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1.
Parasitol Res ; 115(2): 483-7, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26453092

RESUMO

To identify the geographical origins of larvae of Wohlfahrtia magnifica (Diptera: Sarcophagidae) causing myiasis of sheep in Italy, comparative DNA sequence analysis of the mitochondrial cytochrome b gene was performed, based on gene fragments amplified by PCR from genomic DNA isolated from individual specimens. DNA extractions of 19 larvae from Lazio, Molise, Puglia, and Sicilia generated 17 readable sequences homologous to 2 haplotypes, either CB_magn01 or CB_magn02; DNA extracts from 4 adult flies from Calabria (reared from larvae) produced 4 readable sequences belonging to the haplotype CB_magn01. The two haplotypes found represent both the East and West phylogenetic lineages of W. magnifica, which is consistent with the species' arrival from central/southeast Europe (East lineage) and/or from southwest Europe/northwest Africa (West lineage). This is the first report of the sympatric occurrence of the two lineages, which could have resulted from natural or human-assisted dispersal. Polymorphic nuclear loci will have to be characterized in order to explain the origins and lack of mitochondrial haplotype diversity of this pest in Italy, where it poses increasing veterinary problems.


Assuntos
Citocromos b/genética , Genes Mitocondriais , Miíase/veterinária , Sarcofagídeos/genética , Doenças dos Ovinos/parasitologia , Animais , Europa (Continente) , Geografia , Haplótipos , Itália/epidemiologia , Larva , Mitocôndrias , Miíase/epidemiologia , Miíase/parasitologia , Filogenia , Reação em Cadeia da Polimerase , Ovinos , Doenças dos Ovinos/epidemiologia
2.
Annu Rev Entomol ; 58: 227-50, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23317043

RESUMO

Phlebotomines are the sole or principal vectors of Leishmania, Bartonella bacilliformis, and some arboviruses. The coevolution of sand flies with Leishmania species of mammals and lizards is considered in relation to the landscape epidemiology of leishmaniasis, a neglected tropical disease. Evolutionary hypotheses are unresolved, so a practical phlebotomine classification is proposed to aid biomedical information retrieval. The vectors of Leishmania are tabulated and new criteria for their incrimination are given. Research on fly-parasite-host interactions, fly saliva, and behavioral ecology is reviewed in relation to parasite manipulation of blood feeding, vaccine targets, and pheromones for lures. Much basic research is based on few transmission cycles, so generalizations should be made with caution. Integrated research and control programs have begun, but improved control of leishmaniasis and nuisance-biting requires greater emphasis on population genetics and transmission modeling. Most leishmaniasis transmission is zoonotic, affecting the poor and tourists in rural and natural areas, and therefore control should be compatible with environmental conservation.


Assuntos
Controle de Insetos , Insetos Vetores , Leishmaniose , Psychodidae , Animais , Interações Hospedeiro-Parasita , Insetos Vetores/classificação , Insetos Vetores/parasitologia , Insetos Vetores/fisiologia , Insetos Vetores/virologia , Leishmania/fisiologia , Leishmaniose/parasitologia , Leishmaniose/prevenção & controle , Leishmaniose/transmissão , Leishmaniose/veterinária , Lagartos/parasitologia , Mamíferos/parasitologia , Psychodidae/classificação , Psychodidae/parasitologia , Psychodidae/fisiologia , Psychodidae/virologia
3.
Parasitology ; 138(14): 1878-91, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-21914251

RESUMO

The domestic dog is the reservoir host of Leishmania infantum, the causative agent of zoonotic visceral leishmaniasis endemic in Mediterranean Europe. Targeted control requires predictive risk maps of canine leishmaniasis (CanL), which are now explored. We databased 2187 published and unpublished surveys of CanL in southern Europe. A total of 947 western surveys met inclusion criteria for analysis, including serological identification of infection (504, 369 dogs tested 1971-2006). Seroprevalence was 23 2% overall (median 10%). Logistic regression models within a GIS framework identified the main environmental predictors of CanL seroprevalence in Portugal, Spain, France and Italy, or in France alone. A 10-fold cross-validation approach determined model capacity to predict point-values of seroprevalence and the correct seroprevalence class (<5%, 5-20%, >20%). Both the four-country and France-only models performed reasonably well for predicting correctly the <5% and >20% seroprevalence classes (AUC >0 70). However, the France-only model performed much better for France than the four-country model. The four-country model adequately predicted regions of CanL emergence in northern Italy (<5% seroprevalence). Both models poorly predicted intermediate point seroprevalences (5-20%) within regional foci, because surveys were biased towards known rural foci and Mediterranean bioclimates. Our recommendations for standardizing surveys would permit higher-resolution risk mapping.


