Clinical utility of polymerase chain reaction-based detection of Leishmania in the diagnosis of American cutaneous leishmaniasis

Molecular investigation of leishmaniasis in stray dogs in Southwest Iran: Confirmation of cutaneous and visceral species in blood samples

Leishmaniasis, with various clinical manifestations, is prevalent and remains a significant zoonosis and public health concern in Iran. Dogs are the main reservoir of cutaneous and visceral leishmaniasis. A cross-sectional study was conducted to assess leishmaniasis in blood samples from 87 stray dogs (55 without skin lesions and 32 with skin lesions) from shelters in Shiraz, southwest Iran, for the first time. Blood samples were collected from all dogs (with and without skin lesions) and skin lesions from dogs with dermatological lesions. To amplify the conserved region of the Leishmania kDNA minicircle, samples were subjected to a species-specific PCR assay. Skin lesion smears were also assessed by microscopic examination. The PCR amplicons were sequenced, assembled, and multiple-aligned with Leishmania strains retrieved from GenBank. Finally, the phylogenetic analysis was carried out. The results showed 8.05 % (7/87) leishmaniasis in all dogs (with and without skin lesions) and 21.87 % (7/32) in dogs with skin lesions. No Leishmania infection was detected in dogs without skin lesions by PCR. A significant association was found between skin lesions and leishmaniasis (P = 0.001). No significant association was found between sex and infection (P = 0.65). Phylogenetic analysis interestingly identified three species, including L. major, L. tropica, and L. infantum, with 95-98 % identities to documented sequences. Microscopic examination of skin smears confirmed the presence of amastigotes in 15.62 % (5/32) of the dogs with skin lesions. This study highlights the importance of sheltered stray dogs with skin lesions as potential reservoirs in dispersing zoonotic visceral and cutaneous Leishmania spp. in this region. It emphasizes the need for surveillance and control measures in shelters to prevent Leishmania transmission to the vectors, humans, and animal hosts. The study also elucidated that cutaneous parasites, identified more in skin lesions by circulating in dog blood, can be detected using kDNA PCR.

Evaluation of the Diagnostic Sensitivity of the VIASURE Leishmania Real-Time PCR Detection Kit Prototype for the Diagnosis of Cutaneous and Visceral Leishmaniasis

Leishmaniasis is a parasitic disease with clinical presentations that vary from asymptomatic infection to cutaneous, mucocutaneous, or visceral disease. Global change, with migratory movements and travels, among others, has had an impact on the presentation of the clinical forms of leishmaniasis in a given area, hindering its diagnosis. The traditional parasitological techniques have limited sensitivity, and currently, there is no reference or gold-standard molecular diagnostic method. The aim of this study was to evaluate the effectivity of the VIASURE Leishmania Real-Time PCR Detection Kit prototype (CerTest Biotec, Zaragoza, Spain) for the diagnosis of autochthonous and imported leishmaniasis in comparison with two other commercialized molecular kits: STAT-NAT® Leishmania spp. (Sentinel, Milano, Italy) and Leishmania spp. Real-TM PCR Kit (Sacace Biotechnologies, Como, Italy). Four species of Leishmania, L. infantum, L. major, L. braziliensis, and L. panamensis, were targeted to assess analytical sensitivity, whereas diagnostic sensitivity was evaluated by studying a panel of 49 DNA samples from patients with suspected or confirmed Leishmania infection. The prototype could detect all the New and Old World species studied and achieved a limit of detection of 5 × 10-5 ng DNA/μL in all species. Also, it allowed the diagnosis of autochthonous and imported cases of cutaneous and visceral leishmaniasis (VL). Diagnostic sensitivity was 81.8% for the prototype and 100% for the Sacace kit (27 and 33 positive samples detected, respectively). The STAT-NAT® kit failed to detect Vianna species. The VIASURE Leishmania Real-Time PCR Detection Kit prototype was found to have good analytical and diagnostic sensitivity. Using a simple protocol and ready-to-use reagents, results are obtained quickly and are easy to interpret. The evaluation results indicate that the test is a promising candidate for routine diagnosis of cutaneous leishmaniasis and VL in endemic countries, but more studies are necessary to address its sensitivity and specificity.

Post kala-azar dermal leishmaniasis: A threat to elimination program

Leishmaniasis remains a public health concern around the world that primarily affects poor folks of the developing world spanning across 98 countries with mortality of 0.2 million to 0.4 million annually. Post kala-azar dermal leishmaniasis (PKDL) is the late skin manifestation of visceral leishmaniasis (VL). It has been reported that about 2.5% to 20% of patients recovered from VL develop PKDL having stilted macular or nodular lesions with parasites. In the Indian subcontinent (ISC), it manifests a few months after recovery from VL, though in Africa it can occur simultaneously with VL or a little later. New cases of PKDL are also observed without prior VL in the ISC. These individuals with PKDL represent an important but largely neglected reservoir of infection that perpetuates anthroponotic Leishmania donovani transmission in the ISC and can jeopardize the VL elimination program as these cases can infect the sand flies and spread the endemic. Therefore, it becomes imperative to eradicate PKDL as a part of the VL elimination program. With the limited treatment options besides little knowledge on PKDL, this review stands out in focusing on different aspects that should be dealt for sustained VL elimination.

