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

Efficacy of a Combined Herbal Product Containing Indigofera argentea, Pistacia atlantica and Salvia hispanica in Zoonotic Cutaneous Leishmaniasis Patients Treated along Glucantime ®

Background

Leishmaniasis is highly prevalent worldwide, and while conventional medicine offers numerous treatment methods for cutaneous leishmaniasis, Iranian traditional medicine suggests various remedies. We aimed to evaluate the efficacy of an herbal combination containing Indigofera argentea leaves, Pistacia atlantica resin, and Salvia hispanica seeds in patients with zoonotic cutaneous leishmaniasis.

Methods

This study was conducted at the Leishmaniasis Department of Chabahar Health Center in southeastern Iran in 2021. It was a double-blinded randomized clinical trial involving 68 patients enrolled after clinical diagnosis, examination of smear samples using Giemsa staining, and PCR confirmation. The volunteers were randomly divided into intervention and control groups. Both groups received 'Glucantime ® as the primary medication weekly until complete healing or up to 12 weeks. Glucantime ® was administered intralesionally at a dosage of 0.1 cc on the wound's margin, with repeat injections at 1 cm intervals along the wound edge when necessary. In addition to the main drug, the intervention group received the herbal product topically twice daily until wound healing or for up to 4 weeks, while the control group received a placebo in the same manner.

Results

82.35% of patients in the intervention group and 20.58% in the control group achieved complete healing within four weeks. There was a significant difference between the two groups (P < 0.001).

Conclusion

The herbal product demonstrated effectiveness in treating patients with zoonotic cutaneous leishmaniasis.

Diversity and geographical distribution of Leishmania species and the emergence of Leishmania (Leishmania) infantum and L. (Viannia) panamensis in Central-Western Venezuela

Transmission of cutaneous leishmaniasis in Venezuela reveals diverse and changing epidemiological landscapes, as well as a spectrum of clinical phenotypes presumed to be linked to a variety of Leishmania species. Central-western Venezuela constitutes one of the highest endemic epicenters in the country, yet updated molecular epidemiological information is still lacking. Therefore, in this study we aimed to characterize the landscape of circulating Leishmania species across central-western Venezuela through the last two decades, performed comparisons of haplotype and nucleotide diversity, and built a geospatial map of parasite species distribution. A total of 120 clinical samples were collected from patients across the cutaneous disease spectrum, retrieving parasitic DNA, and further characterizing by PCR and sequencing of the HSP70 gene fragment. This data was later collated with further genetic, geospatial and epidemiological analyses. A peculiar pattern of species occurrence including Leishmania (Leishmania) amazonensis (77.63% N=59), Leishmania (Leishmania) infantum (14.47% N=11), Leishmania (Viannia) panamensis (5.26% N=4) and Leishmania (Viannia) braziliensis (2.63% N=2) was revealed, also highlighting a very low genetic diversity amongst all analyzed sequences. Geographical distribution showed that most cases are widely distributed across the greater urban-sub urban area of the Irribaren municipality. L.(L.) amazonensis appears to be widely dispersed throughout Lara state. Statistical analyses failed to reveal significance for any comparisons, leading to conclude a lack of association between the infective Leishmania species and clinical phenotypes. To the best of our knowledge, this is an unprecedented study which addresses comprehensively the geographical distribution of Leishmania species in central-western Venezuela throughout the last two decades, and the first to incriminate L. (L.) infantum as an etiologic agent of cutaneous leishmaniasis in this region. Our findings support that Leishmania endemism in central-western Venezuela is caused mainly by L.(L.) amazonensis. Future studies are needed to unveil additional details on the ecological intricacies and transmission aspects of leishmaniasis (i.e. sampling phlebotomines and mammals) and to adopt adequate public health prevention and control strategies and mitigate disease impact in this endemic region.

PCR for detection of Leishmania donovani from microscopically negative tissue smears of suspected patients in Gondar, Ethiopia

BACKGROUND

As untreated visceral leishmaniasis (VL) is fatal, reliable diagnostics are pivotal for accurate treatment allocation. The current diagnostic algorithm for VL in Ethiopia, which is based on the rK39 rapid diagnostic test and microscopy of tissue smears, lacks sensitivity. This probably leads to missed cases and patients not receiving treatment.