Assuntos
Doenças do Cão/epidemiologia , Leishmania/isolamento & purificação , Leishmaniose/veterinária , Animais , Reservatórios de Doenças , Doenças do Cão/parasitologia , Cães , Meio Ambiente , Europa (Continente)/epidemiologia , Geografia , Leishmania/imunologia , Leishmaniose/epidemiologia , Leishmaniose/parasitologia , Modelos Logísticos , Estudos Soroepidemiológicos
4.
Front Cell Infect Microbiol ; 11: 731595, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34712622

RESUMO

Many laboratory methods are used to diagnose leishmaniasis because it is characterized by varied symptoms and caused by different Leishmania species. A quantitative real-time PCR method based on a TaqMan probe was developed and modified for accurate identification of human cutaneous leishmaniasis (caused by Leishmania major or Leishmania tropica) from endemic areas of Iran. Two gene regions of amino acid permease 3 (AAP3) and cytochrome oxidase II (COII) were considered. Six new sets of species-specific primers and probes were designed. A total of 123 samples were examined and employed to evaluate and validate real-time PCR. According to parasitic load of the genesig®Leishmania Advanced Standard Kit, a serial dilution of purified plasmid (2-2×107 copies/reaction) was prepared under the same conditions for both genes. Specific primers and probes were able to detect three and six parasite copies in AAP3 and COII genes, respectively, and were able to detect three copies of parasites for L. major and L. tropica. The sensitivities of the reference kit and our method were 98.7 and 98.1%, respectively, and specificity was 100% for detecting parasite genomes in all assays. Designed primers and probes performed well in terms of efficiency and regression coefficient. For AAP3 and COII genes, respectively, the linear log range was 7 and the correlation coefficient (R2) was 0.749 and 0.996 for the reference kit using the standard generated curve and 0.98 and 0.96 with serial dilutions of parasite DNA. This research detected L. major and L. tropica definitely and opens the horizon for the other scientists in the multiplex reactions in designing and optimization of the conditions in silico and in vivo.


Assuntos
Leishmania tropica , Leishmaniose Cutânea , Parasitos , Animais , Humanos , Irã (Geográfico) , Leishmania tropica/genética , Leishmaniose Cutânea/diagnóstico , Reação em Cadeia da Polimerase em Tempo Real
5.
Trans R Soc Trop Med Hyg ; 115(6): 699-713, 2021 06 02.
Artigo em Inglês | MEDLINE | ID: mdl-33155034

RESUMO

BACKGROUND: Early exacerbation of cutaneous leishmaniasis is mainly affected by both the salivary and Leishmania parasite components. Little is known of the vaccine combination made by immunogenic proteins of sandfly saliva (SP15) with Leishmania parasites (LeIF) as a single prophylactic vaccine, namely SaLeish. Also, there are no data available to determine the species-specific sequence of SP15 isolated from the Iranian Phlebotomus papatasi. METHODS: Integrated bioinformatics and genetic engineering methods were employed to design, optimize and obtain a vector-parasite-based vaccine formulation in a whole-length fusion form of LeIF-SP15 against leishmaniasis. Holistic gene optimization was initially performed to obtain a high yield of pure 'whole-SaLeish' expression using bioinformatics analyses. Genomic and salivary gland RNAs of wild-caught P. papatasi were extracted and their complementary DNA was amplified and cloned into pJET vector. RESULTS: The new chimeric protein of whole-SaLeish and randomly selected transcripts of native PpIRSP15 (GenBank accession nos. MT025054 and MN938854, MN938855 and MN938856) were successfully expressed, purified and validated by immunoblotting assay. Furthermore, despite the single amino acid polymorphisms of PpIRSP15 found at positions Y23 and E73 within the population of wild Iranian sandflies, antigenicity and conservancy of PpIRSP15 epitopes remained constant to activate T cells. CONCLUSIONS: The SaLeish vaccine strategy takes advantage of a plethora of vector-parasite immunogenic proteins with potential protective efficacy to stimulate both the innate and specific cellular immune responses against Leishmania parasites.


