Test accuracy of polymerase chain reaction methods against conventional diagnostic techniques for Cutaneous Leishmaniasis (CL) in patients with clinical or epidemiological suspicion of CL: Systematic review and meta-analysis

Sampling is decisive to determination of Leishmania (Viannia) species

BACKGROUND

Accuracy of molecular tools for the identification of parasites that cause human cutaneous leishmaniasis (CL) could largely depend on the sampling method. Non-invasive or less-invasive sampling methods such as filter paper imprints and cotton swabs are preferred over punch biopsies and lancet scrapings for detection methods of Leishmania based on polymerase chain reaction (PCR) because they are painless, simple, and inexpensive, and of benefit to military and civilian patients to ensure timely treatment. However, different types of samples can generate false negatives and there is a clear need to demonstrate which sample is more proper for molecular assays.

METHODOLOGY

Here, we compared the sensitivity of molecular identification of different Leishmania (Viannia) species from Peru, using three types of sampling: punch biopsy, filter paper imprint and lancet scraping. Different composite reference standards and latent class models allowed to evaluate the accuracy of the molecular tools. Additionally, a quantitative PCR assessed variations in the results and parasite load in each type of sample.

PRINCIPAL FINDINGS

Different composite reference standards and latent class models determined higher sensitivity when lancet scrapings were used for sampling in the identification and determination of Leishmania (Viannia) species through PCR-based assays. This was consistent for genus identification through kinetoplastid DNA-PCR and for the determination of species using FRET probes-based Nested Real-Time PCR. Lack of species identification in some samples correlated with the low intensity of the PCR electrophoretic band, which reflects the low parasite load in samples.

CONCLUSIONS

The type of clinical sample can directly influence the detection and identification of Leishmania (Viannia) species. Here, we demonstrated that lancet scraping samples consistently allowed the identification of more leishmaniasis cases compared to filter paper imprints or biopsies. This procedure is inexpensive, painless, and easy to implement at the point of care and avoids the need for anesthesia, surgery, and hospitalization and therefore could be used in resource limited settings for both military and civilian populations.

Genetic Diversity of Leishmania major Isolated from Different Dermal Lesions Using ITS2 Region

BACKGROUND AND OBJECTIVE

Cutaneous leishmaniasis (CL) is still considered to be an uncontrolled endemic disease that spreads in many countries. The current study aimed to determine intra-species relationships of L. major using ITS2 sequencing.

METHODS

The study was conducted from the beginning of March to the end of November 2022. All medical information regarding CL was collected from patients of Thi-Qar province who attended the Dermatology Department of Al-Hussein Teaching Hospital in Nasiriyah city. Seventy-three samples were selected for the molecular identification after confirming microscopy with Giemsa stain. In this study, the primers were designed using NCBI GenBank sequence database and Primer 3 plus primer design online software.

RESULTS

The results recorded 21 (28.77%) positive samples of L. major using the internal transcribed spacer 2 region (ITS2) in ribosomal RNA gene. The local L. major IQN.1-IQN.10 were submitted to NCBI GenBank database with accession numbers OM069357.1-OM069366.1, respectively. The phylogenetic analysis revealed that local isolates of L. major showed a close relationship with NCBI-BLAST L. major Iran isolate (KU680848.1).

CONCLUSION

ITS2-PCR is suitable for identifying Leishmania spp. and determining genetic diversity. A phylogenetic data analysis may provide an idea on the genetic homogeneity of local isolates and knowing the genetic origin of the dermal lesion. However, the local isolates showed genetic proximity to the KU680848.1 isolate. This signifies the possibility of infection prevalence from Iranian areas. In general, genetic variation of L. major isolates may give several clinical manifestations of the cutaneous lesion. Therefore, determination of the heterogeneity is important for detecting the infection origin, epidemiology, therapy, and control strategies.

Diagnostic performance of CL Detect rapid-immunochromatographic test for cutaneous leishmaniasis: a systematic review and meta-analysis

BACKGROUND

Sensitive, robust, and fast point-of-care tests are needed for cutaneous leishmaniasis (CL) diagnosis. The recently developed CL Detect rapid test (InBios) for detecting Leishmania peroxidoxin antigen has been evaluated in several studies. However, diagnostic performances were controversial. Therefore, this systematic review and meta-analysis aimed to determine the pooled sensitivity and specificity of CL Detect for CL diagnosis.

