Geographical and Molecular Analysis of Haplotype Variations in Leishmania major Among Infected Iranian Phlebotomus papatasi

PURPOSE

Leishmania major is main causative agent and Phlebotomus papatasi is only proven vector of Zoonotic Cutaneous Leishmaniasis (ZCL) in Iran. Human leishmaniasis is mostly susceptible to climatic conditions and molecular variations of Leishmania parasites within sandflies.

METHODS

L. major was analyzed based on geographical, environmental, climatic changes and haplotype variations within P. papatasi. Molecular tools and different geographical aspects were employed using Arc-GIS software for mapping the geographic distribution of samples and other statistics tests. Fragments of ITS-rDNA, k-DNA, and microsatellite genes of Leishmania were used for PCR, RFLP, sequencing, and phylogenetic analyses.

RESULTS

Totally 81 out of 1083 female P. papatasi were detected with Leishmania parasites: 70 and five were L. major and L. turanica, respectively. Golestan and Fars provinces had the highest (13.64%) and lowest (4.55%) infection rates, respectively. The infection rate among female P. papatasi collected from gerbil burrows was significantly higher (15.15%) than animal shelters, yards, and inside houses (4.48%) (P < 0.0%). Microsatellite was more sensitive (22.72%) than k-DNA (18.8%) and ITS-rDNA (7.48%). More molecular variations of L. major were found in Isfahan province.

CONCLUSIONS

Arc-GIS software and other statistics tests were employed to find Leishmania positive and haplotype variations among sand flies. Geographical situations, altitude, climate, precipitation, humidity, temperature, urbanization, migrations, regional divergences, deforestation, global warming, genome instability, ecology, and biology of the sand flies intrinsically, and the reservoir hosts and neighboring infected locations could be reasons for increasing or decreasing the rate of Leishmania infection and haplotype variations.

Entomological surveillance and spatiotemporal risk assessment of sand fly-borne diseases in Cyprus

Visceral and cutaneous leishmaniases are important public health concerns in Cyprus. Although the diseases, historically prevalent on the island, were nearly eradicated by 1996, an increase in frequency and geographical spread has recently been recorded. Upward trends in leishmaniasis prevalence have largely been attributed to environmental changes that amplify the abundance and activity of its vector, the phlebotomine sand flies. Here, we performed an extensive field study across the island to map the sand fly fauna and compared the presence and distribution of the species found with historical records. We mapped the habitat preferences of Phlebotomus papatasi and P. tobbi, two medically important species, and predicted the seasonal abundance of P. papatasi at unprecedented spatiotemporal resolution using a climate-sensitive population dynamics model driven by high-resolution meteorological forecasting. Our compendium holds a record of 18 species and the locations of a subset, including those of potential public and veterinary health concern. We confirmed that P. papatasi is widespread, especially in densely urbanized areas, and predicted that its abundance uniformly peaks across the island at the end of summer. We identified potential hotspots of P. papatasi activity even after this peak. Our results form a foundation to inform public health planning and contribute to the development of effective, efficient, and environmentally sensitive strategies to control sand fly populations and prevent sand fly-borne diseases.

PpSP32, the Phlebotomus papatasi immunodominant salivary protein, exerts immunomodulatory effects on human monocytes, macrophages, and lymphocytes

BACKGROUND

The saliva of sand flies, vectors of Leishmania parasites, contains several components that exert pharmacological activity facilitating the acquisition of blood by the insect and contributing to the establishment of infection. Previously, we demonstrated that PpSP32 is the immunodominant salivary antigen in humans exposed to Phlebotomus papatasi bites and validated its usefulness as a predictive biomarker of disease. PpSP32, whose functions are little known to date, is an intriguing protein due to its involvement in the etiopathogenesis of pemphigus, an auto-immune disease. Herein, we aimed to better decipher its role through the screening of several immunomodulatory activity either on lymphocytes or on monocytes/macrophages.

METHODS

Peripheral mononuclear cells from healthy volunteers were stimulated with anti-CD3/anti-CD28 antibodies, phytohemagglutinin, phorbol 12-myristate 13-acetate/ionomycin, or lipopolysaccharide in the presence of increasing doses of PpSP32. Cell proliferation was measured after the addition of tritiated thymidine. Monocyte activation was tested by analyzing the expression of CD86 and HLA-DR molecules by flow cytometry. Cytokine production was analyzed in culture supernatants by ELISA. THP-1-derived macrophages were stimulated with LPS in the presence of increasing doses of PpSP32, and cytokine production was analyzed in culture supernatants by ELISA and multiplex technique. The effect of PpSP32 on NF-kB signaling was tested by Western blot. The anti-inflammatory activity of PpSP32 was assessed in vivo in an experimental inflammatory model of carrageenan-induced paw edema in rats.

RESULTS

Our data showed that PpSP32 down-modulated the expression of activation markers in LPS-stimulated monocytes and THP1-derived macrophages. This protein negatively modulated the secretion of Th1 and Th2 cytokines by human lymphocytes as well as pro-inflammatory cytokines by monocytes, and THP1-derived macrophages. PpSP32 treatment led to a dose-dependent reduction of IκB phosphorylation. When PpSP32 was injected into the paw of carrageenan-injected rats, edema was significantly reduced.

CONCLUSIONS

Our data indicates that PpSP32 induces a potent immunomodulatory effect on monocytes and THP-1-derived macrophages. This inhibition could be mediated, among others, by the modulation of the NF-kB signaling pathway. The anti-inflammatory activity of PpSP32 was confirmed in vivo in the carrageenan-induced paw edema model in rats.

Corrigendum: Co-infection of Phlebotomus papatasi (Diptera: Psychodidae) gut bacteria with Leishmania major exacerbates the pathological responses of BALB/c mice

[This corrects the article DOI: 10.3389/fcimb.2023.1115542.].

Co-infection of Phlebotomus papatasi (Diptera: Psychodidae) gut bacteria with Leishmania major exacerbates the pathological responses of BALB/c mice

Clinical features and severity of the leishmaniasis is extremely intricate and depend on several factors, especially sand fly-derived products. Bacteria in the sand fly's gut are a perpetual companion of Leishmania parasites. However, consequences of the concomitance of these bacteria and Leishmania parasite outside the midgut environment have not been investigated in the infection process. Herein, a needle infection model was designed to mimic transmission by sand flies, to examine differences in the onset and progression of L. major infection initiated by inoculation with "low" or "high" doses of Enterobacter cloacae and Bacillus subtilis bacteria. The results showed an alteration in the local expression of pro- and anti-inflammatory cytokines in mice receiving different inoculations of bacteria. Simultaneous injection of two bacteria with Leishmania parasites in the low-dose group caused greater thickness of ear pinna and enhanced tissue chronic inflammatory cells, as well as resulted in multifold increase in the expression of IL-4 and IL-1β and a decrease in the iNOS expression, without changing the L. major burden. Despite advances in scientific breakthroughs, scant survey has investigated the interaction between micro and macro levels of organization of leishmaniasis that ranges from the cellular to macro ecosystem levels, giving rise to the spread and persistence of the disease in a region. Our findings provide new insight into using the potential of the vector-derived microbiota in modulating the vertebrate immune system for the benefit of the host or recommend the use of appropriate antibiotics along with antileishmanial medicines.

major and Transmitted by Phlebotomus papatasi in the North Africa Region, a Systematic Review and a Meta-Analysis

BACKGROUND

In North African countries, zoonotic cutaneous leishmaniasis (ZCL) is a seasonal disease linked to Phlebotomus papatasi, Scopoli, 1786, the primary proven vector of L. major dynamics. Even if the disease is of public health importance, studies of P. papatasi seasonal dynamics are often local and dispersed in space and time. Therefore, a detailed picture of the biology and behavior of the vector linked with climatic factors and the framework of ZCL outbreaks is still lacking at the North African countries' level. Our study aims to fill this gap via a systematic review and meta-analysis of the seasonal incidence of ZCL and the activity of P. papatasi in North African countries. We address the relationship between the seasonal number of declared ZCL cases, the seasonal dynamic of P. papatasi, and climatic variables at the North African region scale.

METHODS

We selected 585 publications, dissertations, and archives data published from 1990 to July 2022. The monthly incidence data of ZCL were extracted from 15 documents and those on the seasonal dynamic of P. papatasi from 11 publications from four North African countries.

RESULTS

Our analysis disclosed that for most studied sites, the highest ZCL incidence is recorded from October to February (the hibernal season of the vector), while the P. papatasi density peaks primarily during the hot season of June to September. Overall, at the North African region scale, two to four months laps are present before the apparition of the scars reminiscent of infection by L. major.

CONCLUSIONS

Such analysis is of interest to regional decision-makers for planning control of ZCL in North African countries. They can also be a rationale on which future field studies combining ZCL disease incidence, vector activity, and climatic data can be built.