American cutaneous leishmaniasis in infancy and childhood

Infant and young child skin diseases are among the most common features of morbidity throughout the tropics. Because the skin is directly exposed to the environment, it is considerably affected by climatic and local conditions such as vectors and microorganisms, as in the case of leishmaniasis. In America the observed magnitude of cutaneous leishmaniasis in children has led to the study of increased risk of exposure of this group due to the possibility of peri- and intradomiciliary transmission. The present review pretends to make a concrete approach all through the broad and main figures of this parasitic disease, including the clinical, physiopathological, epidemiological, diagnostic, and therapeutic aspects, in order to be used as a practical source of reference for pediatricians leading with tropical cutaneous pathology in the region.

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.

New serological tools for improved diagnosis of human tegumentary leishmaniasis

Human tegumentary leishmaniasis (HTL), characterized by skin ulcers that may spread and cause dreadful and massive tissue destruction of the nose and mouth, is considered a neglected tropical disease, and it is a serious threat to global health due to its continuous expansion, favored by the lifecycle of its causative organism that is maintained in domestic animal reservoirs and anthropophilic sand fly species. Serodiagnosis of HTL is a great challenge due to many biological factors, including hampered specificity and/or sensitivity. This investigation addresses the unmet need for new diagnostic markers of HTL, and describes a simple platform to improve the serodiagnosis. A constrained conformational phage display random peptide library combined with a magnetic microsphere-based subtraction strategy was used to identify ligands with potential diagnostic applications. Six clones were selected against IgG antibodies from HTL patients, characterized by sequencing and confirmed by a phage-ELISA using sera from patients developing visceral leishmaniasis (n=20), Chagas disease (n=10), mucosal (n=30) and cutaneous (n=20) leishmaniasis; as well as from healthy subjects living in endemic (n=20) and non-endemic (n=30) areas of leishmaniasis. A wild-type M13-phage clone and a soluble Leishmania antigenic extract were used as negative and positive controls, respectively. Three clones reached 100% sensitivity and specificity, without any cross-reactivity with sera from patients with leishmaniasis-related diseases. Briefly, we describe for the first time a set of serological markers based on three immunodominant mimotopes that showed 100% accuracy, and that could be used in a phage-ELISA assay for the HTL serodiagnosis.

Leishmaniasis: diagnostic issues in Europe

Leishmaniasis is a parasitic disease with clinical presentations that vary from asymptomatic infection to cutaneous, mucocutaneous or visceral disease. Recent epidemiological studies have shown an increased prevalence in Europe largely caused by an increase in international travel, difficulty eradicating leishmanial infection in AIDS patients, and the use of immunosuppressive medications. Clinical diagnosis may be challenging, and parasitological diagnosis entails the use of invasive procedures which may be unrevealing in the immunosuppressed. A number of less invasive tests for the detection of anti-leishmanial antibodies or leishmanial antigen are available but their sensitivity and specificity may vary with the infective species and results have to be interpreted in light of the clinical presentation. The availability of polymerase chain reaction assays amplifying leishmanial genetic material has been a major step forward in improving the diagnosis of leishmanial disease and the response to treatment.

Systematic review of biomarkers to monitor therapeutic response in leishmaniasis

Recently, there has been a renewed interest in the development of new drugs for the treatment of leishmaniasis. This has spurred the need for pharmacodynamic markers to monitor and compare therapies specifically for visceral leishmaniasis, in which the primary recrudescence of parasites is a particularly long-term event that remains difficult to predict. We performed a systematic review of studies evaluating biomarkers in human patients with visceral, cutaneous, and post-kala-azar dermal leishmaniasis, which yielded a total of 170 studies in which 53 potential pharmacodynamic biomarkers were identified. In conclusion, the large majority of these biomarkers constituted universal indirect markers of activation and subsequent waning of cellular immunity and therefore lacked specificity. Macrophage-related markers demonstrate favorable sensitivity and times to normalcy, but more evidence is required to establish a link between these markers and clinical outcome. Most promising are the markers directly related to the parasite burden, but future effort should be focused on optimization of molecular or antigenic targets to increase the sensitivity of these markers. In general, future research should focus on the longitudinal evaluation of the pharmacodynamic biomarkers during treatment, with an emphasis on the correlation of studied biomarkers and clinical parameters.

Leishmaniasis in travelers: a literature review

Leishmaniasis is a vector-borne protozoan infection whose clinical spectrum ranges from asymptomatic infection to fatal visceral leishmaniasis. Over the last decades, an increase in imported leishmaniasis cases in developed, non-endemic countries, have been pointed-out from a review of the international literature. Among the possible causes are increasing international tourism, influx of immigrants from endemic regions and military operations. The main area for the acquisition of cutaneous leishmaniasis, especially for adventure travelers on long-term trips in highly-endemic forested areas, is represented from South America, whereas popular Mediterranean destinations are emerging as the main areas to acquire visceral variant. Leishmaniasis should be considered in the diagnostic assessment of patients presenting with a compatible clinical syndrome and a history of travel to an endemic area, even if this occurred several months or years before. Adventure travelers, researchers, military personnel, and other groups of travelers likely to be exposed to sand flies in endemic areas, should receive counseling regarding leishmaniasis and appropriate protective measures.