METHODS

PubMed, Scopus, EMBASE, ScienceDirect, and Google Scholar were sources of articles. We included studies reporting the diagnostic accuracy of CL Detect and CL-suspected patients in the English language. The methodological qualities of the included studies were appraised using the quality assessment of diagnostic accuracy studies-2 (QUADAS-2). Meta-analysis was conducted using Stata 14.2 and R software.

RESULTS

A total of 9 articles were included. The study sample size ranged from 11 to 274. The sensitivities of the individual studies ranged from 23 to 100%, and the specificities ranged from 78 to 100%. Pooled sensitivity and specificity were 68% (95% CI, 41-86%) and 94% (95% CI, 87-97%), respectively. AUC displayed 0.899. Pooled sensitivity was lower (47%, 95% CI, 34-61%) when PCR was used as a reference than microscopy (83%, 95% CI, 39-97%). Pooled sensitivity was lower (48%, 95% CI, 30-67%) for all lesion durations compared to ≤ 4 months (89%, 95% CI, 43-99%).

CONCLUSIONS

CL Detect has poor sensitivity and does not meet the minimal sensitivity of 95% of target product profiles designed for CL point-of-care tests. Currently, the CL Detect test looks unsuitable for CL diagnosis, despite its high specificity. Findings are limited by the low number of studies available. Further large-scale studies are recommended.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42022323497.

Novel CRISPR-based detection of Leishmania species

Tegumentary leishmaniasis, a disease caused by protozoan parasites of the genus Leishmania, is a major public health problem in many regions of Latin America. Its diagnosis is difficult given other conditions resembling leishmaniasis lesions and co-occurring in the same endemic areas. A combination of parasitological and molecular methods leads to accurate diagnosis, with the latter being traditionally performed in centralized reference and research laboratories as they require specialized infrastructure and operators. Clustered regularly interspaced short palindromic repeats/CRISPR-associated protein (CRISPR/Cas) systems have recently driven innovative tools for nucleic acid detection that combine high specificity, sensitivity and speed and are readily adaptable for point-of-care testing. Here, we harnessed the CRISPR-Cas12a system for molecular detection of Leishmania spp., emphasizing medically relevant parasite species circulating in Peru and other endemic areas in Latin America, with Leishmania (Viannia) braziliensis being the main etiologic agent of cutaneous and mucosal leishmaniasis. We developed two assays targeting multi-copy targets commonly used in the molecular diagnosis of leishmaniasis: the 18S ribosomal RNA gene (18S rDNA), highly conserved across Leishmania species, and a region of kinetoplast DNA (kDNA) minicircles conserved in the L. (Viannia) subgenus. Our CRISPR-based assays were capable of detecting down to 5 × 10⁻² (kDNA) or 5 × 10⁰ (18S rDNA) parasite genome equivalents/reaction with PCR preamplification. The 18S PCR/CRISPR assay achieved pan-Leishmania detection, whereas the kDNA PCR/CRISPR assay was specific for L. (Viannia) detection. No cross-reaction was observed with Trypanosoma cruzi strain Y or human DNA. We evaluated the performance of the assays using 49 clinical samples compared to a kDNA real-time PCR assay as the reference test. The kDNA PCR/CRISPR assay performed equally well as the reference test, with positive and negative percent agreement of 100%. The 18S PCR/CRISPR assay had high positive and negative percent agreement of 82.1% and 100%, respectively. The findings support the potential applicability of the newly developed CRISPR-based molecular tools for first-line diagnosis of Leishmania infections at the genus and L. (Viannia) subgenus levels.

Serological and molecular detection of Leishmania species in dog peripheral blood from Bobo-Dioulasso city, a confirmation of canine leishmaniasis enzootic area for Burkina Faso