METHODOLOGY

We conducted a retrospective study on stored microscopically negative spleen and bone marrow smears from suspected VL patients collected at the Leishmaniasis Research and Treatment Center (LRTC) in Gondar, northern Ethiopia between June 2019 and November 2020. Sociodemographic, clinical and treatment data were collected and samples were tested by real-time PCR targeting kinetoplast DNA.

PRINCIPLE FINDINGS

Among the 191 eligible samples (135 spleen and 56 bone marrow) with a microscopically negative and valid PCR result, 119 (62.3%) were positive by PCR, although Ct values for some were high (median 33.0). Approximately three quarters of these undiagnosed primary VL (77.3%) and relapse (69.6%) patients did not receive antileishmanial treatment. Of the 56 microscopically negative bone marrow samples, 46 (82.1%) were PCR positive, which is considerably higher compared to the microscopically negative spleen samples, for which 73 out of 135 (54.1%) were PCR positive. The odds of being PCR positive were significantly higher for bone marrow aspirates and higher when white blood cell values were lower and splenomegaly (in cm) was more pronounced.

CONCLUSIONS

This study demonstrates that a lot of suspected VL patients remain undiagnosed and untreated. This indicates the urgent need for better diagnostics for VL in the East-African region. The outcomes of PCR positive should be closely monitored and treatment should be provided if the patient deteriorates. In resource limited settings, implementation of PCR on bone marrow aspirate smears of patients with low WBC values and splenomegaly could lead to considerable improvements in patient management.

Ecotin: A versatile protease inhibitor of bacteria and eukaryotes

Serine protease inhibitors are a large family of proteins involved in important pathways and processes, such as inflammatory responses and blood clotting. Most are characterized by a precise mode of action, thereby targeting a narrow range of protease substrates. However, the serine-protease inhibitor ecotin is able to inhibit a broad range of serine proteases that display a wide range of specificities. This specificity is driven by special structural features which allow unique flexibility upon binding to targets. Although frequently observed in many human/animal-associated bacteria, ecotin homologs may also be found in plant-associated taxa and environmental species. The purpose of this review is to provide an update on the biological importance, role in host-microbe interactions, and evolutionary relationship between ecotin orthologs isolated from Eukaryotic and Prokaryotic species across the Tree of Life.

The Geographical Distribution of Human Cutaneous and Visceral Leishmania Species Identified by Molecular Methods in Iran: A Systematic Review With Meta-Analysis

Leishmaniasis is one of the most common vector-borne parasitic diseases in Iran. Leishmania species identification is necessary for epidemiological aspects, precise prognosis, control and treatment of the disease. We systematically searched all the studies, reports, and documentation related to species identification and geographical distribution of causative agents of cutaneous (CL), mucosal (ML), and visceral leishmaniasis (VL) using DNA-based molecular diagnostic techniques in Iran. International databases including PubMed, ScienceDirect, Embase, Google Scholar, Scopus, and Web of Science were systemically searched for English articles and Iran's databases including SID, IranMedex and Magiran were searched for Persian reports and articles. Searches were performed from 1999 to 2019 (20 years). The current review was conducted using the keywords: cutaneous leishmaniasis, visceral leishmaniasis, Leishmania species, Human, Molecular, PCR, and Iran. The study quality was evaluated using the NOS checklist. This meta-analysis procedure was accomplished using STATA, version 2.7.9. Of the 3,426 records identified in the initial search, 154 articles met inclusion criteria and qualified for the systematic review and meta-analysis. In subgroup analysis, the pooled frequency of causative agents of CL isolates was 67.3% (95% CI: 59.51–74.67%) for L. major and 32.1% (95% CI: 24.72–39.87%) for L. tropica. In addition, the pooled frequency of causative agents of VL isolates was 97.1% (95% CI: 94.6–98.8%) for L. infantum and 2.9% (95% CI: 1.12–5.37%) for L. tropica. The findings of this study showed that the main causative agents of CL and VL in Iran are L. major and L. infantum, respectively. Moreover, kinetoplast DNA (kDNA) and internal transcriber spacer (ITS) were the most used markers for identifying Leishmania species. The current study provides valuable data to encourage and direct researchers as well as public health managers in the comprehensive leishmaniasis control and prevention planning in Iran.