Assuntos
Leishmania major , Phlebotomus , Vacinas , Animais , Clonagem Molecular , Biologia Computacional , Expressão Gênica , Irã (Geográfico) , Leishmania major/genética , Phlebotomus/genética , Saliva
6.
PLoS Negl Trop Dis ; 13(3): e0007193, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30830929

RESUMO

OBJECTIVE: To assess the effectiveness of community-wide deployment of insecticide-impregnated collars for dogs- the reservoir of Leishmania infantum-to reduce infantile clinical visceral leishmaniasis (VL). METHODS: A pair matched-cluster randomised controlled trial involving 40 collared and 40 uncollared control villages (161 [95% C.L.s: 136, 187] children per cluster), was designed to detect a 55% reduction in 48 month confirmed VL case incidence. The intervention study was designed by the authors, but implemented by the Leishmaniasis Control Program in NW Iran, from 2002 to 2006. RESULTS: The collars provided 50% (95% C.I. 17·8%-70·0%) protection against infantile VL incidence (0·95/1000/yr compared to 1·75/1000/yr). Reductions in incidence were observed across 76% (22/29) of collared villages compared to pair-matched control villages, with 31 fewer cases by the end of the trial period. In 11 paired villages, no further cases were recorded post-intervention, whereas in 7 collared villages there were 9 new clinical cases relative to controls. Over the trial period, 6,835 collars were fitted at the beginning of the 4 month sand fly season, of which 6.9% (95% C.I. 6.25%, 7.56%) were lost but rapidly replaced. Collar coverage (percent dogs collared) per village varied between 66% and 100%, with a mean annual coverage of 87% (95% C.I. 84·2, 89·0%). The variation in post-intervention clinical VL incidence was not associated with collar coverage, dog population size, implementation logistics, dog owner compliance, or other demographic variables tested. Larger reductions and greater persistence in incident case numbers (indicative of transmission) were observed in villages with higher pre-existing VL case incidence. CONCLUSION: Community-wide deployment of collars can provide a significant level of protection against infantile clinical VL, achieved in this study by the local VL Control Program, demonstrating attributes desirable of a sustainable public health program. The effectiveness is not dissimilar to the community-level protection provided against human and canine infection with L. infantum.


Assuntos
Controle de Doenças Transmissíveis/métodos , Doenças do Cão/prevenção & controle , Inseticidas/administração & dosagem , Leishmania infantum , Leishmaniose Visceral/prevenção & controle , Zoonoses/prevenção & controle , Animais , Criança , Doenças do Cão/epidemiologia , Doenças do Cão/transmissão , Cães , Feminino , Humanos , Incidência , Irã (Geográfico)/epidemiologia , Leishmaniose Visceral/epidemiologia , Leishmaniose Visceral/transmissão , Leishmaniose Visceral/veterinária , Masculino , Razão de Chances , Zoonoses/epidemiologia , Zoonoses/transmissão
7.
Trends Parasitol ; 24(4): 151-3, 2008 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-18314394

RESUMO

Malaria parasites manipulate mosquitoes to ensure transmission between mammalian hosts; painstaking experiments have now demonstrated that another medically important protozoan, Leishmania, enhances its transmission through the adaptive manipulation of one of its sandfly vectors, Lutzomyia longipalpis. Experimental Leishmania infections specifically increased sandfly biting persistence and feeding on multiple hosts, but only if the parasites produced infective forms and a gel plug of filamentous proteophosphoglycan in the anterior midgut of the sandfly. This fundamental research is relevant to vaccine development.