Characterization of the glutathione S-transferase genes in the sand flies Phlebotomus papatasi and Lutzomyia longipalpis shows expansion of the novel glutathione S-transferase xi (X) class

Leishmaniasis control often relies upon insecticidal control of phlebotomine sandfly vector populations. Such methods are vulnerable to the evolution of insecticide resistance via a range of molecular mechanisms. There is evidence that two major resistance mechanisms, target site insensitivity and metabolic resistance, have evolved in some sandfly populations and further genetic characterization of resistance would be useful to understand and combat it. To facilitate the study of the mechanisms of metabolic resistance, here we improved the annotation and characterized a major detoxification gene family, the glutathione-s-transferases (GST), in the genomes of two sand fly species: Phlebotomus papatasi and Lutzomyia longipalpis. The compositions of the GST gene family differ markedly from those of Aedes and Anopheles mosquitoes. Most strikingly, the xi (X) class of GSTs appears to have expanded in both sand fly genomes. Our results provide a basis for further studies of metabolic resistance mechanisms in these important disease vector species.

Effects of multiple feedings on sensitized rabbits on the fitness of Phlebotomus papatasi (Diptera: Psychodidae)

In the present study, we evaluated the effects of antibodies anti-sandfly saliva on the fecundity of Phlebotomus papatasi, vector of zoonotic cutaneous leishmaniasis in the Old World. Rabbits were repeatedly exposed to sandfly bites. Immune sera showed increased levels of anti-sandfly saliva antibody compared to the pre-exposition period. The analysis of biological parameters revealed no decline on the feeding success of females P. papatasi fed on rabbits repeatedly exposed to sandfly bites. Our results showed that anti-sandfly saliva antibodies of rabbits are not detrimental to the fitness of females P. papatasi. Thus, rabbits did not acquire resistance to sandflies following repeated exposures, and that contribute in maintaining a high density of P. papatasi. To control sandfly infestations and Leishmania transmission, more studies are needed for a better understanding of the mechanisms governing the resistance of hosts to bites of sandflies.

Evaluation of Susceptibility Status of Phlebotomus papatasi, the Main Vector of Zoonotic Cutaneous Leishmaniasis, to Different WHO Recommended Insecticides in an Endemic Focus, Central Iran

Background

Among neglected zoonotic diseases, leishmaniases caused by Leishmania parasite through infected female sand fly bite, are a group of diseases found in 98 countries and territories representing a critical burden of disease worldwide. Vector management plays a crucial role in reducing the burden of vector-borne diseases by WHO's global plan. The objective of the current study was to assess the susceptibility status of wild phlebotomine sand flies from Esfahan Province, central Iran, to the recommended insecticides by WHO.

Methods

Sand flies were collected by mouth aspirator in Matin Abad desert Eco-resort and were tested using WHO adult mosquito test kit against Dichlorodiphenyltrichloroethane (DDT) 4%, Deltamethrin 0.05%, Malathion 5% and Propoxur 0.1%. The number of knockdown sand flies were recorded during exposure time in ten minutes interval for DDT and Deltamethrin and they were allowed to recover for 24 hours. Knockdown Time₅₀ (KD₅₀) and KD₉₀ were generated for them using Probit software. They were mounted and identified by valid keys.

Results

Among the tested insecticides against female Phlebotomus papatasi, DDT, Deltamethrin, and Malathion recorded the highest mortality rate of 100%, followed by Propoxur with 92.2% mortality for a one-hour exposure. For DDT, KD₅₀ and KD₉₀ were calculated 21.87 and 42.93 and for Deltamethrin, they were 23.74 and 56.50 minutes respectively. Total sand flies exposed with DDT and Deltamethrin shed their leg(s).

Conclusion

It is concluded that Ph. papatasi from central Iran is susceptible to DDT, Deltamethrin, Malathion, and Propoxur.

Isolation in Natural Host Cell Lines of Wolbachia Strains wPip from the Mosquito Culex pipiens and wPap from the Sand Fly Phlebotomus papatasi

Simple Summary

Diverse strains of Wolbachia bacteria, carried by many arthropods, as well as some nematodes, interact in many different ways with their hosts. These include male killing, reproductive incompatibility, nutritional supplementation and suppression or enhancement of the transmission of diseases such as dengue and malaria. Consequently, Wolbachia have an important role to play in novel strategies to control human and livestock diseases and their vectors. Similarly, cell lines derived from insect hosts of Wolbachia constitute valuable research tools in this field. During the generation of novel cell lines from mosquito and sand fly vectors, we isolated two strains of Wolbachia and demonstrated their infectivity for cells from a range of other insects and ticks. These new insect cell lines and Wolbachia strains will aid in the fight against mosquitoes, sand flies and, potentially, ticks and the diseases that these arthropods transmit to humans and their domestic animals.

Abstract

Endosymbiotic intracellular bacteria of the genus Wolbachia are harboured by many species of invertebrates. They display a wide range of developmental, metabolic and nutritional interactions with their hosts and may impact the transmission of arboviruses and protozoan parasites. Wolbachia have occasionally been isolated during insect cell line generation. Here, we report the isolation of two strains of Wolbachia, wPip and wPap, during cell line generation from their respective hosts, the mosquito Culex pipiens and the sand fly Phlebotomus papatasi. wPip was pathogenic for both new C. pipiens cell lines, CPE/LULS50 and CLP/LULS56, requiring tetracycline treatment to rescue the lines. In contrast, wPap was tolerated by the P. papatasi cell line PPL/LULS49, although tetracycline treatment was applied to generate a Wolbachia-free subline. Both Wolbachia strains were infective for a panel of heterologous insect and tick cell lines, including two novel lines generated from the sand fly Lutzomyia longipalpis, LLE/LULS45 and LLL/LULS52. In all cases, wPip was more pathogenic for the host cells than wPap. These newly isolated Wolbachia strains, and the novel mosquito and sand fly cell lines reported here, will add to the resources available for research on host–endosymbiont relationships, as well as on C. pipiens, P. papatasi, L. longipalpis and the pathogens that they transmit.

Standing genetic variation in laboratory populations of insecticide-susceptible Phlebotomus papatasi and Lutzomyia longipalpis (Diptera: Psychodidae: Phlebotominae) for the evolution of resistance

Insecticides can exert strong selection on insect pest species, including those that vector diseases, and have led to rapid evolution of resistance. Despite such rapid evolution, relatively little is known about standing genetic variation for resistance in insecticide-susceptible populations of many species. To help fill this knowledge gap, we generated genotyping-by-sequencing data from insecticide-susceptible Phlebotomus papatasi and Lutzomyia longipalpis sand flies that survived or died from a sub-diagnostic exposure to either permethrin or malathion using a modified version of the Centers for Disease Control and Prevention bottle bioassay. Multi-locus genome-wide association mapping methods were used to quantify standing genetic variation for insecticide resistance in these populations and to identify specific alleles associated with insecticide survival. For each insecticide treatment, we estimated the proportion of the variation in survival explained by the genetic data (i.e., "chip" heritability) and the number and contribution of individual loci with measurable effects. For all treatments, survival to an insecticide exposure was heritable with a polygenic architecture. Both P. papatasi and L. longipalpis had alleles for survival that resided within many genes throughout their genomes. The implications for resistance conferred by many alleles, as well as inferences made about the utility of laboratory insecticide resistance association studies compared to field observations, are discussed.

First molecular identification of Leishmania major in Phlebotomus papatasi in an outbreak cutaneous leishmaniasis area in Iraq

Cutaneous leishmaniasis (CL) is transmitted by Phlebotomine sand fly vectors, among which Phlebotomus papatasi is prevalent in Western Asia, Northern Africa and Southern Europe, and it is known as a vector for Leishmania major parasite in the world. However, in Iraq, morphological studies showed that P. papatasi is a predominant sand fly species and hypothesised to transmit CL causing Leishmania species including L. major and L. tropica. Few studies have found Leishmania species in sand flies in mixed pools of samples in this country. Accurate identification of sand flies as vectors of Leishmania species is required in Iraq. The current study aims to identify sand fly species, using both morphological and molecular phylogenetic analyses, in a region where CL tends to be endemic. Furthermore, molecular phylogenetic analysis has also used to confirm Leishmania species in the sand fly samples collected in 11 villages between Diyala and Sulaymaniyah Provinces. For the first time, we have found L. major in three individual sand flies, one engorged (with fresh blood meal) and two non-engorged (without visible fresh blood meal) P. papatasi females in an area of CL outbreaks since 2014-till now due to civil wars and internal conflicts happen in the region. Further study should be performed on sand fly population and Leishmania reservoirs in this region.

Efficiency of Two Capture Methods Providing Live Sand Flies and Assessment the Susceptibility Status of Phlebotomus papatasi (Diptera: Psychodidae) in the Foci of Cutaneous Leishmaniasis, Lorestan Province, Western Iran

Background:

The aims of this study were to evaluate the efficiency of two capture methods for providing live sandflies used for determining the susceptibility level of Phlebotomus papatasi, the main vector of zoonotic cutaneous leishmaniasis in Lorestan Province, west of Iran.

Methods:

The sand flies were collected from indoor and outdoor by hand-catch and baited traps during the peak of seasonal activity. The susceptibility level of sand flies was assessed using insecticide-impregnated papers against DDT 4%, bendiocarb 0.1%, permethrin 0.75%, deltamethrin 0.05%, and cyfluthrin 0.15%.

