Cutaneous leishmaniasis: an increasing threat for travellers

Delayed diagnosis among patients with visceral leishmaniasis

We aimed to estimate the diagnostic latency of patients with visceral leishmaniasis (VL). A monocentric retrospective observational study was conducted including all confirmed cases of VL diagnosed from January 2005 to March 2022. Epidemiological and clinical characteristics of patients with VL were collected. The diagnostic latency was defined as the number of days between the first contact with a health-care provider for signs and/or symptoms referable to VL and the laboratory diagnosis of leishmaniasis. Twenty-four cases of VL were included in the study, mostly male (75%) and Italians (79.2%), with a median age of 40 years [Inter Quartile Range (IQR 30-48)]. Fourteen (58.3%) VL cases were people living with HIV (PLWH) and 4 (16.6%) subjects were on immunosuppressive therapy. For VL the median diagnostic latency was 54 days (IQR 28-162). The shorter diagnostic latency was observed in PLWH [31 days (IQR 20-47)] followed by immunocompetent patients [160 days (IQR 133-247)] and those on immunosuppressive therapy [329 days (IQR 200-678)]. Twelve patients (50%) reported at least one medical encounter before the diagnosis of VL and 6 patients received a wrong therapy. Diagnostic delay in VL was significant in patients under immune suppressive treatment.

Assessment of pan-Leishmania detection by recombinase polymerase amplification assay

The spread of vector habitats along with increasing human mobility can introduce atypical Leishmania species and hence can challenge existing diagnostic practices for rapid detection of active infection with species outside the narrow target range. Here we assessed the pan-Leishmania detection ability of isothermal recombinase polymerase amplification (RPA) assays targeting 18S rRNA gene, cathepsin L-like cysteine proteinase B (Cpb) gene, and kinetoplast minicircle DNA (kDNA) regions. While the lowest limit of detection of the 18S rRNA-RPA and Cpb-RPA assays were estimated as 12 and 17 standard DNA molecules, respectively, both assays could amplify genomic DNA of 7 pathogenic Leishmania species. Evaluation of 18S rRNA-RPA and our previously developed kDNA-RPA assays on 70 real-time PCR-positive leishmaniasis samples of varying pathologies resulted in sensitivity rates of 35.71% and 88.57%, respectively, while the combined sensitivity was 98.57%. Combinatorial application of 18S rRNA-RPA and kDNA-RPA assays can be recommended for further diagnostic assessments.

Climate change, human migration, and skin disease: is there a link?

Climate change, exemplified by higher average global temperatures resulting in more frequent extreme weather events, has the potential to significantly impact human migration patterns and health. The consequences of environmental catastrophes further destabilize regions with pre-existing states of conflict due to social, political, and/or economic unrest. Migrants may carry diseases from their place of origin to their destinations and once there may be susceptible to diseases in which they had not been previously exposed to. Skin diseases are among the most commonly observed health conditions observed in migrant populations. To improve awareness among dermatologists of the burden of skin diseases among migrants, the group searched the English language scientific literature to identify articles linking climate change, migration, and skin disease. Skin diseases associated with human migration fall into three major categories: (i) communicable diseases, (ii) noncommunicable diseases, and (iii) environmentally mediated diseases. Adopting comprehensive global strategies to improve the health of migrants requires urgent attention.

Cutaneous leishmaniasis in Louisiana - one-year follow-up: A case report

BACKGROUND

Reports of leishmaniasis are scarce in North America. It is considered to be one of the neglected tropical diseases. It is seen in immigrants from endemic areas to United States. Treatments are not readily available in the United States. Untreated or inadequately treated cutaneous leishmaniasis not only causes localized disfigurement but can advance to more permanent and devastating mucosal disfigurement and perforation, if caused by a species that can also cause mucocutaneous leishmaniasis.

CASE SUMMARY

A 42-year-old human immunodeficiency virus negative male immigrant from Honduras presented to the emergency department of our facility in Louisiana with a 2-mo history of a left lower extremity ulcer. It started as a painless blister that progressed in size and developed into other smaller lesions tracking up the thigh and became tender and erythematous. Clinically looked nontoxic and healthy. He was afebrile. Blood tests, except inflammatory markers, were within normal limits. The cellulitis of the leg was treated with 6 d of vancomycin that also relieved the pain. Skin biopsy was obtained, and histopathology was suspicious for leishmania. Polymerase chain reaction/deoxyribonucleic acid sequencing done by centers for disease control and prevention confirmed the diagnosis as Leishmania panamensis. There was no involvement of naso-oropharyngeal mucosa, confirmed by otolaryngology. The patient was treated with miltefosine for 28 d. Clinic follow-up after approximately 11 mo revealed a healed skin ulcer.

CONCLUSION

Cutaneous leishmaniasis should be in the differential diagnosis of skin ulcers of travelers from endemic areas. Awareness regarding diagnosis and treatment of leishmaniasis needs to be enhanced.

Identification of trypanosomatids and blood feeding preferences of phlebotomine sand fly species common in Sicily, Southern Italy

