specimens of 22 species were retrieved from eight states, providing 29 new municipalities and 48 new localities, being Lutzomyia cruciata, Micropygomyia chiapanensis, and Psathyromyia shannoni the most common species. We presented new historical records of distribution for sand fly species from Morelos (3), Oaxaca (7) and Tabasco (1). The 82.7 % of sand fly species analyzed were distributed in areas with altitudinal ranges below 420 m. The anthropophilic species Psathyromyia shannoni, and Lutzomyia cruciata showed the greatest variability regarding altitudinal range, and climatic preferences, while several wild species showed abiotic preferences. It is likely that the effect of urbanization and climate change generate new beneficial biotopes for the proliferation of the vector sand fly species. Complementary studies that consider seasonality, vegetation types, and change in land use could provide new information to better understand the spread of vector-borne diseases.
PubMed: 38795873
DOI: 10.1016/j.actatropica.2024.107270 -
PloS One 2024This study investigated the sand fly fauna of the municipality Iguatama, in the Midwest Region of Minas Gerais state, Brazil, including Leishmania infection rates and...
This study investigated the sand fly fauna of the municipality Iguatama, in the Midwest Region of Minas Gerais state, Brazil, including Leishmania infection rates and blood meal sources. Sand flies were collected during four periods over the course of a single year, encompassing both dry and rainy seasons, using CDC light traps placed in peridomiciles where dogs were seropositive for visceral leishmaniasis (VL). A total of 762 sand fly specimens, representing 12 species across seven genera, were collected. Lutzomyia longipalpis was the most abundant species, comprising 57.6% of the collected specimens, followed by Nyssomyia neivai (19.6%) and Nyssomyia whitmani (10.5%). Species richness and diversity varied among collection periods, with the highest diversity observed in January 2019. Molecular analysis detected Leishmania DNA in 12.5% of the sand fly specimens, with Le. infantum being the predominant species. Blood meal analysis revealed feeding on multiple vertebrate species, including humans, rats, dogs, and chickens. The presence of Leishmania DNA in sand flies, and the identification of human blood meals, highlight the potential role of these species in VL transmission. These findings underscore the importance of continued surveillance and control measures to prevent the spread of VL and reduce transmission risk in the region.
Topics: Animals; Brazil; Psychodidae; Leishmania; Dogs; Humans; Insect Vectors; Leishmaniasis, Visceral; Rats; Chickens; Feeding Behavior; Biodiversity
PubMed: 38781235
DOI: 10.1371/journal.pone.0302567 -
PLoS Neglected Tropical Diseases May 2024The infectious inoculum of a sand fly, apart from its metacyclic promastigotes, is composed of factors derived from both the parasite and the vector. Vector-derived...
The infectious inoculum of a sand fly, apart from its metacyclic promastigotes, is composed of factors derived from both the parasite and the vector. Vector-derived factors, including salivary proteins and the gut microbiota, are essential for the establishment and enhancement of infection. However, the type and the number of bacteria egested during salivation is unclear. In the present study, sand flies of Phlebotomus papatasi were gathered from three locations in hyperendemic focus of zoonotic cutaneous leishmaniasis (ZCL) in Isfahan Province, Iran. By using the forced salivation assay and targeting the 16S rRNA barcode gene, egested bacteria were characterized in 99 (44%) out of 224 sand flies. Culture-dependent and culture-independent methods identified the members of Enterobacter cloacae and Spiroplasma species as dominant taxa, respectively. Ten top genera of Spiroplasma, Ralstonia, Acinetobacter, Reyranella, Undibacterium, Bryobacter, Corynebacterium, Cutibacterium, Psychrobacter, and Wolbachia constituted >80% of the saliva microbiome. Phylogenetic analysis displayed the presence of only one bacterial species for the Spiroplasma, Ralstonia, Reyranella, Bryobacter and Wolbachia, two distinct species for Cutibacterium, three for Undibacterium and Psychrobacter, 16 for Acinetobacter, and 27 for Corynebacterium, in the saliva. The abundance of microbes in P. papatasi saliva was determined by incorporating the data on the read counts and the copy number of 16S rRNA gene, about 9,000 bacterial cells, per sand fly. Both microbiological and metagenomic data indicate that bacteria are constant companions of Leishmania, from the intestine of the vector to the vertebrate host. This is the first forced salivation experiment in a sand fly, addressing key questions on infectious bite and competent vectors.
Topics: Animals; Phlebotomus; RNA, Ribosomal, 16S; Phylogeny; Saliva; Bacteria; Iran; Insect Vectors; Female; Microbiota; Leishmaniasis, Cutaneous; Male
PubMed: 38771858
DOI: 10.1371/journal.pntd.0012165 -
Parasites & Vectors May 2024Volatile organic compounds (VOCs) are chemicals emitted as products of cell metabolism, which reflects the physiological and pathological conditions of any living... (Review)
Review
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.
