Rapid diagnosis of leishmaniasis by fluorogenic polymerase chain reaction

Metagenomic analysis of microbial cell-free DNA from plasma of patients with suspected infections: performance and therapeutic impact in clinical routine

OBJECTIVES

The sensitivity of blood cultures (BCs) is limited, especially when antimicrobial therapy already has been administered or when non-culturable pathogens are causing the disease. Metagenomic next-generation sequencing of cell-free DNA from plasma has the potential to compensate for the disadvantages of BC diagnostics.

METHODS

We conducted a retrospective study in patients with suspected infections over a period of 3 months. Cell-free DNA from plasma was analysed by metagenomic next-generation sequencing (Illumina NextSeq, 25 million reads per sample, read length 75 base pairs) and sequences were analysed with DISQVER®, a CE-IVDD-labelled software algorithm and curated database. The data were compared with findings obtained with simultaneously taken BC and other microbiological results (±7 days).

RESULTS

DISQVER® analysis was performed on 190 samples from 147 patients (124 adult and 23 paediatric). The median time-to-result including transport was 2 days (interquartile range, 2-3; range, 2-8). DISQVER® detected 158 pathogens (103 bacteria, 49 viruses, 4 fungi, and 1 parasite) in 80 plasma samples (positivity rate 42.1%). The median number of pathogens per positive sample was one (interquartile range, 1-2; range, 1-10). The most common bacteria were Enterobacterales (30.1%; 31/103), anaerobic bacteria (18.4%; 19/103), and Enterococcus spp. (15.5%; 16/103); the most frequent viruses were Epstein-Barr virus (28.6%; 14/49), human herpesvirus 6B (18.4%; 9/49), and human cytomegalovirus (18.4%; 9/49). Mycobacterium avium, Legionella pneumophila, Tropheryma whipplei, Rhizomucor pusillus, and Leishmania infantum were detected in one sample each. Simultaneous BC were positive in only 10.2% (18/176) of the samples, but were mostly (68.2%; 120/176) collected under antibiotic therapy. DISQVER® analysis resulted in 24 treatment changes in 20 patients (13.6%; 20/147; 9 start/escalation, 10 stop/de-escalation, 2 catheter replacements, and 3 other).

DISCUSSION

DISQVER® significantly increased the detection rate of pathogens, led to the diagnosis of serious infections that otherwise would have been missed, and possibly improved the treatment of more than 10% of patients.

Development of species-specific multiplex PCR for Leishmania identification

Leishmaniasis is a diverse group of clinical diseases caused by protozoan parasites of the Leishmania genus. Species-specific identification of Leishmania spp. is challenging due to the high number of different pathogenic species that sometimes co-circulate in the same foci, hampering efforts to effectively control the disease. Multiplex PCR is an attractive alternative for rapid differentiation of Leishmania species with high sensitivity and specificity. We aimed to generate a panel of primers optimized for a multiplex PCR assay capable of identifying different Leishmania species in a single reaction. Species-specific primers were designed based on genomic data using the TipMT tooL. Potential non-specific amplifications of other trypanosomatids as well as human, dog, and sandfly hosts were first evaluated in silico using the Primer-Blast tooL. Species-specific primers for Leishmania amazonensis, Leishmania braziliensis, Leishmania donovani, Leishmania infantum, Leishmania mexicana and for the Leishmania guyanensis complex were tested in vitro. The primers have a limit of detection ranging from 1 to 0.01 ng of parasite gDNA using the same annealing temperature of 66 °C. The primers were specific for their targets when tested against 13 species of Leishmania, six trypanosomatids, and Babesia sp., and to detect the target species in a prepared pool with gDNA of six pathogenic Leishmania species. The designed primers were optimized for multiplex PCR, enabling species-specific identification of all five Leishmania species and one species complex. This new primer set could allow for efficient, fast, and reliable identification of Leishmania parasites.

Novel detection of Leishmania RNA virus-1 (LRV-1) in clinical isolates of Leishmania Viannia panamensis

American tegumentary leishmaniasis comprises a discrete set of clinical presentations endemic to Latin America. Leishmania RNA virus-1 (LRV-1) is a double-stranded RNA virus identified in 20–25% of the Leishmania Viannia braziliensis and L. V. guyanensis, however not in L. V. panamensis. This is the first report of LRV-1 in L. V. panamensis and its associations with clinical phenotypes of ATL. Unique surplus discard clinical isolates of L. V. panamensis were identified from the Public Health Ontario Laboratory (PHOL) and the Leishmania Clinic of the Instituto de Medicina Tropical ‘Alexander von Humboldt’ between 2012 and 2019 and screened for LRV-1 by real-time polymerase chain reaction. Patient isolates were stratified according to clinical phenotype. Of 30 patients with L. V. panamensis, 14 (47%) and 16 (53%) patients had severe and non-severe ATL, respectively. Five (36%) of 14 severe cases and 2 (12%) of 16 non-severe cases were positive for LRV-1, respectively. No differences in sex were observed for clinical phenotype and LRV-1 status. Although an association between LRV-1 status and clinical phenotype was not demonstrated, this is the first description of the novel detection of LRV-1 in L. V. panamensis, a species that has been documented predominantly in Central America.

Spectrum of bacterial pathogens in inflammatory and noninflammatory cutaneous ulcers of American tegumentary leishmaniasis

Background

Cutaneous leishmaniasis (CL) ulcers exhibiting an inflammatory phenotype, characterized by purulent exudate, erythema, pain, and/or lymphatic involvement, are empirically treated with antibiotics.

Objective

The spectrum of bacteria present in localized versus inflammatory phenotypes of CL is elucidated herein.

Methods

Filter paper lesion impressions (FPLIs) from 39 patients with CL (19 inflammatory and 20 noninflammatory ulcers) were evaluated via real-time polymerase chain reaction (qPCR) and end-point PCR targeting: Staphylococcus aureus, Enterobacter cloacae, Streptococcus pyogenes, Enterococcus spp., Citrobacter freundii, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and 16S rDNA. Whole genome sequencing (WGS) was performed on six specimens.

Results

In total, 30/39 (77%) patients' ulcers had ⩾1 bacterium detected, which included the following species: S. aureus (n = 16, 41%), C. freundii (n = 13, 33%), P. aeruginosa (n = 12, 31%), E. cloacae (n = 12, 31%), K. pneumoniae (n = 11, 28%), Enterococcus spp. (n = 7, 18%), E. coli (n = 6, 15%), and S. pyogenes (n = 4, 10). Prevalence of bacterial species did not differ by CL phenotype (p = 0.63). However, patients with inflammatory phenotypes were, on average, over a decade older than patients with noninflammatory phenotypes (42 years vs 27 years) (p = 0.01). The inflammatory phenotype was more prevalent among ulcers of Leishmania Viannia braziliensis (58%) and L. V. panamensis (83%) compared to those of L. V. guyanensis (20%) (p = 0.0369).

Conclusion

The distribution of flora did not differ between inflammatory and noninflammatory CL phenotypes. Further prospective analysis, including additional WGS studies of all CL ulcers for nonbacterial organisms, is necessary to determine the role of empiric antibiotic therapy in inflammatory and purulent CL.