In this study, the presence of Leishmania DNA and blood feeding sources in phlebotomine sand fly species commonly present in Sicily were investigated. A total of 1,866 female sand flies including 176 blood fed specimens were sampled over two seasons in five selected sites in Sicily (southern Italy). Sergentomyia minuta (n = 1,264) and Phlebotomus perniciousus (n = 594) were the most abundant species at all the sites, while three other species from the genus Phlebotomus (i.e., P. sergenti n = 4, P. perfiliewi n = 3 and P. neglectus n = 1) were only sporadically captured. Twenty-eight out of the 1,866 (1.5%) sand flies tested positive for Leishmania spp. Leishmania tarentolae DNA was identified in 26 specimens of S. minuta, while the DNA of Leishmania donovani complex was detected in a single specimen each of S. minuta and P. perniciosus. Interestingly, seven S. minuta specimens (0.4%) tested positive for reptilian Trypanosoma sp. Blood sources were successfully identified in 108 out of 176 blood fed females. Twenty-seven out of 82 blood sources identified in fed females of P. perniciosus were represented by blood of wild rabbit, S. minuta mainly fed on humans (16/25), while the sole P. sergenti fed specimen took a blood meal on rat. Other vertebrate hosts including horse, goat, pig, dog, chicken, cow, cat and donkey were recognized as blood sources for P. perniciosus and S. minuta, and, surprisingly, no reptilian blood was identified in blood-fed S. minuta specimens. Results of this study agree with the well-known role of P. perniciosus as vector of L. infantum in the western Mediterranean; also, vector feeding preferences herein described support the hypothesis on the involvement of lagomorphs as sylvatic reservoirs of Leishmania. The detection of L. donovani complex in S. minuta, together with the anthropophilic feeding-behaviour herein observed, warrants further research to clarify the capacity of this species in the transmission of pathogens to humans and other animals.

Cutaneous Leishmaniasis: A Case Involving the Scalp - Clinical and Videodermoscopic Findings

Cutaneous leishmaniasis (CL) is a worldwide infectious disease caused by flagellate protozoa of the genus <i>Leishmania</i>. In America, the species most commonly responsible for CL are <i>L. mexicana </i>and<i> L. brasiliensis</i>. Usually, in America, it is transmitted by sand flies mainly of the genus <i>Lutzomyia </i>and <i>Psychodopygus</i>. CL most commonly affects exposed areas and is characterized by an erythematous infiltrated and ulcerated papular or nodular lesion. We report a 28-year-old male, with a 6-month history and a previous trip to the forest in the south of Mexico. He presented with an asymptomatic erythematous plaque on his scalp, with slow and progressive nodular lesions with central crusted ulceration, with a raised and well-defined border. On videodermoscopy, we observed erythematous gummy lesions, yellowish scabs, and white star, dotted, hairpin, and glomerular patterns of vessels.

Spatial distribution, Leishmania species and clinical traits of Cutaneous Leishmaniasis cases in the Colombian army

In Colombia, the cutaneous leishmaniasis (CL) is the most common manifestation across the army personnel. Hence, it is mandatory to determine the species associated with the disease as well as the association with the clinical traits. A total of 273 samples of male patients with CL were included in the study and clinical data of the patients was studied. PCR and sequencing analyses (Cytb and HSP70 genes) were performed to identify the species and the intra-specific genetic variability. A georeferenced database was constructed to identify the spatial distribution of Leishmania species isolated. The identification of five species of Leishmania that circulate in the areas where army personnel are deployed is described. Predominant infecting Leishmania species corresponds to L. braziliensis (61.1%), followed by Leishmania panamensis (33.5%), with a high distribution of both species at geographical and municipal level. The species L. guyanensis, L. mexicana and L. lainsoni were also detected at lower frequency. We also showed the identification of different genotypes within L. braziliensis and L. panamensis. In conclusion, we identified the Leishmania species circulating in the areas where Colombian army personnel are deployed, as well as the high intra-specific genetic variability of L. braziliensis and L. panamensis and how these genotypes are distributed at the geographic level.

Colombia is one of the countries with the highest incidence of Cutaneous Leishmaniasis in the world and the army population is the most vulnerable population. Herein, we identified the infecting Leishmania species (L. braziliensis, L. panamensis, L. guyanensis, L. mexicana and L. lainsoni). We also showed the high intra-specific genetic variability of L. braziliensis and L. panamensis and how these genotypes are distributed at the geographic level.

Aspects of the ecology of phlebotomine sand flies (Diptera: Psychodidae) in the Private Natural Heritage Reserve Sanctuary Caraça

Leishmaniases are a set of parasitic diseases of zoonotic origin that are transmitted by sandfly vectors in wild, rural and urban environments. Their distribution is dependent not only the distribution of vectors, but also on the distribution of mammalian reservoirs. Only by understanding the transmission cycle of these diseases, such as knowing the participating vectors and reservoirs, can one can understand the epidemiology and ecological relationships of leishmaniases. Ecotourism has become an important area of economic growth in Brazil. One of the most visited tourist attractions in the state of Minas Gerais, the Reserva Particular do Patrimônio Natural Santuário do Caraça (RPPNSC) is located in the Quadrilátero Ferrífero. The aim of this study was to contribute to the control of leishmaniasis among tourists of the RPPNPC by surveying its sand fly fauna and testing for the presence of Leishmania DNA in females. Twenty-five CDC light traps were exposed on 7 trails of the RPPNPC where samples were collected bimonthly for a year, starting in June 2013. A total of 376 specimens of 18 species and 10 genera of sandflies were captured. The predominant species were Psychodopygus lloydi (72.34%) and Pintomyia monticola (5.59%). HaeIII restriction enzyme detected and characterized Leishmania braziliensis DNA in 2 of the samples for an infection rate of 0.7% (2/266). Recent studies found specimens of Ps. lloyd infected with Leishmania braziliensis elsewhere in Minas Gerais, which may be an indication that this species is involved in the transmission of Leishmania in this state.

Microbiological laboratory diagnostics of neglected zoonotic diseases (NZDs)

This review reports on laboratory diagnostic approaches for selected, highly pathogenic neglected zoonotic diseases, i.e. anthrax, bovine tuberculosis, brucellosis, echinococcosis, leishmaniasis, rabies, Taenia solium-associated diseases (neuro-/cysticercosis & taeniasis) and trypanosomiasis. Diagnostic options, including microscopy, culture, matrix-assisted laser-desorption-ionisation time-of-flight mass spectrometry, molecular approaches and serology are introduced. These procedures are critically discussed regarding their diagnostic reliability and state of evaluation. For rare diseases reliable evaluation data are scarce due to the rarity of samples. If bio-safety level 3 is required for cultural growth, but such high standards of laboratory infrastructure are not available, serological and molecular approaches from inactivated sample material might be alternatives. Multiple subsequent testing using various test platforms in a stepwise approach may improve sensitivity and specificity. Cheap and easy to use tests, usually called "rapid diagnostic tests" (RDTs) may impact disease control measures, but should not preclude developing countries from state of the art diagnostics.