Identification of Leishmania species by high-resolution melting analysis in newly emerged foci in Sabzevar, northeast of Iran

Cutaneous leishmaniasis (CL) is a zoonotic disease with 1 to 1.5 million annual incidences. Microscopic examination of the Giemsa stained slides is the most common diagnostic method for CL. However, this method cannot distinguish leishmania species. Hence the present study was conducted to identify leishmania species by high-resolution melting (HRM) analysis in the newly emerged foci of CL in Sabzevar, northeast of Iran. In this cross-sectional study, fifty patients with suspicious cutaneous lesions referring to the designated health center for diagnosis and treatment of CL in Sabzevar during 2017-2018, were recruited. All collected samples and prepared slides were stained for microscopic examination and then undergone HRM real-time PCR (HRM-PCR) assay to identify species of Leishmania parasites. The results of HRM-PCR technique showed that Leishmania major (L. major) was the dominant causative parasite in the newly emerged foci whereas L. tropica (L. tropica) was positive only in two patients. This was the first time that 7SL RNA-HRM-PCR assay was performed to precisely identify leishmania parasites in the northeast of Iran. We proved the newfound foci in which both L. major and L. tropica were present. In contrast to the recent studies which identified only L. major in the region, we showed that L. tropica was still present.

A long-lasting emerging epidemic of anthroponotic cutaneous leishmaniasis in southeastern Iran: population movement and peri-urban settlements as a major risk factor

Background

Epidemics of cutaneous leishmaniasis (CL) are occurring more frequently and spreading faster and farther than before in many areas of the world. The present study aimed to assess a long-lasting emerging epidemic (2005–2019) of 5532 cases with anthroponotic CL (ACL) in peri-urban areas of Kerman city in southeastern Iran.

Methods

This descriptive-analytical study was carried out for 15 years in Kerman province, southeastern Iran. The data were passively obtained through the health surveillance system and the Kerman Leishmaniasis Research Center. Every subject was diagnosed using direct smear microscopy. The representative causative agent was further examined by ITS1-PCR, PCR-RFLP, 7SL RNA gene sequencing and phylogenetic analyses. For each subject, a case report form designating demographic and clinical data was recorded.

Results

A different pattern of ACL incidence was found in peri-urban areas compared to that in the city of Kerman. The incidence rate of ACL cases has significantly increased (P < 0.001) from 2005 to 2016 in new settlements with a gradual decline after that. The overall average risk of contracting the disease was 7.6 times higher in peri-urban areas compared to Kerman city, an old endemic focus. All isolates consisting of six variants were confirmed to be Leishmania tropica. The overall pattern of the ACL infection indicates that the etiological agent of ACL is propagated and transmitted by the bite of female Phlebotomus sergenti sandflies from person to person from dissimilar clones as reflected by the complexity of the migrants’ backgrounds in the province.

Conclusions

The movement of populations and establishment of new settlements in peri-urban areas close to endemic areas are major risk factors for and are directly linked to CL. The underlying factors of this emerging ACL epidemic caused by L. tropica were disasters and droughts, among others. A robust commitment to a multilateral approach is crucial to make improvements in this area. This will require decisive coordinated actions through all governmental factions and non-governmental organizations. Furthermore, active and passive case detection strategies, early diagnosis, and effective treatment could help control the disease.

High resolution melting assay in discrimination of the main etiologic agents of leishmaniasis in Iran

Background and Objectives:

The three old world Leishmania species i.e., L. major, L. tropica, and L. infantum are considered as potential etiological agents of the various clinical forms of leishmaniasis in Iran. Different species co-exist in some areas. Accurate differentiation between the species is essential for choosing an appropriate therapy. Conventional and gold standard methods for the detection and characterization of parasites are time-consuming, laborious, and have low sensitivity. A polymerase chain reaction followed by high resolution melting (PCR-HRM) analysis has been employed for detection and species identification. Most of the studies suffer from the use of multiple targets and/or requiring more than one reaction to identify a single sample. The present study aimed to design a PCR method based on the amplification of kinetoplast DNA minicircles (kDNA) and HRM analysis of the amplicons for rapid discrimination of the three mentioned species.

