Usefulness of PCR in the diagnosis of cutaneous leishmaniasis in Tunisia

Leishmaniasis - Still a diagnostic challenge: An individual participant data systematic review

Leishmania, endemic in nearly half the world's countries, continues to pose significant diagnostic challenges. Our systematic review sought to analyse problems in diagnosis especially in low- to middle-income countries. The average time from symptom onset to diagnosis was 4.5 years. While microscopic detection often failed, polymerase chain reaction showed high sensitivity. Clinical presentations varied significantly, highlighting the complexity of diagnosing leishmaniasis, especially in patients with prolonged disease in non-endemic areas.

A machine learning-based system for detecting leishmaniasis in microscopic images

Background

Leishmaniasis, a disease caused by a protozoan, causes numerous deaths in humans each year. After malaria, leishmaniasis is known to be the deadliest parasitic disease globally. Direct visual detection of leishmania parasite through microscopy is the frequent method for diagnosis of this disease. However, this method is time-consuming and subject to errors. This study was aimed to develop an artificial intelligence-based algorithm for automatic diagnosis of leishmaniasis.

Methods

We used the Viola-Jones algorithm to develop a leishmania parasite detection system. The algorithm includes three procedures: feature extraction, integral image creation, and classification. Haar-like features are used as features. An integral image was used to represent an abstract of the image that significantly speeds up the algorithm. The adaBoost technique was used to select the discriminate features and to train the classifier.

Results

A 65% recall and 50% precision was concluded in the detection of macrophages infected with the leishmania parasite. Also, these numbers were 52% and 71%, respectively, related to amastigotes outside of macrophages.

Conclusion

The developed system is accurate, fast, easy to use, and cost-effective. Therefore, artificial intelligence might be used as an alternative for the current leishmanial diagnosis methods.

Molecular identification of two newly identified human pathogens causing leishmaniasis using PCR-based methods on the 3' untranslated region of the heat shock protein 70 (type I) gene

PCR-based methods to amplify the 3′ untranslated region (3′-UTR) of the heat shock protein 70 (type I) gene (HSP70-I) have previously been used for typing of Leishmania but not with Leishmania (Mundinia) martiniquensis and L. (Mundinia) orientalis, newly identified human pathogens. Here, the 3′-UTRs of HSP70-I of L. martiniquensis, L. orientalis, and 10 other species were sequenced and analyzed. PCR-Restriction Fragment Length Polymorphism (RFLP) analysis targeting the 3′-UTR of HSP70-I was developed. Also, the detection limit of HSP70-I-3′-UTR PCR methods was compared with two other commonly used targets: the 18S small subunit ribosomal RNA (SSU-rRNA) gene and the internal transcribed spacer 1 region of the rRNA (ITS1-rRNA) gene. Results showed that HSP70-I-3′-UTR PCR methods could be used to identify and differentiate between L. martiniquensis (480–2 bp) and L. orientalis (674 bp) and distinguished them from parasites of the subgenus Viannia and of the subgenus Leishmania. PCR-RFLP patterns of the 3′-UTR of HSP70-I fragments digested with BsuRI restriction enzyme successfully differentiated L. martiniquensis, L. orientalis, L. braziliensis, L. guyanensis = L. panamensis, L. mexicana = L. aethiopica = L. tropica, L. amazonensis, L. major, and L. donovani = L. infantum. For the detection limit, the HSP70-I-3′-UTR PCR method could detect the DNA of L. martiniquensis and L. orientalis at the same concentration, 1 pg/μL, at a similar level to the SSU-rRNA PCR. The PCR that amplified ITS1-rRNA was more sensitive (0.01 pg/μL) than that of the HSP70-I-3′-UTR PCR. However, the sizes of both SSU-rRNA and ITS1-rRNA PCR amplicons could not differentiate between L. martiniquensis and L. orientalis. This is the first report of using HSP70-I-3′-UTR PCR based methods to identify the parasites causing leishmaniasis in Thailand. Also, the BsuRI-PCR-RFLP method can be used for differentiating some species within other subgenera.