Assuntos
Adaptação Fisiológica , Leishmania/patogenicidade , Leishmaniose/transmissão , Psychodidae/parasitologia , Animais , Modelos Animais de Doenças , Comportamento Alimentar/fisiologia , Feminino , Interações Hospedeiro-Parasita/fisiologia , Insetos Vetores/parasitologia , Leishmania/metabolismo , Leishmaniose/metabolismo , Proteínas de Membrana/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Doenças Parasitárias em Animais/parasitologia , Proteoglicanas/metabolismo , Proteínas de Protozoários/metabolismo , Psychodidae/fisiologia , Doenças dos Roedores/parasitologia
8.
J Vector Ecol ; 43(1): 168-178, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29757525

RESUMO

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


Assuntos
Insetos Vetores/parasitologia , Insetos Vetores/patogenicidade , Leishmaniose Cutânea/transmissão , Psychodidae/parasitologia , Psychodidae/patogenicidade , Animais , Brasil , Entomologia , Leishmania/patogenicidade , Leishmaniose Cutânea/parasitologia , Estações do Ano
9.
Parasit Vectors ; 10(1): 157, 2017 Mar 24.
Artigo em Inglês | MEDLINE | ID: mdl-28340594

RESUMO

BACKGROUND: Before 1996 the phlebotomine sand fly Lutzomyia neivai was usually treated as a synonym of the morphologically similar Lutzomyia intermedia, which has long been considered a vector of Leishmania braziliensis, the causative agent of much cutaneous leishmaniasis in South America. This report investigates the likely range changes of both sand fly species in response to a stabilisation climate change scenario (RCP4.5) and a high greenhouse gas emissions one (RCP8.5). METHODS: Ecological niche modelling was used to identify areas of South America with climates currently suitable for each species, and then the future distributions of these climates were predicted based on climate change scenarios. Compared with the previous ecological niche model of L. intermedia (sensu lato) produced using the GARP algorithm in 2003, the current investigation modelled the two species separately, making use of verified presence records and additional records after 2001. Also, the new ensemble approach employed ecological niche modelling algorithms (including Maximum Entropy, Random Forests and Support Vector Machines) that have been widely adopted since 2003 and perform better than GARP, as well as using a more recent climate change model (HadGEM2) considered to have better performance at higher resolution than the earlier one (HadCM2). RESULTS: Lutzomyia intermedia was shown to be the more tropical of the two species, with its climatic niche defined by higher annual mean temperatures and lower temperature seasonality, in contrast to the more subtropical L. neivai. These different latitudinal ranges explain the two species' predicted responses to climate change by 2050, with L. intermedia mostly contracting its range (except perhaps in northeast Brazil) and L. neivai mostly shifting its range southwards in Brazil and Argentina. This contradicts the findings of the 2003 report, which predicted more range expansion. The different findings can be explained by the improved data sets and modelling methods. CONCLUSIONS: Our findings indicate that climate change will not always lead to range expansion of disease vectors such as sand flies. Ecological niche models should be species specific, carefully selected and combined in an ensemble approach.


Assuntos
Mudança Climática , Insetos Vetores , Psychodidae/crescimento & desenvolvimento , Animais , Modelos Teóricos , América do Sul , Análise Espacial , Especificidade da Espécie
10.
Parasit Vectors ; 9: 25, 2016 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-26812963

RESUMO

Visceral Leishmaniasis (VL) is a neglected vector-borne disease. In India, it is transmitted to humans by Leishmania donovani-infected Phlebotomus argentipes sand flies. In 2005, VL was targeted for elimination by the governments of India, Nepal and Bangladesh by 2015. The elimination strategy consists of rapid case detection, treatment of VL cases and vector control using indoor residual spraying (IRS). However, to achieve sustained elimination of VL, an appropriate post elimination surveillance programme should be designed, and crucial knowledge gaps in vector bionomics, human infection and transmission need to be addressed. This review examines the outstanding knowledge gaps, specifically in the context of Bihar State, India.The knowledge gaps in vector bionomics that will be of immediate benefit to current control operations include better estimates of human biting rates and natural infection rates of P. argentipes, with L. donovani, and how these vary spatially, temporally and in response to IRS. The relative importance of indoor and outdoor transmission, and how P. argentipes disperse, are also unknown. With respect to human transmission it is important to use a range of diagnostic tools to distinguish individuals in endemic communities into those who: 1) are to going to progress to clinical VL, 2) are immune/refractory to infection and 3) have had past exposure to sand flies.It is crucial to keep in mind that close to elimination, and post-elimination, VL cases will become infrequent, so it is vital to define what the surveillance programme should target and how it should be designed to prevent resurgence. Therefore, a better understanding of the transmission dynamics of VL, in particular of how rates of infection in humans and sand flies vary as functions of each other, is required to guide VL elimination efforts and ensure sustained elimination in the Indian subcontinent. By collecting contemporary entomological and human data in the same geographical locations, more precise epidemiological models can be produced. The suite of data collected can also be used to inform the national programme if supplementary vector control tools, in addition to IRS, are required to address the issues of people sleeping outside.