Real-time PCR using FRET technology for Old World cutaneous leishmaniasis species differentiation

Background

Recently, there has been a re-emergence of cutaneous leishmaniasis in endemic countries and an increase in imported cases in non-endemic countries by travelers, workers, expatriates, immigrants, and military force personnel. Old World cutaneous leishmaniasis is caused primarily by Leishmania major, L. tropica and L. aethiopica. Despite their low sensitivity, diagnosis traditionally includes microscopic and histopathological examinations, and in vitro cultivation. Several conventional PCR techniques have been developed for species identification, which are time-consuming and labour-intensive. Real-time PCR using SYBR green dye, although provides rapid detection, may generate false positive signals. Therefore, a rapid and easy method such as a FRET-based real-time PCR would improve not only the turn-around time of diagnosing Old World cutaneous Leishmania species but will also increase its specificity and sensitivity.

Methods

A FRET-based real-time PCR assay which amplifies the cathepsin L-like cysteine protease B gene encoding a major Leishmania antigen was developed to differentiate L. major, L. tropica, and L. aethiopica in one single step using one set of primers and probes. Assay performance was tested on cutaneous and visceral strains of Leishmania parasite cultures and isolates of other protozoan parasites as well as human biopsy specimen.

Results

The assay readily differentiates between the three Old World cutaneous leishmaniasis species based on their melting curve characteristics. A single Tm at 55.2 ± 0.5 °C for L. aethiopica strains was distinguished from a single Tm at 57.4 ± 0.2 °C for L. major strains. A double curve with melting peaks at 66.6 ± 0.1 °C and 48.1 ± 0.5 °C or 55.8 ± 0.6 °C was observed for all L. tropica strains. The assay was further tested on biopsy specimens, which showed 100 % agreement with results obtained from isoenzyme electrophoresis and Sanger sequencing.

Conclusion

Currently, there are no published data on real-time PCR using FRET technology to differentiate between Old World cutaneous Leishmania species. In summary, our assay based on specific hybridization addresses the limitations of previous PCR technology and provides a single step, reliable method of species identification and rapid diagnostic applications.

Crystal structures of Leishmania mexicana arginase complexed with α,α-disubstituted boronic amino-acid inhibitors

Leishmania arginase is a potential drug target for the treatment of leishmaniasis because this binuclear manganese metalloenzyme initiates de novo polyamine biosynthesis by catalyzing the hydrolysis of L-arginine to generate L-ornithine and urea. The product L-ornithine subsequently undergoes decarboxylation to yield putrescine, which in turn is utilized for spermidine biosynthesis. Polyamines such as spermidine are essential for the growth and survival of the parasite, so inhibition of enzymes in the polyamine-biosynthetic pathway comprises an effective strategy for treating parasitic infections. To this end, two X-ray crystal structures of L. mexicana arginase complexed with α,α-disubstituted boronic amino-acid inhibitors based on the molecular scaffold of 2-(S)-amino-6-boronohexanoic acid are now reported. Structural comparisons with human and parasitic arginase complexes reveal interesting differences in the binding modes of the additional α-substituents, i.e. the D side chains, of these inhibitors. Subtle differences in the three-dimensional contours of the outer active-site rims among arginases from different species lead to different conformations of the D side chains and thus different inhibitor-affinity trends. The structures suggest that it is possible to maintain affinity while fine-tuning intermolecular interactions of the D side chain of α,α-disubstituted boronic amino-acid inhibitors in the search for isozyme-specific and species-specific arginase inhibitors.

Differential ecological traits of two Phlebotomus sergenti mitochondrial lineages in southwestern Europe and their epidemiological implications

OBJECTIVES

The introduction of leishmaniasis in a new area requires a well-established population of the sandfly vector species of the parasite. No autochthonous cases of anthroponotic cutaneous leishmaniasis have been detected in southwestern Europe, and Leishmania infantum is the only causative agent of leishmaniasis in this area. Phlebotomus sergenti, the main vector of Leishmania tropica, is commonly found in the Iberian Peninsula at sufficient densities to be able to act as a vector. It is characterised by high genetic diversity and classified in four mitochondrial lineages. Our aim was to analyse the composition and distribution of P. sergenti mitochondrial lineages in southwestern Europe given the possibility of phenotypic differences of biomedical importance between them.

METHODS

Sandflies were captured in the Iberian Peninsula and on the Canary and Balearic Islands. Mitochondrial lineage identification of 137 P. sergenti was performed using a novel PCR-RFLP that avoids the necessity of gene sequencing.

RESULTS

Two lineages were evidenced, the typical Iberian one (lineage I) and another, held in common with North Africa (lineage III), that show a distinctive distribution. P. sergenti lineage I shows a better correlation to the bioclimatic diversity in southwestern Europe. Conversely, P. sergenti lineage III prefers warmer temperatures and less precipitation, which are typical of the Mediterranean.

CONCLUSION

Lineage I seems to have adaptive advantages given its wider tolerance to temperature and altitude than lineage III, and it would seem more suitable to lead a potential geographical expansion towards the rest of Europe.