Proteome profiling of human cutaneous leishmaniasis lesion

In this study, we used proteomics and biological network analysis to evaluate the potential biological processes and components present in the identified proteins of biopsies from cutaneous leishmaniasis (CL) patients infected by Leishmania braziliensis in comparison with normal skin. We identified 59 proteins differently expressed in samples from infected and normal skin. Biological network analysis employing identified proteins showed the presence of networks that may be involved in the cell death mediated by cytotoxic T lymphocytes. After immunohistochemical analyses, the expression of caspase-9, caspase-3, and granzyme B was validated in the tissue and positively correlated with the lesion size in CL patients. In conclusion, this work identified differentially expressed proteins in the inflammatory site of CL, revealed enhanced expression of caspase-9, and highlighted mechanisms associated with the progression of tissue damage observed in lesions.

Serological survey of Leishmania infection in blood donors in Salvador, Northeastern Brazil

BACKGROUND

Visceral Leishmaniasis is endemic to Brazil, where it is caused by Leishmania infantum (syn. Leishmania chagasi). Following parasite inoculation, individuals may experience asymptomatic infection, raising the possibility of parasite transmission through the transfusion of contaminated blood products. In the present work, we evaluated the prevalence of asymptomatic Leishmania infection among blood donors in Salvador, northeastern Brazil.

METHODS

Peripheral blood was collected from 700 blood donors attending the Blood Bank of Bahia (HEMOBA/SESAB), from January to September 2010. We evaluated anti-Leishmania serology by ELISA, employing Soluble Leishmania Antigen (sensitivity 90% and specificity 95%). The presence of parasite DNA was determined by qPCR, targeting a single copy gene (G6PD), and by end-point PCR, targeting multiple targets, namely a segment located in the Leishmania rRNA locus (ITS) and the conserved region of kinetoplastid DNA (kDNA) minicircles.

RESULTS

The blood-donor population was comprised of 74.5% of males with a mean age of 34 years. Anti-Leishmania serology by ELISA was positive in 5.4% (38/700) individuals. One individual was also positive for Chagas' disease and another tested positive for Syphilis. Employing qPCR, parasite DNA was not found in any of 38 seropositive samples. However, by ITS PCR, 8/38 (21%) samples were positive and this positivity increased to 26/38 (68%) when we targeted kDNA amplification. Agreement between both techniques (ITS and kDNA PCR) was fair (kappa = 0.219).

CONCLUSIONS

These results indicate that asymptomatic infection is present among the blood donor population of Salvador, a finding that warrants a broader discussion regarding the need to implement specific screening strategies.

Towards a more precise serological diagnosis of human tegumentary leishmaniasis using Leishmania recombinant proteins

Background

Exposure to Leishmania induces a humoral immune response that can be used as a marker of parasite exposure.

Methodology/Principal Findings

Herein, ELISA was used to screen sera from patients with Tegumentary Leishmaniasis (TL) against different L. infantum-chagasi-derived recombinant proteins (rHSP70, rH2A, rH2B, rH3, rH4 and rKMP11). Among the recombinant proteins, rHSP70 and rH2A showed the best reactivity against human sera obtained from endemic areas of TL. Receiver-Operator Characteristics (ROC) curve analysis was used to identify the effectiveness of these proteins for serodiagnosis of TL. ROC curves confirmed the superior performance of rHSP70 and rH2A, in comparison to the other tested recombinant proteins. Additionally, we evaluated the specificity of the response to rHSP70 and rH2A by testing sera obtained from patients with Chagas' disease, Tuberculosis, Leprosy or Systemic Lupus Erythematosus. In this case, rHSP70 displayed an increased ability to discriminate diseases, in comparison to SLA.

Conclusion

Our results raise possibility of using rHSP70 for the serodiagnosis of TL

Direct diagnosis of Leishmania species on serosity materials punctured from cutaneous leishmaniasis patients using PCR-RFLP

This study was aimed at identifying the Leishmania species using serosity materials punctured from skin lesions of cutaneous leishmaniasis (CL) patients by using internal transcribed spacer1 (ITS1) polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP). We used the PCR-RFLP on 60 parasitological confirmed CL patients who referred to leishmaniasis laboratory from the School of Public Health, Tehran University of Medical Sciences. The PCR-RFLP could correctly detect 51 Leishmania species of the 60 confirmed positive specimens, where all the other 10 parasitological (microscopy and culture) negative samples that were prepared from other bacterial- and fungal-infected lesions had negative results. The results also revealed that Leishmania major was the dominant species (53.3%). This study suggests that the PCR-RFLP assay with serosity materials punctured from CL patients using Hae III enzyme is useful for the rapid identification of Leishmania species.