Molecular detection of Leishmania (Sauroleishmania) adleri (Trypanosomatida: Trypanosomatidae) in Sergentomyia sp. sand flies (Diptera: Psychodidae) in Mali and Niger

Phlebotomine sand flies of the genus Sergentomyia are considered to be of minor importance as vectors of Leishmania parasites pathogenic to humans, but are known to transmit lizard parasites of the subgenus Sauroleishmania, including L. (S.) adleri. However, knowledge on the geographic distribution of Sauroleishmania spp. and the infection rates in the vectors is very limited. Therefore, our study aimed (1) to further elucidate the distribution and prevalence of Sauroleishmania spp. in their respective vectors and (2) to assess the potential risk for occasional transmission of Leishmania parasites to international military personnel deployed in camps in Mali and Niger. A total of 1,482 wild-caught sand flies (Sergentomyia spp. and closely related Grassomyia spp.) were screened by real-time PCR for the presence of Leishmania DNA. Thirty-two sand fly pools were tested positive, with six from Mali and 26 from Niger. The DNA of four representative isolates was sequenced. The resulting sequences revealed a homology to L. adleri, which leads to the first report of this species from Mali and Niger to the best of our knowledge. The results suggest that Sergentomyia (Sintonius) clydei might be the natural sand fly vector, while Grassomyia spp. appear to be refractory. No Leishmania sp. pathogenic to humans was detected in these sand flies.

Tegumentary Leishmaniasis in Northeastern Italy from 2017 to 2020: A Neglected Public Health Issue

Tegumentary leishmaniasis (TL) includes cutaneous (CL) and mucosal (ML) leishmaniasis; despite being endemic in southern Europe, it is often underdiagnosed and underreported. This study aimed to retrospectively examine data collected from patients with TL in a selected area of northeastern Italy (Emilia-Romagna region, RER). A network of 10 diagnostic units within RER was established, and TL cases diagnosed in RER from 2017 to 2020 were evaluated. A total of 135 TL cases were collected (62% male, 38% female); patients ranged from 1 to 84 years, with a median age of 57. Among these cases, 113 (84%) were notified to the public health authorities. The average annual incidence of TL was 0.76 cases per 100,000 inhabitants. Infections were acquired within the RER in 84% of cases; the 113 autochthonous cases were distributed in the foothills areas of the region. We provide evidence of a defined spatial distribution of TL cases in a selected area of northeastern Italy, as well as a relevant number of ML cases. Our observations suggest the need to raise awareness about TL among clinicians and pathologists, promote the molecular confirmation of cases by reference laboratories, and encourage the establishment of surveillance networks for this neglected disease.

Quantitative Detection of Leishmania in Rhipicephalus microplus and Amblyomma sabanerae in the Peruvian Amazon Basin

Leishmaniasis is a disease of public importance with a complex transmission cycle. A quantitative PCR was developed by using the small subunit of the ribosomal RNA gene (SSU rRNA) as a DNA target, which is conserved in all Leishmania species. A TaqMan ^® probe was designed to have a high specificity. In all, 22 out of 23 (95.7%) ticks classified as R. microplus tested positive for Leishmania sp. The quantification was between 34.1 and 2197.1 parasites per tick in a range of 12 to 769 fg/uL. In addition, 9 out of 10 (90%) ticks classified as Amblyomma sabanerae tested positive for Leishmania sp. The quantification was between 448.6 and 5428.6 parasites per tick in a range of 157 to 1900 fg/µL. Leishmania sp. was identified in very high percentages in Rhipicephalus microplus and Amblyomma sabanerae from wild Pecari tajacu and Chelonoidis denticulata, in quantities of 34.1 and 5428.6 parasites per arthropod, and this could suggest that the ticks were parasitized by sucking blood from the animals from which they were collected. This is the first report about Leishmania parasites found in wild Rhipicephalus microplus and Amblyomma sabanerae, adding new information about the distribution and epidemiology of the parasite in sylvatic areas.

Elevated baseline expression of seven virulence factor RNA transcripts in visceralizing species of Leishmania: a preliminary quantitative PCR study

Introduction:

Leishmaniasis is a neglected tropical disease that manifests as three major disease phenotypes: cutaneous, mucocutaneous, and visceral. In this preliminary study, we quantified virulence factor (VF) RNA transcript expression in Leishmania species, stratified by geographic origin and propensity for specific disease phenotypes.

Methods:

Cultured promastigotes of 19 Leishmania clinical and ATCC isolates were extracted for total cellular RNA, cDNA was reverse transcribed, and qPCR assays were performed to quantify VF RNA transcript expression for hsp23, hsp70, hsp83, hsp100, mpi, cpb, and gp63.

Results:

Comparison of visceralizing species (Leishmania donovani, Leishmania chagasi, and Leishmania infantum) versus non-visceralizing species [Leishmania (Viannia) spp., Leishmania tropica, Leishmania major, Leishmania mexicana, and Leishmania amazonensis] revealed a significantly greater pooled transcript expression for visceralizing species (p = 0.0032). Similarly, Old World species demonstrated significantly higher VF RNA transcript expression than New World species (p = 0.0015). On a per-gene basis, species with a propensity to visceralize ubiquitously expressed higher levels of gp63 (p = 0.005), cpb (p = 0.0032), mpi (p = 0.0032), hsp23 (p = 0.0039), hsp70 (p = 0.0032), hsp83 (p = 0.0032), and hsp100 (p = 0.0032).

Conclusion:

Here, we provide quantitative, preliminary evidence of elevated VF RNA transcript expression driven largely by the visceralizing causative species of Leishmania. This work highlights the extensive heterogeneity in pathogenicity mechanisms between Leishmania species, which may partly underpin the fatal progression of visceral leishmaniasis.

Impact assessment of different DNA extraction methods for non-invasive molecular diagnosis of tegumentary leishmaniasis

The aim of this study was to evaluate two methods of nucleic acid extraction (spin-column-based method - commercial kit and direct boil - DB) from swab sampling compared to biopsy sampling for the diagnosis of tegumentary leishmaniasis (TL), (cutaneous - CL and mucocutaneous - MCL forms). The impact of these nucleic acid extraction protocols on different types of PCR and LAMP techniques were compared regarding nucleic acid quality, molecular assays accuracy, indirect quantitation, and costs. The evaluated patients were 57 TL cases (36 CL and 21 MCL) and 34 non-cases. Swab samples extracted by the DB method showed a higher DNA degradation rate and worse DNA quality in comparison to the commercial kit. Molecular tests performed on biopsy samples showed identical or higher performance in all analysis, as compared to their own performance on swab samples for TL (CL and MCL). However, only the SSU rRNA TaqMan™ RT-PCR test showed a significant difference between the performance of biopsy and swab samples extracted by commercial kit. The kDNA-cPCR coupled with swab extracted by commercial kit showed the highest accuracy (95.6%) for TL diagnosis. The sensitivity of the LAMP-RT 18S method in swab samples extracted with a commercial kit (82.5%) was close to that found in biopsy samples (86%) for TL diagnosis. The DB extraction method presented the lowest cost. The use of swab as a minimally-invasive sampling method, associated with an efficient nucleic acid extraction protocol, may represent a low-cost alternative for the diagnosis of CL and MCL.