Assuntos
Leishmania donovani/fisiologia , Leishmaniose Visceral/transmissão , Phlebotomus/parasitologia , Animais , Erradicação de Doenças , Humanos , Índia/epidemiologia , Leishmaniose Visceral/epidemiologia , Phlebotomus/fisiologia
11.
PLoS One ; 10(11): e0143282, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26619186

RESUMO

Vector borne diseases are susceptible to climate change because distributions and densities of many vectors are climate driven. The Amazon region is endemic for cutaneous leishmaniasis and is predicted to be severely impacted by climate change. Recent records suggest that the distributions of Lutzomyia (Nyssomyia) flaviscutellata and the parasite it transmits, Leishmania (Leishmania) amazonensis, are expanding southward, possibly due to climate change, and sometimes associated with new human infection cases. We define the vector's climatic niche and explore future projections under climate change scenarios. Vector occurrence records were compiled from the literature, museum collections and Brazilian Health Departments. Six bioclimatic variables were used as predictors in six ecological niche model algorithms (BIOCLIM, DOMAIN, MaxEnt, GARP, logistic regression and Random Forest). Projections for 2050 used 17 general circulation models in two greenhouse gas representative concentration pathways: "stabilization" and "high increase". Ensemble models and consensus maps were produced by overlapping binary predictions. Final model outputs showed good performance and significance. The use of species absence data substantially improved model performance. Currently, L. flaviscutellata is widely distributed in the Amazon region, with records in the Atlantic Forest and savannah regions of Central Brazil. Future projections indicate expansion of the climatically suitable area for the vector in both scenarios, towards higher latitudes and elevations. L. flaviscutellata is likely to find increasingly suitable conditions for its expansion into areas where human population size and density are much larger than they are in its current locations. If environmental conditions change as predicted, the range of the vector is likely to expand to southeastern and central-southern Brazil, eastern Paraguay and further into the Amazonian areas of Bolivia, Peru, Ecuador, Colombia and Venezuela. These areas will only become endemic for L. amazonensis, however, if they have competent reservoir hosts and transmission dynamics matching those in the Amazon region.


Assuntos
Distribuição Animal , Mudança Climática , Ecossistema , Modelos Estatísticos , Psychodidae/fisiologia , Animais , Vetores de Doenças , América do Sul
12.
Parasit Vectors ; 8: 131, 2015 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-25885217

RESUMO

Phlebotomine sand flies are the subject of much research because of the role of their females as the only proven natural vectors of Leishmania species, the parasitic protozoans that are the causative agents of the neglected tropical disease leishmaniasis. Activity in this field was highlighted by the eighth International Symposium on Phlebotomine Sand flies (ISOPS) held in September 2014, which prompted this review focusing on vector control. Topics reviewed include: Taxonomy and phylogenetics, Vector competence, Genetics, genomics and transcriptomics, Eco-epidemiology, and Vector control. Research on sand flies as leishmaniasis vectors has revealed a diverse array of zoonotic and anthroponotic transmission cycles, mostly in subtropical and tropical regions of Africa, Asia and Latin America, but also in Mediterranean Europe. The challenge is to progress beyond descriptive eco-epidemiology, in order to separate vectors of biomedical importance from the sand fly species that are competent vectors but lack the vectorial capacity to cause much human disease. Transmission modelling is required to identify the vectors that are a public health priority, the ones that must be controlled as part of the integrated control of leishmaniasis. Effective modelling of transmission will require the use of entomological indices more precise than those usually reported in the leishmaniasis literature.


