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Background The Middle East respiratory syndrome coronavirus (MERS-CoV) is a highly pathogenic zoonotic betacoronavirus and a global public health concern. Better undersetting of the immune responses to MERS-CoV is needed to characterize the correlates of protection and durability of the immunity and to aid in developing preventative and therapeutic interventions. Although MERS-CoV–specific circulating antibodies could persist for several years post-recovery, their waning raises concerns about their durability and role in protection. Nonetheless, memory B and T cells could provide long-lasting protective immunity despite the serum antibodies levels. Methods Serological and flow cytometric analysis of MERS-CoV–specific immune responses were performed on samples collected from a cohort of recovered individuals who required intensive care unit (ICU) admission as well as hospital or home isolation several years after infection to characterize the longevity and quality of humoral and cellular immune responses. Results Our data showed that MERS-CoV infection could elicit robust long-lasting virus-specific binding and neutralizing antibodies as well as T- and B-cell responses up to 6.9 years postinfection regardless of disease severity or need for ICU admission. Apart from the persistent high antibody titers, this response was characterized by B-cell subsets with antibody-independent functions as demonstrated by their ability to produce tumor necrosis factor α (TNF-α), interleukin (IL)-6, and interferon γ (IFN-γ) cytokines in response to antigen stimulation. Furthermore, virus-specific activation of memory CD8+ and CD4+ T cell subsets from MERS-recovered patients resulted in secretion of high levels of TNF-α, IL-17, and IFN-γ. Conclusions MERS-CoV infection could elicit robust long-lasting virus-specific humoral and cellular responses.

Leishmania ( Mundinia ) procaviensis is a parasitic kinetoplastid that was first isolated from a rock hyrax in Namibia in 1975. We present the complete genome sequence of Leishmania ( Mundinia ) procaviensis isolate 253, strain LV425, sequenced using combined short- and long-read technologies. This genome will contribute to our understanding of hyraxes as a Leishmania reservoir.

Anthroponotic cutaneous leishmaniais (ACL) and zoonotic cutaneous leishmaniasis (ZCL) caused by

When it emerged in late 2019, COVID-19 was carried via travelers to Germany, France and Italy, where freedom of movement accelerated its transmission throughout Europe. However, effective non-pharmaceutical interventions introduced by European governments led to containment of the rapid increase in cases within European nations. Electronic searches were performed to obtain the number of confirmed cases, incident rates and non-pharmaceutical government measures for each European country. The spread and impact of non-pharmaceutical interventions throughout Europe were assessed and visualized. Specifically, heatmaps were used to represent the number of confirmed cases and incident rates for each of the countries over time. In addition, maps were created showing the number of confirmed cases and incident rates in Europe on three different dates (15 March, 15 April and 15 May 2020), which allowed us to assess the geographic and temporal patterns of the disease.

Porcisia hertigi is a parasitic kinetoplastid first isolated from porcupines ( Coendou rothschildi ) in central Panama in 1965. We present the complete genome sequence of P. hertigi , isolate C119, strain LV43, sequenced using combined short- and long-read technologies. This complete genome sequence will contribute to our knowledge of the parasitic genus Porcisia .

Leishmania ( Mundinia ) sp. Ghana is a kinetoplastid parasite isolated in 2015 in Ghana. We report the complete genome sequence of L. ( M. ) sp. Ghana, sequenced using combined short-read and long-read technologies. This will facilitate greater understanding of this novel pathogen and its relationships within the subgenus Mundinia .

Leishmania (Mundinia) enriettii is a parasitic kinetoplastid first isolated from a guinea pig in Brazil in 1946. We present the complete genome sequence of L. ( M. ) enriettii isolate CUR178 strain LV763, sequenced using combined short-read and long-read technologies. This will facilitate a greater understanding of the genome diversity within L. ( M. ) enriettii .

Leishmania (Mundinia) orientalis is a kinetoplastid parasite first isolated in 2014 in Thailand. We report the complete genome sequence of L. ( M. ) orientalis , sequenced using combined short-read and long-read technologies. This will facilitate greater understanding of this novel pathogen and its relationship to other members of the subgenus Mundinia .