L. martiniquensis and L. orientalis, newly identified human pathogens, cause visceral leishmaniasis and cutaneous leishmaniasis in HIV-negative patients, respectively. However, both parasite species cause disseminated cutaneous leishmaniasis accompanying visceral leishmaniasis in HIV-positive patients. Species typing in leishmaniasis is important in diagnostics, epidemiology, and clinical studies. We show here that the 3′-UTR of HSP70-I region is a suitable target for PCR-based identification and discrimination between L. martiniquensis and L. orientalis. The technique is simple to perform and can be implemented in all settings where PCR is available. In species with similar PCR product size, the BsuRI-PCR-RFLP patterns of the 3′-UTR of HSP70-I fragments can be used for differentiating some species within other subgenera. However, where identification of species is essential or there is a travel history outside Thailand, sequencing of the HSP70-I-3′-UTR product or a similar discriminating target sequence is recommended. The PCR-based methods used in this study can also be applicable to the identification of Leishmania species obtained from vectors and reservoirs.

Evaluation of conventional and four real-time PCR methods for the detection of Leishmania on field-collected samples in Ethiopia

In most low-resource settings, microscopy still is the standard method for diagnosis of cutaneous leishmaniasis, despite its limited sensitivity. In Ethiopia, the more sensitive molecular methods are not yet routinely used. This study compared five PCR methods with microscopy on two sample types collected from patients with a suspected lesion to advise on optimal diagnosis of Leishmania aethiopica. Between May and July 2018, skin scrapings (SS) and blood exudate from the lesion spotted on filter paper (dry blood spot, DBS) were collected for PCR from 111 patients of four zones in Southern Ethiopia. DNA and RNA were simultaneously extracted from both sample types. DNA was evaluated by a conventional PCR targeting ITS-1 and three probe-based real-time PCRs: one targeting the SSU 18S rRNA and two targeting the kDNA minicircle sequence (the 'Mary kDNA PCR' and a newly designed 'LC kDNA PCR' for improved L. aethiopica detection). RNAs were tested with a SYBR Green-based RT-PCR targeting spliced leader (SL) RNA. Giemsa-stained SS smears were examined by microscopy. Of the 111 SS, 100 were positive with at least two methods. Sensitivity of microscopy, ITS PCR, SSU PCR, Mary kDNA PCR, LC kDNA PCR and SL RNA PCR were respectively 52%, 22%, 64%, 99%, 100% and 94%. Microscopy-based parasite load correlated well with real-time PCR Ct-values. Despite suboptimal sample storage for RNA detection, the SL RNA PCR resulted in congruent results with low Ct-values. DBS collected from the same lesion showed lower PCR positivity rates compared to SS. The kDNA PCRs showed excellent performance for diagnosis of L. aethiopica on SS. Lower-cost SL RNA detection can be a complementary high-throughput tool. DBS can be used for PCR in case microscopy is negative, the SS sample can be sent to the referral health facility where kDNA PCR method is available.

Development and Assessment of Leishmania major and Leishmania tropica Specific Loop-Mediated Isothermal Amplification Assays for the Diagnosis of Cutaneous Leishmaniasis in Tunisia

Cutaneous leishmaniasis (CL) remains one of the world's most prevalent neglected diseases, particularly in developing countries. Identification of the involved Leishmania species is an important step in the diagnosis and case management process. In this study, we tested simple, rapid, and highly sensitive loop-mediated isothermal amplification (LAMP) assays for Leishmania DNA species-specific detection from cutaneous lesions. Two LAMP assays, targeting cysteine protease B (cpb) gene, were developed to detect and identify Leishmania major and Leishmania tropica species. Loop-mediated isothermal amplification specificity was examined using DNA samples from other Leishmania species and Trypanosoma species. No cross-reactions were detected. The developed LAMP assays exhibited sensitivity with a detection limit of 20 fg and 200 fg for L. major and L. tropica, respectively. Both tests were applied on clinical samples of CL suspected patients living in endemic Tunisian regions and compared with kinetoplast DNA quantitative PCR (qPCR), microscopic, and conventional cpb-based polymerase chain reaction (PCR) assays. Our LAMP tests were able to discriminate between L. major and L. tropica species and showed a sensitivity of 84% and a specificity of 100%. However, when compared with the performance of the diagnostic tests with latent class analysis (LCA), our LAMP assays show a sensitivity of 100%. These assays can be used as a first-line molecular test for early diagnosis and prompt management of CL cases in public health programs.