Materials and Methods:

DNA from reference strains including L. major, L. tropica, and L. infantum and fifty-eight strains subjected to PCR-HRM analysis targeting kDNA. All the samples were also analyzed by conventional kDNA-PCR.

Results:

The PCR-HRM analysis allowed discrimination between the three Old World species. The normalized HRM curves for the amplicons of kDNA indicated a unique and repeatable melting plot for each species, even in combination with human and mouse genomic DNA. Conventional kDNA-PCR could not properly discriminate L. tropica from L. infantum.

Conclusion:

PCR-HRM analysis of kDNA proved to be fast and accurate for discrimination of L. major, L. tropica, and L. infantum.

Comparison of parasite load by qPCR and histopathological changes of inner and outer edge of ulcerated cutaneous lesions of cutaneous leishmaniasis

Background

Cutaneous leishmaniasis (CL) is an infectious vector-borne disease caused by protozoa of the Leishmania genus that affects humans and animals. The distribution of parasites in the lesion is not uniform, and there are divergences in the literature about the choice of the better sampling site for diagnosis–inner or outer edge of the ulcerated skin lesion. In this context, determining the region of the lesion with the highest parasite density and, consequently, the appropriate site for collecting samples can define the success of the laboratory diagnosis. Hence, this study aims to comparatively evaluate the parasite load by qPCR, quantification of amastigotes forms in the direct exam, and the histopathological profile on the inner and outer edges of ulcerated CL lesions.

Methods

Samples from ulcerated skin lesions from 39 patients with confirmed CL were examined. We performed scraping of the ulcer inner edge (base) and outer edge (raised border) and lesion biopsy for imprint and histopathological examination. Slides smears were stained by Giemsa and observed in optical microscopy, the material contained on the smears was used to determine parasite load by quantitative real-time PCR (qPCR) with primers directed to the Leishmania (Viannia) minicircle kinetoplast DNA. The histopathological exam was performed to evaluate cell profile, tissue alterations and semi-quantitative assessment of amastigote forms in inner and outer edges.

Principal findings

Parasite loads were higher on the inner edge compared to the outer edge of the lesions, either by qPCR technique (P<0.001) and histopathological examination (P< 0.003). There was no significant difference in the parasite load between the imprint and scraping on the outer edge (P = 1.0000).

Conclusion/Significance

The results suggest that clinical specimens from the inner edge of the ulcerated CL lesions are the most suitable for both molecular diagnosis and direct parasitological examination.

An impedimetric genosensor for Leishmania infantum based on electrodeposited cadmium sulfide nanosheets

It is estimated that there are 400000 new cases of visceral leishmaniasis each year, with about 30,000 deaths. Therefore, detection of this pathogen and its species is highly vital for overall health of the community. In the present research, a DNA-based biosensor, namely genosensor, was introduced for detection of genomic DNA of Leishmania infantum. The genosensor was fabricated based on the transduction of cadmium sulfide nanosheets and recognition of a particular single stranded DNA sequence, and worked in label-, marker-, tag- and PCR-free manners. Impedimetric measurements were performed in a wide range of frequency (recording Nyquist diagrams) without applying external force (working at open circuit potential) upon hybridization of DNA targets with the cadmium sulfide nanosheets surface-immobilized probe. The genosensor detected the complementary DNA strand in a concentration range of 1.0 × 10^-14 to 1.0 × 10^-6 mol L^-1 and a detection limit (DL) of 0.81 fmol L^-1 (6.5 fg mL^-1), and genomic DNA of Leishmania infantum in a concentration range of 5-50 ng μL^-1 and a DL of 1.2 ng μL^-1. The genosensor had a very good selectivity, fabrication reproducibility and stability, and was applicable for practical applications.

Diagnostic performance of a qPCR for Leishmania on stained cytological specimens and on filter paper impressions obtained from cutaneous lesions suggestive of canine leishmaniosis

BACKGROUND

Detection of Leishmania in cutaneous lesions is possible by visualization of amastigotes. Detection of Leishmania DNA by PCR presents greater sensitivity, and PCR has been used to diagnose cutaneous leishmaniosis in humans using noninvasive clinical specimens.