Assuntos
Transmissão de Doença Infecciosa/prevenção & controle , Entomologia/tendências , Controle de Insetos/métodos , Controle de Insetos/tendências , Leishmaniose/epidemiologia , Leishmaniose/prevenção & controle , Psychodidae/fisiologia , África/epidemiologia , Animais , Ásia/epidemiologia , Europa (Continente)/epidemiologia , Humanos , Insetos Vetores , América Latina/epidemiologia , Clima Tropical
13.
Philos Trans R Soc Lond B Biol Sci ; 370(1665)2015 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-25688012

RESUMO

Arguably one of the most important effects of climate change is the potential impact on human health. While this is likely to take many forms, the implications for future transmission of vector-borne diseases (VBDs), given their ongoing contribution to global disease burden, are both extremely important and highly uncertain. In part, this is owing not only to data limitations and methodological challenges when integrating climate-driven VBD models and climate change projections, but also, perhaps most crucially, to the multitude of epidemiological, ecological and socio-economic factors that drive VBD transmission, and this complexity has generated considerable debate over the past 10-15 years. In this review, we seek to elucidate current knowledge around this topic, identify key themes and uncertainties, evaluate ongoing challenges and open research questions and, crucially, offer some solutions for the field. Although many of these challenges are ubiquitous across multiple VBDs, more specific issues also arise in different vector-pathogen systems.


Assuntos
Mudança Climática , Clima , Doenças Transmissíveis/transmissão , Vetores de Doenças , Animais , Humanos , Fatores Socioeconômicos
14.
Clin Epidemiol ; 6: 147-54, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24833919

RESUMO

Leishmania species are the causative agents of leishmaniasis, a neglected tropical disease. These parasitic protozoans are usually transmitted between vertebrate hosts by the bite of blood sucking female phlebotomine sand flies. This review focuses on the two parasites causing most human visceral leishmaniasis (VL), which leads to substantial health problems or death for up to 400,000 people per year. Except for travel cases, Leishmania donovani infections are restricted to the (sub-)tropics of Asia and Africa, where transmission is mostly anthroponotic, while Leishmania infantum occurs in the drier parts of Latin America as well as in the Mediterranean climate regions of the Old World, with the domestic dog serving as the main reservoir host. The prevalence of VL caused by L. infantum has been declining where living standards have improved. In contrast, infections of L. donovani continue to cause VL epidemics in rural areas on the Indian subcontinent and in East Africa. The current review compares and contrasts these continental differences and suggests priorities for basic and applied research that might improve VL control. Transmission cycles, pathogenesis, diagnosis, treatment and prognosis, prevention (including vector control), surveillance, transmission modeling, and international control efforts are all reviewed. Most case detection is passive, and so routine surveillance does not usually permit accurate assessments of any changes in the incidence of VL. Also, it is not usually possible to estimate the human inoculation rate of parasites by the sand fly vectors because of the limitations of survey methods. Consequently, transmission modeling rarely passes beyond the proof of principle stage, and yet it is required to help develop risk factor analysis for control programs. Anthroponotic VL should be susceptible to elimination by rapid case detection and treatment combined with local vector control, and one of the most important interventions may well be socioeconomic development.

16.
Evol Appl ; 5(3): 293-305, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25568049

RESUMO

Vaccine development is informed by a knowledge of genetic variation among antigen alleles, especially the distribution of positive and balancing selection in populations and species. A combined approach using population genetic and phylogenetic methods to detect selective signatures can therefore be informative for identifying vaccine candidates. Parasitic Leishmania species cause the disease leishmaniasis in humans and mammalian reservoir hosts after inoculation by female phlebotomine sandflies. Like other arthropod vectors of disease agents, sandflies use salivary peptides to counteract host haemostatic and immunomodulatory responses during bloodfeeding, and these peptides are vaccine candidates because they can protect against Leishmania infection. We detected no contemporary adaptive selection on one salivary peptide, apyrase, in 20 populations of Phlebotomus ariasi, a European vector of Leishmania infantum. Maximum likelihood branch models on a gene phylogeny showed apyrase to be a single copy in P. ariasi but an ancient duplication event associated with temporary positive selection was observed in its sister group, which contains most Mediterranean vectors of L. infantum. The absence of contemporary adaptive selection on the apyrase of P. ariasi may result from this sandfly's opportunistic feeding behaviour. Our study illustrates how the molecular population genetics of arthropods can help investigate the potential of salivary peptides for disease control and for understanding geographical variation in vector competence.