Diagnosing Cutaneous leishmaniasis using Fluorescence in Situ Hybridization: the Sri Lankan Perspective

Cutaneous leishmaniasis (CL) caused by Leishmania donovani MON-37 is becoming a major public health problem in Sri Lanka, with 100 new cases per month being reported in endemic regions. Diagnosis of CL is challenging for several reasons. Due to relative specificity and rapidity we propose Fluorescence in Situ Hybridization as a diagnostic tool for CL. The objective was to evaluate the potential of Fluorescence in Situ Hybridization as a diagnostic method for Cutaneous leishmaniasis in Sri Lanka. Literature on current laboratory tests used to diagnose Cutaneous leishmaniasis in Sri Lanka and globally was reviewed. Sri Lankan data were reviewed systematically following the PRISMA guidelines. A narrative of the results is presented. There is currently no gold standard diagnostic method for Cutaneous leishmaniasis. Fluorescence in Situ Hybridization has been previously applied to detect dermal pathologies including those involving infectious agents, and its use to detect the Leishmania parasite in human cutaneous lesions reported in small number of studies, generally with limited numbers of subjects. Advantages of FISH has been specificity, cost and ease-of-use compared to the alternatives. Based on the available literature and our current work, FISH has potential for diagnosing CL and should now be evaluated in larger cohorts in endemic regions. FISH for CL diagnosis could find application in countries such as Sri Lanka, where laboratory facilities may be limited in rural areas where the disease burden is highest.

Isolation and Molecular Identification of Leishmania spp. in Patients With Cutaneous Leishmaniasis in Golestan Province, Iran

Background and aims: Cutaneous leishmaniasis is a major health issue in many parts of Iran. Diagnosis of cutaneous leishmaniasis in a non-endemic area is not as simple as that in endemic foci. The management and treatment of this disease are global dilemmas. The purpose of this study was to identify Leishmania species isolated from human cutaneous leishmaniasis lesions in patients referred to health centers of Golestan province, Iran. Methods: Cutaneous leishmaniasis patients with suspected lesions were clinically examined. History of journey to the endemic areas of zoonotic cutaneous leishmaniasis and/or anthroponotic cutaneous leishmaniasis and the characteristics of their lesion(s) were recorded. Diagnosis of the lesion was done by using direct smear microscopy and conventional polymerase chain reaction. Results: Out of 360 patients, 202 (57.4 %) were male and 158 (42.8 %) were female. A total of 360 samples were selected from different cities. The number of infected samples in the cities is as follows: Azad Shahr [3 (1.5%)], Aq Qala [11 (5.7%)], Ali Abad [4 (2.1%)], Bandar Turkmen [3 (1.5%)], Bandar Gaz [2 (1%)], Ramian [3 (1.5%)], Kalaleh [23 (12.1%)], Kord koy [1 (0.5%)], Galikesh [7 (3.7 %)], Gomishan [12 (3.6 %)], Gorgan [13 (6.8 %)], Gonbad Qabus [99 (52.1 %)], Marave Tappe [7 (3.6%)] and Minoodasht [2 (1%)]. In the molecular investigations, 186 (96.8%) samples were observed to acquire rural cutaneous leishmaniasis, 4 (2.1%) to acquire urban cutaneous leishmaniasis and 170 (47.2%) to be uninfected. Conclusion: Although history of visiting endemic areas is an important factor to be considered in diagnosis, parasitological confirmation is necessary for the initiation of treatment.

Evaluation of point-of-care tests for cutaneous leishmaniasis diagnosis in Kabul, Afghanistan

Background

Kabul (Afghanistan) is a major focus of cutaneous leishmaniasis (CL) caused by Leishmania tropica. Microscopy remains the reference test for diagnosis despite its low performance. We evaluated whether Loopamp™ Leishmania Detection Kit (Loopamp) and CL Detect™ Rapid Test (CL Detect), detecting Leishmania DNA and antigen, respectively could improve CL diagnosis.

Methods

A diagnostic accuracy study with prospective inclusion was conducted in a leishmaniasis reference clinic in Kabul. Slit skin samples from CL suspects were analysed by microscopy. Samples taken with a dental broach were tested with CL Detect, Loopamp, and PCR. All samples were transferred to the Academic Medical Center (AMC, the Netherlands) for PCR and Loopamp analyses. The diagnostic performance of the tests was evaluated against a reference combining microscopy and PCR.

Findings

274 CL suspects were included in the study. In Kabul, CL Detect had a 65·4% sensitivity [95% Confidence Interval (CI): 59.2–71.2%] and a 100% specificity [95% CI: 80.5–100%], while these were 87.6% [95%CI: 82.9–91.3%] and 70.6% [95% CI: 44.0–89.7%] for Loopamp. At AMC the Loopamp's sensitivity (92.2% [95% CI: 88.2–95.2%]) and specificity (94.1% [95% CI: 71.3–99.8%]) were higher. An algorithm where CL Detect negative suspects would be tested by Loopamp yielded a 93.4% sensitivity [95% CI: 89.6–96.1%] and a 94.1% specificity [95% CI: 71.3–99.8%] when Loopamp's performance at AMC was used.