Hormone levels are associated with clinical markers and cytokine levels in human localized cutaneous leishmaniasis

Leishmaniasis is a serious health problem in several parts of the world, and localized cutaneous leishmaniasis (LCL) is the most frequent presentation of the tegumentary form of this disease cluster. Clinical presentations of leishmaniasis are influenced by both parasite and host factors, with emphasis on the host immune response. Alterations in plasma hormone levels have been described in many infections, and changes in hormone levels could be related to an imbalanced cytokine profile. In the present work, we evaluated a group of patients with LCL to determine changes in plasma hormone levels (cortisol, DHEA-S, estradiol, prolactin and testosterone) and their association with clinical markers of disease (lesion size, dose used to reach cure and time to cure) and with cytokines produced by PBMC stimulated by SLA (IFN-γ, IL-10 and TNF-α). Individuals with LCL exhibited lower plasma levels of DHEA-S, prolactin and testosterone compared with sex-matched controls, whereas levels of cortisol and estradiol were similar between patients and controls. Plasma levels of cortisol, estradiol or prolactin positively correlated with at least one clinical parameter. Cortisol and prolactin levels exhibited a negative correlation with levels of IFN-γ, whereas no correlation was observed with IL-10 or TNF-α levels. A decrease in DHEA-S levels was observed in male LCL patients when compared to male healthy controls. No other differences between the sexes were observed. Our results indicate a role for neuroendocrine regulation that restricts Th1 responses in human LCL. It is possible that, although impairing parasite killing, such neuroimmunomodulation may contribute to limiting tissue damage.

Simplified molecular detection of Leishmania parasites in various clinical samples from patients with leishmaniasis

Background

Molecular methods to detect Leishmania parasites are considered specific and sensitive, but often not applied in endemic areas of developing countries due to technical complexity. In the present study isothermal, nucleic acid sequence based amplification (NASBA) was coupled to oligochromatography (OC) to develop a simplified detection method for the diagnosis of leishmaniasis. NASBA-OC, detecting Leishmania RNA, was evaluated using clinical samples from visceral leishmaniasis patients from East Africa (n = 30) and cutaneous leishmaniasis from South America (n = 70) and appropriate control samples.

Results

Analytical sensitivity was 10 parasites/ml of spiked blood, and 1 parasite/ml of culture. Diagnostic sensitivity of NASBA-OC was 93.3% (95% CI: 76.5%-98.8%) and specificity was 100% (95% CI: 91.1%-100%) on blood samples, while sensitivity and specificity on skin biopsy samples was 98.6% (95% CI: 91.2%-99.9%) and 100% (95% CI: 46.3%-100%), respectively.

Conclusion

The NASBA-OC format brings implementation of molecular diagnosis of leishmaniasis in resource poor countries one step closer.

[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.

Comparative study of amplification systems in immunoenzyme assays for the diagnosis of American tegumentary leishmaniasis

We compared the accuracy and reliability of three amplification systems for enzyme immunoassays in the detection of specific IgG antibodies for the diagnosis of cutaneous leishmaniasis caused by Leishmania (Viannia) braziliensis in patients from an endemic area in Rio de Janeiro, Brazil. Partially soluble antigens obtained from the promastigote forms of L. (V.) braziliensis were used. For development of the reaction, two chromogens, 1,2-orthophenylenediamine (OPD) and 3,3',5,5'-tetramethylbenzidine (TMB), and a fluorogen, 4-methylumbelliferylphosphate (MUP), were tested. The performance of each system was compared using the following parameters: accuracy, intraclass correlation coefficient (ICC), and area under the receiver operating characteristic (ROC) curve. Sensitivity was the same (97.4%) for all systems. The reliability was excellent (ICC = 98.6, 98.7, and 99.1%) and specificity was 93.7, 95.8, and 97.4% for OPD, MUP, and TMB, respectively, showing no statistical significance. Despite the absence of differences in the performance of the three systems, the use of TMB is suggested because of its operational advantages, such as low cost compared with fluorogens, easy manipulation, greater stability, and lower toxicity.

Leishmania OligoC-TesT as a simple, rapid, and standardized tool for molecular diagnosis of cutaneous leishmaniasis in Peru

Molecular methods such as PCR have become attractive tools for diagnosis of cutaneous leishmaniasis (CL), both for their high sensitivity and for their specificity. However, their practical use in routine diagnosis is limited due to the infrastructural requirements and the lack of any standardization. Recently, a simplified and standardized PCR format for molecular detection of Leishmania was developed. The Leishmania OligoC-TesT is based on simple and rapid detection using a dipstick with PCR-amplified Leishmania DNA. In this study, we estimated the diagnostic accuracy of the Leishmania OligoC-TesT for 61 specimens from 44 CL-suspected patients presenting at the leishmaniasis clinic of the Instituto de Medicina Tropical Alexander von Humboldt, Peru. On the basis of parasitological detection and the leishmanin skin test (LST), patients were classified as (i) confirmed CL cases, (ii) LST-positive cases, and (iii) LST-negative cases. The sensitivities of the Leishmania OligoC-TesT was 74% (95% confidence interval (CI), 60.5% to 84.1%) for lesion aspirates and 92% (95% CI, 81.2% to 96.9%) for scrapings. A significantly higher sensitivity was observed with a conventional PCR targeting the kinetoplast DNA on the aspirates (94%) (P = 0.001), while there was no significant difference in sensitivity for the lesion scrapings (88%) (P = 0.317). In addition, the Leishmania OligoC-TesT was evaluated for 13 CL-suspected patients in two different peripheral health centers in the central jungle of Peru. Our findings clearly indicate the high accuracy of the Leishmania OligoC-TesT for lesion scrapings for simple and rapid molecular diagnosis of CL in Peru.