OBJECTIVES

Study I: to determine if Leishmania DNA could be efficiently extracted and amplified from archived Diff-Quik^® -stained slides of cytological specimens from canine cutaneous lesions. Study II: to evaluate the diagnostic performance of a Leishmania-quantitative (q)PCR on stained cytological specimens and on filter paper impressions (FPI) obtained from cutaneous lesions suggestive of canine leishmaniosis (CanL).

ANIMALS

Samples from cutaneous lesions of 54 dogs.

METHODS AND MATERIALS

Study I: Leishmania-qPCR was performed on 19 glass slides (from nine dogs) with cytologically visible amastigotes. Fifteen slides with no visible amastigotes, obtained from 12 dogs seronegative for Leishmania by ELISA, served as controls. Study II: Leishmania-qPCR was performed on glass slides and FPI from cutaneous lesions compatible with clinical leishmaniosis in 33 dogs.

RESULTS

Study I: all slides with visible amastigotes had positive qPCR, whereas all control slides yielded negative results. Study II: of 13 dogs definitively diagnosed with clinical leishmaniosis, eight had visible amastigotes on cytology, whereas Leishmania-qPCR was positive on 11 glass slides and 13 FPI. Leishmaniosis was ruled out by standard methods in 20 dogs, four of which yielded positive qPCR on FPI and/or glass slides.

CONCLUSIONS AND CLINICAL IMPORTANCE

Leishmania-DNA can be detected efficiently by qPCR from cutaneous cytological specimens and FPI to diagnose Leishmania infection in dogs with cutaneous lesions suggestive of CanL.

Cutaneous leishmaniasis: an epidemiological study in southwest of Iran

The current study was aimed to evaluate the frequency and epidemiological aspects of cutaneous leishmaniasis (CL) in the southwest of Iran, an endemic focus for the leishmaniasis from 2014 to 2017. In the present retrospective cross-sectional study, all suspicious CL persons who were referred to health centers affiliated to Abadan School of Medical Sciences (Abadan and Khorramshahr cities) were tested. In this regard, both clinical and parasitological (staining with Giemsa) verifications were performed to diagnose a case. Furthermore, a structured questionnaire containing some demographic details was applied for each positive patient. In total, 151 and 132 positive CL cases were identified in Abadan and Khorramshahr cities, respectively. More frequency of CL was observed during the Winter season, among male subjects, and in urban inhabitants in both cities. The incidence of CL based on age distribution was higher in the age range of 20-30 years than others. Besides, the hands and feet were the most involved organs. Although the frequency of CL has declined in the region, CL is still a public health problem. More appropriate control strategies are required to limit and eliminate the infection in the future.

Electrochemical quantitation of Leishmania infantum based on detection of its kDNA genome and transduction of non-spherical gold nanoparticles

Detecting and monitoring the pathogens with high selectivity and sensitivity is critical for public health. In the present study, we demonstrated a specific analytical strategy for sensitive detection of Leishmania infantum genome. The developed sensor utilized toluidine blue as a hybridization indicator and a Leishmania infantum-specific capture DNA sequence immobilized on a high-surface area gold nanostructure as an electrochemical transducer. The produced analytical response was based on the hybridization of the single-stranded DNA from the target with the immobilized DNA sequence at the electrode surface. The developed DNA sensor in this study was successfully employed to detect a synthetic Leishmania infantum target sequence in a wide concentration range from 1 × 10^-18 to 1 × 10^-10 mol L^-1 with a detection limit of 0.2 amol L^-1 with the ability to discriminate the target sequence from mismatched sequences. Moreover, the designed DNA sensor showed a good reproducibility and stability during repeated regeneration and hybridization cycles. The DNA sensor could detect Leishmania infantum genome in a wide concentration range from 15 to 50 ng μL^-1 with a detection limit of 29 ng μL^-1. Furthermore, clinical trials confirmed the applicability of the developed DNA sensor for practical applications.