Outbreak of Cutaneous Leishmaniasis in Peruvian Military Personnel Undertaking Training Activities in the Amazon Basin, 2010

Military personnel deployed to the Amazon Basin are at high risk for cutaneous leishmaniasis (CL). We responded to an outbreak among Peruvian Army personnel returning from short-term training in the Amazon, conducting active case detection, lesion sample collection, and risk factor assessment. The attack rate was 25% (76/303); the incubation period was 2-36 weeks (median = 8). Most cases had one lesion (66%), primarily ulcerative (49%), and in the legs (57%). Real-time polymerase chain reaction (PCR) identified Leishmania (Viannia) braziliensis (59/61 = 97%) and L. (V.) guyanensis (2/61 = 3%). Being male (risk ratio [RR] = 4.01; P = 0.034), not wearing long-sleeve clothes (RR = 1.71; P = 0.005), and sleeping in open rooms (RR = 1.80; P = 0.009) were associated with CL. Sodium stibogluconate therapy had a 41% cure rate, less than previously reported in Peru (~70%; P < 0.001). After emphasizing pre-deployment education and other basic prevention measures, trainees in the following year had lower incidence (1/278 = 0.4%; P < 0.001). Basic prevention can reduce CL risk in deployed militaries.

Epidemiology of Imported Leishmaniasis in Italy: Implications for a European Endemic Country

In the past decade, the number of imported leishmaniasis cases has increased in countries of Western Europe. The trend is associated with increasing travels, ecotourism activity, military operations and immigration. While in endemic countries leishmaniasis is usually well diagnosed, accurate patient history and parasite identification are necessary to distinguish between autochthonous and imported cases. This is particularly important, as new Leishmania species/genotypes may be introduced and transmitted by local phlebotomine vectors without appropriate surveillance, with unpredictable consequences. We report on the surveillance of imported leishmaniasis performed by the Leishmania Identification Reference Centre of Rome from 1986 through 2012, involving health care centres from 16/20 Italian regions. Suspected imported cases were analyzed and conclusions were based on clinical, epidemiological and diagnostic findings. Over the years, different parasite identification methods were employed, including MultiLocus Enzyme Electrophoresis and molecular techniques combining disease diagnosis (SSU rDNA nested-PCR) and Leishmania typing (nuclear repetitive sequence and ITS-1 PCR-RFLPs). A total of 105 imported cases were recorded (annual range: 0-20) of which 36 were visceral (VL) (16 HIV-coinfections) and 69 cutaneous (CL) cases; 85 cases (52 CL) were from the Old World and 20 (17 CL) from the New World. Eight Leishmania species were identified, of which 7 were exotic to Italy. VL importation until 1995 was associated with the spread of Mediterranean Leishmania-HIV co-infections in early 1990s. Following the introduction of HAART treatment, such cases became occasional in Italians but relatively frequent among immigrants. In contrast, a steady increase of CL cases was observed from different areas of the Old and New Worlds, that in recent years included mainly immigrants ‘visiting friends and relatives’ and Italian tourists. This positive trend likely depends on better diagnosis and reporting; however, we suspect that many CL cases remained unrecognized. Given the relatively low incidence of leishmaniasis importation, the risk of introduction of exotic parasites appears limited, although the detection of anthroponotic species requires attention.

Coinjection with TLR2 agonist Pam3CSK4 reduces the pathology of leishmanization in mice

Cutaneous leishmaniasis caused by Leishmania major is an emergent, uncontrolled public health problem and there is no vaccine. A promising prophylactic approach has been immunotherapy with Toll-like receptor (TLR) agonists to enhance parasite-specific immune responses. We have previously reported that vaccination of C57BL/6 mice with live L. major plus the TLR9 agonist CpG DNA prevents lesion development and confers immunity to reinfection. Our current study aims to investigate whether other TLR agonists can be used in leishmanization without induction of lesion formation. We found that live L. major plus the TLR2 agonist Pam3CSK4 reduced the pathology in both genetically resistant (C57BL/6) and susceptible (BALB/c) mouse strains. The addition of Pam3CSK4 activated dermal dendritic cells and macrophages to produce greater amounts of proinflammatory cytokines in both mouse strains. Both Th1 and Th17 responses were enhanced by leishmanization with L. major plus Pam3CSK4 in C57BL/6 mice; however, Th17 cells were unchanged in BALB/c mice. The production of IL-17 from neutrophils was enhanced in both strains infected with L. major plus Pam3CSK4. However, the sustained influx of neutrophils in sites of infection was only observed in BALB/c mice. Our data demonstrate that the mechanism behind leishmanization with TLR agonists may be very different depending upon the immunological background of the host. This needs to be taken into account for the rational development of successful vaccines against the disease.

Cutaneous leishmaniasis is a skin infection caused by a protozoan parasite Leishmania major (L. major). The only available treatment option is chemotherapy, which is toxic and expensive. Currently, there is no vaccine. Although inoculation of virulent L. major (leishmanization) that provides effective protection in humans was widely applied, it was discontinued due to safety concerns. To improve the safety of leishmanization, we applied agonists of Toll-like receptor in the leishmanization to induce parasite-specific immune responses. In particular, we show here that inoculation with live L. major plus a TLR2 agonist Pam3CSK4 in both resistant (C57BL/6) and susceptible (BALB/c) mouse strains completely prevents the development of lesion and decreases parasite burden. The improved pathology is associated with enhanced production of IL-6 and IL-12 from dermal dendritic cells and macrophages. Both Th1 and Th17 responses are enhanced in C57BL/6 mice. Although only the Th1 response was enhanced in BALB/c mice in the presence of Pam3CSK4, there is an enhanced and sustained neutrophil influx at sites of infection. Overall, our study reveals the clinical significance of TLR2 agonist in treating cutaneous leishmaniasis. However, the protective mechanism may be quite different depending upon the genetic background of the host.