Interpretation

The high specificity of CL Detect and the performance of Loopamp allow their use in a diagnostic algorithm that would minimize the number of CL patients referred for confirmation.

Fund

Federal Ministry of Education and Research, Germany.

Accuracy of a Rapid Diagnostic Test Based on Antigen Detection for the Diagnosis of Cutaneous Leishmaniasis in Patients with Suggestive Skin Lesions in Morocco

In rural areas in Morocco, diagnosing cutaneous leishmaniasis (CL) can be challenging. We evaluated the accuracy of a rapid diagnostic test (RDT) based on antigen detection, CL Detect Rapid Test^™ (Inbios International Inc., Seattle, WA), in this setting. We consecutively recruited patients with new skin ulcers in nine primary health centers. We took a dental broach sample for the RDT and two other tissue samples by scraping the border and center of the lesion with a scalpel and smearing it on a slide. We duplicated each smear by pressing a clean slide against it and processed the slides by microscopy, polymerase chain reaction (PCR) internal transcribed spacer 1, and kDNA minicircle PCR. In a subgroup with positive PCR, the Leishmania species was identified using PCR-restriction fragment length polymorphism and PCR-sequencing of hsp70 genes. A participant with positive microscopy and/or PCR was considered a confirmed CL case. We computed sensitivity (Se) and specificity (Sp) of the RDT compared with this reference standard (ClinicalTrials.gov registration: NCT02979002). Between December 2016 and July 2017, we included 219 patients, 50% of them were under 18 years old. Rapid diagnostic test Se was 68% [95% confidence interval (CI): 61–74], Sp 94% [95% CI: 91–97], positive predictive value 95% [95% CI: 92–98], and negative predictive value 64% [95% CI: 58–70]. Despite its low Se, this novel RDT is a useful addition to clinical management of CL in Morocco, especially in isolated localities. Rapid diagnostic test–positive lesions can be treated as CL; but when RDT negative, microscopy should be done in a second step. The Se of the RDT can probably be optimized by improving the sampling procedure.

Analytical Performance of Four Polymerase Chain Reaction (PCR) and Real Time PCR (qPCR) Assays for the Detection of Six Leishmania Species DNA in Colombia

Leishmaniasis comprises a spectrum of parasitic diseases caused by protozoans of the genus Leishmania. Molecular tools have been widely employed for the detection of Leishmania due to its high sensitivity and specificity. However, the analytical performance of molecular platforms as PCR and real time PCR (qPCR) including a wide variety of molecular markers has never been evaluated. Herein, the aim was to evaluate the analytical performance of 4 PCR-based assays (designed on four different targets) and applied on conventional and real-time PCR platforms. We evaluated the analytical performance of conventional PCR and real time PCR, determining exclusivity and inclusivity, Anticipated Reportable Range (ARR), limit of detection (LoD) and accuracy using primers directed to kDNA, HSP70, 18S and ITS-1 targets. We observed that the kDNA was the most sensitive but does not meet the criterion of exclusivity. The HSP70 presented a higher LoD in conventional PCR and qPCR in comparison with the other markers (1 × 10¹ and 1 × 10^-1 equivalent parasites/mL respectively) and had a higher coefficient of variation in qPCR. No statistically significant differences were found between the days of the test with the four molecular markers. The present study revealed that the 18S marker presented the best performance in terms of analytical sensitivity and specificity for the qPCR in the species tested (species circulating in Colombia). Therefore, we recommend to explore the analytical and diagnostic performance in future studies using a broader number of species across America.

Evaluation of a hypothetical protein for serodiagnosis and as a potential marker for post-treatment serological evaluation of tegumentary leishmaniasis patients

The serodiagnosis for tegumentary leishmaniasis (TL) presents problems related to the sensitivity and/or specificity of the tests. In the present study, an enzyme-linked immunosorbent assay (ELISA) technique was used to evaluate the performance from a Leishmania braziliensis hypothetical protein, LbHyM, in an attempt to compare its serological reactivity with a soluble Leishmania antigenic preparation (SLA) for the serodiagnosis of cutaneous (CL) and mucosal (ML) leishmaniasis. LbHyM was predicted to be a kinesin-like protein by bioinformatics tools. Serum samples were collected from both CL and ML patients, as well as from those with Chagas disease and from healthy subjects living in endemic or non-endemic areas of TL. Also, sera were collected from patients before and after the treatments, seeking to evaluate their serological follow-up in relation to the anti-protein and anti-parasite antibody levels. When an ELISA-rLbHyM assay was performed, it proved to be significantly more sensitive than ELISA-L. braziliensis SLA in detecting both CL and ML patients. Also, when using sera from Chagas disease patients, the ELISA-rLbHyM proved to be more specific than ELISA-SLA. The anti-protein and anti-parasite antibody levels were also evaluated 6 months after the treatments, and treated patients showed significantly lower levels of specific-rLbHyM antibodies, when compared to the anti-parasite antibody levels. In conclusion, the ELISA-rLbHyM assay can be considered a confirmatory serological technique for the serodiagnosis of L. braziliensis infection and can also be used in the serological follow-up of treated patients, aiming to correlate the low anti-protein antibody levels with the improvement of the healthy state of the patients.