Results:

A total of 2486 live sandflies were caught from both indoor and outdoor places. Totally 849 sand flies were caught from outdoors with a sex ratio(SR) 0.1 versus 1637 sand flies collected from indoor using the hand-catch method with SR= 0.6. The dominant species of sand flies was Ph. papatasi in the study area. Mortality rates of outdoor-collected sand flies were exposed to DDT 4%, deltamethrin 0.05%, permethrin 0.75%, and bendiocarb 0.1%, and mortality rate ranged from 92.0–97.9% and for indoor-collected sand flies were 87.7–96.8%. Both outdoor and indoor collected sand flies were susceptible to cyfluthrin 0.15% that caused 100% mortality.

Conclusion:

Based on the findings, the most appropriate method for collecting the live female Ph. papatasi is the baited traps due to providing enough females is necessary for conducting the susceptibility tests. The finding indicated that Ph. papatasi was resistant to DDT, under ’verification required’ status to deltamethrin, permethrin, bendiocarb, and susceptible to cyfluthrin.

Comparative evaluation of salivary glands proteomes from wild Phlebotomus papatasi-proven vector of zoonotic cutaneous leishmaniasis in Iran

BACKGROUND

Zoonotic Cutaneous Leishmaniasis is increasing in the world and Phlebotomus papatasi as a proven vector was considered in different aspects for disease control. Sandfly saliva contains proteins which provoke host immune system. These proteins are candidates for developing vaccines.

OBJECTIVES

The main purpose of this research was comparing evaluation of salivary glands proteomes from wild P. papatasi. Extracting these proteins and purifying of original SP15 as inducer agent in vector salivary glands from endemic leishmaniasis foci were other objectives.

METHODS

Adult sandflies were sampled using aspirators and funnel traps from three endemic foci in 2017-2018. Each pair of salivary glands of unfed females was dissected and proteins were extracted using thermal shocking and sonication methods. Purification was performed through RP-HPLC. All equivalent fractions were added together in order to reach sufficient protein concentration. Protein content and profile determination were examined with SDS-PAGE.

RESULTS

The protein concentration of whole-salivary glands of specimens was determined approximately 1.6 µg/µl (Isfahan) and 1 µg/µl (Varamin and Kashan). SDS-PAGE revealed 10 distinct bands between 10 and 63 kDa. Analysis of proteomes showed some similarities and differences in the chromatograms of different foci. SDS-PAGE of all collected fractions revealed SP15-like proteins were isolated in 24 min from Varamin, 26 to 30 min from Kashan and 29.4 min from Isfahan and were around 15 kDa.

CONCLUSIONS

Isolation of salivary components of Iranian wild P. papatasi is very important for finding potential proteins in vaccine development and measuring control strategy of zoonotic cutaneous leishmaniasis in Iran and this could be concluded elsewhere in the world.

Seasonal Distribution of Phlebotomus papatasi, Vector of Zoonotic Cutaneous Leishmaniasis

PURPOSE

The activity of Phlebotomus papatasi Scopoli, a vector of cutaneous leishmaniasis, is known to be seasonal, but the information describing these patterns is sparse in time and space. The purpose of his paper is to conduct a meta-analysis to depict the seasonality of P. papatasi at the global scale.

METHODS

The current paper uses data from a collection of 1200 scientific papers, where 300 are about the vector and 36 include monthly data (of 61 sites) of the P. papatasi from 15 countries published from 1994 to 2017.

RESULTS

The activity peaked mainly in dry periods in all explored sites. A map of seasonal distribution depicted a peak activity in August, followed by September. Geographically (geographic preference), August and September at the latitude 33° showed the highest abundance at a global scale. Concerning the latitude P. papatasi distribution, the high number is localized between 27° and 35°. However, the high number of this species according to the longitude is localized between - 4° and 58°, which shows a high interval of activity. Locally, for the habitat preference, the findings show a preference of this vector to indoor than to outdoor.

CONCLUSIONS

All these results can be helpful in identifying the period and sites of a future potential risk of leishmaniasis. This is the first attempt at the update of the vector activity both at global and local scale.

Population Genetics of Phlebotomus papatasi from Endemic and Nonendemic Areas for Zoonotic Cutaneous Leishmaniasis in Morocco, as Revealed by Cytochrome Oxidase Gene Subunit I Sequencing

Zoonotic cutaneous leishmaniasis (ZCL) caused by Leishmania major Yakimoff & Shokhor and transmitted by Phlebotomus papatasi (Scopoli) is a public health concern in Morocco. The disease is endemic mainly in pre-Saharan regions on the southern slope of the High Atlas Mountains. The northern slope of the High Atlas Mountains and the arid plains of central Morocco remain non-endemic and are currently considered high risk for ZCL. Here we investigate and compare the population genetic structure of P. papatasi populations sampled in various habitats in historical foci and non-endemic ZCL areas. A fragment of the mtDNA cytochrome oxidase I (COI) gene was amplified and sequenced in 59 individuals from 10 P. papatasi populations. Haplotype diversity was probed, a median-joining network was generated (F_ST) and molecular variance (AMOVA) were analyzed. Overall, we identified 28 haplotypes with 32 distinct segregating sites, of which seven are parsimony informative. The rate of private haplotypes was high; 20 haplotypes (71.4%) are private ones and exclusive to a single population. The phylogenetic tree and the network reconstructed highlight a genetic structuration of these populations in two well defined groups: Ouarzazate (or endemic areas) and Non-Ouarzazate (or nonendemic areas). These groups are separated by the High Atlas Mountains. Overall, our study highlights differences in terms of population genetics between ZCL endemic and non-endemic areas. To what extent such differences would impact the transmission of L. major by natural P. papatasi population remains to be investigated.

sergenti as Vectors of Leishmaniasis in Ardabil Province, Iran

Cutaneous leishmaniosis (CL) is the most common form of leishmaniasis.CL caused by L. major and L. tropica is endemic in 17 provinces of Iran. This study was carried out to elucidate situation of CL in Ardabil province and to predict distribution of Phlebotomus papatasi and Phlebotomus sergenti (Diptera: Psychodidae) as vectors of CL in the region. In this cross-sectional study, data on CL patients were collected from local health centers of Ardabil province, Iran during 2006-2018 to establish a geodatabase using ArcGIS10.3. A total of 20 CL cases were selected randomly and skin samples were collected and analyzed by PCR method. MaxEnt 3.3.3 model was used to determine ecologically suitable niches for the main vectors. A total, 309 CL human cases were reported and the highest incidence rate of disease was occurred in Bilasavar (37/100,000) and Germi (35/100,000). A total of 2,794 sand flies were collected during May to October 2018. The environmentally suitable habitats for P. papatasi and P. sergenti were predicted to be present in northern and central areas of Ardabil province. The most variable that contributed ratio in the modeling were Isothermality and slope factors. Ardabil province is possibly an endemic are for CL. The presence of P. papatasi and P. sergenti justifies local transmission while the vectors of CL are existing in the northern and central areas of the province.

Monitoring of Laboratory Reared of Phlebotomus papatasi (Diptera: Psychodidae), Main Vector of Zoonotic Cutaneous Leishmaniasis to Different Imagicides in Hyper endemic Areas, Esfahan Province, Iran

Background:

In domestic and per domestic area, insecticides such as DDT, malathion, fenitrothion, propoxur and, more recently, synthetic pyrethroids such as deltamethrin and lambda-cyhalothrin, have been successfully used to control sand flies in many countries. The present study reports the results of time-mortality bioassay to DDT 4%, lambda-cyhalothrin 0.05%, permethrin 0.75%, cyfluthrin 0.15% and deltamethrin 0.05% in recently colonized Phlebotomus papatasi populations in Iran.

Methods:

The insecticide susceptibility status of P. papatasi laboratory population was assessed during 2016–2017, following the standard WHO technique for mosquito (WHO, 2013) based on diagnostic dose. Sand flies collected from rural area of Badrood (Matin Abad), Natanz County, Esfahan Province, using aspirator.

Results:

Susceptibility test to DDT and pyrethroids was assessed on 3534 laboratory-reared P. papatasi (1746 females and 1788 males). The LT ₅₀ and LT ₉₀ values were measured using probit analysis and regression lines. The test results against males of P. papatasi revealed that LT ₅₀ values to DDT 4%, Permethrin 0.75%, Deltamethrin 0.05%, Cyfluthrin 0.15% and Lambdacyhalothrin 0.05% were 439.28, 108.90, 97.75, 5.00 and 57.84 seconds. The figures for females were 641.62, 136.15, 146.44, 8.71 and 72.69 seconds, respectively.

Conclusion:

According to presented results, the reared population of sand flies collected from a hyper-endemic region of Esfahan Province is still susceptible to prethroids and Resistance candidate to DDT 4%.