We provide the raw and processed data produced during the genome sequencing of isolates from six species of parasites from the sub-family Leishmaniinae: Leishmania martiniquensis (Thailand), Leishmania orientalis (Thailand), Leishmania enriettii (Brazil), Leishmania sp. Ghana, Leishmania sp. Namibia and Porcisia hertigi (Panama). De novo assembly was performed using Nanopore long reads to construct chromosome backbone scaffolds. We then corrected erroneous base calling by mapping short Illumina paired-end reads onto the initial assembly. Data has been deposited at NCBI as follows: raw sequencing output in the Sequence Read Archive, finished genomes in GenBank, and ancillary data in BioSample and BioProject. Derived data such as quality scoring, SAM files, genome annotations and repeat sequence lists have been deposited in Lancaster University’s electronic data archive with DOIs provided for each item. Our coding workflow has been deposited in GitHub and Zenodo repositories. This data constitutes a resource for the comparative genomics of parasites and for further applications in general and clinical parasitology., Measurement(s)DNA • genome • sequence_assembly • sequence feature annotationTechnology Type(s)DNA sequencing • Oxford Nanopore Sequencing • Illumina sequencing • sequence assembly process • sequence annotationSample Characteristic - OrganismLeishmaniinaeSample Characteristic - LocationNamibia • Thailand • Ghana • Brazil Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.15134085

All healthy humans have high levels of natural anti-α-galactosyl (α-Gal) antibodies (elicited by yet uncharacterized glycotopes), which may play important roles in immunoglycomics: (a) potential protection against certain parasitic and viral zoonotic infections; (b) targeting of α-Gal-engineered cancer cells; (c) aiding in tissue repair; and (d) serving as adjuvants in α-Gal-based vaccines. Patients with certain protozoan infections have specific anti-α-Gal antibodies, elicited against parasite-derived α-Gal-bearing glycotopes. These glycotopes, however, remain elusive except for the well-characterized glycotope Galα1,3Galβ1,4GlcNAcα, expressed by Trypanosoma cruzi. The discovery of new parasitic glycotopes is greatly hindered by the enormous structural diversity of cell-surface glycans and the technical challenges of classical immunoglycomics, a top-down approach from cultivated parasites to isolated glycans. Here, we demonstrate that reversed immunoglycomics, a bottom-up approach, can identify parasite species-specific α-Gal-bearing glycotopes by probing synthetic oligosaccharides on neoglycoproteins. This method was tested here seeking to identify as-yet unknown glycotopes specific for Leishmania major, the causative agent of Old-World cutaneous leishmaniasis (OWCL). Neoglycoproteins decorated with synthetic α-Gal-containing oligosaccharides derived from L. major glycoinositolphospholipids served as antigens in a chemiluminescent enzyme-linked immunosorbent assay using sera from OWCL patients and noninfected individuals. Receiver-operating characteristic analysis identified Galpα1,3Galfβ and Galpα1,3Galfβ1,3Manpα glycotopes as diagnostic biomarkers for L. major-caused OWCL, which can distinguish with 100% specificity from heterologous diseases and L. tropica-caused OWCL. These glycotopes could prove useful in the development of rapid α-Gal-based diagnostics and vaccines for OWCL. Furthermore, this method could help unravel cryptic α-Gal-glycotopes of other protozoan parasites and enterobacteria that elicit the natural human anti-α-Gal antibodies.

We present the LGAAP computational pipeline, which was successfully used to assemble six genomes of the parasite subfamily Leishmaniinae to chromosome-scale completeness from a combination of long- and short-read sequencing data. LGAAP is open source, and we suggest that it may easily be ported for assembly of any genome of comparable size (∼35 Mb).

Leishmania (Mundinia) martiniquensis is a kinetoplastid parasite that was first isolated in 1995 on Martinique. We report the first complete genome for Leishmania martiniquensis from Asia, isolate LSCM1, strain LV760, which was sequenced using combined short-read and long-read technologies. This will facilitate greater understanding of the evolution of the geographically dispersed subgenus Mundinia.