Cutaneous Leishmaniasis in Khyber Pakhtunkhwa Province of Pakistan: Clinical Diversity and Species-Level Diagnosis

This study primarily aimed to identify the causative species of cutaneous leishmaniasis (CL) in the Khyber Pakhtunkhwa Province of Pakistan and to distinguish any species-specific variation in clinical manifestation of CL. Diagnostic performance of different techniques for identifying CL was assessed. Isolates of Leishmania spp. were detected by in vitro culture, polymerase chain reaction (PCR) on DNA extracted from dried filter papers and microscopic examination of direct lesion smears from patients visiting three major primary care hospitals in Peshawar. A total of 125 CL patients were evaluated. Many acquired the disease from Peshawar and the neighboring tribal area of Khyber Agency. Military personnel acquired CL while deployed in north and south Waziristan. Leishmania tropica was identified as the predominant infecting organism in this study (89.2%) followed by Leishmania major (6.8%) and, unexpectedly, Leishmania infantum (4.1%). These were the first reported cases of CL caused by L. infantum in Pakistan. PCR diagnosis targeting kinetoplast DNA was the most sensitive diagnostic method, identifying 86.5% of all samples found positive by any other method. Other methods were as follows: ribosomal DNA PCR (78.4%), internal transcribed spacer 2 region PCR (70.3%), culture (67.1%), and microscopy (60.5%). Clinical examination reported 14 atypical forms of CL. Atypical lesions were not significantly associated with the infecting Leishmania species, nor with “dry” or “wet” appearance of lesions. Findings from this study provide a platform for species typing of CL patients in Pakistan, utilizing a combination of in vitro culture and molecular diagnostics. Moreover, the clinical diversity described herein can benefit clinicians in devising differential diagnosis of the disease.

Molecular prevalence and estimated risk of cutaneous leishmaniasis in Libya

BACKGROUND/PURPOSE

Cutanoeus leishmaniasis (CL) is an endemic disease in the Mediterranean area including Libya. The aim of the present study is to detect the prevalent Leishmania species obtained from smeared cutaneous lesions in addition to studying the diverse sociodemographic risk factors of the reported cases from different provinces of Libya.

METHODS

A total of 250 archived microscopic slides from clinically suspected cases of CL attending the leishmaniasis clinic in the Dermatology Department, Tripoli Central Hospital, Tripoli, Libya, were microscopically examined. Leishmania-DNA was amplified using combined polymerase chain reaction (PCR) targeting kinetoplast-DNA (kDNA) and ribosomal internal transcribed spacer 1 (ITS1)-DNA with restriction fragment length polymorphism analysis for direct Leishmania species identification.

RESULTS

Using kDNA and ITS1-PCR, 22.5% and 20% of cases were positive, respectively. Only 14.4% of cases were positive using microscopy. Nominating ITS1-PCR as the reference standard, kDNA-PCR assay was highly sensitive while microscopy was 100% specific but of limited sensitivity (72%) with a substantial agreement and an overall accuracy of 94.4%. Leishmania major and Leishmania tropica were the predominant species reported from the north-western provinces including Tripoli, Zintan, and Gharyan with their related subprovinces; Asabaa, Mizdan, Alkawasem, and Alorban. CL prevailed more among men and residents of rural areas. House wives and students were the most affected professions. Children were the least affected, while the middle-aged were the most affected age group.

CONCLUSION

L. major and L. tropica are the predominant species in the north-western regions of Libya. ITS1-PCR-restriction fragment length polymorphism assay offered a sensitive, specific, and faster diagnostic method especially with negative parasitologic examination.