Modelling and evaluating the risk of zoonotic cutaneous leishmaniasis in selected areas of Kerman Province, south of Iran

Cutaneous leishmaniasis (CL) remains a public health problem in the world, particularly in tropical and sub-tropical countries. This study aimed to determine the hotspots of CL in Kerman Province of Iran and model their potential for the establishment of new disease foci. All documents related to studies conducted in Kerman Province on CL published between 1978 and 2017 were retrieved and categorized. Spatial distributions of the vector, reservoir and human infection of CL were mapped. MaxEnt ecological model was used to predict the environmental suitability of the vector and reservoir(s) of zoonotic cutaneous leishmaniasis (ZCL). The most hazardous sites with the potential for the establishment of new disease foci were determined for field operations. Statistics of new cases of CL was obtained from the Center for Disease Control (CDC) of the ministry of health for the period 2011-2016. A total of 6,056 cases of CL were recorded, while we found a decreasing pattern in the incidence of CL from 46.48 per 100,000 inhabitants to 22.97. The best ecological niches for Phlebotomus papatasi are located in the central, western, northwest and southwest regions of the province. Also, environmental suitability for the reservoirs was highest in the central, southern and southwestern regions. The model predicted the gerbils can be present in some foci of anthroponotic cutaneous leishmaniasis (ACL). However, this result should be confirmed through a precise field study, and if validated, plans should be made to prevent the emergence of new foci of ZCL in the risk areas.

[Soil Analysis of Potential Breeding Sites of Sand Flies (Diptera: Psychodidae) in Aichoun Locality, Central Morocco]

The epidemiology of leishmaniasis is related with habitat and behavior of the sand fly vector. Each species of sand flies (Diptera: Psychodidae) has a specific characteristic of their sites for the development of their immatures. Information on natural breeding sites of phlebotomine sand flies is limited, due to the difficulty of isolation of immature from the soil. This study, realized from May 2014 to September 2014, aimed to determine the effect of properties of soil on behavior and abundance of sand flies in breeding habitat in Aichoun locality. Sand flies were collected using sticky papers (21 × 27.3 cm) coated with castor oil in four stations. The total of traps in each trapping campaign is 32. Soil samples were collected each month and they were extracted and tested. The different chemical parameters have been studied: electrical conductivity, equivalent humidity, total of calcareous, organic matter, assimilable phosphorus, and exchangeable potassium, pH, organic carbon. Statistical analysis was performed by principal component analysis (PCA). The dominant leishmaniasis vectors in Aichoun are Phlebotomus sergenti and Phlebotomus perniciosus. A total of 1685 sand flies were collected belonging to five species in the genera Phlebotomus and Sergentomyia, namely Ph. sergenti (84.62%), Ph. perniciosus (8.54%), Phlebotomus papatasi (6.17%), Phlebotomus longicuspis (0.35%) and Sergentomyia minuta (0.29%). The chemical tests of potential breeding sites of sand flies, determined for sixteen samples, showed a correlation between the abundance of sand flies (especially the ecological requirements of larval development of the three species incriminated in transmission of the disease of cutaneous leishmaniasis) and the chemical parameters studied. The results found in this work, realized for the first time in Morocco, will be of great contribution to the control program of sand flies vectors at local and national level and as an indicator for the determination of leishmaniasis risk areas as well as to establish effective control strategies.

Designing and Introducing a New Artificial Feeding Apparatus for Sand Fly Rearing

BACKGROUND

Due to strict ethical rules, the risk of accidental disease transmission and the most importantly, inconvenience regarding using of live animals, artificial feeding apparatus has been developed for colonization of haematophagous insects. Rearing of sandfly is more difficult than other haematophagous insects.

METHODS

In the current study, a new apparatus for membrane feeding of Phlebotomus papatasi was designed, made and compared with available apparatus in Sand Fly Insectary, Tehran University of Medical Sciences, Tehran, Iran, in 2014.

RESULTS

In comparison to other apparatus designed for artificial feeding of other arthropods, our designed apparatus had the highest performance which after up to 1h, the majority of sand flies landed and took blood and among tested membranes, chicken skin was proved the most efficient membrane.

CONCLUSION

Sand fly artificial feeding apparatus can be used at least for rearing of Ph. papatasi.

Development of a Diagnostic Marker for Phlebotomus papatasi to Initiate a Potential Vector Surveillance Program in North America

Phlebotomus papatasi, an Old World sand fly species, is primarily responsible for the transmission of leishmaniasis, a highly infectious and potentially lethal disease. International travel, especially military rotations, between domestic locations and P. papatasi-prevalent regions in the Middle East poses an imminent threat to the public health of US citizens. Because of its small size and cryptic morphology, identification of P. papatasi is challenging and labor-intensive. Here, we developed a ribosomal DNA-polymerase chain reaction (PCR)-based diagnostic assay that is capable of detecting P. papatasi genomic DNA from mixed samples containing multiple sand flies native to the Americas. Serial dilution of P. papatasi samples demonstrated that this diagnostic assay could detect one P. papatasi from up to 255 non-target sand flies. Due to its simplicity, sensitivity and specificity, this rapid identification tool is suited for a long-term surveillance program to screen for the presence of P. papatasi in the continental United States and to reveal geographical regions potentially vulnerable to sand fly-borne diseases.

Modeling spatial risk of zoonotic cutaneous leishmaniasis in Central Iran

Zoonotic Cutaneous Leishmaniasis (ZCL) is one of the endemic diseases in central part of Iran. The aim of this cross-sectional study was to find the areas with a higher risk of infection considering the distribution of vector, reservoir hosts and human infection. Passive data recorded the positive cases of cutaneous leishmaniasis in Yazd province health center were collected for 10 years, from 2007 to 2016 at the County level. Considering all earlier studies conducted in Yazd province, records of Phlebotomus papatasi, the main vector of ZCL, and Rhombomys opimus, the main reservoir of ZCL, were collected and entered in a database. ArcGIS and MaxEnt model were used to map and predict the best ecological niches for both vector and reservoir. The most cumulative incidence of the disease was found to be in Khatam County, south of Yazd province. The area under curve (AUC) for R. opimus and P. papatasi was 0.955 and 0.914, respectively. We found higher presence probability of both vector and reservoir in central and eastern parts of the province. The jackknife test indicated that temperature and normalized difference vegetation index (NDVI) had the most effect on the model for the vector and reservoir, respectively. The areas with higher presence probability for the reservoirs and vectors were considered having the higher potential for ZCL transmission. These findings can be used to prevent and control the disease.

Bionomics of phlebotomine sand flies species (Diptera: Psychodidae) and their natural infection with Leishmania and Crithidia in Fars province, southern Iran

Phlebotominae sand flies are involved in human diseases, such as leishmaniasis, and cause a considerable number of deaths every year. Besides, some of them have been identified as allergen sources or the potential mechanical vectors related to nosocomial infections. The present study aimed to assess the monthly activity, fauna, and detection of protozoan agents in phlebotomine sand flies using polymerase chain reaction (PCR) in re-emerging zoonotic cutaneous leishmaniasis foci of Shiraz and Kharameh in Fars province, southern Iran during 2016-2017. To determine the monthly activity, sand flies were caught from indoors and outdoors of both studied areas. Afterward, all female phlebotomine sand flies were processed for DNA extraction and PCR assays for Leishmania and Crithidia detections. During the study, 6975 sand flies of 16 species (eight Phlebotomus and eight Sergentomyia species) were caught in both foci. Sand flies' monthly activities started in early April and terminated in late November and October. Additionally, two active peaks of sand flies were observed in both foci; first in June and second in August to September. Phlebotomus papatasi (47.1%) was the most dominant species in out/indoors of both Shiraz (31.1%) and Kharameh (16.0%). It was also the only species which was found infected with Leishmania major, indeed, 2.68% and 2.53% of P. papatasi were infected to L. major in Kharameh and Shiraz, respectively. However, none of the female sand flies was positive for Crithidia spp. Despite various control strategies, especially against Leishmania, considerable cases of leishmaniasis are recorded from Iran every year. Phlebotomine plays the main role in transmission of Leishmania in these foci. Therefore, further studies are needed to determine the role of different phlebotomine species in epidemiological aspects of leishmaniasis.

Some epidemiological aspects of cutaneous leishmaniasis with emphasis on vectors and reservoirs of disease in the borderline of Iran and Iraq

Cutaneous leishmaniasis (CL) is endemic and a major health problem in 17 provinces out of 31 in Iran. This study aimed to determine vectors and reservoirs of the disease using molecular techniques in the borderline of Iran and Iraq. Sand flies and rodents were sampled using sticky paper traps and metal wire live traps, respectively, in the selected villages. About 10% of archived confirmed human positive slides was randomly checked for Leishmania by PCR-RFLP assay. The female sand flies were dissected in alcohol 96% in a sterile condition, the head and two segments of the abdomen end permanently mounted for identification and the remaining of body used for DNA extraction. The direct parasitological tests were carried out on the stained slides of rodents for Leishmania as well as PCR-RFLP assay used for molecular detection of parasite. A total of 2050 sand flies were identified comprising of Phlebotomus papatasi, Sergentomyia sintoni, Se. clydei, Se. mervynae, Se. theodori, Se. dentate and Se. iranica. The Ph. papatasi was ranked as a prevailing sand fly species. Molecular tests on female sand flies revealed infection of Ph. papatasi to Leishmania major. Direct parasitology and molecular tests confirmed of 20% infection to L. major among the sole rodents species "Tatera indica". Due to wide dispersion of rodents colonies in the area and long favorite climate condition for sand flies, the CL foci will be provided the health risk for the religious tourists.

sergenti (Diptera: Psychodidae) main cutaneous leishmaniasis vectors, introduction of a new subgroup wSerg

Sand flies of Phlebotomus papatasi and P. sergenti are the main vectors of cutaneous leishmanisis (CL) in the old world. We aimed to screen Iranian P. papatasi and P. sergenti for their natural infections with Wolbachia and to determine their phylogenetic association with other species. Wolbachia surface protein (wsp) gene was PCR amplified from DNA extracted from Phlebotomus species, sequenced, and were analysed in combination with wsp sequences related to Phelebtominae and other insects. All Wolbachia-infecting Iranian sand flies of P. papatasi and P. sergenti were classified in the Supergroup A., Wolbachia isolated from P. sergenti were clustered in a new subgroup within Supergroup A so-called wSreg. The Wolbachia strains identified from the P. papatasi clustered mainly in the subgroup wPap and partly in wSerg. Multiple Wholbachia infection within a single population of P.papatasi warrants investigation on existence and intensity of cytoplasmic incompatibility between the wPap and wSerg subgroups.