Leishmania RNA virus-1 is similarly detected among metastatic and non-metastatic phenotypes in a prospective cohort of American Tegumentary Leishmaniasis

American Tegumentary Leishmaniasis (ATL) is an endemic and neglected disease of South America. Here, mucosal leishmaniasis (ML) disproportionately affects up to 20% of subjects with current or previous localised cutaneous leishmaniasis (LCL). Preclinical and clinical reports have implicated the Leishmania RNA virus-1 (LRV1) as a possible determinant of progression to ML and other severe manifestations such as extensive cutaneous and mucosal disease and treatment failure and relapse. However, these associations were not consistently found in other observational studies and are exclusively based on cross-sectional designs. In the present study, 56 subjects with confirmed ATL were assessed and followed out for 24-months post-treatment. Lesion biopsy specimens were processed for molecular detection and quantification of Leishmania parasites, species identification, and LRV1 detection. Among individuals presenting LRV1 positive lesions, 40% harboured metastatic phenotypes; comparatively 58.1% of patients with LRV1 negative lesions harboured metastatic phenotypes (p = 0.299). We found treatment failure (p = 0.575) and frequency of severe metastatic phenotypes (p = 0.667) to be similarly independent of the LRV1. Parasite loads did not differ according to the LRV1 status (p = 0.330), nor did Leishmanin skin induration size (p = 0.907) or histopathologic patterns (p = 0.780). This study did not find clinical, parasitological, or immunological evidence supporting the hypothesis that LRV1 is a significant determinant of the pathobiology of ATL.

The Leishmania RNA virus-1 (LRV1) has been implicated as a possible modulator agent in the pathogenesis of leishmaniasis. In-vivo and in-vitro studies have depicted specific mechanisms of how LRV1 could lead to metastasis. Clinical studies and epidemiological evidence have both supported and rejected the hypothesis that LRV1 is a relevant determinant of progression, treatment failure and clinical severity of American Tegumentary Leishmaniasis (ATL). This lack of consistency between preclinical and clinical reports requires further longitudinal studies to clarify the role of LRV1 in ATL. Due to the complex nature of ATL, as other frequent human diseases, these studies should tackle multiple determinants of pathogenicity, including LRV1 status, parasite features, immune status, and prevalent comorbidities affecting individuals in endemic settings. Also, critical methodological aspects allowing for the reliable identification and quantification of LRV1 should be guaranteed.

Comparison of Three In-House Real PCR Assays Targeting Kinetoplast DNA, the Small Subunit Ribosomal RNA Gene and the Glucose-6-Phosphate Isomerase Gene for the Detection of Leishmania spp. in Human Serum

To perform PCR from serum for the diagnosis of visceral leishmaniasis is convenient and much less invasive than the examination of deeper compartments such as bone marrow. We compared three Leishmania-specific real-time PCRs with three different molecular targets (kinetoplast DNA, the small subunit-ribosomal RNA-(ssrRNA-)gene, the glucose-6-phosphate isomerase-(gpi-)gene) regarding their sensitivity and specificity in human serum. Residual sera from previous diagnostic assessments at the German National Reference Center for Tropical Pathogens Bernhard Nocht Institute for Tropical Medicine Hamburg and the Swiss Tropical and Public Health Institute were used. The sensitivities of kinetoplast DNA-PCR, ssrRNA-gene PCR, and gpi-PCR were 93.3%, 73.3%, and 33.3%, respectively, with 15 initial serum samples from visceral leishmaniasis patients, as well as 9.1%, 9.1%, and 0.0%, respectively, with 11 follow-up serum samples taken at various time points following anti-leishmanial therapy. Specificity was 100.0% in all assays as recorded with 1.137 serum samples from deployed soldiers and migrants without clinical suspicion of visceral leishmaniasis. Kinetoplast-DNA PCR from serum was confirmed as a sensitive and specific approach for the diagnosis of visceral leishmaniasis. The results also indicate the suitability of serum PCR for diagnostic follow-up after therapy, in particular regarding therapeutic failure in case of persisting positive PCR results.

Prospection of immunological biomarkers for characterization and monitoring of asymptomatic Leishmania (Leishmania) infantum infection

In areas endemic for Leishmania infantum, an asymptomatic infection may be an indicator of the extent of transmission. The main goal of this study was to evaluate the applicability of measuring circulating immunological biomarkers as an alternative strategy to characterize and monitor L. infantum asymptomatic infections in combination with serological methods. To this end, 179 children from a region endemic for visceral leishmaniasis (VL), aged 1-10 years old, selected from a cross-sectional study, were identified as asymptomatic (n = 81) or uninfected (n = 98) by qPCR and/or serological tests (ELISA using L. infantum soluble antigen and rK39), and, together with serum samples of children diagnosed with VL (n = 43), were subjected to avidity tests and cytokine levels measurement. Avidity rates (AR) ranging from 41 to 70% were found in 29 children (66%) from the asymptomatic group. On the other hand, high AR (above 70%) were observed in 27 children (64%) from the VL group. Logistic Regression and Classification and Regression Tree (CART) analyses demonstrated that lower AR and IFN-γ production associated with higher IL-17A levels were hallmarks in asymptomatic L. infantum infections. Therefore, this study proposes an association of immunological biomarkers that can be used as a complementary strategy for the characterization and monitoring of asymptomatic VL infections in children living in endemic areas.

Leishmania RNA Virus 1 (LRV-1) in Leishmania (Viannia) braziliensis Isolates from Peru: A Description of Demographic and Clinical Correlates

RNA virus 1-1 (LRV-1-1) is a dsRNA virus identified in isolates of Leishmania (Viannia) braziliensis and thought to advance localized cutaneous leishmaniasis (LCL) to mucocutaneous or mucosal leishmaniasis (MCL/ML). We examined the prevalence of LRV-1 and its correlation to phenotypes of American tegumentary leishmaniasis caused by L. (V.) braziliensis from Peru to better understand its epidemiology. Clinical isolates of L. (V.) braziliensis were screened for LRV-1 by real-time polymerase chain reaction (PCR) and stratified according to the phenotype: LCL (< 4 ulcers in number) MCL/ML; inflammatory ulcers (erythematous, purulent, painful ulcers with or without lymphatic involvement) or multifocal ulcers (≥ 4 in ≥ 2 anatomic sites). Proportionate LRV-1 positivity was compared across phenotypes. Of 78 L. (V.) braziliensis isolates, 26 (54.2%) had an inflammatory phenotype, 22 (28%) had the MCL/ML phenotype, whereas 30 (38.5%) had LCL. Mucocutaneous or mucosal leishmaniasis was found exclusively in adult male enrollees. Leishmania RNA virus 1 positivity by phenotype was as follows: 9/22 (41%) with MCL/ML; 5/26 (19%) with an inflammatory/multifocal cutaneous leishmaniasis phenotype; and 7/30 (23%) with LCL (P = 0.19). Leishmania RNA virus 1 positivity was not associated with age (P = 0.55) or gender (P = 0.49). Relative LRV-1 copy number was greater in those with MCL/ML than those with inflammatory/multifocal CL (P = 0.02). A direct association between LRV-1 status and clinical phenotype was not demonstrated; however, relative LRV-1 copy number was highest in those with MCL/ML. Future analyses to understand the relationship between viral burden and pathogenesis are required to determine if LRV-1 is truly a contributor to the MCL/ML phenotype.