Outbreaks of Old World cutaneous leishmaniasis (CL) have significantly increased due to the conflicts in the Middle East, with most of the cases occurring in resource-limited areas such as refugee settlements. The standard methods of diagnosis include microscopy and parasite culture, which have several limitations. To address the growing need for a CL diagnostic that can be field applicable, we have identified five candidate neoglycoproteins (NGPs): Galα (NGP3B), Galα(1,3)Galα (NGP17B), Galα(1,3)Galβ (NGP9B), Galα(1,6)[Galα(1,2)]Galβ (NGP11B), and Galα(1,3)Galβ(1,4)Glcβ (NGP1B) that are differentially recognized in sera from individuals withLeishmania majorinfection as compared with sera from heterologous controls. These candidates contain terminal, non-reducing α-galactopyranosyl (α-Gal) residues, which are known potent immunogens to humans. Logistic regression models found that NGP3B retained the best diagnostic potential (area under the curve from receiver-operating characteristic curve = 0.8). Our data add to the growing body of work demonstrating the exploitability of the human anti-α-Gal response in CL diagnosis.

Background In the Kingdom of Saudi Arabia (KSA), Leishmania major and L. tropica are the main causative agents of Old World cutaneous leishmaniasis (CL). The national CL treatment regimen consists of topical 1% clotrimazole/2% fusidic acid cream followed by 1–2 courses of intralesional sodium stibogluconate (SSG); however, treatment efficacy is highly variable and the reasons for this are not well understood. In this study, we present a complete epidemiological map of CL and determined the efficacy of the standard CL treatment regime in several endemic regions of KSA. Results Overall, three quarters of patients in all CL-endemic areas studied responded satisfactorily to the current treatment regime, with the remaining requiring only an extra course of SSG. The majority of unresponsive cases were infected with L. tropica. Furthermore, the development of secondary infections (SI) around or within the CL lesion significantly favoured the treatment response of L. major patients but had no effect on L. tropica cases. Conclusions The response of CL patients to a national treatment protocol appears to depend on several factors, including Leishmania parasite species, geographical location and occurrences of SI. Our findings suggest there is a need to implement alternative CL treatment protocols based on these parameters. Electronic supplementary material The online version of this article (10.1186/s13071-019-3453-4) contains supplementary material, which is available to authorized users.

Background Major depressive disorder (MDD) associated with chronic neglected tropical diseases (NTDs) has been identified as a significant and overlooked contributor to overall disease burden. Cutaneous leishmaniasis (CL) is one of the most prevalent and stigmatising NTDs, with an incidence of around 1 million new cases of active CL infection annually. However, the characteristic residual scarring (inactive CL) following almost all cases of active CL has only recently been recognised as part of the CL disease spectrum due to its lasting psychosocial impact. Methods and findings We performed a multi-language systematic review of the psychosocial impact of active and inactive CL. We estimated inactive CL (iCL) prevalence for the first time using reported WHO active CL (aCL) incidence data that were adjusted for life expectancy and underreporting. We then quantified the disability (YLD) burden of co-morbid MDD in CL using MDD disability weights at three severity levels. Overall, we identified 29 studies of CL psychological impact from 5 WHO regions, representing 11 of the 50 highest burden countries for CL. We conservatively calculated the disability burden of co-morbid MDD in CL to be 1.9 million YLDs, which equalled the overall (DALY) disease burden (assuming no excess mortality in depressed CL patients). Thus, upon inclusion of co-morbid MDD alone in both active and inactive CL, the DALY burden was seven times higher than the latest 2016 Global Burden of Disease study estimates, which notably omitted both psychological impact and inactive CL. Conclusions Failure to include co-morbid MDD and the lasting sequelae of chronic NTDs, as exemplified by CL, leads to large underestimates of overall disease burden., Author summary Cutaneous leishmaniasis is a highly prevalent vector-borne disease affecting large parts of Latin America and the Middle East, as well as parts of Northern Africa. There are several types of Cutaneous leishmaniasis, almost all of which have an active phase characterized by a disfiguring lesion (typically on exposed parts of the body), which then becomes a permanent scar (the inactive phase). We recently published an article highlighting the impact of the inactive scarring phase of CL on affected individuals, which is associated with high levels of stigma. Nevertheless, this aspect of the disease is not considered in its own right when calculating the overall disease burden by the Global Burden of Disease (GBD) Studies. In this article we estimate the prevalence of depression (major depressive disorder) in cutaneous leishmaniasis, in both the active and inactive forms. We then show the contribution of inactive CL to the overall disease burden estimates when included, which is due to the large psychological impact it has on those affected by it. We also highlight the importance of further similar efforts for other NTDs which have a chronic course, and which are also not sufficiently included in disease burden calculations at present.