Comparison of clinical samples and methods in chronic cutaneous leishmaniasis

This study aimed at finding out the most effective clinical samples and methods in chronic cutaneous leishmaniasis (CCL). Smear, aspiration fluid, and filter paper samples were taken from 104 skin lesions of suspected cases with CCL, and they were compared using microscopic examination, culture, and molecular methods. We characterized four different forms of CCL and identified the causative agents in CCL forms using high-resolution melting curve real-time polymerase chain reaction assay. We observed that smear was detected to be the most sensitive (63.5%) among clinical samples, and real-time polymerase chain reaction method was the most sensitive (96.8%) among the methods used in diagnosis of CCL. We identified 68.8% Leishmania tropica and 31.2% L. infantum in papular lesions, 69.2% L. infantum and 30.8% L. tropica in nodular lesions, 57.9% L. tropica and 42.1% L. major in ulcerating plaque lesions, and 55.5% L. tropica and 44.5% L. major in noduloulcerative lesions in CCL patients.

Molecular technique for detection of Leishmania infantum isolates in Iran

Introduction:

Leishmania infantum is the causative agent of autochthonous cutaneous and visceral cases of leishmaniasis and transmitted by female sandflies. The dogs are considered the main reservoir hosts; however, there are the reports on Leishmania infection in other animals. In this study, occurrence types of L. infantum isolates have been analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique.

Materials and Methods:

In this experimental study, 77 samples were cultured and prepared for microscopic study and examined through PCR-RFLP. The samples were used for both deoxyribonucleic acid (DNA) and smear-slide preparations. The DNAs were amplified by PCR for the detection of Leishmania subgenus and PCR products were restricted with HaeIII for the species differentiation.

Results:

The visceral Leishmania parasites were genotyped as L. infantum. It was also determined sensitivity in PCR (100%) was higher than microscopic examination.

Conclusion:

PCR-RFLP technique appears to be most sensitive for the detection and differentiation of L. infantum. There exists a relationship between genetic heterogeneousness and clinical manifestation and geographical regions of this disease in human.

Development and evaluation of a loop-mediated isothermal amplification assay for rapid detection of Leishmania infantum in canine leishmaniasis based on cysteine protease B genes

We developed a Leishmania infantum specific LAMP assay that was carried out using a set of, six primers targeting the cysteine protease B multi copy gene of L. infantum. Our result shows that we, successfully detect the L. infantum DNA and that amplification is specific as no cross reaction was seen, with L. major, L. tropica, L. turanica, L. aethiopica, L. tarentolae, L. gerbilii, Trypanosoma cruzi or, human genomic DNA. When compared to conventional cpb based PCR, the sensitivity of LAMP assay, was higher with a detection limit of 50 fg/μl of genomic L. infantum parasite DNA. Accurate and rapid, diagnosis of canine leishmaniasis (CanL) is an important issue that allows early treatment and, prevents transmission. Our developed LAMP assay was used to evaluate occurrences of Leishmania infantum in seventy five (75) dogs from the field. Blood samples were used to perform LAMP assay, classical PCR, IFAT and microscopy that was used as gold standard. The IFAT in addition to, microscopy, are the basic techniques used for CanL diagnosis at the School of Veterinary Medicine, where we obtained our samples. Compared to molecular methods, the serology (IFAT) test shows the, best sensitivity (88.57%) with, however, a much lower specificity (52.5%) due to a relatively high, number of false-positive results (22 animals). The PCR assay shows a low sensitivity (37.14%) and, specificity around (82.5%). Our LAMP assay shows a suitable sensitivity (54%) and a good specificity, (80%), with however, positive (70%) and negative (66%) predictive values. Furthermore, the best, positive likelihood ratio (LR+) was obtained by LAMP assay (2.7). This technique presents the highest, kappa value (with a fair agreement of 0.34). Moreover, the relative stability of the reagents indicates, that LAMP may be a good alternative to a conventional PCR, especially under field conditions. Finally in, a brief cost evaluation, the LAMP assay compares favorably with other molecular diagnostic tests. This, is the first study that evaluates the L. infantum specific LAMP alongside other diagnostics tools for, CanL. Our results indicate a suitable sensitivity and specificity for the developed LAMP assay that could, has usefulness application on dogs and human L. infantum diagnosis.

Old World cutaneous leishmaniasis: diagnosis and treatment

Cutaneous leishmaniasis is a major world health problem. Diagnosis is suspected on evocative clinical presentation in patients living in or coming from endemic areas. Several methods have been used. The smear is a simple investigation used in endemic regions. The culture enables to identify the specimen. PCR has a high sensitivity. Montenegro's reaction is used in the epidemiological study. Pentavalent antimony derivatives remain the mainstay of systemic treatment. Their efficiency is well established. Their toxicity should be researched. Other treatments can be utilized, such as miltefosine. Local therapy is used in uncomplicated lesions. Injections of the pentavalent antimony derivate, cryotherapy and paromomycin ointmentsis are important options and should be used more frequently in Old World leishmaniasis.