Autochthonous Cases of Mucosal Leishmaniasis in Northeastern Italy: Clinical Management and Novel Treatment Approaches

Mucosal leishmaniasis (ML) is a rare clinical variant of tegumentary leishmaniasis in Mediterranean Europe. Here we report on three autochthonous cases of head and neck ML in patients living in Northeastern Italy. Patients presented with non-specific, long-standing symptoms of upper respiratory tract involvement, mimicking other diseases. Parasitological diagnosis was reached by histopathology, immunohistochemistry and molecular biology on tissue specimens. Leishmania infantum was identified by molecular typing in all three cases. All patients reached a complete remission with protracted multivalent antileishmanial drugs; in one case, a novel approach of combined medical and endoscopic surgical treatment was carried out. High clinical suspicion led to a prompt diagnosis and deployment of a multivalent treatment. ML should be considered in the differential diagnosis of nasal, oral, and pharyngolaryngeal lesions in endemic areas. A prompt diagnosis is mandatory to establish a correct management; different antileishmanial medications as well as endoscopic surgical options may be required to reach a complete remission.

PCR primers designed for new world Leishmania: A systematic review

Studies of the primers that were designed to detect New World Leishmania were systematically reviewed to report the characteristics of each target, detection limit, specificity of the primers designed and diagnostic sensibility. The papers identified in the databases PubMed and Web of Science involved 50 studies. Minicircle is the most applied target in molecular research for diagnosis, due to its high sensitivity in detecting Leishmania in different clinical samples, a characteristic that can be partially attributed to the higher number of copies of the minicircle per cell. The other molecular targets shown in this review were less sensitive to diagnostic use because of the lower number of copies of the target gene per cell, but more specific for identification of the subgenus and/or species. The choice of the best target is an important step towards the result of the research. The target allows the design of primers that are specific to the genus, subgenus or a particular species and also imparts sensitivity to the method for diagnosis. The findings of this systematic review provide the advantages and disadvantages of the main molecular targets and primers designed for New World Leishmania, offering information so that the researcher can choose the PCR system best suited to their research need. This is a timely and extremely thorough review of the primers designed for New World Leishmania.

A survey of sand flies (Diptera, Phlebotominae) along recurrent transit routes in Serbia

Serbia was a country endemic for leishmaniasis with rich and abundant sand fly fauna during the middle of the 20^th century. After 1968, the disease was considered as eradicated, and as a consequence, all research on vectors and pathogens was neglected. The recent detection of Leishmania infantum in sand flies and confirmed cases of leishmaniasis in humans and dogs indicated the risk of re-emergence in Serbia. Also, for millions of refugees/immigrants, Serbia is a transit route between East-Mediterranean and Middle-East countries, and Central/North Europe, and it is under constant risk of vector and disease introduction. Primary objectives of this research were to determine which sand fly species are present around transit routes, whether they include vectors of the Leishmania spp. moreover, is/are Leishmania spp. present in the vectors. Surveys were conducted at 55 locations, organised in four clusters, which covered main immigrant routes and shelters/camps as well as tourist/trade transit routes. In total, 367 sand fly specimens were collected. Nine species were identified: Phlebotomus papatasi, P. perfiliewi, P. tobbi, P. neglectus, P. sergenti, P. alexandri, P. simici, P. balcanicus and P. mascittii. Detection of P. alexandri represents the first record in Serbia. The diversity of sand fly species increased while the number of collected specimens per night decreased during the period of research neglection. Phlebotomus neglectus, a proven vector of L. infantum, was a predominant species in all surveyed clusters, and in 56,52% of locations, it was the only species present. Although all detected species are regarded either as proven or suspected vectors of Leishmania spp., screening of females for Leishmania presence resulted negative. Our study provides insight into the significant changes of sand fly fauna in Serbia during the end of XX and beginning of XXI century. Diverse sand fly fauna in Serbia suggests that the establishment of new leishmaniasis foci is possible.

Susceptibility testing of Leishmania spp. against amphotericin B and fluconazole using the Sensititre™ YeastOne™ YO9 platform

BACKGROUND

Current drug regimens for cutaneous leishmaniasis (CL) include toxic systemic therapies such as amphotericin B (AB) and pentavalent antimonials. Fluconazole (FZ) is a well-tolerated potential oral alternative for the management CL. To date, few objective data exist to guide clinical decision-making when selecting a therapeutic agent a priori, and standardized, clinically-approved drug susceptibility testing platforms for Leishmania spp. have yet to be established. The Sensititre™ YeastOne™ YO9 plate is a commercialized drug susceptibility plate including AB and FZ used for routine testing of non-fastidious yeast. Our objective was to adapt the readily available Sensititre™ YeastOne™ YO9 plate, to determine drug susceptibility profiles of AB and FZ in cultured isolates of Old World and New World Leishmania spp. for the treatment of CL.

METHODS

Promastigotes were cultured in Tobie's medium with Locke's overlay until log phase growth was achieved, inoculated into the Sensititre™ system, and incubated over 96 H. minimum inhibitory concentrations (MICs) were determined colorimetrically, and promastigote death was assessed by conventional microscopy out to 96- h. Colour change correlated to MIC values.

RESULTS

All strains tested exhibited MIC values for FZ that were ≥ 256 μg/mL. New World strains demonstrated reduced susceptibility to AB (0.25 μg/mL - 0.50 μg/mL AB) compared to Old World strains at 0.12 μg/mL AB (p = 0.02). Seventeen (61%) of 28 Viannia isolates versus 82% (27/33) of non-Viannia isolates were resistant at 0.12 μg/mL AB (p = 0.09). For L. V. braziliensis isolates, mean MIC for AB was 0.375 ± 0.14 μg/mL (range 0.25-0.50 μg/mL), while for isolates of L. V. panamensis it was 0.314 ± 0.26 μg/mL (range 0.12-1.0 μg/mL).

CONCLUSIONS

We adapted the Sensititre™ YeastOne™ YO9 plate for testing of Leishmania spp. susceptibility profiles for commonly used antifungals in the treatment of CL, including AB and FZ. Given its current utility in mycology, optimization of the system for potential clinical implementation in parasitology should be pursued. However evaluation of clinically relevant amastigote-stage stages, and higher concentrations of FZ beyond the upper limit concentration of the Sensititre™ YeastOne™ Y09 plate would be required.