Molecular epidemiology of imported cases of leishmaniasis in Australia from 2008 to 2014

Leishmaniasis is a vector borne disease caused by protozoa of the genus Leishmania. Human leishmaniasis is not endemic in Australia though imported cases are regularly encountered. This study aimed to provide an update on the molecular epidemiology of imported leishmaniasis in Australia. Of a total of 206 biopsies and bone marrow specimens submitted to St Vincent’s Hospital Sydney for leishmaniasis diagnosis by PCR, 55 were found to be positive for Leishmania DNA. All PCR products were subjected to restriction fragment length polymorphism analysis for identification of the causative species. Five Leishmania species/species complexes were identified with Leishmania tropica being the most common (30/55). Travel or prior residence in a Leishmania endemic region was the most common route of acquisition with ~47% of patients having lived in or travelled to Afghanistan. Cutaneous leishmaniasis was the most common manifestation (94%) with only 3 cases of visceral leishmaniasis and no cases of mucocutaneous leishmaniasis encountered. This report indicates that imported leishmaniasis is becoming increasingly common in Australia due to an increase in global travel and immigration. As such, Australian clinicians must be made aware of this trend and consider leishmaniasis in patients with suspicious symptoms and a history of travel in endemic areas. This study also discusses the recent identification of a unique Leishmania species found in native kangaroos and a potential vector host which could create the opportunity for the establishment of a local transmission cycle within humans.

Species-directed therapy for leishmaniasis in returning travellers: a comprehensive guide. PLoS Negl Trop Dis. 2014;8:e2832. [PMID: 24787001 PMCID: PMC4006727 DOI: 10.1371/journal.pntd.0002832]

Background

Leishmaniasis is increasingly reported among travellers. Leishmania species vary in sensitivity to available therapies. Fast and reliable molecular techniques have made species-directed treatment feasible. Many treatment trials have been designed poorly, thus developing evidence-based guidelines for species-directed treatment is difficult. Published guidelines on leishmaniasis in travellers do not aim to be comprehensive or do not quantify overall treatment success for available therapies. We aimed at providing comprehensive species-directed treatment guidelines.

Methodology/Principal Findings

English literature was searched using PubMed. Trials and observational studies were included if all cases were parasitologically confirmed, the Leishmania species was known, clear clinical end-points and time points for evaluation of treatment success were defined, duration of follow-up was adequate and loss to follow-up was acceptable. The proportion of successful treatment responses was pooled using mixed effects methods to estimate the efficacy of specific therapies. Final ranking of treatment options was done by an expert panel based on pooled efficacy estimates and practical considerations. 168 studies were included, with 287 treatment arms. Based on Leishmania species, symptoms and geography, 25 clinical categories were defined and therapy options ranked. In 12/25 categories, proposed treatment agreed with highest efficacy data from literature. For 5/25 categories no literature was found, and in 8/25 categories treatment advise differed from literature evidence. For uncomplicated cutaneous leishmaniasis, combination of intralesional antimony with cryotherapy is advised, except for L. guyanensis and L. braziliensis infections, for which systemic treatment is preferred. Treatment of complicated (muco)cutaneous leishmaniasis differs per species. For visceral leishmaniasis, liposomal amphotericin B is treatment of choice.

Conclusions/Significance

Our study highlights current knowledge about species-directed therapy of leishmaniasis in returning travellers and also demonstrates lack of evidence for treatment of several clinical categories. New data can easily be incorporated in the presented overview. Updates will be of use for clinical decision making and for defining further research.

Human leishmaniasis is caused by unicellular parasites that are injected into the skin by sand-flies, small, flying insects. Many different Leishmania species cause various manifestations of disease, both of the skin and internal organs. Leishmaniasis is a curable disease but clear guidelines on the best available treatment are lacking. Leishmania species differ in sensitivity to available drugs. Until recently, identification of the infecting Leishmania parasite was laborious, thus therapy could not precisely be targeted to the infecting species, in contrast to many other infectious diseases. Nowadays, Leishmania parasites can be identified relatively easily with new DNA techniques. We studied efficacy of therapies for diseases due to different Leishmania species, limited to the English literature. Efficacy was summarized and presented in an easy to read format. Because of difficulties with identification of parasite species in earlier studies, quality of evidence was often limited. Our findings are a major help for clinicians to easily find optimal treatment for specific patients. Moreover, our results demonstrate where additional research is needed to further improve treatment of leishmaniasis.

Predicting the risk of an endemic focus of Leishmania tropica becoming established in south-western Europe through the presence of its main vector, Phlebotomus sergenti Parrot, 1917

The aim of the study was the construction of risk maps for exposure to Phlebotomus sergenti, the main vector of Leishmania tropica, with a view to identifying hot spots for the potential establishment of this parasite in the southwest of Europe. Data were collected on the presence/absence of this vector and the ecological and climatic characteristics of 662 sampling sites located in the southeast, centre and northeast of the Iberian Peninsula (south-western Europe). The environmental factors associated with the distribution of P. sergenti were determined. The best predictors for the presence of this dipteran were ‘altitude’, ‘land use’, ‘land surface temperature’, ‘aspect’, ‘adjacent land cover’, ‘absence of vegetation in wall’ and the ‘absence of PVC pipes in the drainage holes of retaining walls’. Risk maps for exposure to the vector were drawn up based on these variables. The validation of the predictive risk model confirmed its usefulness in the detection of areas with a high risk of P. sergenti being present. These locations represent potential hot spots for an autochthonous focus of L. tropica becoming established. The risk maps produced for P. sergenti presence revealed several areas in the centre and south of the Iberian Peninsula to be the most prone to this process, which would make it possible for the disease to enter south-western Europe.