Topics: Animals; Volatile Organic Compounds; Psychodidae; Ticks; Humans; Culicidae; Behavior, Animal; Vector Borne Diseases; Female; Mosquito Vectors; Plasmodium falciparum
PubMed: 38755646
DOI: 10.1186/s13071-024-06299-1 -
Anais Da Academia Brasileira de Ciencias 2024Aiming to compare and update the sand fly fauna of Portão de Pedra site, Sumidouro District, Rio de Janeiro State, Brazil, and considering the environmental changes...
Aiming to compare and update the sand fly fauna of Portão de Pedra site, Sumidouro District, Rio de Janeiro State, Brazil, and considering the environmental changes occurred, the biology and ecology of the local sandfly species were examined five years later as a complementary study carried. Captures were made in the cave, surroundings of cave and forest of the region, from 6 p.m. to 6 a.m. Among the 2323 sandflies of eigth species of the Lutzomyia were captured: L. gasparviannai, L. edwardsi, L. tupynambai, L. hirsuta, L. whitmani, L. migonei, L. intermedia, Lutzomyia. sp and one species of the Brumptomyia Kind: B. brumpti. In 2009 and 2010 were collected 1756 samples from ten species of the former genus and two of the second. L. gasparviannai was predominant, in the three collection sites, in both periods. Five species implicated as vectors of Leishmania: L. intermedia, L. whitmani, L. migonei, L. hirsuta and L. davisi have been collected in the area. Poisson regression and ANOVA were used to perform statistical analysis of species most relevant. The record of L. intermedia and a case of American tegumentary leishmaniasis are relevant to the public health of municipality and of state of Rio de Janeiro.
Topics: Animals; Psychodidae; Brazil; Insect Vectors; Population Density; Female; Male; Seasons; Ecosystem
PubMed: 38747792
DOI: 10.1590/0001-3765202420230872 -
Microorganisms Apr 2024The present work assessed the experimental susceptibility of and to () and (.) . A () - combination was used as a susceptible control. Wild-caught and...
The present work assessed the experimental susceptibility of and to () and (.) . A () - combination was used as a susceptible control. Wild-caught and laboratory-bred were membrane-fed on blood with a 5 × 10/mL log-phase promastigote culture suspension and dissected on days 2 and 8 post-blood meal (pbm) for analysis focused on the assessment of parasitoses, as well as placement and promastigote morphotyping. Survival curves were constructed. In all combinations, promastigotes were observed on day 8 pbm. For both species, in , the presence of parasites was observed up to the stomodeal valve, while in , the presence of parasites was observed up to the cardia. There were no significant differences in parasitosis between () and () in either or . Six morphological promastigote forms were distinguished in Giemsa-stained gut smears. The survival curves of all combinations decreased and were affected differently by several -parasite combinations, as well with -uninfected blood. These findings stress as experimentally susceptible to spp. and suggest the putative susceptibility of to () and () .
PubMed: 38674753
DOI: 10.3390/microorganisms12040809 -
Journal of Vector Borne Diseases Jan 2024In Brazil, one of the visceral leishmaniasis control measures in urban environments is the elimination of Lutzomyia longipalpis, which occurs through the application of...
BACKGROUND OBJECTIVES
In Brazil, one of the visceral leishmaniasis control measures in urban environments is the elimination of Lutzomyia longipalpis, which occurs through the application of pyrethroid insecticides with residual action in homes and outbuildings. Due to the loss of sensitivity of this vector to these insecticides, the search for more efficient insecticide compounds against L. longipalpis has been intensified. The objective of this work was to evaluate the toxicity of Trixis vauthieri essential oil on adult sandflies of the species L. longipalpis, and identify the phytochemical composition of these essential oils.
METHODS
Essential oils from leaves collected from T. vauthieri at different times were obtained at concentrations of 5, 10 and 20 mg/mL. Twenty sandflies were exposed to the essential oils and the mortality was evaluated after 1, 2, 4, 16, 24, 48 and 72 h. The chemical constituents of the essential oil were also identified.
RESULTS
The essential oils of T. vauthieri at a concentration of 20 mg/mL were the most toxic to sandflies, reaching a mortality rate of 98.33% and 95%, respectively, after 72 h of exposure. The analysis of chemical constituents revealed the presence of triterpenes and/or steroids, tannins, flavonoids, alkaloids, saponins and coumarins.