To the Editor: War, infection, and disease have always made intimate bedfellows, with disease recrudescence characterizing most conflict zones (1). Recently, increasing violence from civil war and terrorist activity in the Middle East has caused the largest human displacement in decades. A neglected consequence of this tragedy has been the reemergence of a cutaneous leishmaniasis epidemic. Old World cutaneous leishmaniasis is one of the most prevalent insectborne diseases within the World Health Organization’s Eastern Mediterranean Region (2). Zoonotic cutaneous leishmaniasis is caused by the protozoan parasite Leishmania major, which is transmitted through the infectious bite of the female Phlebotomus papatasi sand fly; the animal reservoirs are the rodent genera Rhombomys, Psammomys, and Meriones. Anthroponotic cutaneous leishmaniasis is caused by L. tropica and transmitted between humans by the Ph. sergenti sand fly. Until 1960, cutaneous leishmaniasis prevalence in Syria was restricted to 2 areas to which it is endemic (Aleppo and Damascus); preconflict (c. 2010) incidence was 23,000 cases/year (3). However, in early 2013, an alarming increase to 41,000 cutaneous leishmaniasis cases was reported (3,4). The regions most affected are under Islamic State control; 6,500 cases occurred in Ar-Raqqah, Diyar Al-Zour, and Hasakah. Because these places are not historical hotspots of cutaneous leishmaniasis, this change might be attributed to the massive human displacement within Syria and the ecologic disruption of sand fly (Ph. papatasi) habitats. According to the United Nations High Commissioner for Refugees, >4.2 million Syrians have been displaced into neighboring countries; Turkey, Lebanon, and Jordan have accepted most of these refugees. As a result, cutaneous leishmaniasis has begun to emerge in areas where displaced Syrians and disease reservoirs coexist (5). According to the Lebanese Ministry of Health, during 2000–2012, only 6 cutaneous leishmaniasis cases were reported in Lebanon. However in 2013 alone, 1,033 new cases were reported, of which 96.6% occurred among the displaced Syrian refugee populations (5). Similarly in Turkey, nonendemic parasite strains L. major and L. donovani were introduced by incoming refugees (6). Many of the temporary refugee settlements are predisposed to increased risk because of malnutrition, poor housing, absence of clean water, and inadequate sanitation. The combination of favorable climate, abundant sand fly populations, displaced refugees, and deficient medical facilities and services has created an environment conducive to cutaneous leishmaniasis reemergence. For example, refugee settlements in Nizip in southern Turkey have reported several hundred cases (7). Using current datasets published in English and Arabic, we mapped cutaneous leishmaniasis prevalence within Syria and its neighboring countries (Figure). Our results demonstrate that cutaneous leishmaniasis prevalence coincides with the presence of refugee camps (Figure, panel A), which is plausible given the strong association between disease outbreaks and refugee settlements (8). The deterioration of Syrian health systems, including the cessation of countrywide vector control programs, has created an ideal environment for disease outbreaks (9). Likewise, the sand fly vectors are widely distributed throughout the Middle East; expansive Ph. papatasi and Ph. sergenti sand fly populations exist in Syria and Iraq (4). The presence of these vectors in regions of instability can create new cutaneous leishmaniasis foci, which might have debilitating, and often stigmatizing, consequences for residents and deployed military personnel (10). In addition, the distribution of Leishmania spp. overlaps with sand fly habitats (Figure, panel B) and disease reservoirs (W. Al-Salem, unpub. data). Consequently, the movement of large refugee populations into regions that are ill-equipped to manage imported cutaneous leishmaniasis has resulted in outbreaks in Turkey and Lebanon (5,6). Figure Cutaneous leishmaniasis prevalence within Syria and neighboring countries of the World Health Organization’s Eastern Mediterranean Region, 2013. A) Prevalence among refugee camps. Case data were taken from http://datadryad.org/resource/doi:10.5061/dryad.05f5h ... Our findings emphasize the importance of contemporaneous disease tracking to identify human populations at highest disease risk. To ameliorate the current cutaneous leishmaniasis crisis, particularly during the winter when cases start to appear, accurate disease monitoring and strategic training of persons based within refugee camps (medical staff, aid workers, volunteers, and military personnel) needs to be prioritized. Moreover, clinicians and other medical personnel residing in refugee-hosting countries must be suitably trained to diagnose cutaneous leishmaniasis because other local diseases (e.g., sarcoidosis and cutaneous tuberculosis) can have similar manifestations. Along with vector and rodent control, new cutaneous leishmaniasis outbreaks should be managed by prompt diagnosis and treatment, which are even more pertinent given that L. tropica–associated cutaneous leishmaniasis typically is resistant to several treatment regimens. In summary, the coexistence of sand fly populations and Leishmania spp. within refugee camps, together with the considerable influx of persons who already have cutaneous leishmaniasis, create a dangerous cocktail that can lead to an outbreak unprecedented in modern times.