Canine leishmaniasis is increasingly reported worldwide and represent a threat to both animal and human health. In a previous pilot study conducted in Bobo-Dioulasso, the second town of Burkina Faso, we reported five cases of canine leishmaniasis. With the perspective of a One Health action plan, and in the context of increasing urbanization, this study aimed to provide new information on Leishmania spp in dogs in this city. A cross-sectional survey was carried out from May to August 2018 in six districts of the city in order to record clinical and biological data from domestic dogs randomly selected per district. Blood samples were collected into EDTA tubes (4-5 mL), treated and stored at -20 °C until further analyses. The infection status of the dogs was performed by serological tests using plasma, and real time-PCR (RT-PCR) to detect Leishmania parasites using buffy coats. Nested PCR was used for typing the Leishmania species in dogs which were found to be RT-PCR positive. A total of 147 dogs were examined clinically and sampled for blood collection, including 53.7% females and 46.3% of males with a median age of 3 years. The seroincidence of Leishmania parasites within this dog population was 4.76% (95% CI:2.26-9.72). The incidence of Leishmania was 10.88% (95% CI: 6.73-17.11) by RT-PCR which was significantly more sensitive (p = 0,047) and a fair concordance was observed between both tests (Kappa = 0.39, p < 0.001). The characterization of Leishmania species revealed that L. major was circulating in this domestic dog population. Our results confirmed the persistence of zoonotic circulation of Leishmania parasites such as L. major currently in Bobo-Dioulasso city and highlight the need for targeted interventions in order to control transmission of leishmaniasis in this region.

Development and Preliminary Evaluation of a Nanoparticle-Assisted PCR Assay for the Detection of Cryptosporidium parvum in Calves

C. parvum is an important diarrheal pathogen in humans and animals, especially in young hosts. To accurately and rapidly detect C. parvum infection in calves, we established a nano-PCR assay targeting the cgd3_330 gene for the specific detection of C. parvum. This nano-PCR assay was ten times more sensitive than that of the normal PCR assay by applying the same primers and did not cross-react with C. andersoni, C. bovis, C. ryanae, Balantidium coli, Enterocytozoon bieneusi, Giardia lamblia, and Blastocystis sp. To further test the nano-PCR in clinical settings, a total of 20 faecal samples from calves were examined by using the nano-PCR, the normal PCR, and the nested PCR assays. The positive rates were 30% (6/20), 30% (6/20), and 25% (5/20) for the nano-PCR, the normal PCR, and the nested PCR assays, respectively, indicating that the nano-PCR and the normal PCR assays had the same positive rate (30%). Taken together, the present study could provide a candidate method for the specific detection of C. parvum infection in calves in clinical settings.

Isothermal Nucleic Acid Amplification to Detect Infection Caused by Parasites of the Trypanosomatidae Family: A Literature Review and Opinion on the Laboratory to Field Applicability

Isothermal amplification of nucleic acids has the potential to be applied in resource-limited areas for the detection of infectious agents, as it does not require complex nucleic purification steps or specific and expensive equipment and reagents to perform the reaction and read the result. Since human and animal infections by pathogens of the Tryponasomatidae family occur mainly in resource-limited areas with scant health infrastructures and personnel, detecting infections by these methodologies would hold great promise. Here, we conduct a narrative review of the literature on the application of isothermal nucleic acid amplification for Trypanosoma and Leishmania infections, which are a scourge for human health and food security. We highlight gaps and propose ways to improve them to translate these powerful technologies into real-world field applications for neglected human and animal diseases caused by Trypanosomatidae.

First Report of an Asymptomatic Leishmania (Viannia) shawi Infection Using a Nasal Swab in Amazon, Brazil

The state of Pará has recorded seven Leishmania species that cause tegumentary leishmaniasis (TL). Leishmania species induce distinct immunological responses from the host and exhibit resistance to Glucantime, the first-line drug treatment for TL in Brazil.

OBJECTIVE

Identify the etiology of TL in an Amazonian city in the state of Pará.

MATERIAL AND METHODS

Eleven patients with TL were recruited and nasal swabs, lesion swabs, and skin fragments samples were collected. In the control group (n = 6), only the nasal swabs were collected. Polymerase Chain Reaction (PCR) amplification of the gene region hsp70-234 was performed using the extracted DNA from the samples, from which nine patients with TL and five in the control group were positive. Products were sequenced, mounted in CAP3 software, aligned using MAFFT v.7.221, edited in Geneious software v.8.1.7, and compared and aligned with sequences available in GenBank using the BLAST tool.

RESULTS

For patients with TL, six molecular diagnosis at the species level (L. (Viannia) braziliensis (n = 5/9), L. (Viannia) shawi (n = 1/9)) and three at the genus level (Leishmania sp. (n = 3/9)) were obtained. In the control group, four individuals were infected with Leishmania sp. (n = 4/5) and L. (V.) shawi (n = 1/5).