INTERPRETATION CONCLUSION
The results obtained suggest that T. vauthieri essential oil is fairly promising as an insecticidal potential against L. longipalpis. A more detailed analysis of the oil's phytochemical composition is necessary to identify active and pure compounds that can be used in vector control of visceral leishmaniasis.
Topics: Animals; Psychodidae; Oils, Volatile; Insecticides; Leishmaniasis, Visceral; Brazil; Insect Vectors; Plant Leaves; Female; Plant Oils
PubMed: 38648417
DOI: 10.4103/0972-9062.383642 -
Frontiers in Immunology 2024Cutaneous leishmaniasis is a neglected vector-borne parasitic disease prevalent in 92 countries with approximately one million new infections annually. Interactions...
INTRODUCTION
Cutaneous leishmaniasis is a neglected vector-borne parasitic disease prevalent in 92 countries with approximately one million new infections annually. Interactions between vector saliva and the human host alter the response to infection and outcome of disease.
METHODS
To characterize the human immunological responses developed against saliva of , a vector, we repeatedly exposed the arms of 14 healthy U.S volunteers to uninfected bites. Blood was collected a week after each exposure and used to assess total IgG antibodies against the proteins of salivary gland homogenate (SGH) and the levels of IFN-gamma and IL-10 from peripheral blood mononuclear cells (PBMCs) stimulated with SGH or recombinant sand fly proteins. We analyzed skin punch biopsies of the human volunteer arms from the insect bite site and control skin site after multiple exposures (four volunteers) using immunohistochemical staining.
RESULTS
A variety of immediate insect bite skin reactions were observed. Late skin reactions to insect bites were characterized by macular hyperpigmentation and/or erythematous papules. Hematoxylin and eosin staining showed moderate mononuclear skin infiltrate with eosinophils in those challenged recently (within 2 months), eosinophils were not seen in biopsies with recall challenge (6 month post bites). An increase in plasma antigen-specific IgG responses to SGH was observed over time. Western Blot results showed strong plasma reactivity to five salivary proteins. Importantly, volunteers developed a cellular immunity characterized by the secretion of IFN-gamma upon PBMC stimulation with SGH and recombinant antigens.
DISCUSSION
Our results demonstrate that humans mounted a local and systemic immune response against salivary proteins. Specifically, PduM02/SP15-like and PduM73/adenosine deaminase recombinant salivary proteins triggered a Th1 type immune response that might be considered in future development of a potential vaccine.
Topics: Animals; Humans; Phlebotomus; Leukocytes, Mononuclear; Insect Bites and Stings; Immunity, Cellular; Antigens; Immunoglobulin G; Salivary Proteins and Peptides
PubMed: 38633260
DOI: 10.3389/fimmu.2024.1335307 -
PloS One 2024In Nepal, visceral leishmaniasis (VL) has been targeted for elimination as a public health problem by 2026. Recently, increasing numbers of VL cases have been reported...
In Nepal, visceral leishmaniasis (VL) has been targeted for elimination as a public health problem by 2026. Recently, increasing numbers of VL cases have been reported from districts of doubtful endemicity including hills and mountains, threatening the ongoing VL elimination program in Nepal. We conducted a multi-disciplinary, descriptive cross-sectional survey to assess the local transmission of Leishmania donovani in seven such districts situated at altitudes of up to 1,764 meters in western Nepal from March to December 2019. House-to-house surveys were performed for socio-demographic data and data on past and current VL cases. Venous blood was collected from all consenting individuals aged ≥2 years and tested with the rK39 RDT. Blood samples were also tested with direct agglutination test, and a titer of ≥1:1600 was taken as a marker of infection. A Leishmania donovani species-specific PCR (SSU-rDNA) was performed for parasite species confirmation. We also captured sand flies using CDC light traps and mouth aspirators. The house-to-house surveys documented 28 past and six new VL cases of which 82% (28/34) were without travel exposure. Overall, 4.1% (54/1320) of healthy participants tested positive for L. donovani on at least one serological or molecular test. Among asymptomatic individuals, 17% (9/54) were household contacts of past VL cases, compared to 0.5% (6/1266) among non-infected individuals. Phlebotomus argentipes, the vector of L. donovani, was found in all districts except in Bajura. L. donovani was confirmed in two asymptomatic individuals and one pool of sand flies of Phlebotomus (Adlerius) sp. We found epidemiological and entomological evidence for local transmission of L. donovani in areas previously considered as non-endemic for VL. The national VL elimination program should revise the endemicity status of these districts and extend surveillance and control activities to curb further transmission of the disease.
Topics: Animals; Humans; Leishmaniasis, Visceral; Nepal; Cross-Sectional Studies; Leishmania donovani; Phlebotomus; Psychodidae
PubMed: 38630746
DOI: 10.1371/journal.pone.0289578