17.
J Vector Ecol ; 36 Suppl 1: S17-22, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21366771

RESUMO

I review species concepts, the taxonomy of phlebotomine sand flies, and some transmission cycles of leishmaniasis in order to illustrate the difficulties of classifying these vectors in a way that will be ideal both for medical parasitologists and sand fly specialists. Choices will have to be made between different classifications, either maintaining a practical one containing few vectorial genera (mostly Phlebotomus for the Old World and Lutzomyia for the Neotropics) or changing the generic names of many vectors so that the classification represents an evolutionary hypothesis. However, sand flies also transmit arboviruses and members of other sand fly genera bite humans, and so vectorial status alone might not provide the criteria for recognizing only a few genera. Vectorial roles are often determined by species-level co-evolution of susceptibility to Leishmania species, with selection being initiated and maintained by ecological contacts. There is only imperfect co-cladogenesis of genus-level groups or subgeneric complexes of sand flies and Leishmania species. Natural hybridization between sand fly species has been recorded in several species complexes, and this highlights the need to focus on gene flow and the distribution of phenotypes of biomedical importance, not on taxa.


Assuntos
Insetos Vetores/classificação , Psychodidae/classificação , Animais , Ecologia , Insetos Vetores/crescimento & desenvolvimento , Insetos Vetores/parasitologia , Leishmaniose/transmissão , Psychodidae/crescimento & desenvolvimento , Psychodidae/parasitologia
18.
Acta Trop ; 119(2-3): 131-7, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21605538

RESUMO

From 2009 to 2010, 3129 sandflies were caught in CDC light traps placed in various habitats in Ghomrassen, Tataouine governorate, southeast Tunisia, a mixed focus of human cutaneous leishmaniasis caused by Leishmania tropica and Leishmania major. Species diversity was quantified in anthropogenic, semi-anthropogenic and semi-natural locations. Sandflies were identified according to morphological characters and also by the comparative sequence analysis of a fragment of the mitochondrial cytochrome b gene to distinguish between two putative local vectors of L. tropica, namely Phlebotomus chabaudi and Phlebotomus riouxi. The lowest sandfly diversities were found in L. major sites, where the incriminated vector P. papatasi predominated in the burrows of the rodent reservoir hosts (Meriones) as well as inside and outside houses of human cases. In L. tropica sites, the incriminated peri-domestic vector Phlebotomus sergenti was the most abundant species inside houses, whereas P. riouxi or P. chabaudi was the dominant species in the semi-natural rocky habitats favoured by the putative rodent reservoir, Ctenodactylus gundi. All specimens of P. chabaudi identified molecularly had the diagnostic cytochrome b characters of P. riouxi, indicating either that the latter represents only a geographical variant of P. chabaudi or that these two species may sometimes hybridize.


Assuntos
Vetores de Doenças , Ecossistema , Gerbillinae/crescimento & desenvolvimento , Leishmania major/isolamento & purificação , Leishmania tropica/isolamento & purificação , Leishmaniose Cutânea/epidemiologia , Phlebotomus/crescimento & desenvolvimento , Animais , Citocromos b/genética , DNA Mitocondrial/química , DNA Mitocondrial/genética , Feminino , Variação Genética , Humanos , Masculino , Phlebotomus/anatomia & histologia , Phlebotomus/classificação , Phlebotomus/genética , Tunísia/epidemiologia
19.
Vector Borne Zoonotic Dis ; 11(7): 823-34, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21254904