CONCLUSION

This is the first report of L. (V.) shawi infection in the mucosal secretion of a healthy person in Brazil. Moreover, genetic variants were identified in the haplotypes of L. (V.) braziliensis in the gene sequence hsp70-234.

Diagnosis of visceral and cutaneous leishmaniasis using loop-mediated isothermal amplification (LAMP) protocols: a systematic review and meta-analysis

Sensitive, reliable and fast diagnostic tools that are applicable in low-resource settings, at the point of care (PoC), are seen as crucial in the fight against visceral leishmaniasis (VL) and cutaneous leishmaniasis (CL). Addressing the need for a PoC test, several diagnostic tests, including serological and molecular methods, have been developed and evaluated in the past. One promising molecular method, already implemented for diagnosis of a range of diseases, is the loop-mediated isothermal amplification (LAMP) protocol. In this systematic review and meta-analysis, using a comprehensive search strategy, we focus on studies evaluating the performance of LAMP for the diagnosis of leishmaniasis in humans and other mammals such as dogs, compared with microscopy and/or any other molecular diagnostic method. A meta-analysis, pooling sensitivity and specificity rates and calculating areas under the curve (AUCs) in summary receiver operating characteristic (SROC) plots, was conducted on datasets extracted from studies, grouped by clinical condition and sample type. We found high sensitivity and specificity for LAMP when compared with microscopy and PCR using blood samples, with pooled estimate values of > 90% for all subgroups, corresponding to calculated AUC values > 0.96, except for LAMP compared to microscopy for diagnosis of CL. However, only a limited number of studies were truly comparable. Most of the observed heterogeneity is likely based on true differences between the studies rather than sampling error only. Due to simple readout methods and low laboratory equipment requirements for sample preparation compared to other molecular methods, LAMP is a promising candidate for a molecular (near-)PoC diagnostic method for VL and CL.

Meta-analysis of variable-temperature PCR technique performance for diagnosising Schistosoma japonicum infections in humans in endemic areas

BACKGROUND

As China is moving onto schistosomiasis elimination/eradication, diagnostic methods with both high sensitivity and specificity for Schistosoma japonicum infections in humans are urgently needed. Microscopic identification of eggs in stool is proven to have poor sensitivity in low endemic regions, and antibody tests are unable to distinguish between current and previous infections. Polymerase chain reaction (PCR) technologies for the detection of parasite DNA have been theoretically assumed to show high diagnostic sensitivity and specificity. However, the reported performance of PCR for detecting S. japonicum infection varied greatly among studies. Therefore, we performed a meta-analysis to evaluate the overall diagnostic performance of variable-temperature PCR technologies, based on stool or blood, for detecting S. japonicum infections in humans from endemic areas.

METHODS

We searched literatures in eight electronic databases, published up to 20 January 2021. The heterogeneity and publication bias of included studies were assessed statistically. The risk of bias and applicability of each eligible study were assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 tool (QUADAS-2). The bivariate mixed-effects model was applied to obtain the summary estimates of diagnostic performance. The hierarchical summary receiver operating characteristic (HSROC) curve was applied to visually display the results. Subgroup analyses and multivariate regression were performed to explore the source of heterogeneity. This research was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines and was registered prospectively in PROSPERO (CRD42021233165).

RESULTS

A total of 2791 papers were retrieved. After assessing for duplications and eligilibity a total of thirteen publications were retained for inclusion. These included eligible data from 4268 participants across sixteen studies. High heterogeneity existed among studies, but no publication bias was found. The pooled analyses of PCR data from all included studies resulted in a sensitivity of 0.91 (95% CI: 0.83 to 0.96), specificity of 0.85 (95% CI: 0.65 to 0.94), positive likelihood ratio of 5.90 (95% CI: 2.40 to 14.60), negative likelihood ratio of 0.10 (95% CI: 0.05 to 0.20) and a diagnostics odds ratio of 58 (95% CI: 19 to 179). Case-control studies showed significantly better performances for PCR diagnostics than cross-sectional studies. This was further evidenced by multivariate analyses. The four types of PCR approaches identified (conventional PCR, qPCR, Droplet digital PCR and nested PCR) differed significantly, with nested PCRs showing the best performance.