Evaluation of the NovaLisa™ Leishmania Infantum IgG ELISA in A Reference Diagnostic Laboratory in A Non-Endemic Country

Anti-Leishmania antibodies may be detectable in patients with leishmaniasis. Here, we compared a commercial enzyme-linked immunosorbent assay (ELISA) for the detection of anti-Leishmania antibodies, with an immunofluorescence antibody test (IFAT) that is no longer commercially available. Eighty-six serum samples from 73 patients were tested. The results obtained by the NovaLisa™ Leishmania infantum IgG ELISA, interpreted according to the instructions of the manufacturer, but with a modified cut-off for borderline positive values, were compared with the IFAT results that were already available. Moreover, Leishmania Western blot IgG results were available for 43 of the samples. The overall concordance of ELISA and IFAT was 67%. The ELISA and IFAT tests scored as 24% and 15% of the samples being positive, respectively, while 13% and 33% scored as borderline-positive, respectively. Using a Western blot (WB) as the reference, the sensitivities and specificities for the positive plus borderline-positive samples combined was 95.5% (95% confidence interval (CI), 77.2–99.9%) and 81.0% (95% CI, 58.1–94.6%) for ELISA, and 95.5% (95% CI, 77.2–99.9%) and 42.9% (95% CI, 21.8–66.0%) for IFAT, respectively. Overall, the ELISA proved to be a cost-effective alternative to the IFAT, due to its higher accuracy and specificity, and with a consequently lower number of confirmatory WB tests being required. Lastly, we also present data on the associations between seroconversion and the type of leishmaniasis.

Double Infection With Leishmania tropica and L. major in an HIV Patient Controlled With High Doses of Amphotericin B

We present a unique case of disseminated Leishmaniasis in an HIV patient. Two different Leishmania species were identified by genomic sequencing in both bone marrow and skin. The Leishmania infection could be suppressed but not cured, despite a high dose of amphotericin B of nearly 65 g over more than 6 years.

Analytical Performance of a Loop-Mediated Isothermal Amplification Assay for Leishmania DNA Detection in Sandflies and Direct Smears of Patients with Cutaneous Leishmaniasis

Loop-mediated isothermal amplification (LAMP) is ideal for the detection of Leishmania DNA as it is a quick and easy-to-perform test that does not require complex or sophisticated equipment or infrastructure. However, the application of this technique in the detection of Leishmania DNA has not been comprehensively analyzed to date (analytical validation). Our objective was to evaluate the sensitivity and analytical specificity (anticipated reportable range [ARR], the limit of detection [LoD], and accuracy) of LAMP targeting the 18S rRNA gene in the diagnosis of six New World Leishmania species. We then applied the validated LAMP assay across 50 samples of sandflies and 50 direct smears from a recent outbreak of cutaneous leishmaniasis in Colombia to determine its diagnostic performance. The LAMP assay exclusively amplified the DNA of Leishmania spp., and an ARR of between 1 × 104 and 1 × 10-2 equivalent parasites/mL was determined. An LoD of 1 × 10-2 equivalent parasites/mL was established and there was no statistically significant variation in terms of accuracy. Finally, a sensitivity of 100% in direct smears and sandflies samples was calculated and a specificity of 90.9% for direct smears using microscopy as reference and 96.8% for sandflies using real-time polymerase chain reaction as reference were determined. To our knowledge, this is the first attempt to analytically validate a LAMP test to detect Leishmania DNA, which showed good diagnostic potential from sandflies and direct smear samples.

Serological and molecular tools to diagnose visceral leishmaniasis: 2-years' experience of a single center in Northern Italy

The diagnosis of visceral leishmaniasis (VL) remains challenging, due to the limited sensitivity of microscopy, the poor performance of serological methods in immunocompromised patients and the lack of standardization of molecular tests. The aim of this study was to implement a combined diagnostic workflow by integrating serological and molecular tests with standardized clinical criteria. Between July 2013 and June 2015, the proposed workflow was applied to specimens obtained from 94 in-patients with clinical suspicion of VL in the Emilia-Romagna region, Northern Italy. Serological tests and molecular techniques were employed. Twenty-one adult patients (22%) had a confirmed diagnosis of VL by clinical criteria, serology and/or real-time polymerase chain reaction; 4 of these patients were HIV-positive. Molecular tests exhibited higher sensitivity than serological tests for the diagnosis of VL. In our experience, the rK39 immunochromatographic test was insufficiently sensitive for use as a screening test for the diagnosis of VL caused by L. infantum in Italy. However, as molecular tests are yet not standardized, further studies are required to identify an optimal screening test for Mediterranean VL.

Exploring prognosis in chronic relapsing visceral leishmaniasis among HIV-infected patients: Circulating Leishmania DNA

BACKGROUND

Visceral leishmaniasis (VL) affecting HIV-infected patients is considered a challenging condition because of its high mortality and relapse rates. The approach of this condition is still surrounded by many uncertainties, especially regarding the criteria to institute and discontinue secondary prophylaxis for VL. The aim of this study was to evaluate the Leishmania parasitism kinetic assessed by polymerase chain reaction (PCR) as a possible tool in the prognostic assessment in a context in which patients are receiving highly active antiretroviral therapy and secondary prophylaxis.

METHODS

A prospective observation of Leishmania-HIV-co infected patients was performed and two groups with distinct clinical prognosis unpredicted by their CD4 count at the moment of VL diagnosis and not related to their HIV load control were confirmed.

RESULTS

Relapsing (R) and non-relapsing (NR) patients had similar antiviral therapy use rates, CD4 lymphocyte count medians and HIV load levels at VL-diagnosis. At the 12-month follow-up, R-patients presented a significantly lower CD4 lymphocyte count than NR-patients, without difference in HIV load control. The time between HIV and VL diagnoses was longer in the R than NR-group. Comparison between Kaplan-Meier relapse-free survival curves (time to relapse) using a log rank test showed that patients presenting circulating Leishmania DNA had a significantly higher risk of clinical VL relapse within 4 months after a positive test (p=0.001).

CONCLUSIONS

These results reinforce that a negative PCR could be a useful tool to support prophylaxis interruption among patients with CD4 counts above 200cells/mm³ and that a positive PCR suggests imminent VL relapse.

Leishmania infections: Molecular targets and diagnosis

Progress in the diagnosis of leishmaniases depends on the development of effective methods and the discovery of suitable biomarkers. We propose firstly an update classification of Leishmania species and their synonymies. We demonstrate a global map highlighting the geography of known endemic Leishmania species pathogenic to humans. We summarize a complete list of techniques currently in use and discuss their advantages and limitations. The available data highlights the benefits of molecular markers in terms of their sensitivity and specificity to quantify variation from the subgeneric level to species complexes, (sub) species within complexes, and individual populations and infection foci. Each DNA-based detection method is supplied with a comprehensive description of markers and primers and proposal for a classification based on the role of each target and primer in the detection, identification and quantification of leishmaniasis infection. We outline a genome-wide map of genes informative for diagnosis that have been used for Leishmania genotyping. Furthermore, we propose a classification method based on the suitability of well-studied molecular markers for typing the 21 known Leishmania species pathogenic to humans. This can be applied to newly discovered species and to hybrid strains originating from inter-species crosses. Developing more effective and sensitive diagnostic methods and biomarkers is vital for enhancing Leishmania infection control programs.