Background Protozoan parasites from the genus Leishmania cause broad clinical manifestations known as leishmaniases, which affect millions of people worldwide. Cutaneous leishmaniasis (CL), caused by L. major, is one the most common forms of the disease in the Old World. There is no preventive or therapeutic human vaccine available for L. major CL, and existing drug treatments are expensive, have toxic side effects, and resistant parasite strains have been reported. Hence, further therapeutic interventions against the disease are necessary. Terminal, non-reducing, and linear α-galactopyranosyl (α-Gal) epitopes are abundantly found on the plasma membrane glycolipids of L. major known as glycoinositolphospholipids. The absence of these α-Gal epitopes in human cells makes these glycans highly immunogenic and thus potential targets for vaccine development against CL. Methodology/Principal findings Here, we evaluated three neoglycoproteins (NGPs), containing synthetic α-Gal epitopes covalently attached to bovine serum albumin (BSA), as vaccine candidates against L. major, using α1,3-galactosyltransferase-knockout (α1,3GalT-KO) mice. These transgenic mice, similarly to humans, do not express nonreducing, linear α-Gal epitopes in their cells and are, therefore, capable of producing high levels of anti-α-Gal antibodies. We observed that Galα(1,6)Galβ-BSA (NGP5B), but not Galα(1,4)Galβ-BSA (NGP12B) or Galα(1,3)Galα-BSA (NGP17B), was able to significantly reduce the size of footpad lesions by 96% in comparison to control groups. Furthermore, we observed a robust humoral and cellular immune response with production of high levels of protective lytic anti-α-Gal antibodies and induction of Th1 cytokines. Conclusions/Significance We propose that NGP5B is an attractive candidate for the study of potential synthetic α-Gal-neoglycoprotein-based vaccines against L. major infection., Author summary Despite a worldwide prevalence, cutaneous leishmaniasis (CL) remains largely neglected, with no prophylactic or therapeutic vaccine available. In the Old World, CL is mainly caused by either Leishmania major or L. tropica parasites, which produce localized cutaneous ulcers, often leading to scarring and social stigma. Currently, the disease has reached hyperendemicity levels in the Middle East due to conflict and human displacement. Furthermore, the first choice of treatment in that region continues to be pentavalent antimonials, which are costly and highly toxic, and current vector control measures alone are not sufficient to stop disease transmission. Hence, a vaccine against CL would be very beneficial. Previous studies have demonstrated that sugars are promising vaccine candidates against leishmaniasis, since most parasite species have a cell surface coat composed of immunogenic sugars, including linear α-galactopyranosyl (α-Gal) epitopes, which are absent in humans. Here, we have developed an α-Gal-based vaccine candidate, named NGP5B. When tested in transgenic mice which like humans lack α-Gal epitopes in their cells, NGP5B was able to induce a significant partial protection against L. major infection, by significantly reducing mouse footpad lesions and parasite burden. Altogether, we propose NGP5B as a promising preventive vaccine for CL caused by L. major.