CONCLUSIONS

Variable-temperature PCR has a satisfactory performance for diagnosing S. japonicum infections in humans in endemic areas. More high quality studies on S. japonicum diagnostic techniques, especially in low endemic areas and for the detection of dual-sex and single-sex infections are required. These will likely need to optimise a nested PCR alongside a highly sensitive gene target. They will contribute to successfully monitoring endemic areas as they move towards the WHO 2030 targets, as well as ultimately helping areas to achieve these goals.

Comprehensive review of conventional and state-of-the-art detection methods of Cryptosporidium

Cryptosporidium is a critical waterborne protozoan pathogen found in water resources that have been a major cause of death and serious illnesses worldwide, costing millions of dollars annually for its detection and treatment. Over the past several decades, substantial efforts have been made towards developing techniques for the detection of Cryptosporidium. Early diagnostic techniques were established based on the existing tools in laboratories, such as microscopes. Advancements in fluorescence microscopy, immunological, and molecular techniques have led to the development of several kits for the detection of Cryptosporidium spp. However, these methods have several limitations, such as long processing times, large sample volumes, the requirement for bulky and expensive laboratory tools, and the high cost of reagents. There is an urgent need to improve these existing techniques and develop low-cost, portable and rapid detection tools for applications in the water quality industry. In this review, we compare recent advances in nanotechnology, biosensing and microfluidics that have facilitated the development of sophisticated tools for the detection of Cryptosporidium spp.Finally, we highlight the advantages and disadvantages, of these state-of-the-art detection methods compared to current analytical methodologies and discuss the need for future developments to improve such methods for detecting Cryptosporidium in the water supply chain to enable real-time and on-site monitoring in water resources and remote areas.

Transmission patterns of Leishmania tropica around the Mediterranean basin: Could Morocco be impacted by a zoonotic spillover?

Cutaneous leishmaniasis (CL) due to Leishmania tropica is a neglected tropical disease characterized by a wide geographical distribution in the Mediterranean basin and is endemic in several of its countries. In addition, the vector Phlebotomus sergenti is abundantly present all around the basin. Its transmission cycle is still subject to debate. In some countries, the presence of an animal reservoir has been confirmed. In Morocco, CL due to L. tropica has risen since the 1980s and has spread widely to become the most abundant form of leishmaniasis in the territory. However, the anthroponotic transmission is so far the only recognized mode, despite recordings of L. tropica infection in animal hosts. In this review article, we assess the situation of CL due to L. tropica in the Mediterranean basin with a focus on Morocco and gather knowledge about any potential zoonotic transmission in the country. A concomitant zoonotic transmission could explain the persistence of the disease in areas where human protective measures combined with vector management did not help reduce the disease burden.

Cutaneous leishmaniasis (CL) due to Leishmania tropica is a neglected tropical disease still considered to be anthroponotic in Morocco despite evidence of zoonotic transmission in other endemic countries of the Mediterranean basin. Its high incidence in the country makes it necessary to investigate whether or not a potential concomitant zoonotic transmission exists alongside the anthroponotic one. Moreover, several reports of natural animal infection have been noted in the country. In this paper, we review how CL due to L. tropica is present around the Mediterranean basin, with a particular focus on the Moroccan foci, and try to unveil the existence of a zoonotic transmission in the area. A deep understanding of the transmission patterns of L. tropica in the region is necessary for the implementation of effective control measures and a better assessment of the disease burden. In addition, the complexity of this neglected disease requires more fundamental and applied research to unveil potential factors involved in its spread.

Imported leishmaniasis in travelers: a 7-year retrospective from a Parisian hospital in France

BACKGROUND

Leishmaniases are regularly seen in non-endemic areas due to the increase of international travels. They include cutaneous leishmaniases (CL) and mucocutaneous (MC) caused by different Leishmania species, and visceral leishmaniases (VL) which present with non-specific symptoms.

METHODS

We reviewed all consecutive leishmaniasis cases seen between September 2012 and May 2020. The diagnostic strategy included microscopy after May-Grünwald-Giemsa staining, a diagnostic quantitative PCR (qPCR) assay, and species identification based on sequencing of the cytochrome b gene.

RESULTS

Eighty-nine patients had a definitive leishmaniasis diagnosis. Nine patients had VL with Leishmania infantum. Eighty patients had CL. Twelve patients acquired CL after trips in Latin America (7 Leishmania guyanensis, 2 Leishmania braziliensis, 2 Leishmania mexicana, and 1 Leishmania panamensis). Species could be identified in 63 of the 68 CLs mainly after travel in North Africa (59%) with Leishmania major (65%), Leishmania tropica/killicki (24%), and L. infantum (11%), or in West Sub-Saharan Africa (32%), all due to L. major. The median day between appearance of the lesions and diagnosis was 90 [range 60-127].