Immune Activation and Bacterial Translocation: A Link between Impaired Immune Recovery and Frequent Visceral Leishmaniasis Relapses in HIV-Infected Patients

The maintenance of chronic immune activation due to leishmaniasis or even due to microbial translocation is associated with immunosenescence and may contribute to frequent relapses. Our aim was to investigate whether patients with HIV-associated visceral leishmaniasis (VL/HIV) who experience a single episode of VL have different immunological behaviors in comparison to those who experience frequent relapses. VL/HIV patients were allocated to non-relapsing (NR, n = 6) and relapsing (R, n = 11) groups and were followed from the active phase of VL up to 12 months post-treatment (mpt). The patients were receiving highly active antiretroviral therapy (HAART) and secondary prophylaxis after VL therapy. During active VL, the two groups were similar in all immunological parameters, including the parasite load. At 6 and 12 mpt, the NR group showed a significant gain of CD4⁺ T cells, a reduction of lymphocyte activation, and lower soluble CD14 and anti-Leishmania IgG3 levels compared to the R group. The viral load remained low, without correlation with the activation. The two groups showed elevated but similar percentages of senescent T cells. These findings suggest a decreased ability of the R group to downmodulate immune activation compared to the NR group. Such functional impairment of the effector response may be a useful indicator for predicting clinical prognosis and recommending starting or stopping secondary prophylaxis.

Diagnosis and Treatment of Leishmaniasis: Clinical Practice Guidelines by the Infectious Diseases Society of America (IDSA) and the American Society of Tropical Medicine and Hygiene (ASTMH)

It is important to realize that leishmaniasis guidelines cannot always account for individual variation among patients. They are not intended to supplant physician judgment with respect to particular patients or special clinical situations. The IDSA and ASTMH consider adherence to these guidelines to be voluntary, with the ultimate determinations regarding their application to be made by the physician in the light of each patient's individual circumstances.

Detection of Leishmania infantum and a Novel Phlebovirus (Balkan Virus) from Sand Flies in Albania

OBJECTIVE

To organize entomological campaigns to trap sand flies in selected regions of Albania and to test them for the presence of existing or new phleboviruses and for leishmania DNA.

METHODS

Sand flies were collected in 14 locations from May to October 2014 using three different types of traps. Pools with a maximum of 30 individuals were prepared according to gender, trapping site, and trapping date; they were tested for the presence of (1) phlebovirus RNA with three different PCR systems (2) and Leishmania DNA using two different real-time PCR assays.

RESULTS

A total of 972 sand flies (568 females, 404 males) were aliquoted to 55 pools. Three pools (in two different regions) were positive for Leishmania infantum. Two pools (Kruje region) were positive for phlebovirus RNA and a 575-nucleotide (nt) colinearized sequence of a novel virus most closely related to but clearly distinct from Tehran virus (16% and 3% divergence at nt and amino acid levels). Next generation sequencing analysis indicated that this virus might be transmitted by either Phlebotomus neglectus, Phlebotomus tobbi, or both vectors.

CONCLUSIONS

Visceral leishmaniasis has been clinically recognized in Albania for at least 80 years; however, this is the first time that L. infantum, detected by molecular means, has been reported in sand flies in Albania. At the outset of this study, only Adria virus (Salehabad species) was recognized in Albania. A novel virus, Balkan virus, was identified and genetic analysis revealed that it belongs to the Sandfly fever Naples virus group containing human pathogens.

Detection and quantification of Leishmania infantum in naturally and experimentally infected animal samples

Leishmania infantum is one of the causative agents of visceral leishmaniasis (VL). VL is the most severe form of leishmaniasis and can be fatal if it is not properly treated. Although several PCR works are intended to detect L. infantum, in silico analysis of available primers and/or primer-probes reveals potential cross species amplification. Here, a TaqMan-based quantitative real time PCR (qPCR) assay was developed for specific detection and quantitation of L. infantum in tissue samples from experimentally or naturally infected animals, mice or dogs, respectively. For this assay, primers and probes were designed for the kinetoplast minicircle DNA of L. infantum. The qPCR assay achieved a detection limit of 0.01pg of parasite DNA, and allowed specific amplification of L. infantum in both asymptomatic and symptomatic naturally infected dogs with inter-assay variation coefficients between 0.05-0.11. There was no cross amplification with dog DNA or with L. braziliensis, L. donovani, L. major, L. tropica or Trypanosoma cruzi. In addition, our assay detected a significantly higher parasite load in symptomatic than in the asymptomatic animals (p<0.0001). We believe this approach will be a valuable tool for the specific detection of L. infantum in regions of sympatric transmission of VL-causing parasites.

Regulatory IgDhi B Cells Suppress T Cell Function via IL-10 and PD-L1 during Progressive Visceral Leishmaniasis

During visceral leishmaniasis (VL), Th1-based inflammation is induced to control intracellular parasites. Inflammation-based pathology was shown to be dampened by IL-10 and eventual programmed death 1-mediated T cell exhaustion. Cell type(s) responsible for the initiation of T cell-produced IL-10 during VL are unknown. CD19(+), CD5(-), CD1d(-), IgD(hi) regulatory B cells from healthy controls produced IL-10 in the absence of infection or stimulation, in contrast to IgD(lo/neg) B cells. IgD(hi) B cells may have a de novo versus induced regulatory program. The population of IgD(hi) B cells increased 3-fold as VL progressed. B cells from VL dogs were necessary and sufficient to suppress Th1 cell effector function. IgD(hi) B cells induced IL-10 production by T cells and IgD(lo) B cells. Blockage of B cell-specific PD-L1 restored Th1 responses. IgD(hi) regulatory B cells represent a novel regulatory B cell that may precipitate T cell exhaustion during VL.

Concurrent visual diagnosis and susceptibility profiling of the first line drug against visceral leishmaniasis by plasmonic detection of PCR amplified genetic biomarker

Visceral form of leishmaniasis (also known as Kala-azar) is a fatal neglected tropical disease affecting 95 countries worldwide. Recently, substantial proportion of resistance related treatment failure cases have been reported against its first line drug, sodium-antimony gluconate (SAG). We report an easy, fast, sensitive and cheap visual diagnosis and SAG susceptibility profiling for this disease based on recently recognized genetic biomarker and gold nanoparticle based plasmonic detection phenomenon. This is a non-gel, non-culture based detection technique, which can be used as simultaneous high throughput detection and SAG-susceptibility profiling in Leishmania endemic resource stringent countries.