This article considers the current public health perspective on cutaneous leishmaniasis (CL) and its implications for incidence, prevalence, and global burden of disease calculations. CL is the most common form of leishmaniasis and one of a small number of infectious diseases increasing in incidence worldwide [1] due to conflict and environmental factors in the Middle East (“Old World”) and the Americas (“New World”)—regions where it is most prevalent. Recently, the disease has reached hyperendemic levels in the conflict zones of the Syrian Arab Republic, Iraq, and Afghanistan while simultaneously affecting refugees from those regions [2]. Nevertheless, CL is not seen as a priority for policymakers because it is not life limiting. This is evidenced by a lack of commitment in recent years to preventive campaigns and patient provision (limited diagnostic capacity, knowledge of treatment, drug availability) in a number of endemic countries.

Background Visceral leishmaniasis (VL), caused predominantly by Leishmania donovani and transmitted by both Phlebotomus orientalis and Phlebotomus martini, is highly endemic in East Africa where approximately 30 thousands VL cases are reported annually. The largest numbers of cases are found in Sudan - where Phlebotomus orientalis proliferate in Acacia forests especially on Sudan’s eastern border with Ethiopia, followed by South Sudan, Ethiopia, Somalia, Kenya and Uganda. Long-standing civil war and unrest is a dominant determinant of VL in East African countries. Here we attempt to identify the correlation between VL epidemics and civil unrest. Objective and methodology In this review, literature published between 1955 and 2016 have been gathered from MSF, UNICEF, OCHA, UNHCR, PubMed and Google Scholar to analyse the correlation between conflict and human suffering from VL, which is especially apparent in South Sudan. Findings Waves of forced migration as a consequence of civil wars between 1983 and 2005 have resulted in massive and lethal epidemics in southern Sudan. Following a comprehensive peace agreement, but especially with increased allocation of resources for disease treatment and prevention in 2011, cases of VL declined reaching the lowest levels after South Sudan declared independence. However, in the latest epidemic that began in 2014 after the onset of a civil war in South Sudan, more than 1.5 million displaced refugees have migrated internally to states highly endemic for VL, while 800,000 have fled to neighboring countries. Conclusion We find a strong relationship between civil unrest and VL epidemics which tend to occur among immunologically naïve migrants entering VL-endemic areas and when Leishmania-infected individuals migrate to new areas and establish additional foci of disease. Further complicating factors in East Africa’s VL epidemics include severe lack of access to diagnosis and treatment, HIV/AIDS co-infection, food insecurity and malnutrition. Moreover, cases of post-kala-azar dermal leishmaniasis (PKDL) can serve as important reservoirs of anthroponotic Leishmania parasites.

Together, the Hajj and Umrah rank among the leading global venues that host annual mass human migrations. The Hajj is an annual pilgrimage to the Islamic holy city of Makkah in Saudi Arabia (Fig 1). It is considered a religious obligation for all adult Muslims worldwide who have the physical and financial ability and draws an estimated 2–3 million people annually [1]. Umrah is an Islamic pilgrimage to Makkah, which occurs at times other than the period of the Hajj—the period of Ramadan (fasting month) is considered the peak period [2]. In 2018, the Hajj is scheduled to take place in August, while Ramadan will occur between May and June [2]. Open in a separate window Fig 1 Outline map of Saudi Arabia and surrounding countries. The capital Riyadh, the two holy cities Makkah and Medina, and other cities mentioned in this paper are shown. Original figure.