Population genetics analysis of Phlebotomus papatasi sand flies from Egypt and Jordan based on mitochondrial cytochrome b haplotypes

BACKGROUND

Phlebotomus papatasi sand flies are major vectors of Leishmania major and phlebovirus infection in North Africa and across the Middle East to the Indian subcontinent. Population genetics is a valuable tool in understanding the level of genetic variability present in vector populations, vector competence, and the development of novel control strategies. This study investigated the genetic differentiation between P. papatasi populations in Egypt and Jordan that inhabit distinct ecotopes and compared this structure to P. papatasi populations from a broader geographical range.

METHODS

A 461 base pair (bp) fragment from the mtDNA cytochrome b (cyt b) gene was PCR amplified and sequenced from 116 individual female sand flies from Aswan and North Sinai, Egypt, as well as Swaimeh and Malka, Jordan. Haplotypes were identified and used to generate a median-joining network, F _ST values and isolation-by-distance were also evaluated. Additional sand fly individuals from Afghanistan, Iran, Israel, Jordan, Libya, Tunisia and Turkey were included as well as previously published haplotypes to provide a geographically broad genetic variation analysis.

RESULTS

Thirteen haplotypes displaying nine variant sites were identified from P. papatasi collected in Egypt and Jordan. No private haplotypes were identified from samples in North Sinai, Egypt, two were observed in Aswan, Egypt, four from Swaimeh, Jordan and two in Malka, Jordan. The Jordan populations clustered separately from the Egypt populations and produced more private haplotypes than those from Egypt. Pairwise F _ST values fall in the range 0.024-0.648.

CONCLUSION

The clustering patterns and pairwise F _ST values indicate a strong differentiation between Egyptian and Jordanian populations, although this population structure is not due to isolation-by-distance. Other factors, such as environmental influences and the genetic variability in the circulating Le. major parasites, could possibly contribute to this heterogeneity. The present study aligns with previous reports in that pockets of genetic differentiation exists between populations of this widely dispersed species but, overall, the species remains relatively homogeneous.

Development of polymorphic EST microsatellite markers for the sand fly, Phlebotomus papatasi (Diptera: Psychodidae)

Background

Phlebotomus papatasi is a widely distributed sand fly species in different tropical and sub-tropical regions including the Middle East and North Africa. It is considered an important vector that transmits Leishmania major parasites, the causative agents of cutaneous leishmaniasis. The development of microsatellite markers for this sand fly vector is of high interest to understand its population structure and to monitor its geographic dispersal.

Results

Fourteen polymorphic microsatellite markers were developed with simple di-, tri- and tetra-nucleotide repeats. The F statistics calculated for the 14 markers revealed high genetic diversity; expected heterozygosity (He) ranged from 0.407 to 0.767, while observed heterozygosity (Ho) was lower and ranged from 0.083 to 0.514. The number of alleles sampled fall in the range of 9–29. Three out of 14 markers deviated from Hardy-Weinberg expectations, no significant linkage disequilibrium was detected and high values for inbreeding coefficient (F_IS) were likely due to inbreeding.

Conclusions

The development of these functional microsatellites enable a high resolution of P. papatasi populations. It opens a path for researchers to perform multi locus-based population genetic structure analyses, and comparative mapping, a part of the efforts to uncover the population dynamics of this vector, which is an important global strategy for understanding the epidemiology and control of leishmaniasis.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-2770-3) contains supplementary material, which is available to authorized users.

Lipophosphoglycan polymorphisms do not affect Leishmania amazonensis development in the permissive vectors Lutzomyia migonei and Lutzomyia longipalpis

Background

Lipophosphoglycan (LPG) is a dominant surface molecule of Leishmania promastigotes. Its species-specific polymorphisms are found mainly in the sugars that branch off the conserved Gal(β1,4)Man(α1)-PO₄ backbone of repeat units. Leishmania amazonensis is one of the most important species causing human cutaneous leishmaniasis in the New World. Here, we describe LPG intraspecific polymorphisms in two Le. amazonensis reference strains and their role during the development in three sand fly species.

Results

Strains isolated from Lutzomyia flaviscutellata (PH8) and from a human patient (Josefa) displayed structural polymorphism in the LPG repeat units, possessing side chains with 1 and 2 β-glucose or 1 to 3 β-galactose, respectively. Both strains successfully infected permissive vectors Lutzomyia longipalpis and Lutzomyia migonei and could colonize their stomodeal valve and differentiate into metacyclic forms. Despite bearing terminal galactose residues on LPG, Josefa could not sustain infection in the restrictive vector Phlebotomus papatasi.

Conclusions

LPG polymorphisms did not affect the ability of Le. amazonensis to develop late-stage infections in permissive vectors. However, the non-establishment of infection in Ph. papatasi by Josefa strain suggested other LPG-independent factors in this restrictive vector.

Assessing the insecticide susceptibility status of field population of Phlebotomus papatasi (Diptera: Psychodidae) in a hyperendemic area of zoonotic cutaneous leishmaniasis in Esfahan Province, Central Iran

Leishmaniasis is a Neglected Tropical Disease (NTD) and emerging parasitic infection that affect mainly poor regions around the world. This study aimed to determine the baseline susceptibility of Phlebotomus papatasi to commonly used insecticides in a hyper endemic area using WHO standard procedure in central Iran. A total of 4-5 replicates containing 120-200 sand flies were used for each insecticide. Baseline susceptibility to DDT and pyrethroids was assessed on 5326 specimens collected from the study area. The LT₅₀ and LT₉₀ values were measured according to the World Health Organisation test using probit analysis and regression lines. The test results against males P. papatasi revealed that LT₅₀ values to DDT 4%,Permethrin 0.75%, Deltamethrin 0.05%, Cyfluthrin 0.15% and Lambdacyhalothrin 0.05% were 564.07, 38.08, 1.95, 0.60 and 9.78s and the figures for females were 584.44, 110.10, 11.64, 1.53 and 16.91s, respectively. Our results indicated that P. papatasi as the main cutaneous leishmaniasis vector was susceptible to Cyfluthrin 0.15%, Lambdacyhalothrin 0.05%, Permethrin 0.75% and Deltamethrin 0.05% and tolerant to DDT 4%. This study was carried out in one out of many Leishmaniasis foci in Iran. We recommend that future studies incorporate other regions and use the same procedure for monitoring and evaluating sand fly resistance. Also, WHO can provide a specific guideline and create a test kit for sand fly resistance monitoring and for applying susceptibility test because the tubes prepared for mosquitoes are not actually fit for sand flies.

Epidemiological Study on Cutaneous Leishmaniasis in an Endemic Area, of Qom Province, Central Iran

BACKGROUND

Cutaneous leishmaniasis (CL) is one of the most important health problems in many areas of Iran. There are two forms of the disease in Iran, anthroponotic and zoonotic CL. This study conducted to assess the epidemiological situation of CL in an endemic area of Qom Province, central Iran from Apr to Nov 2015.

METHODS

The sticky paper traps and aspirating tubes were used for collecting adult sand flies. Sherman traps and small insect nets were used to capture rodents and small mammals. Giemsa staining was used for preparing the expanded smear and followed by PCR for identifying the causative agent in human, vectors, and reservoirs. In this study, relative frequency of CL was also calculated.

RESULTS

Fourteen species of Phlebotomine sand flies were collected. Phlebotomus papatasi (61.74%) was the predominant species through the period of activity. Overall, 62 Meriones libycus, 8 Nesokia indica, 4 Mus musculus, 16 Allactaga elater and 2 Hemiechinus auritis were caught. PCR technique showed 6 out of 150 P. papatasi (2%), two out of 62 M. libycus (3.23%) and all of suspected human's skin tissue samples (100%) were infected with Leishmania major. The relative frequency of CL was 0.30%.

CONCLUSION

This is the first detection of L. major within P. papatasi, M. libycus and human in Kahak District in Qom Province of Iran. Zoonotic cycle of CL exists in this area, L. major is the causative agent, P. papatasi is the main vector and M. libycus is the main reservoir of the disease.

Assessing the Ovarian Accessory Glands to Determine the Parity of Phlebotomus papatasi, Vector of Zoonotic Cutaneous Leishmaniasis, under Laboratory Condition

BACKGROUND

Zoonotic cutaneous leishmaniasis (ZCL) is a neglected tropical disease prevailed in many rural areas of 17 out of 31 provinces in Iran. The main vector of the disease is Phlebotomus papatasi and the causative agent is Leishmania major in ZCL foci of Iran. In the current study we investigated the validity of accessory glands secretions as an indicator to recognize parous from nulliparous Ph. papatasi females under laboratory conditions.