Identification of Leishmania parasites in clinical samples obtained from cutaneous leishmaniasis patients using PCR-RFLP technique in endemic region, Sanliurfa province, in Turkey

Antroponotic cutaneous leishmaniasis (ACL) is an endemic disease and one of the major health problems in Sanliurfa province located in the southeastern region of Turkey. Leishmania tropica is confirmed as the causative agent of ACL in this region. In Sanliurfa city alone, the recorded total cases of ACL were 6,817 between 2001 and 2006. We aimed to determine the effectiveness of a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method for identification and differentiation of the Leishmania parasite in comparison to direct microscopic examination of clinical samples. The lesion exudates were collected from 51 ACL suspected patients and used for smear-slide preparations and DNA isolation. The isolated DNA was amplified by PCR, including primers selected on repetitive DNA for identification of a Leishmania subgenus, and the amplified DNA was restricted by HaeIII restriction endonuclease. The PCR-RFLP results showed that only L. tropica exists in this province. It is also determined that the positivity rate with PCR was higher (96%) than by microscopic examination (64%) in the diagnosis of ACL. Our results indicate that the PCR-RFLP method is more sensitive and specific for the detection and differentiation of agents of ACL in this area.

Treatment assessment by monitoring parasite load in skin biopsies from patients with cutaneous leishmaniasis, using quantitative nucleic acid sequence-based amplification

BACKGROUND

Current diagnostic methods for cutaneous leishmaniasis (CL) have low sensitivity or are not useful for treatment follow-up. We previously described the quantitative nucleic acid sequence-based amplification (QT-NASBA) method as a sensitive and specific assay for detection and quantification of Leishmania parasites in skin biopsies. This assay could be a valuable instrument for monitoring response to treatment of CL and identifying treatment failures at an early stage.

AIM

QT-NASBA results of skin biopsies at the end and 6 weeks after treatment from patients with proven CL on various treatment regimens were compared with clinical outcome.

METHODS

The QT-NASBA assay measured the parasite load in skin biopsies before, at the end and 6 weeks after treatment. The results were compared with treatment outcome (clinical cure, delayed healing response or treatment failure) up to 6 months after treatment.

RESULTS

In total, 137 skin biopsies were obtained from 53 patients. A positive QT-NASBA result 6 weeks after treatment was significantly associated with treatment failure/delayed healing up to 6 months (P < 0.001). The positive predictive value (PPV) was 100% and the negative predictive value (NPV) was 92% (95% CI 82-100%). QT-NASBA results at the end of treatment and clinical outcome showed a less significant association (P < 0.05), with a PPV of 46% (95% CI 16-75% and an NPV of 89% (95% CI 79-99%).

CONCLUSIONS

The QT-NASBA assay is a useful instrument to monitor parasite load in skin biopsies of patients with CL 6 weeks after treatment and can help to predict clinical outcome.

Comparison between quantitative nucleic acid sequence-based amplification, real-time reverse transcriptase PCR, and real-time PCR for quantification of Leishmania parasites

DNA or RNA amplification methods for detection of Leishmania parasites have advantages regarding sensitivity and potential quantitative characteristics in comparison with conventional diagnostic methods but are often still not routinely applied. However, the use and application of molecular assays are increasing, but comparative studies on the performance of these different assays are lacking. The aim of this study was to compare three molecular assays for detection and quantification of Leishmania parasites in serial dilutions of parasites and in skin biopsies collected from cutaneous leishmaniasis (CL) patients in Manaus, Brazil. A serial dilution of promastigotes spiked in blood was tested in triplicate in three different runs by quantitative nucleic acid sequence-based amplification (QT-NASBA), quantitative real-time reverse transcriptase PCR (qRT-PCR), and quantitative real-time PCR (qPCR). In addition, the costs, durations, and numbers of handling steps were compared, and 84 skin biopsies from patients with suspected CL were tested. Both QT-NASBA and qRT-PCR had a detection limit of 100 parasites/ml of blood, while qPCR detected 1,000 parasites/ml. QT-NASBA had the lowest range of intra-assay variation (coefficients of variation [CV], 0.5% to 3.3%), while qPCR had the lowest range of interassay variation (CV, 0.4% to 5.3%). Furthermore, qRT-PCR had higher r2 values and amplification efficiencies than qPCR, and qPCR and qRT-PCR had faster procedures than QT-NASBA. All assays performed equally well with patient samples, with significant correlations between parasite counts. Overall, qRT-PCR is preferred over QT-NASBA and qPCR as the most optimal diagnostic assay for quantification of Leishmania parasites, since it was highly sensitive and reproducible and the procedure was relatively fast.