Cutaneous leishmaniasis in the Nalut District, Libyan Arab Jamahiriya: a clinico-epidemiologic study and Leishmania species identification

Cutaneous leishmaniasis (CL), an endemic disease in the littoral zones of the Mediterranean area, the Middle East, East Africa, and especially in Libya, has not been fully documented. The present study clarifies the clinico-epidemiologic profile of CL and the molecular genotyping of the Leishmania spp. in the Nalut district, Libya. Two hundred and twenty-three CL patients were examined at the out-patient clinics of Nalut Hospital from March 2006 to February 2007. CL was diagnosed by clinical, microscopic, culture, polymerase chain reaction (PCR), and PCR-restriction fragment length polymorphism (RFLP) analyses. The disease was observed year-round, with the highest prevalence between November and February. Fifty-nine percent of patients were younger than 20 yr. Nodulo-ulcerative lesions, indurated ulcers, papulo-ulcerative lesions, and subcutaneous nodular lesions were observed in 170, 25, 15, and 13 patients, respectively. Two hundred patients (89.7%) had dry type of lesions, whereas 23 patients (10.3%) presented a wet type of lesion. One hundred and fifty-nine (71.3%) of 223 patients were confirmed positive for CL by the presence of the amastigote form of Leishmania by stained Giemsa smear, and 170 (76.2%) were positive according to the presence of the promastigote form of Leishmania by culture in RPMI 1640 medium supplemented with 10% fetal bovine serum (FBS). PCR confirmed 203 (91.0%) positive cases. Genotyping of Leishmania spp. by RFLP analysis revealed that L. tropica was the most common species at all ages, and L . infantum was second under 20 yr of age. In summary, CL is endemic in the Nalut district, Libya; PCR was the most sensitive parasite diagnostic test, and L. tropica was the most common species.

Diagnosis and identification of Leishmania spp. from Giemsa-stained slides, by real-time PCR and melting curve analysis in south-west of Iran

BACKGROUND

The aim of present study was describing a real-time PCR assay for the diagnosis and direct identification of Leishmania species on Giemsa-stained slides in south-west of Iran.

MATERIALS AND METHODS

Altogether, 102 Giemsa-stained slides were collected from different part of south-west of Iran between 2008 and 2011. All the Giemsa-stained slides were examined under light microscope. After DNA extraction, real-time PCR amplification and detection were conducted with fluorescent SYBR Green I. For identification, PCR products were analysed with melting curve analysis.

RESULTS

One hundred and two archived slides from suspected lesion examined by microscopy and real-time PCR. The sensitivity of the real-time PCR on Giemsa-stained slid was 98% (96/102). The melting curve analysis (T(m)) were 88·3±0·2°C for L. tropica (MHOM/IR/02/Mash10), 86·5±0·2°C for L. major (MHOM/IR/75/ER) and 89·4±0·3°C for L. infantum (MCAN/IR/97/LON 49), respectively.

CONCLUSION

This study is first report in use of real-time PCR for diagnosis and identification of Leishmania spp. in Iran. Up to now, in Iran, the majority of identification of Leishmania species is restriction fragment length polymorphism (PCR-RFLP) of ITS1 and kinetoplast DNA. Our data showed that Giemsa-stained slides that were stored more than 3 years, can be use for Leishmania DNA extraction and amplification by real-time PCR. Compared to conventional PCR-based methods, the real-time PCR is extremely rapid with results and more samples can be processed at one time.

[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.

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.

Atypical presentation of Old-World cutaneous leishmaniasis, diagnosis and species identification by PCR

BACKGROUND

The diagnosis of cutaneous leishmaniasis (CL) is traditionally based on microscopic demonstration of amastigote forms in tissue biopsies or smears. However, this method usually presents low sensitivity, and in atypical forms, CL may be overlooked because of similarity to other dermal diseases. Thus, it is necessary to apply specific diagnostic methods as polymerase chain reaction (PCR).

OBJECTIVE

To evaluate the possible advantage of PCR in the diagnosis and species identification of CL in patients with atypical clinical presentation.

