Comparison of various sample preparation methods for PCR diagnosis of visceral leishmaniasis using peripheral blood

Multicentric comparative analytical performance study for molecular detection of low amounts of Toxoplasma gondii from simulated specimens

Although screening for maternal toxoplasmic seroconversion during pregnancy is based on immunodiagnostic assays, the diagnosis of clinically relevant toxoplasmosis greatly relies upon molecular methods. A problem is that this molecular diagnosis is subject to variation of performances, mainly due to a large diversity of PCR methods and primers and the lack of standardization. The present multicentric prospective study, involving eight laboratories proficient in the molecular prenatal diagnosis of toxoplasmosis, was a first step toward the harmonization of this diagnosis among university hospitals in France. Its aim was to compare the analytical performances of different PCR protocols used for Toxoplasma detection. Each center extracted the same concentrated Toxoplasma gondii suspension and tested serial dilutions of the DNA using its own assays. Differences in analytical sensitivities were observed between assays, particularly at low parasite concentrations (<or=2 T. gondii genomes per reaction tube), with "performance scores" differing by a 20-fold factor among laboratories. Our data stress the fact that differences do exist in the performances of molecular assays in spite of expertise in the matter; we propose that laboratories work toward a detection threshold defined for a best sensitivity of this diagnosis. Moreover, on the one hand, intralaboratory comparisons confirmed previous studies showing that rep529 is a more adequate DNA target for this diagnosis than the widely used B1 gene. But, on the other hand, interlaboratory comparisons showed differences that appear independent of the target, primers, or technology and that hence rely essentially on proficiency and care in the optimization of PCR conditions.

PCR for diagnosis and assessment of cure in kala-azar patients in Bangladesh

The study evaluated the usefulness of Leishmania-nested polymerase chain reaction (Ln-PCR) for diagnosis of kala-azar and assessed its role as a test of cure among kala-azar patients in Bangladesh. Peripheral blood buffy coat Ln-PCR was done in ninety-seven (97) clinically suspected patients of kala-azar, in forty (40) healthy controls from both endemic and non-endemic areas, and in forty-six (46) patients after completion of treatment with sodium stibogluconate (SSG). The Ln-PCR results were compared with Leishmania donovani parasite load graded by 1+ to 6+ in all smear-positive L. donovani cases. Out of 97 clinically suspected kala-azar patients, 94 were parasitologically confirmed. Ln-PCR was found positive in 91 of 94 parasitologically positive patients of kala-azar at diagnosis, indicating its diagnostic sensitivity as 97%. None of the controls was found positive for Ln-PCR, indicating its diagnostic specificity to be 100%. About 9% of kala-azar patients having been graded 1+ parasitic load had negative Ln-PCR results. After completion of treatment, Ln-PCR was positive in 4 patients (8.4%) out of 46 cases, indicating its role in demonstrating the absence of parasites 30 days after completion of treatment in 91.6% of the treated patients. This limited study suggests that Ln-PCR is a highly sensitive and specific test for the diagnosis of visceral leishmaniasis and can be used as a test of cure. Thus, efforts should be made to establish this useful method at least in the tertiary care hospitals and, if possible, at the district-level hospitals, especially in the endemic areas of Bangladesh.

[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.

Molecular diagnosis of canine visceral leishmaniasis: identification of Leishmania species by PCR-RFLP and quantification of parasite DNA by real-time PCR

The efficacies of polymerase chain reaction (PCR) procedures for the diagnosis of canine visceral leishmaniasis (CVL), and of PCR-restriction fragment length polymorphism (RFLP) analysis for the identification of Leishmania species, have been assessed. Quantitative real-time PCR employing a SYBR Green dye-based system was standardised for the quantification of Leishmania kDNA minicircles. Skin, peripheral blood and bone marrow samples collected from 217 dogs, asymptomatic or symptomatic for CVL, were analysed. The PCR method, which was based on the amplification of a 120 bp kDNA fragment conserved across Leishmania species, was able to detect the presence in clinical samples of protozoan parasite DNA in amounts as low as 0.1 fg. Bone marrow and skin samples proved to be more suitable than peripheral blood for the detection of Leishmania by PCR and presented positive indices of 84.9% and 80.2%, respectively. PCR-RFLP analysis indicated that 192 of the PCR-positive dogs were infected with Leishmania infantum chagasi, whilst L. braziliensis was identified in two other animals. Quantitative PCR revealed that bone marrow samples from dogs presenting positive conventional tests contained a higher number of copies of Leishmania kDNA than peripheral blood, although no significant differences were detected between symptomatic and asymptomatic dogs in terms of parasite load. This study demonstrates that PCR can be used for the detection of Leishmania in clinical samples derived from naturally infected dogs, and that PCR-RFLP represents a rapid and sensitive tool for the identification of Leishmania species. Additionally, qPCR is effective in quantifying Leishmania DNA load in clinical samples.

Detection of Leishmania kDNA in human serum samples for the diagnosis of visceral leishmaniasis

The performance of PCR to detect Leishmania kDNA in serum for the diagnosis of visceral leishmaniasis (VL) was assessed in serum samples from 65 patients with VL, 17 non-infected individuals and 17 patients with other febrile hepatosplenic diseases. Serum PCR showed a sensitivity of 85%, specificity of 100% and efficiency of 90%. The sensitivity values obtained for blood PCR (97%) and rK39 ELISA (95%) were significantly higher (P=0.01) than the values observed for L. chagasi ELISA (88%) and serum PCR (85%), whilst no difference was observed among the specificity rates obtained with rK39 ELISA (94%; P=0.47) and L. chagasi ELISA (85%; P=0.06). This work suggests that the use of serum samples may be an alternative for the diagnosis of VL when peripheral blood samples are not available or require significant operational efforts.