METHODS

Over 235 laboratory-reared females of Ph. papatasi were dissected in 6 groups including: newly emerged, one hour, one day, two days, and three days after blood feeding and also after oviposition under stereo microscope for their parity in 2014-2015.

RESULTS

Transparent glands were compatible with nulliparous only in newly emerged sand flies. In sand flies dissected after oviposition, accessory glands were rather large as a result of oviposition though they were transparent.

CONCLUSION

The accessory glands secretions could not be as an indicator for distinguishing parous from nulliparous of Ph. papatasi females.

Predicting the Distribution of Phlebotomus papatasi (Diptera: Psychodidae), the Primary Vector of Zoonotic Cutaneous Leishmaniasis, in Golestan Province of Iran Using Ecological Niche Modeling: Comparison of MaxEnt and GARP Models

Zoonotic cutaneous leishmaniasis (ZCL) is a prevalent vector-borne disease in the Golestan province of Iran, with Phlebotomus papatasi (Scopoli, 1786) serving as the main vector. The aim of this study was to model the probability of presence of this species in the study area, and to determine the underlying factors affecting its distribution. Three villages were selected from each county of the province and visited monthly for investigating ZCL. Sticky paper traps were used for collecting the sand flies to determine the species present. The presence of Ph. papatasi was modeled using genetic algorithm for rule-set production (GARP) and maximum entropy (MaxEnt) techniques. Both models showed the central and northern parts of the province with lowland areas were more vulnerable to Ph. papatasi propagation, in comparison with the southern parts with mountainous and forest areas. The area under curve (AUC) of MaxEnt model for the training points was calculated as 0.90, indicating excellent performance of the model in predicting Ph. papatasi distribution. Jackknife test showed that the factors with the greatest influence in vector distribution were slope, vegetation cover, annual mean temperature, and altitude. By using ecological niche models, it is possible to identify areas with higher probability of presence of Ph. papatasi, which guides public health policy makers for planning better vector control interventions.

Insecticide resistance in phlebotomine sandflies in Southeast Asia with emphasis on the Indian subcontinent

BACKGROUND

Visceral leishmaniasis, commonly known as kala-azar in India, is a global public health problem. In Southeast Asia, Bangladesh, Bhutan, India, Nepal, Sri Lanka and Thailand are endemic for visceral leishmaniasis. The role of sandflies as the vector of kala-azar was first confirmed in 1942 in India. Insecticide resistance in Phlebotomus argentipes Annandale and Brunetti, the vector of kala-azar in the Indian subcontinent, was first reported in 1987 in Bihar, India. This article provides a scoping review of the studies undertaken from 1959 to 2015 on insecticide resistance in P. argentipes and P. papatasi (Scopoli), the vectors of visceral and cutaneous leishmaniasis respectively, in Southeast Asia, mainly in Bangladesh, India, Nepal and Sri Lanka.

RESULTS

Studies undertaken in areas of Bihar and West Bengal in India where kala-azar is endemic have reported resistance of P. argentipes to DDT, while in non-endemic areas it has been reported to be susceptible. In areas of Nepal bordering India, there are indications of resistance to DDT; biochemical resistance has been reported in Sri Lanka. No laboratory studies have been undertaken in Bangladesh; however, the sandfly vector is reported to be still susceptible to pyrethroids in all kala-azar endemic areas in the aforementioned countries.

CONCLUSIONS

Studies are needed to determine the resistance of sandfly vectors to all available classes of potential insecticides in kala-azar endemic areas. There is a need to assess the impact of indoor residual spraying with DDT and pyrethroids on the incidence of kala-azar in India where 54 districts remain endemic for the disease, strengthen entomological surveillance capacity, and develop and implement an insecticide management plan. Alpha-cypermethrin indoor residual spraying has been introduced in 33 kala-azar endemic districts in Bihar State of India in a pilot trial; the outcomes should be used to inform decisions on expanding coverage with alpha-cypermethrin in all remaining endemic districts to achieve the revised goal of elimination of visceral leishmaniasis by 2020.

Differential expression profiles of the salivary proteins SP15 and SP44 from Phlebotomus papatasi

Background

Sand fly saliva has been shown to help parasite establishment and to induce immune responses in vertebrate hosts. In the current study, we investigated the pattern of expression of two Phlebotomus papatasi salivary transcripts in specific physiological and seasonal conditions at a hyperendemic area of zoonotic cutaneous leishmaniasis (ZCL) in Iran.

Methods

Sand flies were collected during 2012–2013, and grouped according to physiological stages such as unfed, fed, semi-gravid, gravid, parous, nulliparous, infected or non-infected with Leishmania major and also based on the season in which they were collected. Quantitative Real-Time PCR was applied for assessment of the expression of two relevant salivary transcripts, PpSP15 and PpSP44, associated to protection from and exacerbation of ZCL, respectively.

Results

The expression of PpSP15 and PpSP44 transcripts was significantly up-regulated (1.74 and 1.4 folds, respectively) in blood fed compared to unfed flies. Among four groups of fed, unfed, semi-gravid and gravid flies, the lowest levels of PpSP15 and PpSP44 expression were observed in gravid flies. Additionally, the expression levels of both PpSP15 and PpSP44 transcripts in P. papatasi collected during summer were significantly up-regulated (3.7 and 4.4 folds, respectively) compared to spring collections. In addition, the PpSP15 transcript exhibited a significant up-regulation (P < 0.05) in non-infected flies compared to those infected with L. major.

Conclusions

This study contributes to our knowledge of the differential expression of salivary genes among different groups within a P. papatasi population under natural field conditions. Cutaneous and visceral leishmaniasis are of public health importance in many parts of Iran and neighbouring countries where P. papatasi is the proven and dominant sand fly vector for ZCL, the most prevalent and endemic form of the disease in Iran. Therefore, the current study could be helpful in understanding the influence of salivary genes on Leishmania transmission by phlebotomine sand flies. Our findings demonstrate the differential expression of salivary transcripts under various physiological conditions potentially influencing the sand fly capacity for parasite transmission as well as the outcome of disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-016-1633-z) contains supplementary material, which is available to authorized users.

Human immune response to salivary proteins of wild-caught Phlebotomus papatasi

Phlebotomine sand flies are the known vectors of Leishmania parasites. New approaches in vaccination against Leishmania have investigated the possibility of integrating Phlebotomus papatasi salivary proteins to enhance the immune response and protect against the transmission of the infection. The aim of the present study was to screen human immune responses to wild sand fly saliva and evaluate immunogenic salivary proteins. Blood samples were collected from donors in control and sand fly infested areas. Antibodies specific for sand fly antigens in donor plasma were probed using immunoblotting. In addition, recall proliferation capability of peripheral blood mononuclear cells (PBMC) was tested after sand fly salivary homogenates stimulation. The significant immunogenic salivary proteins (SPs) identified by immunoblotting were SP28, SP32, and SP36. A specific proliferative response of PBMC after stimulation with sand fly salivary homogenates was evident in donors that have antibody responses against sand fly salivary proteins. Individuals with antibody recognition to a higher number of salivary proteins (i.e., 3 or more SP bands) showed lower PBMC proliferative responses after in vitro stimulation with salivary gland homogenates (SGH) only in the sand fly infested, leishmaniasis free area. Interestingly, the presence of a humoral immune response to many SP antigens inversely correlates with a strong cell-mediated immune response (CMI). It was also noticed that some other heavily expressed antigens, in sand fly salivary homogenate, lack or have weak humoral immune reactivity in exposed individuals. Therefore, considering these antigens alone as CMI activators, without including the immunodominant humoral immune response proteins, needs future investigation.

Diagnostic doses and times for Phlebotomus papatasi and Lutzomyia longipalpis sand flies (Diptera: Psychodidae: Phlebotominae) using the CDC bottle bioassay to assess insecticide resistance

BACKGROUND

Insecticide resistance to synthetic chemical insecticides is a worldwide concern in phlebotomine sand flies (Diptera: Psychodidae), the vectors of Leishmania spp. parasites. The CDC bottle bioassay assesses resistance by testing populations against verified diagnostic doses and diagnostic times for an insecticide, but the assay has been used limitedly with sand flies. The objective of this study was to determine diagnostic doses and diagnostic times for laboratory Lutzomyia longipalpis (Lutz & Nieva) and Phlebotomus papatasi (Scopoli) to ten insecticides, including pyrethroids, organophosphates, carbamates, and DDT, that are used worldwide to control vectors.

METHODS

Bioassays were conducted in 1,000-ml glass bottles each containing 10-25 sand flies from laboratory colonies of L. longipalpis or P. papatasi. Four pyrethroids, three organophosphates, two carbamates and one organochlorine, were evaluated. A series of concentrations were tested for each insecticide, and four replicates were conducted for each concentration. Diagnostic doses were determined only during the exposure bioassay for the organophosphates and carbamates. For the pyrethroids and DDT, diagnostic doses were determined for both the exposure bioassay and after a 24-hour recovery period.