Development of a TaqMan Array Card for Acute-Febrile-Illness Outbreak Investigation and Surveillance of Emerging Pathogens, Including Ebola Virus

Acute febrile illness (AFI) is associated with substantial morbidity and mortality worldwide, yet an etiologic agent is often not identified. Convalescent-phase serology is impractical, blood culture is slow, and many pathogens are fastidious or impossible to cultivate. We developed a real-time PCR-based TaqMan array card (TAC) that can test six to eight samples within 2.5 h from sample to results and can simultaneously detect 26 AFI-associated organisms, including 15 viruses (chikungunya, Crimean-Congo hemorrhagic fever [CCHF] virus, dengue, Ebola virus, Bundibugyo virus, Sudan virus, hantaviruses [Hantaan and Seoul], hepatitis E, Marburg, Nipah virus, o'nyong-nyong virus, Rift Valley fever virus, West Nile virus, and yellow fever virus), 8 bacteria (Bartonella spp., Brucella spp., Coxiella burnetii, Leptospira spp., Rickettsia spp., Salmonella enterica and Salmonella enterica serovar Typhi, and Yersinia pestis), and 3 protozoa (Leishmania spp., Plasmodium spp., and Trypanosoma brucei). Two extrinsic controls (phocine herpesvirus 1 and bacteriophage MS2) were included to ensure extraction and amplification efficiency. Analytical validation was performed on spiked specimens for linearity, intra-assay precision, interassay precision, limit of detection, and specificity. The performance of the card on clinical specimens was evaluated with 1,050 blood samples by comparison to the individual real-time PCR assays, and the TAC exhibited an overall 88% (278/315; 95% confidence interval [CI], 84% to 92%) sensitivity and a 99% (5,261/5,326, 98% to 99%) specificity. This TaqMan array card can be used in field settings as a rapid screen for outbreak investigation or for the surveillance of pathogens, including Ebola virus.

Spleen nodules: a potential hallmark of Visceral Leishmaniasis in young children

BACKGROUND

Visceral leishmaniasis (VL) is a severe disease caused by Leishmania infantum in the Mediterranean basin, and is associated with considerable morbidity and mortality. Infantile VL may begin suddenly, with high fever and vomiting, or insidiously, with irregular daily fever, anorexia, and marked splenomegaly. Delays in diagnosis of VL are common, highlighting the need for increased awareness of clinicians for VL in endemic European countries.

CASE PRESENTATION

We report 4 cases of young children in northern Italy presenting with persistent fever of unknown origin and diagnosed with VL by serological and molecular methods. At the time of diagnosis, these patients showed an unusual echographic pattern characterized by multiple iso-hypoechoic nodules associated with splenomegaly.

CONCLUSION

We suggest that detection of spleen nodules represents a signature of VL in infants, thus helping to diagnose systemic Leishmania infantum infection in children.

Detection of a broad range of Leishmania species and determination of parasite load of infected mouse by real-time PCR targeting the arginine permease gene AAP3

Leishmaniasis is one of the world's most neglected infectious diseases, affecting around 12 million people and more than 350 million at risk of infection. The clinical picture varies from self-healing cutaneous lesions to severe visceral infections, but still no commercial vaccines for humans are available and the currently used drugs have unpleasant side effects. Here we report a real-time PCR assay targeting the arginine permease gene AAP3 that can be applied for all the nine different species of the Leishmania genus tested; 4 Old World species and 5 New World species, from both L. (Leishmania) and L. (Viannia) subgenera. No cross-reaction was seen with Trypanosoma cruzi, Trypanosoma brucei, human or mouse genomic DNA. The assay has a high sensitivity, with a limit of detection of 10fg DNA for L. (L.) major and L. (L.) donovani, and 100fg DNA for L. (V.) braziliensis, and can be used for both qualitative and quantitative purposes. This AAP3-Assay, run in duplex with a host specific gene-assay, was also successfully used for quantification of parasite load of footpads from L. (L.) major-infected mice. It can therefore be a valuable tool in applications like monitoring effects of drugs, the selection of vaccine candidates and in screening patients, including asymptomatic carriers.

Real-time Leishmania genus master mix: a platform compatibility and stability study

Performing diagnostics and vector-pathogen surveillance in austere environments is challenging. On-site diagnostic/detection mitigates vector-borne disease complications during military or humanitarian deployments to disease endemic locals. The mobile molecular diagnostic platform, Joint Biological Agent Identification and Diagnostic System (JBAIDS; BioFire Diagnostics Inc., Salt Lake City, UT, USA), rapidly identifies biothreat pathogens. Although ideal for remote diagnostics, the platform was validated for specific pathogens of insignificant epidemiological consequence. Recognizing the JBAIDS's remote diagnostic/detection versatility, we tested a Leishmania genus real-time PCR master mix validated for use on the SmartCycler® (Cepheid, Sunnyvale, CA, USA) for concomitant use on the JBAIDS. We evaluated assay sensitivity, precision, and specificity of one or more Leishmania spp. on the JBAIDS and found that the JBAIDS produces superior detection sensitivity and specificity compared to the SmartCycler®. We also examined the storage stability of a bulk lot preparation of the Leishmania genus real-time PCR master mix on the SmartCycler® to ensure that long periods of frozen storage that would translate to a field environment with the JBAIDS were not detrimental to the reagent. We found that the bulk master mix maintains its stability over a 13-month time period. Overall, these studies confirm JBAIDS's versatility and demonstrate a streamlined assay development approach where reagents are compatible with both platforms.

Presence of Leishmania and Brucella species in the golden jackal Canis aureus in Serbia

The golden jackal Canis aureus occurs in south-eastern Europe, Asia, the Middle East, the Caucasus, and Africa. In Serbia, jackals neared extinction; however, during the last 30 years, the species started to spread quickly and to increase in number. Few studies in the past have revealed their potential role as carriers of zoonotic diseases. Animal samples were collected over a three-year period (01/2010–02/2013) from 12 sites all over Serbia. Of the tissue samples collected, spleen was chosen as the tissue to proceed; all samples were tested for Leishmania species and Brucella species by real-time PCR. Of the 216 samples collected, 15 (6.9%) were positive for Leishmania species, while four (1.9%) were positive for B. canis. The potential epidemiologic role of the golden jackal in carrying and dispersing zoonotic diseases in Serbia should be taken under consideration when applying surveillance monitoring schemes.

Programmed death 1-mediated T cell exhaustion during visceral leishmaniasis impairs phagocyte function

Control of Leishmania infantum infection is dependent upon Th1 CD4(+) T cells to promote macrophage intracellular clearance of parasites. Deficient CD4(+) T cell effector responses during clinical visceral leishmaniasis (VL) are associated with elevated production of IL-10. In the primary domestic reservoir of VL, dogs, we define occurrence of both CD4(+) and CD8(+) T cell exhaustion as a significant stepwise loss of Ag-specific proliferation and IFN-γ production, corresponding to increasing VL symptoms. Exhaustion was associated with a 4-fold increase in the population of T cells with surface expression of programmed death 1 (PD-1) between control and symptomatic populations. Importantly, exhausted populations of CD8(+) T cells and to a lesser extent CD4(+) T cells were present prior to onset of clinical VL. VL-exhausted T cells did not undergo significant apoptosis ex vivo after Ag stimulation. Ab block of PD-1 ligand, B7.H1, promoted return of CD4(+) and CD8(+) T cell function and dramatically increased reactive oxygen species production in cocultured monocyte-derived phagocytes. As a result, these phagocytes had decreased parasite load. To our knowledge, we demonstrate for the first time that pan-T cell, PD-1-mediated, exhaustion during VL influenced macrophage-reactive oxygen intermediate production. Blockade of the PD-1 pathway improved the ability of phagocytes isolated from dogs presenting with clinical VL to clear intracellular parasites. T cell exhaustion during symptomatic canine leishmaniasis has implications for the response to vaccination and therapeutic strategies for control of Leishmania infantum in this important reservoir species.