Evaluation of a microculture method for isolation of Leishmania parasites from cutaneous lesions of patients in Peru

Traditional culture of Leishmania spp. is labor intensive and has poor sensitivity. We evaluated a microculture method for the diagnosis of cutaneous leishmaniasis in consecutive patients presenting to the Leishmaniasis Clinic at the Instituto de Medicina Tropical Alexander von Humboldt, Peru, for evaluation of skin lesions. Lesion aspirates were cultured in duplicate and parallel in traditional culture tubes containing modified Novy-MacNeal-Nicolle (NNN) medium or Roswell Park Memorial Institute medium 1640 with 10% fetal bovine serum (10% RPMI) and in 70-microl capillary tubes containing a mixture of lesion aspirate and 10% RPMI. For sensitivity analysis, the consensus standard was considered to be a positive result in any two of the following four tests: Giemsa-stained lesion smear, culture, kinetoplast DNA PCR, or leishmanin skin test. The outcome measures were sensitivity and time to culture positivity. Forty-five patients with 62 skin lesions were enrolled in the study, of which 53 lesions fulfilled the consensus criteria for a final diagnosis of cutaneous leishmaniasis. Of these 53 lesions, 39 were culture positive: 38 in capillary tubes, 29 in traditional culture tubes with modified NNN medium, and 19 in traditional culture tubes with 10% RPMI medium. The sensitivity of microculture was 71.7%, versus 54.7% for traditional culture with NNN (P, 0.038) and 35.8% with 10% RPMI (P, <0.001). The mean times to culture positivity were 4.2 days by microculture, 5.2 days in NNN, and 6 days in 10% RPMI (P, 0.009). We have demonstrated that microculture is a more sensitive and time-efficient means of isolating Leishmania parasites from cutaneous lesions than traditional culture.

Leishmaniasis

Epidemiology, disease patterns, immunology, diagnosis, treatment and control measures of leishmaniasis are described. Various issues relating to leishmaniasis are highlighted: the relative lack of importance given to this disease compared with other infections, climate change and its possible impact on extension of endemicity of this infection, and new diagnostic tests which are improving diagnosis, especially in resource poor areas. Other important aspects discussed include the potential for newer oral therapy to change the way this disease is managed; Leishmania-HIV coinfection and groups at risk; and development of an effective vaccine.

Leishmaniasis

Epidemiology, disease patterns, immunology, diagnosis, treatment and control measures of leishmaniasis are described. Various issues relating to leishmaniasis are highlighted: the relative lack of importance given to this disease is compared with other infections, climate change and its possible effect on extension of endemicity of this infection, and new diagnostic tests that are helping better diagnosis, especially in resource-poor areas. Other important aspects discussed include the potential for newer oral treatment to change the way this disease is managed; leishmania-HIV coinfection and groups at risk; and the development of an effective vaccine.

Diagnóstico molecular da taxa de infecção natural de flebotomíneos (Psychodidae, Lutzomyia) por Leishmania sp na Amazônia maranhense

A taxa de infecção natural de três diferentes espécies de flebotomíneos por Leishmania foi estudada usando a técnica de reação em cadeia da polimerase. Primers específicos para Leishmania foram designados para examinar se os pools de flebotomíneos estavam infectadas. Um total de 1.100 fêmeas separadas em pools de 10 indivíduos foram examinados, consistindo de 50 Lutzomyia whitmani, 43 Lutzomyia triacantha e 17 Lutzomyia choti. De todos os pools analisados, 4 de Lutzomyia whitmani estavam positivos, mas nenhum pool das duas espécies restantes estava infectado. Deste modo, uma taxa de infecção de 0,4% foi verificada neste estudo. Esta taxa de infecção associada a estudos anteriores sugere que Lutzomyia whitmani transmite Leishmania aos mamíferos em Buriticupu, Maranhão.

Montenegro's skin reactions and antibodies against different Leishmania species in dogs from a visceral leishmaniosis endemic area

In this study, humoral (circulating anti-Leishmania antibodies) and cellular (Montenegro's skin test) immune responses of dogs from an endemic area of visceral leishmaniosis were tested using Leishmania chagasi, Leishmania amazonensis and Leishmania braziliensis antigens. The antibody response was tested in three animal groups, selected according to their anti-L. chagasi antibody activity, as measured by ELISA in the serum: 19 negative (O.D. below 0.30), seven with undefined (O.D. between 0.40 and 0.70) and 12 positive (O.D. above 1.0) ELISA result. In the group of animals with positive ELISA, the antibody activity against L. chagasi antigens (mean O.D.=1.31) was significantly higher (ANOVA, P<0.01) than against L. amazonensis (mean O.D.=0.88) or L. braziliensis (mean O.D.=0.87) antigens. The Montenegro's skin test results obtained with L. chagasi and L. braziliensis antigens showed a fair agreement (kappa=0.309). The same was observed when antigens from L. braziliensis and L. amazonensis were compared (kappa=0.374), whereas a moderate agreement between the results from tests performed with L. chagasi and L. amazonensis antigens was observed (kappa=0.530). The induration areas obtained with L. braziliensis antigen were smaller than those obtained with the other antigens. The data presented herein indicate that the use of antigens from different Leishmania species may interfere with the results of the immunological tests performed in dogs in an endemic area of visceral leishmaniosis.

Cutaneous leishmaniasis: an increasing threat for travellers

Analysis of the literature on cutaneous leishmaniasis in low-prevalence countries suggests an increase in imported cases that is attributable to the growing phenomenon of international tourism, migration and military operations in highly endemic regions. Cases of imported cutaneous leishmaniasis are often missed initially, but diagnosis can be made non-invasively by PCR using skin scrapings of lesions as starting material. Cutaneous leishmaniasis is an emerging threat for travellers and should be considered in all patients presenting with slow-to-heal ulcers.