Imported leishmaniasis in the Netherlands from 2005 to 2012: epidemiology, diagnostic techniques and sequence-based species typing from 195 patients

Leishmaniasis is an imported disease in the Netherlands. We report data for the period between 2005 and 2012, on clinical presentation, country where leishmaniasis was acquired, and causative species, for 195 civilian and military patients who had travelled abroad. Most patients were affected by cutaneous leishmaniasis (CL) (n=185 patients), while visceral leishmaniasis (VL) (n=8 patients) and mucocutaneous leishmaniasis (n=2 patients) were less frequently observed. All VL patients had been infected in Europe. CL was mainly acquired in Afghanistan, Surinam, Morocco and Spain. The majority of CL patients consisted of military personnel (55%, 102/185), 78 of whom had been infected during an outbreak in Afghanistan. Parasitological diagnosis was made by a combination of polymerase chain reaction (PCR), microscopy and culture. Compared to a standard of parasitological proof by any method other than the one under consideration, sensitivities of the individual methods ranged from 73% to 98%. Microscopy was least sensitive, but is fast and cheap. Mini-exon repeat PCR combines high sensitivity and specificity, and allows differentiation between species by sequencing of the PCR product. Eight different species or species complexes were identified, allowing species-specific therapy. Four patients proved infected with Leishmania naiffi, a hitherto rarely described cause of leishmaniasis. In comparison to previous decennia, an increase in cutaneous leishmaniasis was observed in our hospital, both in civilian and military patients who had travelled abroad. This calls for increased awareness among clinicians, availability of diagnostic tests and species-specific treatment guidelines in non-endemic countries.

Impact of global change on transmission of human infectious diseases

Global change, which refers to large-scale changes in the earth system and human society, has been changing the outbreak and transmission mode of many infectious diseases. Climate change affects infectious diseases directly and indirectly. Meteorological factors including temperature, precipitation, humidity and radiation influence infectious disease by modulating pathogen, host and transmission pathways. Meteorological disasters such as droughts and floods directly impact the outbreak and transmission of infectious diseases. Climate change indirectly impacts infectious diseases by altering the ecological system, including its underlying surface and vegetation distribution. In addition, anthropogenic activities are a driving force for climate change and an indirect forcing of infectious disease transmission. International travel and rural-urban migration are a root cause of infectious disease transmission. Rapid urbanization along with poor infrastructure and high disease risk in the rural-urban fringe has been changing the pattern of disease outbreaks and mortality. Land use changes, such as agricultural expansion and deforestation, have already changed the transmission of infectious disease. Accelerated air, road and rail transportation development may not only increase the transmission speed of outbreaks, but also enlarge the scope of transmission area. In addition, more frequent trade and other economic activities will also increase the potential risks of disease outbreaks and facilitate the spread of infectious diseases.

Crystal structure of arginase from Leishmania mexicana and implications for the inhibition of polyamine biosynthesis in parasitic infections

Arginase from parasitic protozoa belonging to the genus Leishmania is a potential drug target for the treatment of leishmaniasis because this binuclear manganese metalloenzyme catalyzes the first committed step in the biosynthesis of polyamines that enable cell growth and survival. The high resolution X-ray crystal structures of the unliganded form of Leishmania mexicana arginase (LmARG) and four inhibitor complexes are now reported. These complexes include the reactive substrate analogue 2(S)-amino-6-boronohexanoic acid (ABH) and the hydroxylated substrate analogue nor-N(ω)-hydroxy-l-arginine (nor-NOHA), which are the most potent arginase inhibitors known to date. Comparisons of the LmARG structure with that of the archetypal arginase, human arginase I, reveal that all residues important for substrate binding and catalysis are strictly conserved. However, three regions of tertiary structure differ between the parasitic enzyme and the human enzyme corresponding to the G62 - S71, L161 - C172, and I219 - V230 segments of LmARG. Additionally, variations are observed in salt link interactions that stabilize trimer assembly in LmARG. We also report biological studies in which we demonstrate that localization of LmARG to the glycosome, a unique subcellular organelle peculiar to Leishmania and related parasites, is essential for robust pathogenesis.

Clinical findings and management of imported cutaneous leishmaniasis: report of 14 cases from Austria

BACKGROUND

The management of cutaneous leishmaniasis in non-endemic countries is challenging due to the wide variety of clinical manifestations and little information available on treatment modalities for travellers.

METHODS

Retrospective analysis and follow-up investigation in patients with imported cutaneous leishmaniasis managed at the General Hospital Vienna from 2004 to 2010.

RESULTS

In total, 14 patients with cutaneous leishmaniasis were analyzed. The time to diagnosis ranged between weeks and several months and up to four consultations were necessary before diagnosis was accomplished. Histological investigations performed in all patients were diagnostic for CL in 8 (57%) patients. PCR analyses were performed in 12 patients and were positive in 10 (83%) patients. All six patients with negative histological results for CL tested positive in the PCR analysis. Treatment regimens applied included systemic therapy with liposomal amphotericin B, miltefosine, or fluconazole, and local therapy with cryotherapy, paromomycin ointment, photodynamic therapy, surgery, and various combinations.

CONCLUSIONS

The present analysis strongly suggests that awareness of CL among physicians and travellers remains low and highlights the need to harmonize diagnostic and treatment guidelines for cutaneous and mucosal leishmaniasis in European travellers. Diagnostic outcome can be improved by combining histology and PCR in patients with suspected cutaneous leishmaniasis.

Cutaneous leishmaniasis after travel to Cyprus and successful treatment with miltefosine

A patient presenting with an atypical manifestation of cutaneous leishmaniasis after travel to Cyprus was successfully treated with miltefosine. The K26 typing revealed a hitherto undescribed strain of the Leishmania donovani/infantum complex as the causing agent.

Leishmaniasis: new insights from an old and neglected disease. Eur J Clin Microbiol Infect Dis. 2012;31:109-118. [PMID: 21533874 DOI: 10.1007/s10096-011-1276-0]

Leishmaniases are a clinically heterogeneous group of diseases caused by protozoa of the genus Leishmania. There is growing evidence that the true incidence of the disease is underestimated, especially in hyperendemic regions. Moreover, climate changes together with the increasing movement of humans and animals raise concerns about the possible introduction of Leishmania infection in previously spared areas. The disease is emerging in immunocompromised patients undergoing bone marrow or solid organ transplantation or treatment with biologic drugs. Furthermore, the deployment of military troops and travel to endemic areas are associated with the observation of a growing number of patients with cutaneous disease. Improvement in diagnostic methods, both in the field and in specialized laboratories, has been obtained through the implementation of molecular amplification methods and using the rK39 antigen as the substrate. Finally, new therapeutic approaches are gaining attention, such as the use of miltefosine for cutaneous leishmaniasis and paromomycin for visceral leishmaniasis, as well as the use of various antileishmanial drugs in combination.