Metacaspase-binding peptide inhibits heat shock-induced death in Leishmania (L.) amazonensis

Leishmania (Leishmania) amazonensis is an important agent of cutaneous leishmaniasis in Brazil. This parasite faces cell death in some situations during transmission to the vertebrate host, and this process seems to be dependent on the activity of metacaspase (MCA), an enzyme bearing trypsin-like activity present in protozoans, plants and fungi. In fact, the association between MCA expression and cell death induced by different stimuli has been demonstrated for several Leishmania species. Regulators and natural substrates of MCA are poorly known. To fulfill this gap, we have employed phage display over recombinant L. (L.) amazonensis MCA to identify peptides that could interact with the enzyme and modulate its activity. Four peptides were selected for their capacity to specifically bind to MCA and interfere with its activity. One of these peptides, similar to ecotin-like ISP3 of L. (L.) major, decreases trypsin-like activity of promastigotes under heat shock, and significantly decreases parasite heat shock-induced death. These findings indicate that peptide ligands identified by phage display affect trypsin-like activity and parasite death, and that an endogenous peptidase inhibitor is a possible natural regulator of the enzyme.

The new situation of cutaneous leishmaniasis after Syrian civil war in Gaziantep city, Southeastern region of Turkey

Cutaneous leishmaniasis (CL) is an important public health problem with around 2.000 autochthonous reported cases each year in Turkey. Due to the civil war in Syria, Turkey received around three million refugees and they are mainly located at either camps or homes in south/southeastern part of Turkey. In the present study, we aimed to collect samples from CL suspected patients admitting to State Hospital in Gaziantep City and perform parasitological and DNA-based techniques for diagnosis as well as species identification of the parasite for better understanding the prevalence of each species among Turkish and Syrian patients in the region. The collection of samples was carried out between January 2009 and July 2015. The lesion aspiration samples were taken and stained with Giemsa stain followed by microscopical examination for parasitological diagnosis. After the DNA extraction from Giemsa stained slides, real time and semi-nested PCRs both targeting ITS1 region were performed for molecular diagnosis and species identification. A total of 567 people were admitted to the hospital with the suspicion of CL and 263 (46.4%) of them were found to be positive by parasitological examination. One hundred seventy-four (66.15%), 88 (33.46%) and 1 (0.38%) of them were Turkish, Syrians and Afghan, respectively. Slide samples obtained from 34 CL suspected patients were analyzed by PCR and 20 of them were found positive. Eighteen (13 Turkish and 13 Syrians) of the positive samples were identified as L. tropica, while two (1 Turkish and 1 Syrian) of them were L. infantum. In conclusion, the effects of Syrian civil war on the epidemiology of CL in Gaziantep city is demonstrated in the present study. The use of molecular tool in the diagnosis of leishmaniasis is effective, sensitive and time saving which will enable the species typing. Species typing of the causative agent in endemic areas will bring valuable data to epidemiological knowledge.

Geographic Distribution of Leishmania Species in Ecuador Based on the Cytochrome B Gene Sequence Analysis

A countrywide epidemiological study was performed to elucidate the current geographic distribution of causative species of cutaneous leishmaniasis (CL) in Ecuador by using FTA card-spotted samples and smear slides as DNA sources. Putative Leishmania in 165 samples collected from patients with CL in 16 provinces of Ecuador were examined at the species level based on the cytochrome b gene sequence analysis. Of these, 125 samples were successfully identified as Leishmania (Viannia) guyanensis, L. (V.) braziliensis, L. (V.) naiffi, L. (V.) lainsoni, and L. (Leishmania) mexicana. Two dominant species, L. (V.) guyanensis and L. (V.) braziliensis, were widely distributed in Pacific coast subtropical and Amazonian tropical areas, respectively. Recently reported L. (V.) naiffi and L. (V.) lainsoni were identified in Amazonian areas, and L. (L.) mexicana was identified in an Andean highland area. Importantly, the present study demonstrated that cases of L. (V.) braziliensis infection are increasing in Pacific coast areas.