Métodos subsidiários para o diagnóstico da Leishmaniose tegumentar americana (LTA): comparação dos resultados do seqüenciamento de DNA e da PCR-RFLP para determinação da espécie de leishmania em amostras cutâneo-mucosas

FUNDAMENTOS: Métodos moleculares têm-se mostrados mais eficazes para o diagnóstico da LTA. OBJETIVOS: Comparar os resultados da intradermorreação de Montenegro (IRM), presença de leishmania em biópsia (Bc), reação de imunofluorescência indireta (Rifi), seqüenciamento de DNA e PCR-RFLP (-restriction fragment lenght polymorphism) para o diagnóstico da LTA. MÉTODOS: Foram estudados 152 pacientes com LTA. Para a PCR em Bc, utilizaram-se primers específicos para seqüência de 120bp do kDNA do minicírculo comum a todas as espécies de leishmanias. O produto da PCR, utilizado para seqüenciamento e para restrição enzimática com Hae III, foi comparado às culturas L. (L.) amazonensis e L. (V.) braziliensis. RESULTADOS: Houve predomínio do sexo masculino (75%), da cor branca (80%) e da profissão urbana (48%). A idade variou de três a 77 anos, com 56,5% entre 21 e 50 anos. 65,8% eram do Estado de São Paulo, prevalecendo a forma cutânea (79,6%). A IRM foi positiva em 73,4%, e a Rifi em 59,7%, enquanto a Bc evidenciou presença de leishmania em 30,6%. A PCR foi positiva em 81,6%, e a PCR-RFLP identificou L. (V.) braziliensis como espécie predominante (66%), o que também ocorreu com o seqüenciamento. Comparando PCR-RFLP e seqüenciamento, houve 61% de concordância entre os resultados, mostrando significância da PCR-RFLP para L. (V.) braziliensis. CONCLUSÕES: A IRM e a PCR foram estatisticamente equivalentes como métodos subsidiários para o diagnóstico da LTA, a PCR-RFLP e o seqüenciamento também o foram na identificação das espécies de leishmania, o primeiro apresentando menores custo e tempo de execução comparado ao seqüenciamento de DNA.

Comparison of polymerase chain reaction with other laboratory methods for the diagnosis of American cutaneous leishmaniasis: diagnosis of cutaneous leishmaniasis by polymerase chain reaction

An evaluation of 5 laboratory methods for diagnosing American cutaneous leishmaniasis (ACL) was carried out on patients from an endemic area of Brazil. From 164 patients presenting cutaneous lesions, and suspected to have ACL, 133 (81.1%) were confirmed for the disease by Montenegro skin test (MST) and/or parasitologic examination (PE). In both groups of patients, the positivity of polymerase chain reaction (PCR) was similar to that of immunofluorescence assay and enzyme-linked immunosorbent assay, and higher than that of MST and PE (P < .05). In the group of patients suspected to have ACL, PCR presented the same positivity as PE and MST together. No correlation between positivity of the laboratory methods and clinical or epidemiologic aspects was observed. Our data confirmed the value of PCR as an alternative laboratory method for diagnosing ACL, especially for those patients with negative PE and MST.

Quantitative nucleic acid sequence-based assay as a new molecular tool for detection and quantification of Leishmania parasites in skin biopsy samples

Currently available methods for the diagnosis of cutaneous leishmaniasis (CL) have low sensitivities or are unable to quantify the number of viable parasites. This constitutes a major obstacle for the diagnosis of the disease and for the study of the effectiveness of treatment schedules and urges the development of improved detection methods. In this study, quantitative nucleic acid sequence-based amplification (QT-NASBA) technology was used to detect and quantify Leishmania parasites in skin biopsy samples from CL patients. The assay is based on the detection of a small subunit rRNA (18S rRNA), which may allow for the detection of viable parasites. The QT-NASBA assay was evaluated using in vitro-cultured promastigotes and amastigotes and 2-mm skin biopsy samples from Old and New World CL patients. The study demonstrated that the lower detection limit of the QT-NASBA was two parasites per biopsy sample. Parasites could be quantified in a range of 2 to 11,300,000 parasites per biopsy sample. The QT-NASBA could detect levels of parasites 100-fold lower than those detected by conventional PCR. Test evaluation revealed that the QT-NASBA had a sensitivity of 97.5% and a specificity of 100% in the present study. The QT-NASBA is a highly sensitive and specific method that allows quantification of both Old and New World Leishmania parasites in skin biopsy samples and may provide an important tool for diagnosis as well as for monitoring the therapy of CL patients.