Comparison of parasitological, serological, and molecular tests for visceral leishmaniasis in HIV-infected patients: a cross-sectional delayed-type study

The aim of this study was to evaluate the accuracy of invasive and non-invasive tests for diagnosis of visceral leishmaniasis (VL) in a large series of human immunodeficiency virus (HIV)-infected patients. In this delayed-type cross-sectional study, 113 HIV-infected symptomatic patients were evaluated by an adjudication committee after clinical follow-up to establish the presence or absence of VL as the target condition (reference test). The index tests were recombinant K39 antigen-based immunochromatographic test (rK39), indirect fluorescent antibody test (IFAT), prototype kit of direct agglutination test (DAT-LPC), and real-time polymerase chain reaction (qPCR) in peripheral blood. Compared with parasitological test and adjudication committee diagnosis or latent class model analyses, IFAT and rk39 dipstick test presented the lowest sensitivity. DAT-LPC exhibited good overall performance, and there was no statistical difference between DAT-LPC and qPCR diagnosis accuracy. Real-time PCR emerges as a less invasive alternative to parasitological examination for confirmation of cases not identified by DAT.

Low parasite load estimated by qPCR in a cohort of children living in urban area endemic for visceral leishmaniasis in Brazil

BACKGROUND

An important issue associated with the control of visceral leishmaniasis is the need to identify and understand the relevance of asymptomatic infection caused by Leishmania infantum. The aim of this study was to follow the course of asymptomatic L. infantum infection in children in an area of Brazil where it is endemic. The children were assessed twice during a 12-month period.

METHODOLOGY

In this population study, 1875 children, ranging from 6 months to 7 years of age, were assessed. Blood samples were collected on filter papers via finger prick and tested by ELISA (L. infantum soluble antigen and rk39). Seropositives samples (n = 317) and a number of seronegatives samples (n = 242) were subjected to qPCR. After 12 months, blood samples were collected from a subgroup of 199 children and tested for Leishmania spp. to follow the course of infection.

PRINCIPAL FINDINGS

At baseline qPCR testing identified 82 positive samples. The prevalence rate, as estimated for 1875 children based on the qPCR results, was 13.9%. The qPCR testing of whole blood samples collected from a cohort of children after 12 months (n = 199) yielded the following results: of the 44 (22.1%) children with positive qPCR results at baseline, only 10 (5.0%) remained positive, and 34 (17.1%) became negative; and of the 155 (77.9%) children with negative qPCR results, 131 (65.8%) remained negative, and 24 (12.1%) became positive at the follow-up measurement. The samples with positive findings at baseline (n = 82) had a mean of 56.5 parasites/mL of blood; and at follow-up the mean positive result was 7.8 parasites/mL.

CONCLUSIONS

The peripheral blood of asymptomatic children had a low and fluctuating quantity of Leishmania DNA and a significant decrease in parasitemia at 1-year follow-up. Quantitative PCR enables adequate monitoring of Leishmania infection.

Lipsosomal amphotericin B for treatment of cutaneous leishmaniasis

Treatment options for cutaneous leishmaniasis in the United States are problematic because the available products are either investigational, toxic, and/or of questionable effectiveness. A retrospective review of patients receiving liposomal amphotericin B through the Walter Reed Army Medical Center for the treatment of cutaneous leishmaniasis during 2007-2009 was conducted. Twenty patients who acquired disease in five countries and with five different strains of Leishmania were treated, of whom 19 received a full course of treatment. Sixteen (84%) of 19 experienced a cure with the initial treatment regimen. Three patients did not fully heal after an initial treatment course, but were cured with additional dosing. Acute infusion-related reactions occurred in 25% and mild renal toxicity occurred in 45% of patients. Although the optimum dosing regimen is undefined and the cost and toxicity may limit widespread use, liposomal amphotericin B is a viable treatment alternative for cutaneous leishmaniasis.

[Choice of primers: a determining element in molecular diagnosis of cutaneous leishmaniasis]

The cutaneous leishmaniasis (CL) is a parasitic disease which represents a serious problem for the public health not only in Tunisia but also all over the world. Its diagnosis is based on the techniques which are usually used, direct examination and in vitro culture. Because of several factors, these techniques lack sensitivity. The molecular biology, which is indeed more rapid and more sensitive, has proved its effectiveness in diagnosis of the CL. There are two main aims for our research work. First, to show the contribution of the Polymerase Chain Reaction (PCR) during the diagnosis of CL (of course by comparing the results obtained when using this technique with those found through the direct examination); second, to compare the two pairs of primers which amplify the leishmanien gene coding for the 18s ribosomal sub-unit: the pair R221/R332 (PCR1) and the pair Lei70L/Lei70R (PCR2). Our work was carried out upon 299 samples. One hundred and eighty-eight of them were positive using the direct examination and/or the PCR and 111 were negative. Only two samples were positive using of course the direct examination in comparison with 74 which were positive when using only the PCR (PCR1 and/or PCR2). Among these 74 samples, 64 where positive using only PCR2 in comparison with two samples which were positive using only PCR1. The eight remaining samples were at once positive for the PCR1 and the PCR2. The PCR (notably the PCR2) has proved a more significant percentage of positivity in comparison with direct examination: 98.98% for the PCR and 60.6% for direct examination.

Role of Leishmania spp. infestation in nondiagnostic cutaneous granulomatous lesions: report of a series of patients from a Western Mediterranean area

BACKGROUND

Leishmaniasis is a parasitic disease prevalent in countries of the Mediterranean area.

OBJECTIVES

The potential role of Leishmania as the aetiological factor for cutaneous granulomatous lesions in a series of patients from a Western Mediterranean area was evaluated. The practical usefulness of Leishmania-specific polymerase chain reaction (PCR) amplification and immunohistochemical techniques in skin biopsy specimens was assessed.

METHODS

Twenty-five skin biopsies diagnosed as nonspecific granulomatous dermatoses were included in the study. A panel of histopathological features was blindly evaluated by two independent observers. Only those cases showing nondiagnostic clinicopathological features and lacking demonstrable microorganisms after bacteriological, mycological or mycobacteriological cultures and specific stains (Ziehl-Neelsen, Giemsa, Gram, periodic acid-Schiff stains) were finally selected. Quantitative real-time PCR was performed in all selected samples. In available samples, immunohistochemical detection of specific Leishmania spp. antigens was also performed.

RESULTS

From the selected 25 biopsies, Leishmania spp. DNA was detected by real-time PCR in 13 cases. In seven of eight PCR-positive cases the presence of a varying density of amastigotes could also be demonstrated immunohistochemically.

CONCLUSIONS

Leishmania infection seems to be an important aetiological factor in cutaneous granulomatous lesions showing nondiagnostic features in endemic areas. In such areas, Leishmania-specific PCR amplification and/or immunohistochemical studies may be useful diagnostic tools. These techniques may be specifically indicated in the evaluation of patients showing nonspecific granulomatous inflammatory infiltrates of unknown aetiology lacking the histopathological evidence of parasites.