Protein network prediction and topological analysis in Leishmania major as a tool for drug target selection

Background

Leishmaniasis is a virulent parasitic infection that causes a worldwide disease burden. Most treatments have toxic side-effects and efficacy has decreased due to the emergence of resistant strains. The outlook is worsened by the absence of promising drug targets for this disease. We have taken a computational approach to the detection of new drug targets, which may become an effective strategy for the discovery of new drugs for this tropical disease.

Results

We have predicted the protein interaction network of Leishmania major by using three validated methods: PSIMAP, PEIMAP, and iPfam. Combining the results from these methods, we calculated a high confidence network (confidence score > 0.70) with 1,366 nodes and 33,861 interactions. We were able to predict the biological process for 263 interacting proteins by doing enrichment analysis of the clusters detected. Analyzing the topology of the network with metrics such as connectivity and betweenness centrality, we detected 142 potential drug targets after homology filtering with the human proteome. Further experiments can be done to validate these targets.

Conclusion

We have constructed the first protein interaction network of the Leishmania major parasite by using a computational approach. The topological analysis of the protein network enabled us to identify a set of candidate proteins that may be both (1) essential for parasite survival and (2) without human orthologs. These potential targets are promising for further experimental validation. This strategy, if validated, may augment established drug discovery methodologies, for this and possibly other tropical diseases, with a relatively low additional investment of time and resources.

Infection with arginase-deficient Leishmania major reveals a parasite number-dependent and cytokine-independent regulation of host cellular arginase activity and disease pathogenesis

The balance between the products of L-arginine metabolism in macrophages regulates the outcome of Leishmania major infection. L-arginine can be oxidized by host inducible NO synthase to produce NO, which contributes to parasite killing. In contrast, L-arginine hydrolysis by host arginase blocks NO generation and provides polyamines, which can support parasite proliferation. Additionally, Leishmania encode their own arginase which has considerable potential to modulate infectivity and disease pathogenesis. In this study, we compared the infectivity and impact on host cellular immune response in vitro and in vivo of wild-type (WT) L. major with that of a parasite arginase null mutant (arg(-)) L. major. We found that arg(-) L. major are impaired in their macrophage infectivity in vitro independent of host inducible NO synthase activities. As with in vitro results, the proliferation of arg(-) L. major in animal infections was also significantly impaired in vivo, resulting in delayed onset of lesion development, attenuated pathology, and low parasite burden. Despite this attenuated pathology, the production of cytokines by cells from the draining lymph node of mice infected with WT and arg(-) L. major was similar at all times tested. Interestingly, in vitro and in vivo arginase levels were significantly lower in arg(-) than in WT-infected cases and were directly correlated with parasite numbers inside infected cells. These results suggest that Leishmania-encoded arginase enhances disease pathogenesis by augmenting host cellular arginase activities and that contrary to previous in vitro studies, the host cytokine response does not influence host arginase activity.

Epidemiology of neglected tropical diseases in transplant recipients: review of the literature and experience of a Brazilian HSCT center

The rising success rate of solid organ (SOT) and haematopoietic stem cell transplantation (HSCT) and modern immunosuppression make transplants the first therapeutic option for many diseases affecting a considerable number of people worldwide. Consequently, developing countries have also grown their transplant programs and have started to face the impact of neglected tropical diseases (NTDs) in transplant recipients. We reviewed the literature data on the epidemiology of NTDs with greatest disease burden, which have affected transplant recipients in developing countries or may represent a threat to transplant recipients living in other regions. Tuberculosis, Leprosy, Chagas disease, Malaria, Leishmaniasis, Dengue, Yellow fever and Measles are the topics included in this review. In addition, we retrospectively revised the experience concerning the management of NTDs at the HSCT program of Amaral Carvalho Foundation, a public transplant program of the state of São Paulo, Brazil.

Tropical medicine rounds: Treatment of Old World cutaneous leishmaniasis with dapsone, itraconazole, cryotherapy, and imiquimod, alone and in combination

BACKGROUND

Cutaneous leishmaniasis (CL) is a major public health problem. The currently available therapies are expensive, not freely available, toxic, and not always curative. A simple, effective, noninvasive therapeutic approach is required for the treatment of CL.

AIMS

To determine the clinical patterns of CL and to report our experience in the management of CL.

METHODS

One hundred and ten patients with CL seen between January 2005 and December 2007 were included in this study. The diagnosis was based on clinical features, parasitologic diagnosis, histopathology, and culture. Each patient was treated according to disease severity with either topical (cryotherapy or imiquimod) or systemic (itraconazole or dapsone) monotherapy, or a combination of these modalities.

RESULTS

CL was more common in adult expatriate men, with the upper limbs as the most commonly affected site. Noduloulcerative CL was the most common presentation (84.6%). Atypical CL was found in 18 patients. Skin biopsy was the most common diagnostic technique (66.6%). Monotherapy showed an overall success rate of 56.41%, whereas combination therapy was successful in 69.56% of cases. Cryotherapy alone was successful in 68.18% of cases. Imiquimod alone was ineffective.

CONCLUSION

A stepwise approach represents a rational and practical way of confirming CL. A combination of itraconazole/dapsone and topically applied imiquimod is safe, simple, and effective for the treatment of CL. More studies are needed to establish the role of such an approach. Cryotherapy is also safe, simple and effective for the treatment of CL.