RESULTS

Both species are highly susceptible to the carbamates as their diagnostic doses are under 7.0 μg/ml. Both species are also highly susceptible to DDT during the exposure assay as their diagnostic doses are 7.5 μg/ml, yet their diagnostic doses for the 24-h recovery period are 650.0 μg/ml for Lu. longipalpis and 470.0 μg/ml for P. papatasi.

CONCLUSIONS

Diagnostic doses and diagnostic times can now be incorporated into vector management programs that use the CDC bottle bioassay to assess insecticide resistance in field populations of Lu. longipalpis and P. papatasi. These findings provide initial starting points for determining diagnostic doses and diagnostic times for other sand fly vector species and wild populations using the CDC bottle bioassay.

major in North-East of Iran

BACKGROUND

Leishmaniasis is an important public health disease in many developing countries as well in Iran. The main objective of this study was to investigate on leishmania infection of wild caught sand flies in an endemic focus of disease in Esfarayen district, north east of Iran.

METHODS

Sand flies were collected by sticky papers and mounted in a drop of Puri's medium for species identification. Polymerase chain reaction techniques of kDNA, ITS1-rDNA, followed by restriction fragment length polymorphism were used for identification of DNA of Leishmania parasites within infected sand flies.

RESULTS

Among the collected female sand flies, two species of Phlebotomus papatasi and Phlebotomus salehi were found naturally infected with Leishmania major. Furthermore, mixed infection of Leishmania turanica and L. major was observed in one specimen of P. papatasi. Sequence analysis revealed two parasite ITS1 haplotypes including three L. major with accession numbers: KJ425408, KJ425407, KM056403 and one L. turanica. (KJ425406). The haplotype of L. major was identical (100%) to several L. major sequences deposited in GenBank, including isolates from Iran, (Gen Bank accession nos.AY573187, KC505421, KJ194178) and Uzbekistan (Accession no.FN677357).

CONCLUSION

To our knowledge, this is the first detection of L. major within wild caught P. salehi in northeast of Iran.

A proteomic map of the unsequenced kala-azar vector Phlebotomus papatasi using cell line

The debilitating disease kala-azar or visceral leishmaniasis is caused by the kinetoplastid protozoan parasite Leishmania donovani. The parasite is transmitted by the hematophagous sand fly vector of the genus Phlebotomus in the old world and Lutzomyia in the new world. The predominant Phlebotomine species associated with the transmission of kala-azar are Phlebotomus papatasi and Phlebotomus argentipes. Understanding the molecular interaction of the sand fly and Leishmania, during the development of parasite within the sand fly gut is crucial to the understanding of the parasite life cycle. The complete genome sequences of sand flies (Phlebotomus and Lutzomyia) are currently not available and this hinders identification of proteins in the sand fly vector. The current study utilizes a three frame translated transcriptomic data of P. papatasi in the absence of genomic sequences to analyze the mass spectrometry data of P. papatasi cell line using a proteogenomic approach. Additionally, we have carried out the proteogenomic analysis of P. papatasi by comparative homology-based searches using related sequenced dipteran protein data. This study resulted in the identification of 1313 proteins from P. papatasi based on homology. Our study demonstrates the power of proteogenomic approaches in mapping the proteomes of unsequenced organisms.

The flagellar protein FLAG1/SMP1 is a candidate for Leishmania-sand fly interaction

Leishmaniasis is a serious problem that affects mostly poor countries. Various species of Leishmania are the agents of the disease, which take different clinical manifestations. The parasite is transmitted by sandflies, predominantly from the Phlebotomus genus in the Old World and Lutzomyia in the New World. During development in the gut, Leishmania must survive various challenges, which include avoiding being expelled with blood remnants after digestion. It is believed that attachment to the gut epithelium is a necessary step for vector infection, and molecules from parasites and sand flies have been implicated in this attachment. In previous work, monoclonal antibodies were produced against Leishmania. Among these an antibody was obtained against Leishmania braziliensis flagella, which blocked the attachment of Leishmania panamensis flagella to Phlebotomus papatasi guts. The protein recognized by this antibody was identified and named FLAG1, and the complete FLAG1 gene sequence was obtained. This protein was later independently identified as a small, myristoylated protein and called SMP1, so from now on it will be denominated FLAG1/SMP1. The FLAG1/SMP1 gene is expressed in all developmental stages of the parasite, but has higher expression in promastigotes. The anti-FLAG1/SMP1 antibody recognized the flagellum of all Leishmania species tested and generated the expected band by western blots. This antibody was used in attachment and infection blocking experiments. Using the New World vector Lutzomyia longipalpis and Leishmania infantum chagasi, no inhibition of attachment ex vivo or infection in vivo was seen. On the other hand, when the Old World vectors P. papatasi and Leishmania major were used, a significant decrease of both attachment and infection were seen in the presence of the antibody. We propose that FLAG1/SMP1 is involved in the attachment/infection of Leishmania in the strict vector P. papatasi and not the permissive vector L. longipalpis.

Zoonotic disease in a peripheral population: persistence and transmission of Leishmania major in a putative sink-source system in the Negev Highlands, Israel

Populations at the edge of their geographic distributions are referred to as peripheral populations. Very little attention has been given to this topic in the context of persistence of infectious disease in natural populations. In this study, we examined this question using zoonotic cutaneous leishmaniasis (ZCL) caused by Leishmania major in the Negev Desert of Israel as a model system. Here, we suggest that the regional persistence of Phlebotomus papatasi populations and L. major transmission in the Sede Boqer region could be explained through processes akin to sink-source and/or mainland-island metapopulation dynamics. Given its potentially enzootically superior ecological conditions, we hypothesize that the Zin Valley ecotope constitutes the "mainland" or the "source" patch for the Sede Boqer area where L. major transmission is persistent and resistant to local extinctions (die-outs) whereas the local sand fly populations on the Zin Plateau ("island patch" or "sink patch") are more prone to local extinctions. Between 2007 and 2008, we trapped sand flies and sand rats in the two areas and compared sand fly abundance and L. major infection prevalence in both. In both 2007 and 2008, sand fly abundance was high and continuous in the Zin Wadi but low and discontinuous in the Zin Plateau. Infection prevalence of sand rats was significantly higher in the Wadi (13%) compared with the Zin Plateau (3%). Minimum infection rate in sand flies did not differ significantly between the two areas. Overall, our results are consistent with the premise that the Zin Valley population is relatively robust in terms of L. major transmission, whereas transmission is potentially more tenuous in the plateau. Understanding the biotic and abiotic processes enabling the persistence of L. major and other vector-borne diseases in peripheral disease foci is important for predicting the effect of anthropogenic land use and climate change.

Assessing Insecticide Susceptibility of Laboratory Lutzomyia longipalpis and Phlebotomus papatasi Sand Flies (Diptera: Psychodidae: Phlebotominae)

Chemical insecticides are effective for controlling Lutzomyia and Phlebotomus sand fly (Diptera: Psychodidae) vectors of Leishmania parasites. However, repeated use of certain insecticides has led to tolerance and resistance. The objective of this study was to determine lethal concentrations (LCs) and lethal exposure times (LTs) to assess levels of susceptibility of laboratory Lutzomyia longipalpis (Lutz and Nieva) and Phlebotomus papatasi (Scopoli) to 10 insecticides using a modified version of the World Health Organization (WHO) exposure kit assay and Centers for Disease Control and Prevention (CDC) bottle bioassay. Sand flies were exposed to insecticides coated on the interior of 0.5-gallon and 1,000-ml glass bottles. Following exposure, the flies were allowed to recover for 24 h, after which mortality was recorded. From dose-response survival curves for L. longipalpis and P. papatasi generated with the QCal software, LCs causing 50, 90, and 95% mortality were determined for each insecticide. The LCs and LTs from this study will be useful as baseline reference points for future studies using the CDC bottle bioassays to assess insecticide susceptibility of sand fly populations in the field. There is a need for a larger repository of sand fly insecticide susceptibility data from the CDC bottle bioassays, including a range of LCs and LTs for more sand fly species with more insecticides. Such a repository would be a valuable tool for vector management.

Species diversity of sand flies and ecological niche model of Phlebotomus papatasi in central Iran

Cutaneous leishmaniasis (CL) is the most important vector-borne disease in Iran. Qom Province is a very important area in the case of CL transmission, because of high traffic population from other parts of the country, or even other countries, as well as existence of confirmed foci of the disease. The aim of this study was to determine the ecology of sand flies in two different climates of this province and model the distribution of the main vector. Sand flies were collected monthly during April 2013-April 2014, at 22 urban/rural collection sites. Site selection was constrained by the geographical distribution of CL cases in recent years. Shannon-Weiner and Evenness indices were used to compare diversity in two studied climates. ArcGIS and MaxEnt were used to map and predict the appropriate ecological niches for sand flies. Totally, 5389 sand flies were collected and 12 species were identified. The most abundant species were Sergentomyia sintoni, P. papatasi, P. sergenti s.l. and Phlebotomus alexandri. Two peaks of activity were found in May and August in lowlands; while in mountainous areas they were observed in June and September. Species diversity in mountainous areas was found to be higher than in lowlands. The environmental variable with the highest gain in MaxEnt model was the monthly mean of (max temp-min temp). A big part of the lowland areas provides good ecological niches for P. papatasi and therefore higher transmission potential. These findings can be used in stratification of potential for CL transmission in Qom province.