CONCLUSIONS

Our diagnostic strategy allows both positive diagnoses and species identifications. Travelers in West Sub-Saharan Africa and North Africa should be better aware of the risk of contracting leishmananiasis.

Molecular Diagnosis of Leishmaniasis: Quantification of Parasite Load by a Real-Time PCR Assay with High Sensitivity

Real-time PCR was developed to quantify Leishmania infantum kinetoplast DNA and optimized to achieve a sensitivity of 1 parasite/mL. For this purpose, we cloned the conserved kDNA fragment of 120 bp into competent cells and correlated them with serial dilutions of DNA extracted from reference parasite cultures calculating that a parasite cell contains approximately 36 molecules of kDNA. This assay was applied to estimate parasite load in clinical samples from visceral, cutaneous leishmaniasis patients and infected dogs and cats comparing with conventional diagnosis. The study aimed to propose a real-time PCR for the detection of Leishmania DNA from clinical samples trying to solve the diagnostic problems due to the low sensitivity of microscopic examination or the low predictive values of serology and resolve problems related to in vitro culture. The quantitative PCR assay in this study allowed detection of Leishmania DNA and quantification of considerably low parasite loads in samples that had been diagnosed negative by conventional techniques. In conclusion, this quantitative PCR can be used for the diagnosis of both human, canine and feline Leishmaniasis with high sensitivity and specificity, but also for evaluating treatment and the endpoint determination of leishmaniasis.

Diagnosing human cutaneous leishmaniasis using fluorescence in situ hybridization

Cutaneous leishmaniasis (CL) is endemic in Sri Lanka. Giemsa-stained slit-skin-smears (SSS-Giemsa) and histology are routinely used in diagnosis with a sensitivity of 40-70%. PCR currently has limited accessibility. Therefore, we assessed the sensitivity and specificity of a previously described fluorescence in situ hybridization assay, on skin smears and biopsy samples to overcome the limitations encountered with routine diagnostic methods.Samples from a total of 123 suspected CL patients were collected and subjected to SSS-Giemsa, fluorescence in situ hybridization (FISH) on slit skin smears (SSS-FISH), formalin-fixed-paraffin-embedded-tissues stained with Hematoxylin & Eosin staining (FFPE-H&E) and FISH on formalin-fixed-paraffin-embedded-tissues (FFPE-FISH). Negative controls of 61 patient samples were collected from a CL non-endemic area and subjected to the same procedures. The gold standard PCR was used as a comparator. For FISH, two previously described cyanine 3 tagged Leihsmania genus-specific probes were used.Compared to PCR, SSS-Giemsa, SSS-FISH, FFPE-H&E, and FFPE-FISH had sensitivities of 76.5%, 79.1%, 50.4% and 80.9%, respectively. Routine diagnostic tests (SSS-Giemsa and FFPE-H&E) had a specificity of 100%. SSS-FISH and FFPE-FISH had specificities of 96.7% and 93.4%, respectively. FFPE-FISH had a statistically significant higher diagnostic performance than FFPE-H&E (p < 0.001). The relative performance of SSS-Giemsa, SSS-FISH and FFPE-FISH was similar (p > 0.05 for all comparisons).We conclude that FFPE-FISH is a more accurate diagnostic tool than FFPE-H&E. SSS-FISH did not have an additional advantage over SSS-Giemsa in diagnosis. However, SSS-FISH could be recommended as a minimally invasive method in studies assessing wound healing where immunological probes are used.

Effectiveness of miltefosine in cutaneous leishmaniasis caused by Leishmania tropica in Pakistan after antimonial treatment failure or contraindications to first line therapy-A retrospective analysis

Background

Cutaneous leishmaniasis (CL) is a neglected tropical skin disease, caused by Leishmania protozoa. In Pakistan, where CL caused by L. tropica is highly endemic, therapy with pentavalent antimonials is the standard of care, but has significant toxicity when used in systemic therapy, while are no evidence-based safer alternative treatment options for L. tropica. The efficacy of oral miltefosine has not been studied in CL caused by L. tropica. We evaluated effectiveness and tolerability of miltefosine in patients with previous treatment failure or with contraindications to systemic antimonial treatment.