Vaccination with live Leishmania major and CpG DNA promotes interleukin-2 production by dermal dendritic cells and NK cell activation

Cutaneous leishmaniasis due to Leishmania major is an emerging, chronic parasitic disease that causes disfigurement and social stigmatization. Drug therapy is inadequate, and there is no vaccine. Inoculation of virulent parasites (leishmanization) is the only intervention that has ever provided protection, because it mimics natural infection and immunity, but it was discontinued due to safety concerns (uncontrolled vaccinal lesions). In an effort to retain the benefits (immunity) while avoiding the side effects (lesions) of leishmanization, we immunized C57BL/6 mice with L. major and CpG DNA (Lm/CpG). This combination prevented lesions while inducing immunity. Also, the vaccination with live parasites and the Toll-like receptor 9 agonist enhanced innate immune responses by activating dermal dendritic cells (DCs) to produce cytokines. Here we report that the Lm/CpG vaccine induced dermal DCs, but not bone marrow-derived DCs, to produce interleukin-2 (IL-2). The release of this unusual DC-derived cytokine was concomitant with a peak in numbers of NK cells that produced gamma interferon (IFN-gamma) and also enhanced activation of proliferation of IFN-gamma+ CD4+ T cells. Parasite growth was controlled in Lm/CpG-vaccinated animals. This is the first demonstration of the ability of dermal DCs to produce IL-2 and of the activation of NK cells by vaccination in the context of leishmaniasis. Understanding how the Lm/CpG vaccine enhances innate immunity may provide new tools to develop vaccines against L. major, other chronic infectious diseases, or other conditions, such as cancer.

The antituberculosis drug pyrazinamide affects the course of cutaneous leishmaniasis in vivo and increases activation of macrophages and dendritic cells

Antileishmanial therapy is suboptimal due to toxicity, high cost, and development of resistance to available drugs. Pyrazinamide (PZA) is a constituent of short-course tuberculosis chemotherapy. We investigated the effect of PZA on Leishmania major promastigote and amastigote survival. Promastigotes were more sensitive to the drug than amastigotes, with concentrations at which 50% of parasites were inhibited (MIC(50)) of 16.1 and 8.2 microM, respectively (48 h posttreatment). Moreover, 90% of amastigotes were eliminated at 120 h posttreatment, indicating that longer treatments will result in parasite elimination. Most strikingly, PZA treatment of infected C57BL/6 mice resulted in protection against disease and in a 100-fold reduction in the parasite burden. PZA treatment of J774 cells and bone marrow-derived dendritic cells and macrophages increased interleukin 12, tumor necrosis factor alpha, and activation marker expression, as well as nitric oxide production, suggesting that PZA enhances effective immune responses against the parasite. PZA treatment also activates dendritic cells deficient in Toll-like receptor 2 and 4 expression to initiate a proinflammatory response, confirming that the immunostimulatory effect of PZA is directly caused by the drug and is independent of Toll-like receptor stimulation. These results not only are strongly indicative of the promise of PZA as an alternative antileishmanial chemotherapy but also suggest that PZA causes collateral immunostimulation, a phenomenon that has never been reported for this drug.

Leishmaniasis, an emerging imported infection: report of 20 cases from Australia

Leishmaniasis is a protozoan infection rarely reported in Australia. However, with the advent of increased international tourism and migration of refugees from endemic regions, leishmaniasis has emerged as an increasingly imported infection. We report 20 cases (17 cutaneous, 2 visceral, and 1 post-kala-azar dermal leishmaniasis). These data highlight the range of species causing leishmaniasis imported in Australia and demonstrate the importance of species identification in determining proper treatment.

Immunomodulatory effects associated with a live vaccine against Leishmania major containing CpG oligodeoxynucleotides

The inoculation of live Leishmania major to produce a lesion that heals (leishmanization) is to date the only vaccine against cutaneous leishmaniasis that has proven effective in humans, but it still has an unacceptable frequency of large ulcerating lesions that are slow to heal or, in rare cases, non-healing. We have previously shown that C57BL/6 mice vaccinated intradermally with 10(4) L. major/50 microg CpG oligodeoxynucleotides develop little or no dermal lesions and show early containment of parasite growth in the vaccination site, eliminating safety concerns related to the inoculation of live organisms. The addition of CpG to the live vaccine resulted in early activation of dermal dendritic cells and increased IL-6 production, as well as in a reduction in the accumulation of Foxp3(+)CD4(+)CD25(+) regulatory T (T(reg)) cells that naturally occurs in the skin following Leishmania infection. Neutralization of IL-6 caused the development of larger lesions and increased local T(reg) cell numbers. Transfer of vaccine-primed dendritic cells into IL-6-deficient mice mitigated lesion development, indicating that IL-6 reconstitution limited pathology in the vaccination site.

The current status of zoonotic leishmaniases and approaches to disease control

Leishmaniases are a complex of world-wide diseases with a range of clinical and epidemiological features caused by Leishmania spp. of protozoan parasites. Among 15 well-recognised Leishmania species known to infect humans, 13 have zoonotic nature, which include agents of visceral, cutaneous and mucocutaneous forms of the disease in both the Old and New Worlds. Currently, leishmaniases show a wider geographic distribution and increased global incidence of human disease than previously known. Environmental, demographic and human behavioural factors contribute to the changing landscape of leishmaniasis, which includes increasing risk factors for zoonotic cutaneous leishmaniases and new scenarios associated with the zoonotic visceral leishmaniases. The latter consist of the northward spread of Leishmania infantum transmission in Europe and America, the identification of unusual mammal hosts, and the decline of HIV-Leishmania co-infections in southern Europe following the introduction of the highly active antiretroviral therapy. Few advances have been made in the surveillance and control of the zoonotic leishmaniasis, however a number of tools have been developed for the control of the canine reservoir of L. infantum. These include: (i) several canine vaccine candidates, in particular an FML Leishmania enriched fraction showing good clinical protection, has been registered in Brazil for veterinary use; (ii) a number of insecticide-based preparations have been specifically registered for dog protection against sand fly bites. Laboratory and field studies have shown improved efficacy of these preparations for both individual and mass protection.