Identification and expression of a new member of the pyrokinin/pban gene family in the sand fly Phlebotomus papatasi

The major family of neuropeptides (NPs) derived from the pk (pyrokinin)/pban (pheromone biosynthesis activating neuropeptide) gene are defined by a common FXPRL-NH2 or similar sequence at the C-termini. This family of peptides has been found in all insect groups investigated to date and is implicated in regulating various physiological functions, including pheromone biosynthesis and diapause, but other functions are still largely unknown in specific life stages. Here we identify two isoforms of pk/pban cDNA encoding the PBAN domain from the sand fly Phlebotomus papatasi. The two pk/pban isoforms have the same sequence except for a 63 nucleotide difference between the long and short forms, and contain no alternative mRNA splicing site. Two NP homologues, DASGDNGSDSQRTRPPFAPRLamide and SLPFSPRLamide are expected, however, sequence corresponding to the diapause hormone was not found in the P. papatasi pk/pban gene. The PBAN-like amino acid sequence homologue SNKYMTPRL is conserved in the gene, but there is no cleavage site for processing a functional peptide. Characterizing the expression of the isoforms in developmental stages and adults indicates that the short form is differentially transcribed depending on the life stage. The P. papatasi pk/pban gene is the only known pk/pban gene with two transcriptional isoforms and from examination of endoproteolytic cleavage sites is expected to produce fewer peptides than most of the pk/pban genes elucidated to date; only Drosophila melanogaster is simpler with a single NP detected by mass spectroscopy. A phylogenetic analysis showed P. papatasi pk/pban grouped more closely with other nematoceran flies rather than higher flies.

Modeling the Distribution of Cutaneous Leishmaniasis Vectors (Psychodidae: Phlebotominae) in Iran: A Potential Transmission in Disease Prone Areas

Cutaneous leishmaniasis (CL) is now the main vector-borne disease in Iran. Two forms of the disease exist in the country, transmitted by Phlebotomus papatasi and Phlebotomus sergenti s.l. Modeling distribution of the vector species is beneficial for preparedness and planning to interrupt the transmission cycle. Data on sand fly distribution during 1990-2013 were used to predict the niche suitability. MaxEnt algorithm model was used for prediction using bioclimatic and environmental variables (precipitation, temperature, altitude, slope, and aspect). Regularized training, area under the curve, and unregularized training gains were 0.916, 0.915, and 1.503, respectively, for Ph. papatasi. These values were calculated as 0.987, 0.923, and 1.588 for Ph. sergenti s.l. The jackknife test showed that the environmental variable with the highest gain when used in isolation has the mean temperature of the wettest quarter for both species, while slope decreases the gain the most when it is omitted from the model. Classification of probability of presence for two studied species was performed on five classes using equal intervals in ArcGIS. More than 60% probability of presence was considered as areas with high potential of CL transmission. These areas include arid and semiarid climates, mainly located in central part of the country. Mean of altitude, annual precipitation, and temperature in these areas were calculated 990 and 1,235 m, 273 and 226 mm, and 17.5 and 16.4°C for Ph. papatasi and Ph. sergenti s.l., respectively. These findings can be used in the prediction of CL transmission potential, as well as for planning the disease control interventions.

Seasonal and Physiological Variations of Phlebotomus papatasi Salivary Gland Antigens in Central Iran

BACKGROUND

Sand fly saliva helps parasite establishment and induce immune responses in vertebrate hosts. In the current study, we investigated the modulation of Phlebotomus papatasi salivary gland antigen expression by seasonal and biological factors.

METHODS

Sand flies were grouped according to physiological stages such as unfed, fed, semi-gravid, gravid, parous, nulliparous, infected or non-infected with Leishmania major and based on the season in which they were collected. Salivary gland antigens (SGAs) were analyzed using SDS-PAGE and the antibody response against SGAs in Rhombomys opimus was determined by ELISA and Western blot.

RESULTS

The highest protein content was found in the salivary glands of unfed sand flies. The saliva content was higher in parous compared to nulliparous, in summer compared to spring, and in Leishmania-infected compared to non-infected flies. The salivary gland lysate (SGL) electrophoretic pattern variations were observed among sand flies with various physiological stages particularly from 4-9 protein bands of 14-70 kDa. The SGL of unfed and gravid flies had extra protein bands compared to fed and semi-gravid sand flies. There was missing protein bands in SGL of parous compared to nulliparous; and in summer compared to spring collected flies. Rhombomys opimus serum reacted strongly with an antigenic band of around 28 kDa in the SGL of all sand fly groups.

CONCLUSION

Certain biological and environmental characteristics of wild populations of vector sand flies affect the protein content and antigenicity of saliva. This might have an important implication in the design of vector-based vaccines.

Blood-Feeding Behaviors of Anopheles stephensi but not Phlebotomus papatasi are Influenced by Actively Warming Guinea Pigs (Cavia porcellus) Under General Anesthesia

Animal models are often used to study hematophagous insect feeding behavior and evaluate products such as topical repellents. However, when these models are used the study animals often experience significant drops in core body temperature because of the effects of anesthesia. This study used a guinea pig model to investigate whether maintaining a normothermic core body temperature during anesthesia influenced the rate of Anopheles stephensi and Phlebotomus papatasi blood feeding. Experiments were conducted with anesthetized animals that had their body temperatures either maintained with a warming device or were allowed to drop naturally. Results showed that when guinea pigs were actively warmed by a heating device, An. stephensi feeding behavior was similar at the beginning and end of anesthesia. However, when a warming device was not used, fewer An. stephensi took a blood meal after the animals' temperatures had dropped. Phlebotomus papatasi were not as sensitive to changes in temperature and feeding rates were similar whether a warming device was used or not. These results are discussed and it is recommended that warming devices are used when conducting feeding experiments with insects sensitive to changes in host body temperature, such as An. stephensi.

Phlebotomus papatasi exposure cross-protects mice against Leishmania major co-inoculated with Phlebotomus duboscqi salivary gland homogenate

Leishmania parasites are inoculated into host skin together with sand fly saliva and multiple exposures to uninfected sand fly bites protect mice against Leishmania infection. However, sand fly vectors differ in composition of the saliva and therefore the protection elicited by their salivary proteins was shown to be species-specific. On the other hand, the optimal vaccine based on sand fly salivary proteins should be based on conserved salivary proteins conferring cross-reactivity. In the present study we therefore focused on cross-protective properties of saliva from Phlebotomus papatasi and Phlebotomus duboscqi, the two natural vectors of Leishmania major. Two groups of mice exposed to bites of P. papatasi and two control, non-immunized groups were infected with L. major promastigotes along with either P. papatasi or P. duboscqi salivary gland homogenate. All mice were followed for the development of Leishmania lesions, parasite burdens, specific antibodies, and for production of NO, urea, or cytokines by peritoneal macrophages. Protection against Leishmania infection was observed not only in exposed mice challenged with homologous saliva but also in the group challenged with P. duboscqi saliva. Comparing both exposed groups, no significant differences were observed in parasite load, macrophage activity, or in the levels of anti-L. major and anti-P. papatasi/P. duboscqi antibodies. This is the first study showing cross-protection caused by salivary antigens of two Phlebotomus species. The cross-protective effect suggests that the anti-Leishmania vaccine based on P. papatasi salivary proteins might be applicable also in areas where L. major is transmitted by P. duboscqi.

Epidemiological study on sand flies in an endemic focus of cutaneous leishmaniasis, bushehr city, southwestern iran

Cutaneous leishmaniasis is the most important health problem in the city of Bushehr, southwestern Iran. The objective of the study was to determine some ecological aspects of sand flies in the city during 2010–2011. Sand flies were collected monthly from outdoors and indoors by sticky traps at four selected districts of the city. They were also dissected and examined by nested-PCR for identification of the parasite during August–September of 2011. A total of 1234 adult sand flies were collected and 6 species including 3 of Genus Phlebotomus and 3 of Genus Sergentomyia were identified. Four species including P. papatasi (3.98%), P. sergenti (1.14%), S. tiberiadis (87.18%), and S. baghdadis (7.7%) were found indoors. Six species including P. papatasi (3.47%), P. sergenti (3.17%), P. alexandri (0.1%), S. tiberiadis (77.74%), S. baghdadis (15.41%), and one female of S. clydei (0.11%) were collected from outdoors. Sand flies started to appear from March and disappear at the end of January. There was only one peak in the density curve in July. The study revealed that S. tiberiadis and S. baghdadis could enter indoors which 89 and 81.8% of them were found blood-fed, respectively. Moreover, P. papatasi, S. tiberiadis, and S. baghdadis were active indoors and outdoors in most months of the year. Nested-PCR of P. papatasi females was positive against kinetoplast DNA of L. major and L. turanica and also mixed natural infections were found by L. gerbilli and L. turanica. Moreover, mixed infections by L. major and L. turanica were observed in this species. Sergentomyia clydei and S. tiberiadis were found to be negative to any DNA of Leishmania species. Phlebotomus sergenti females were found infected with DNA of L. turanica and this is the first report of natural infection and detection of the parasite from this sand fly species in worldwide.