SUMMARYIn the Kingdom of Saudi Arabia (KSA), Old World cutaneous leishmaniasis (CL) is mainly caused byLeishmania majorandLeishmania tropicaparasites. Diagnosis of CL is predominately made by clinicians, who at times fail to detect the disease and are unable to identify parasite species. Here, we report the development of a chemiluminescent enzyme-linked immunosorbent assay (CL-ELISA) to measure the levels of anti-α-galactosyl antibodies in human sera. Using this assay, we have found that individuals infected with eitherLeishmaniaspp. had significantly elevated levels (up to 9-fold higher) of anti-α-Gal IgG compared to healthy control individuals. The assay sensitivity was 96% forL. major(95% CI; 94–98%) and 91% forL. tropica(95% CI; 86–98%) infections and therefore equivalent to restriction fragment length polymorphism-polymerase chain reaction analysis of parasiteITS1gene. In addition, the assay had higher sensitivity than microscopy analysis, which only detected 68 and 45% of theL. majorandL. tropicainfections, respectively. Interestingly, up to 2 years following confirmed CL cure individuals had 28-fold higher levels of anti-α-Gal IgG compared to healthy volunteers. Monitoring levels of anti-α-Gal antibodies can be exploited as both a diagnostic tool and as a biomarker of cure of Old World CL in disease elimination settings.

Background Phlebotomine sand flies transmit the haemoflagellate Leishmania, the causative agent of human leishmaniasis. The Leishmania promastigotes are confined to the gut lumen and are exposed to the gut microbiota within female sand flies. Here we study the colonisation resistance of yeast and bacteria in preventing the establishment of a Leishmania population in sand flies and the ability of Leishmania to provide colonisation resistance towards the insect bacterial pathogen Serratia marcescens that is also pathogenic towards Leishmania. Methods We isolated microorganisms from wild-caught and laboratory-reared female Lutzomyia longipalpis, identified as Pseudozyma sp. Asaia sp. and Ochrobactrum intermedium. We fed the females with a sugar meal containing the microorganisms and then subsequently fed them with a bloodmeal containing Leishmania mexicana and recorded the development of the Leishmania population. Further experiments examined the effect of first colonising the sand fly gut with L. mexicana followed by feeding with, Serratia marcescens, an insect bacterial pathogen. The mortality of the flies due to S. marcescens was recorded in the presence and absence of Leishmania. Results There was a reduction in the number of flies harbouring a Leishmania population that had been pre-fed with Pseudozyma sp. and Asaia sp. or O. intermedium. Experiments in which L. mexicana colonised the sand fly gut prior to being fed an insect bacterial pathogen, Serratia marcescens, showed that the survival of flies with a Leishmania infection was significantly higher compared to flies without Leishmania infection. Conclusions The yeast and bacterial colonisation experiments show that the presence of sand fly gut microorganisms reduce the potential for Leishmania to establish within the sand fly vector. Sand flies infected with Leishmania were able to survive an attack by the bacterial pathogen that would have killed the insect and we concluded that Leishmania may benefit its insect host whilst increasing the potential to establish itself in the sand fly vector. We suggest that the increased ability of the sand fly to withstand a bacterial entomopathogen, due to the presence of the Leishmania, may provide an evolutionary pressure for the maintenance of the Leishmania-vector association. Electronic supplementary material The online version of this article (doi:10.1186/1756-3305-7-329) contains supplementary material, which is available to authorized users.