Identification of causative Leishmania species in Giemsa-stained smears prepared from patients with cutaneous leishmaniasis in Peru using PCR-RFLP

A PCR-Restriction Fragment Length Polymorphism (RFLP) targeting the mannose phosphate isomerase gene was established to differentiate Leishmania species distributed near the Department of Huanuco, Peru. The technique was applied to 267 DNA samples extracted from Giemsa-stained smears of cutaneous lesions taken from patients suspected for cutaneous leishmaniasis in the area, and the present status of causative Leishmania species was identified. Of 114 PCR-amplified samples, 22, 19, 24 and 49 samples were identified to be infected by Leishmania (Viannia) braziliensis, L. (V.) peruviana, L. (V.) guyanensis, and a hybrid of L. (V.) braziliensis/L. (V.) peruviana, respectively, and the validity of PCR-RFLP was confirmed by sequence analysis. Since PCR-RFLP is simple and rapid, the technique will be a useful tool for the epidemiological study of leishmaniasis.

An electrochemical genosensor for Leishmania major detection based on dual effect of immobilization and electrocatalysis of cobalt-zinc ferrite quantum dots

Identification of Leishmania parasites is important in diagnosis and clinical studies of leishmaniasis. Although epidemiological and clinical methods are available, they are not sufficient for identification of causative agents of leishmaniasis. In the present study, quantum dots of magnetic cobalt-zinc ferrite (Co0.5Zn0.5Fe2O4) were synthesized and characterized by physicochemical methods. The quantum dots were then employed as an electrode modifier to immobilize a 24-mer specific single stranded DNA probe, and fabrication of a label-free, PCR-free and signal-on electrochemical genosensor for the detection of Leishmania major. Hybridization of the complementary single stranded DNA sequence with the probe under the selected conditions was explored using methylene blue as a redox marker, utilizing the electrocatalytic effect of the quantum dots on the methylene blue electroreduction process. The genosensor could detect a synthetic single stranded DNA target in a range of 1.0×10(-11) to 1.0×10(-18)molL(-1) with a limit of detection of 2.0×10(-19)molL(-1), and genomic DNA in a range of 7.31×10(-14) to 7.31×10(-6)ngμL(-1) with a limit of detection of 1.80×10(-14)ngμL(-1) with a high selectivity and sensitivity.

Identification of Leishmania Species Isolated from Human Cutaneous Leishmaniasis in Mehran, Western Iran Using Nested PCR

BACKGROUND

The incidence of cutaneous leishmaniasis in the city of Mehran has risen sharply in recent years because the city borders Iraq, which has allowed entrance of different Leishmania strains. These strains have different shapes, periods of disease, and healing of lesions. The present study identified and determined cutaneous leishmaniasis species in this region.

METHODS

This cross-sectional study was carried out by preparing slides from 92 patients with suspected cutaneous leishmaniasis lesions from Mehran during 2012-2013. Parasite genomic DNA was extracted and CSB2XF and CSB1XR primers were used to amplify the Leishmania minicircle kDNA regions. The parasite species were detected by specific 13Z and LIR primers by applying nested PCR technique.

RESULTS

All banding patterns were diagnosed as L. major parasite by comparison of standard models with amplified fragments 560 bp in length from bands. The patients were 56.5% male and 43.5% female. The most frequently-infected age group was the 21-30 years group at a rate of 27.2%. About 56.3% of patients had a single lesion and a significant correlation was observed between age and number of lesions (P > 0.05).

CONCLUSION

The nested PCR technique was shown to be an effective method with high sensitivity and specificity for identification of human Leishmania parasites. Molecular analysis revealed that parasites isolated from Mehran were identified as L. major and the disease was rural in form.

The associations of Leishmania major and Leishmania tropica aspects by focusing their morphological and molecular features on clinical appearances in Khuzestan Province, Iran

Cutaneous leishmaniasis has various phenotypic aspects consisting of polymorphic amastigotes with different genetic ranges. Samples were collected from suspected patients of Khuzestan province. Prepared smears were stained, scaled, and measured using ocular micrometer. The Cyt b, ITS-rDNA, and microsatellite genes of Leishmania were amplified and Leishmania species were identified by molecular analyses. Of 150 examined suspected patients, 102 were identified to Leishmania species (90 L. major, nine L. tropica, and three unidentified). The amastigotes of 90 L. major had regular and different irregular shapes within three clinical lesions with no and/or low genetic diversity. Three haplotypes of Cyt b of L. major were found but no variation was observed using ITS-rDNA gene. Interesting findings were that all nine L. tropica had regular amastigote shapes with more genetic variations, also a patient which had coinfection of L. major, L. tropica, and Crithidia. At least two L. major and L. tropica were identified in suspected patients of the regions. Different irregular amastigotes' shapes of L. major can be explained by various reservoir hosts and vectors. In contrast, more molecular variations in L. tropica could be justified by genetic characters. Unidentified Leishmania could be mixed pathogens or nonpathogens with mammals' Leishmania or Crithidia.