RESUMO

Hungary is regarded as free of leishmaniasis because only a few imported cases have been reported. However, southern Hungary has a sub-Mediterranean climate, and so it was included in the EU FP6 EDEN project, which aimed to map the northern limits of canine leishmaniasis (CanL) in Europe. The numbers of traveling and imported dogs have increased in the last decade, raising concerns about the introduction of CanL caused by Leishmania infantum. Serum samples were collected from 725 dogs (22 localities, 6 counties) that had never traveled to endemic countries, as well as from other potential reservoir hosts (185 red foxes and 13 golden jackals). All sera were tested by the indirect fluorescent antibody test, but they were sero-negative using the OIE cut-off of 1:80 serum dilution except for those of two dogs resident since birth in southern Hungary. These had not received a blood transfusion, but the mode of transmission is unclear because no sandfly vectors were caught locally. From 2006 to 2009, phlebotomine sandflies were sampled in the summer months at 47 localities of 8 counties. They were trapped with castor-oil-impregnated sticky-paper, light, and CO(2)-baited traps. Small numbers of two vectors of Leishmania infantum were found. Phlebotomus neglectus occurred in three villages near to Croatia and one in north Hungary at latitude 47 °N, and Phlebotomus perfiliewi perfiliewi was trapped at two sites in a southeastern county close to the sites where it was first found in 1931-1932. Our report provides baseline data for future investigations into the northward spread of CanL into Hungary, which we conclude has yet to occur.


Assuntos
Doenças do Cão/parasitologia , Doenças do Cão/transmissão , Insetos Vetores/parasitologia , Leishmaniose/veterinária , Phlebotomus/parasitologia , Tunga/parasitologia , Animais , Clima , Doenças do Cão/sangue , Doenças do Cão/epidemiologia , Cães , Feminino , Geografia , Hungria/epidemiologia , Leishmania infantum/isolamento & purificação , Leishmaniose/epidemiologia , Leishmaniose/transmissão , Masculino , Inquéritos e Questionários
20.
PLoS One ; 6(8): e20817, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21857899

RESUMO

BACKGROUND: Zoonotic visceral leishmaniasis is endemic in the Mediterranean Basin, where the dog is the main reservoir host. The disease's causative agent, Leishmania infantum, is transmitted by blood-feeding female sandflies. This paper reports an integrative study of canine leishmaniasis in a region of France spanning the southwest Massif Central and the northeast Pyrenees, where the vectors are the sandflies Phlebotomus ariasi and P. perniciosus. METHODS: Sandflies were sampled in 2005 using sticky traps placed uniformly over an area of approximately 100 by 150 km. High- and low-resolution satellite data for the area were combined to construct a model of the sandfly data, which was then used to predict sandfly abundance throughout the area on a pixel by pixel basis (resolution of c. 1 km). Using literature- and expert-derived estimates of other variables and parameters, a spatially explicit R(0) map for leishmaniasis was constructed within a Geographical Information System. R(0) is a measure of the risk of establishment of a disease in an area, and it also correlates with the amount of control needed to stop transmission. CONCLUSIONS: To our knowledge, this is the first analysis that combines a vector abundance prediction model, based on remotely-sensed variables measured at different levels of spatial resolution, with a fully mechanistic process-based temperature-dependent R(0) model. The resulting maps should be considered as proofs-of-principle rather than as ready-to-use risk maps, since validation is currently not possible. The described approach, based on integrating several modeling methods, provides a useful new set of tools for the study of the risk of outbreaks of vector-borne diseases.


Assuntos
Doenças do Cão/parasitologia , Insetos Vetores/parasitologia , Leishmaniose Visceral/veterinária , Phlebotomus/parasitologia , Algoritmos , Animais , Surtos de Doenças/prevenção & controle , Doenças do Cão/epidemiologia , Doenças do Cão/prevenção & controle , Cães , Feminino , França/epidemiologia , Sistemas de Informação Geográfica , Geografia , Humanos , Leishmania infantum/isolamento & purificação , Leishmaniose Visceral/parasitologia , Leishmaniose Visceral/transmissão , Modelos Biológicos , Phlebotomus/classificação , Medição de Risco , Fatores de Risco , Especificidade da Espécie , Temperatura , Zoonoses/epidemiologia , Zoonoses/parasitologia
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