Advances in leishmaniasis

Governed by parasite and host factors and immunoinflammatory responses, the clinical spectrum of leishmaniasis encompasses subclinical (inapparent), localised (skin lesions), and disseminated infection (cutaneous, mucosal, or visceral). Symptomatic disease is subacute or chronic and diverse in presentation and outcome. Clinical characteristics vary further by endemic region. Despite T-cell-dependent immune responses, which produce asymptomatic and self-healing infection, or appropriate treatment, intracellular infection is probably life-long since targeted cells (tissue macrophages) allow residual parasites to persist. There is an epidemic of cutaneous leishmaniasis in Afghanistan and Pakistan and of visceral infection in India and Sudan. Diagnosis relies on visualising parasites in tissue or serology; culture and detection of parasite DNA are useful in the laboratory. Pentavalent antimony is the conventional treatment; however, resistance of visceral infection in India has spawned new treatment approaches--amphotericin B and its lipid formulations, injectable paromomycin, and oral miltefosine. Despite tangible advances in diagnosis, treatment, and basic scientific research, leishmaniasis is embedded in poverty and neglected. Current obstacles to realistic prevention and proper management include inadequate vector (sandfly) control, no vaccine, and insufficient access to or impetus for developing affordable new drugs.

Polymerase chain reaction (PCR) is highly sensitive for diagnosis of mucosal leishmaniasis

We evaluated the use of polymerase chain reaction (PCR) for diagnosis of mucosal leishmaniasis (ML) in an endemic area in Acre, Brazil, where Leishmania braziliensis is present. Leishmania DNA was detected 34 of 35 cases, yielding a positivity rate of 97.1%, which was higher than the positivity rates for all of the other diagnostic methods studied, namely Montenegro skin test (MST), anti-Leishmania serological testing and microscopic examination of lesion biopsy specimens. These findings have led us to propose guidelines for the diagnosis of ML that use PCR as the principal method of parasitological confirmation of cases.

Applications of molecular methods for Leishmania control

This article reviews the recent advances made in the field of human leishmaniasis. Special emphasis is placed upon the application of various molecular tools for accurate and rapid diagnosis, understanding the mechanisms of drug resistance and identification of vaccine candidates. The focus will be on the major role played by recombinant antigens in the immunoserodiagnosis and progress of the Leishmania genome project, which has enabled researchers to design better PCR primers and molecular probes for microarrays. A special interest is placed on the recombinant antigen (rK39) cloned from the Leishmania chagasi kinesin gene and a very recently cloned recombinant antigen (KE16) from the Old World Leishmania donovani species with high sensitivity and specificity. Advances made in the specific PCR primer designed to diagnose and differentiate various species and strains of Leishmania causing visceral and post-kala-azar-dermal leishmaniasis have been covered. Molecular methods (e.g., DNA and protein microarrays) applied to understanding the pathobiology of the parasite, mechanism of host invasion, drug interaction and drug resistance to develop effective therapeutic molecules, gene expression profiling studies that have opened doors to understand many host-parasite relations, effective therapy and vaccine candidates are extensively covered in this review.

Recent developments in Leishmaniasis: Epidemiology, diagnosis, and treatment

The outbreaks of cutaneous disease caused by Leishmania tropica in Afghan refugees, visceral disease in Sudanese refugees, and cutaneous disease caused by Leishmania major in American forces in Iraq are examples of the large number of cases of leishmaniasis that can result when naive human populations intrude into regions where transmission is endemic. Injections of pentavalent antimony for 20 to 30 days have been the standard treatment for all forms of leishmaniasis, but resistance is growing and antimonials have moderate toxicity. Two major advances in the treatment of visceral leishmaniasis have been made in the past few years. Liposomal amphotericin B cures virtually all patients, with little side effects. Miltefosine is the first oral agent that is effective. For cutaneous disease, alternatives to antimony have been effective in certain regions but have not yet been generally evaluated.

Role of costimulatory molecules in immune response of patients with cutaneous leishmaniasis

T cell-mediated immunity is critical in resistance against Leishmania parasites, and T cell activation requires signals provided by costimulatory molecules. Herein we evaluated the role of costimulatory molecules on cytokine production and T cell surface molecule expression by peripheral blood mononuclear cells (PBMC) from cutaneous leishmaniasis (CL) patients. PBMC from CL patients were stimulated with soluble Leishmania antigen (SLA, 10 microg/ml), in the presence or absence of soluble CTLA4-Ig to block CD28-B7 interaction or in the presence or absence of anti-human CD40L to block CD40-CD40L interaction. Supernatants were harvested to evaluate tumor necrosis factor alpha (TNF-alpha), interleukin 10 (IL-10), transforming growth factor beta (TGF-beta) and interferon gamma (IFN-gamma) production by ELISA. Cells were harvested after 48 h of culture, stained for specific activation markers and analyzed by flow cytometry. Results show that the blockade of CD28-B7 interaction by CTLA4-Ig downmodulated IFN-gamma, IL-10, and TNF-alpha secretion by PBMC from CL patients. No alteration was detected on either TGF-beta production or the expression of CTLA44 or CD25 on CD4+ and CD8+ T cells. When the CD40-CD40L interaction was blockade using anti-CD40L, we did not observe changes in cytokine production or in surface molecule expression. The blockade of the CD28-B7 interactions by CTLA4-Ig also did not alter cytokine production in volunteers immunized against tetanus toxoid (TT). Taken together, these data suggest that the interaction of CTLA4 and CD28-B7 is a TGF-beta-independent mechanism that specifically downmodulates the immune response in cutaneous leishmaniasis patients.