SYBR green-based detection of Leishmania infantum DNA using peripheral blood samples

Parasitological methods for the diagnosis of visceral leishmaniasis (VL) require invasive sampling procedures. The aim of this study was to detect Leishmania infantum (L. infantum) DNA by real time-PCR method in peripheral blood of symptomatic VL patient and compared its performance with nested PCR, an established molecular method with very high diagnostic indices. 47 parasitologically confirmed VL patients diagnosed by direct agglutination test (DAT > 3200), bone marrow aspiration and presented characteristic clinical features (fever, hepatosplenomegaly, and anemia) and 40 controls (non-endemic healthy control-30, Malaria-2, Toxoplasma gondii-2, Mycobacterium tuberculosis-2, HBV-1, HCV-1, HSV-1 and CMV-1) were enrolled in this study. SYBR-green based real time-PCR and nested PCR was performed to amplify the Kinetoplast DNA minicircle gene using the DNA extracted from Buffy coat. From among 47 patients, 45 (95.7 %) were positive by both nested-PCR and real time-PCR. These results indicate that real time-PCR was not only as sensitive as a nested-PCR assay for detection of Leishmania kDNA in clinical sample, but also more rapid. The advantage of real time-PCR based methods over nested-PCR is simple to perform, more faster in which nested-PCR requires post-PCR processing and reducing contamination risk.

Comparison between conventional and real-time PCR assays for diagnosis of visceral leishmaniasis

The diagnosis of visceral leishmaniasis (VL) is a challenging issue and several studies worldwide have evaluated the different tools to reach a diagnostic solution. The polymerase chain reaction (PCR) has proven to be effective in detecting the genome of Leishmania species in different biological samples. In this study, we compared the conventional PCR and real-time PCR using the Sybr Green system and their application in molecular diagnosis of visceral leishmaniasis in peripheral blood as a biological sample. The genus-specific conserved region of kinetoplast DNA (kDNA) was the target of amplification. We studied 30 samples from patients with suspect of visceral leishmaniasis who were treated by the Medical Clinic of Santa Casa de Belo Horizonte Hospital, Brazil. Among the samples studied, 19 had a confirmed diagnosis for VL by serology and/or by clinical findings. Among these 19 samples, 63% (n = 12) presented positive results for serology and 79% (n = 15) positive results in both PCR methodologies. This fact suggests that the PCR technique can assist in the diagnosis of visceral leishmaniasis in patients who do not have detectable antibodies by serology but can present the genome of the parasite circulating in whole blood. Also, it was possible to observe that there was conformity between the results of the techniques of cPCR and qPCR using the Sybr Green system in 100% of samples analyzed. These data suggest that both PCR techniques were equally effective for detection of the genome of the parasite in the patient's blood.

Identification of leishmania species using PCR assay on giemsa-stained slides prepared from cutaneous leishmaniasis patients

BACKGROUND

Leishmaniasis is a group of diseases that are created by intracellular parasites of Leishmania. Cutaneous leishmaniasis is considered as one of the health problems in some provinces of Iran.

METHODS

In this study, a total of 178 Giemsa-stained slides from confirmed cases of cutaneous leishmaniasis were examined. The slides were prepared from the patients with cutaneous leishmaniasis that referred to health centers and infected during the epidemic of cutaneous leishmaniasis in Poldokhtar city, Lorestan Province, Iran in 2006.Genomic DNA from each slide was extracted. After DNA extraction, ITS-PCR was used.

RESULTS

Out of 178 slides, 129 (72.47%) samples had a band in the range of 485 bp and 49 (27.53%) samples 626 bp that matched L. tropica and L. major standard samples, respectively.

CONCLUSION

This study showed that Leishmania DNA could be efficiently extracted and amplified even from old Giemsa-stained microscopic slides that were stored more than 6 yr. In this study was shown that both L. tropica and L. major species exist in Lorestan Province.