The Syrian refugee crisis has precipitated a catastrophic outbreak of Old World cutaneous leishmaniasis now affecting hundreds of thousands of people living in refugee camps or trapped in conflict zones. A similar situation may also be unfolding in eastern Libya and Yemen. Leishmaniasis has been endemic in Syria for over two centuries, with the first case ever reported being as early as 1745, when it was known as the “Aleppo boil” [1,2]. Old World cutaneous leishmaniasis (CL) is characterized most notably by disfiguring skin lesions, nodules, or papules, and in the Middle East and North Africa (MENA) region it is primarily caused either by Leishmania tropica (anthroponotic) or L. major (zoonotic), with some sporadic cases also caused by L. infantum (Box 1) [3–5]. In North Africa, a chronic form of CL also can be caused by L. killicki [6–7]. Box 1. Old World Cutaneous Leishmaniasis (CL) in the MENA Region Anthroponotic CL Major etiologic agent: Leishmania tropica [4,5,7] Major vector: Phlebotomus sergenti [4,5] Zoonotic CL Major etiologic agent: L. major [4,5,7] Minor etiologic agent: L. infantum [4,5] Vectors: Ph. papatasi for L. major; Ph. perfiliewi, Ph. perniciosus, Ph. longicuspis, and Ph. ariasi for L. infantum [5] Major animal reservoirs: Rodents (L. major) and dogs (L. infantum) [4,7] Although Old World CL is generally not fatal, clinical symptoms can lead to disfiguring scars that result in social stigmatization and psychological consequences. The World Health Organization (WHO) has estimated that around 2.4 million disability-adjusted life years (DALYs) are lost due to CL and visceral leishmaniasis (VL) globally [8]; however, the number of DALYs attributed to CL is still under evaluation. The 2013 Global Burden of Disease Study determined that CL causes only 41,700 DALYs [9], while other studies have found that these figures may represent profound underestimates [10,11]. Studies observing the impact of marring CL facial scars have found that the social stigmatization involved leads to anxiety, depression, and decreased quality of life for patients [12]. The scars can lead to a changed perception of self and can limit individuals’ abilities to participate in society, further decreasing their social, psychological, and economic well-being, as employment opportunities become scarce. Women, adolescents, and children are particularly susceptible to the social stigmatization of disfiguring scars [13]. The hardships caused by CL extend beyond physical symptoms and manifest most prominently in patients’ social, psychological, and economic well-being. Like many neglected tropical diseases (NTDs), CL not only occurs in settings of poverty but the disease also has the ability to perpetuate and reinforce poverty, catalyzing a positive feedback loop between disease and poverty [14]. For many of these reasons, the WHO classifies leishmaniasis as one of 17 NTDs [15], although the cutaneous form is often not prioritized in major global health initiatives, unlike the NTDs now targeted by integrated preventive chemotherapy [11].

Background The sandfly Phlebotomus papatasi is the vector of Leishmania major, the main causative agent of Old World cutaneous leishmaniasis (CL) in Saudi Arabia. Sandflies inject saliva while feeding and the salivary protein PpSP32 was previously shown to be a biomarker for bite exposure. Here we used recombinant PpSP32 to evaluate human exposure to Ph. papatasi bites, and study the association between antibody response to saliva and CL in endemic areas in Saudi Arabia. Methodology/Principal Findings In this observational study, anti-PpSP32 antibodies, as indicators of exposure to sandfly bites, were measured in sera from healthy individuals and patients from endemic regions in Saudi Arabia with active and cured CL. Ph. papatasi was identified as the primary CL vector in the study area. Anti-PpSP32 antibody levels were significantly higher in CL patients presenting active infections from all geographical regions compared to CL cured and healthy individuals. Furthermore, higher anti-PpSP32 antibody levels correlated with the prevalence and type of CL lesions (nodular vs. papular) observed in patients, especially non-local construction workers. Conclusions Our findings suggest a possible correlation between the type of immunity generated by the exposure to sandfly bites and disease outcome., Author Summary Leishmania is transmitted by the bite of infected female sandflies. When a sandfly bites a vertebrate host, it injects a cocktail of salivary proteins meant to facilitate blood feeding. The constant exposure to sandfly bites in endemic areas triggers a humoral response against the major antigenic components in the saliva. These antibodies can be then exploited to measure exposure to vector sandflies, which is useful for surveillance in leishmaniasis control programmes. In Saudi Arabia, cutaneous leishmaniasis (CL) is mainly transmitted by the Phlebotomus papatasi sandfly. Here we study the recognition of the main antigenic salivary protein from Ph. papatasi, PpSP32, in leishmaniasis patients and healthy individuals from three CL endemic areas in Saudi Arabia. Anti-PpSP32 antibody levels were significantly higher in CL patients presenting active infections from all geographical regions compared to the CL-cured and healthy individuals. Furthermore, higher anti-PpSP32 antibody levels correlated with the prevalence and type of CL lesions observed in patients. Our results suggest that previous long-term exposure to sandfly saliva can have a role in modulating the severity of leishmaniasis infection, resulting in a milder form of the disease.