Methods

A retrospective review was conducted of a cohort of CL patients who were treated with a 28-day course of miltefosine between December 2017 and August 2019, in urban Quetta, Pakistan, an area endemic for L. tropica. Descriptive analyses were performed, and effectiveness was assessed by initial response after treatment, and final cure at routine follow up visits, six weeks to three months post-treatment. Tolerability was assessed by routinely reported adverse events.

Results

Of the 76 CL patients in the cohort, 42 (55%) had contraindications to systemic antimonial treatment, and 34 (45%) had failure or relapse after antimonial treatment. Twelve patients defaulted during treatment and 12 patients were lost to follow up. In the remaining 52 patients, final cure rate was 77% (40/52). In those with contraindications to systemic antimonial treatment the final cure rate was 83% (24/29) and in the failure and relapse group 70% (16/23). Twenty-eight patients (40.0%) reported 39 mild to moderate adverse events with the main complaints being nausea (41.0%), general malaise (25.6%), and stomach pain (12.8%).

Conclusion

Results indicate that miltefosine is an effective second line treatment in CL in areas endemic for L. tropica. Prospective studies with systematic follow up are needed to obtain definitive evidence of effectiveness and tolerability, including identification of risk factors for miltefosine treatment failure.

Cutaneous Leishmaniasis (CL) is a neglected tropical skin disease, which globally affects an estimated 0.6 to 1 million people. The skin disease is caused by the protozoa Leishmania and is transmitted by phlebotomine sandflies in Old World CL (OWCL). In Pakistan, CL is highly endemic, especially in the provinces Balochistan and Khyber Pashtunkwa, where L. tropica is the main causative species. In this context, untreated CL often leads to stigmatisation and severe (psycho)social suffering, due to the disfiguring ulcerating wounds and scars. The mainstay treatment is with pentavalent antimonials, and evidence for efficacy of alternative treatments for L. tropica is lacking. Médecins sans Frontières (MSF) has specialised treatment centres in Balochistan (Quetta and Kuchlak), where in December 2017 miltefosine was introduced for patients who did not respond to, or had contraindications for antimonials. In this study, we showed favourable outcomes of miltefosine as second-line treatment for these CL patients.

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.

Application of Quantitative PCR in the Diagnosis and Evaluating Treatment Efficacy of Leishmaniasis

Leishmaniasis is still a serious neglected tropical disease that may cause death in infected individuals. At present, the clinical diagnosis and treatment monitoring still rely on parasitological culture and microscopy that needs experienced technicians. The low sensitivity and inconvenience of microscopic examination could cause misdiagnosis and relapse of leishmaniasis. There is an urgent need for developing a sensitive and easily operated diagnostic method for the diagnosis and disease management of leishmaniasis. Thus, a quantitative real-time PCR (qPCR) based on the conversed regions of kinetoplast minicircle DNA (mkDNA) of Leishmania spp. was developed to detect different species of Leishmania. The designed mkDNA-based qPCR was able to detect as low as one copy of Leishmania mkDNA or DNA from single parasite. It also detected Pan-Leishmania protozoa including Leishmania donovani, Leishmania infantum and Leishmania major without cross-reaction with other pathogen DNAs available in our lab. This method was clinically applied to quantitatively detect skin lesion samples from 20 cutaneous leishmaniasis (CL) and bone marrow and/or PBMC samples from 30 current and cured visceral leishmaniasis (VL) patients, and blood samples from 11 patients with other infections and 5 normal donors as well. Total 20 skin lesion samples from current CL patients and 20 bone marrow and/or PBMC samples from current VL patients were all detected as positive with qPCR without cross-reaction with samples from patients with malaria, brucellosis and dengue or normal donors. Two VL patients with parasite converted to microscopically negative after treatment were detected positive with qPCR. The patients with bigger skin lesion in CL and higher level of immunoglobulin or splenomegaly in VL, had the higher parasite load detected by qPCR. The parasite load was significantly reduced after treatment. In conclusion, the mkDNA-based qPCR assay that we developed in this study can be used not only for diagnosis of both cutaneous and visceral leishmaniasis with high sensitivity and specificity, but also for evaluating the severity and treatment efficacy of this disease, presenting a rapid and accurate tool for clinical surveillance, treatment monitoring and the end point determination of leishmaniasis.