METHODS

Fifty-one patients clinically suspected of CL with positive and negative controls were tested. After microscopic examination, extraction of DNA was performed on their smears and analysed by two specific PCR assays for diagnosis and species identification. For these methods, conserved and variable regions of kinetoplastic DNA (KDNA) of Leishmania species have been amplified, respectively. Atypical forms of CL were evaluated among PCR-positive patients.

RESULTS

PCR results were positive in 37 out of 51 cases (72.5%), among whom microscopic examination revealed Leishmania amastigotes in only 3 (5.9%). Among these patients, 10 (27%) had atypical presentation of CL; using species-specific primers, 6 patients had Leishmania major, 3 had Leishmania tropica and 1 patient had no species diagnosis. None of the samples of other dermal diseases revealed positive results (specificity, 100%). All patients were successfully treated by CL-specific drug regimens.

DISCUSSION

The results showed that KDNA PCR methods have a higher sensitivity compared with microscopic method. Moreover, PCR could identify the parasite species for specific therapy. Microscopic method had low sensitivity and less value in chronic and atypical CL cases.

[Sporotrichoid cutaneous leishmaniasis in Tunisia: a clinical and histological study]

BACKGROUND

The sporotrichoid variety of cutaneous leishmaniasis is defined by the presence of dermal and hypodermal nodules along the lymphatic stream, and remote from the primary inoculation lesions. This clinical form is usually considered rare. The aim of our study was to investigate the epidemiological, clinical, histological and evolutionary particularities of sporotrichoid cutaneous leishmaniasis in the south of Tunisia.

PATIENTS AND METHODS

During a systematic study of all cases of cutaneous leishmaniasis from the south of Tunisia diagnosed in our hospital in 2002, sporotrichoid forms were diagnosed on the basis of clinical criteria. In all cases of sporotrichoid cutaneous leishmaniasis, the principal clinical characters were systematically specified. Cutaneous biopsies of subcutaneous nodules were performed in six cases.

RESULTS

Of 102 patients with cutaneous leishmaniasis, 19 presented sporotrichoid cutaneous leishmaniasis, that is, a frequency of 19%. Between two and 20 painless subcutaneous nodules were arranged in linear strings on the upper leg in 79% of cases. Time to appearance varied between 12 days and one year after the primary lesions. Fourteen appeared without any preliminary treatment for cutaneous leishmaniasis and five appeared after Glucantime infiltration in the primary lesions. Biopsies of the nodules showed an inflammatory infiltrate composed of lymphocytes and histiocytes. This infiltrate was particularly dense and rich in plasmocytes at the level of the deep dermis. The biopsies were deep enough to involve the hypoderm in one case and the same type of infiltrate was noted at the level of interlobular septa. A small number amastigotes was seen in one deep biopsy sample. Outcome was favourable in all cases under treatment.

CONCLUSION

Sporotrichoid cutaneous leishmaniasis appears to be common in the south of Tunisia, were cutaneous leishmaniasis is dominant because of Leishmania major. It is not associated with a poor prognosis.

Detection and species identification of Old World Leishmania in clinical samples using a PCR-based method

The aim of this study was to develop a simple, low-cost method for the detection and species differentiation of Leishmania directly from clinical samples, for routine use in a parasitology laboratory. A total of 87 samples was used, including 60 peripheral blood, seven bone marrow and 17 skin lesion material samples, derived from Greek patients with visceral or cutaneous leishmaniasis, and three reference strains. PCR was performed using primers designed to amplify the internal transcribed spacer 1 (ITS1) region of the rRNA gene. Identification of the Leishmania species studied was achieved by digestion with a single restriction endonuclease (RFLP), single-strand conformational polymorphism (SSCP) and DNA sequencing of the PCR-generated fragments. Typing identified all visceral and one cutaneous leishmaniasis strains as L. infantum, twelve of the cutaneous leishmaniasis strains as L. tropica and four as L. major. The described PCR method proved efficient for the detection of pathogenic Leishmania species in various clinical samples, most importantly in peripheral blood samples. Furthermore, PCR followed by a simple RFLP using a single restriction endonuclease was capable of identifying all Leishmania species commonly encountered in Greece.

Cutaneous leishmaniasis

Cutaneous leishmaniasis is a widespread tropical infection caused by numerous different species of Leishmania protozoa that are transmitted by sandflies. Its clinical presentations are extremely diverse and dependent on a variety of parasite and host factors that are poorly understood. Diagnosis should aim to identify the exact species involved, but this requires laboratory investigations that are not widely available. No single ideal treatment has been identified, and those available are limited by variable success rates and toxicity. Clinical guidelines are needed to make better use of the investigations and treatments that do exist. Prevention is currently limited to bite prevention measures.