Leishmania donovani and cutaneous leishmaniasis, Sri Lanka

To investigate the relationship of cutaneous leishmaniasis isolates from Sri Lanka to known species, we performed DNA sequencing and microsatellite analyses. We identified Leishmania donovani as the agent of Sri Lanka cutaneous leishmaniasis and showed that these parasites are closely related to those causing visceral leishmaniasis in the Indian subcontinent.

Sensitivity and specificity of polymerase chain reaction in Giemsa-stained slides for diagnosis of visceral leishmaniasis in children

The aim of this study was to evaluate the sensitivity and specificity of polymerase chain reaction (PCR) in the detection of Leishmania DNA in archived Giemsa-stained bone marrow slides for diagnosis of visceral leishmaniasis (VL), and to compare PCR with conventional diagnostic techniques, like direct microscopy and parasite culture. Specimens of archived Giemsa-stained bone marrow slides from 91 patients with VL and from 79 controls with other diseases or conditions were studied. PCR showed the highest sensitivity (92.3%) and had good specificity (97.5%). Direct examination detected 79.1% and culture 59% of positive samples. In addition, PCR was able to detect VL in 16 of 19 patients (84.2%) with negative microscopy. PCR in Giemsa-stained bone marrow slides is a suitable tool for confirming diagnosis in patients with VL and may be useful in the diagnosis of difficult cases. Slide smears are easily stored, do not require special storage conditions such as low temperatures, and can be easily mailed to centers where PCR is available, making it an excellent option for diagnosis in the field.

American tegumentary leishmaniasis: direct species identification of Leishmania in non-invasive clinical samples

Species identification is highly relevant for improved prognosis and adequate treatment of American tegumentary leishmaniasis (ATL). PCR-based methods are available for this purpose but should be simplified to improve accessibility. As a first step in this process, this paper describes a simplified protocol for collection of clinical samples. Using samples from 44 Bolivian patients with confirmed ATL, we demonstrated that hsp70 PCR-RFLP on skin scrapings collected with a tooth pick allowed identification of the parasite species with a sensitivity of 95% and specificity of 100%. Our method should greatly facilitate individual patient management and epidemiological surveillance of ATL.

Fecal specimens preparation methods for PCR diagnosis of human taeniosis

Sample preparation and DNA extraction protocols for DNA amplification by PCR, which can be applied in human fecal samples for taeniasis diagnosis, are described. DNA extracted from fecal specimens with phenol/chloroform/isoamilic alcohol and DNAzol reagent had to be first purified to generate fragments of 170 pb and 600 pb by HDP2-PCR. This purification step was not necessary with the use of QIAmp DNA stool mini kit. Best DNA extraction results were achieved after eggs disruption with glass beads, either with phenol/chloroform/isoamilic alcohol, DNAzol reagent or QIAmp DNA stool mini kit.

Fast extraction, amplification and analysis of genes from human blood

In order to shorten the time spent on the sample preparation for gene analysis, a novel method was proposed through the combination of fast DNA extraction and purification by Generation capture disk, amplification by capillary polymerase chain reaction, and confirmation of amplification products by microchip electrophoresis. With this method, 3 microL blood was enough to obtain adequate target fragments in human genes. Under the optimal conditions in each step, the sample preparation for eight fragments in beta-globin gene and four fragments in ras gene could be finished within 20 min. Since all the experiments were performed on commercial instruments, this method showed a wide range of applicability. In addition, other advantages such as fast speed and low consumption of samples were demonstrated. All these merits proved that such a combination method was of great potential for the clinical diagnostics.

Trypanosomatid protozoa: a simplified DNA isolation procedure

A non-toxic and versatile protein salting-out DNA extraction method is here described for convenient and rapid extraction of nuclear DNA molecules from trypanosomatids. The procedure just involves four manipulations, does not require any organic solvent, and is performed in less than 1h in a single tube. DNA yields obtained were similar to those from commercial kits and phenol-chloroform procedures. Samples extracted by this method were suitable for PCR and subsequent analyses. The reduced manual labour involved was perceived as an important benefit in medical diagnosis routine use as well as for large-scale taxonomic and eco-epidemiological studies of trypanosomatids.

TaqMan-based detection of Leishmania infantum DNA using canine samples

Leishmaniasis is a typical example of a worldwide diffused zoonosis. Geographic distribution depends on the presence of sand fly vectors and animal reservoirs. In Southern Europe, canines are considered the main reservoir of infection, and the phlebotomines are the vectors. In Sicily, as in all Mediterranean areas, sand flies are present almost all year around because the climate permits an uninterrupted lifecycle for the vectors. Visceral leishmaniasis is becoming a real public health concern especially in endemic areas; in fact, it is an opportunistic infection in immunocompromised patients and in HIV-positive subjects. In Italy, the visceral form of the disease is due exclusively to Leishmania infantum ZMON1, and its prevalence is growing. We have developed a highly accurate, reproducible, and sensible real-time polymerase chain reaction (PCR) assay. In a procedure that used a specific couple of primers, a 117-bp fragment was amplified from minicircle kinetoplast DNA (kDNA). The assay was able to detect even a single parasite (200 fg of DNA). In fact, a single parasite contains hundreds of kinetoplast minicircles for each class. We applied a rapid extraction method coupled with the real-time PCR assay. It was not only as sensitive as a conventional PCR assay for detection of Leishmania kDNA, but also more rapid. The assay is useful for the diagnosis of leishmaniasis in dogs and humans, and it facilitates the monitoring of parasite levels during pharmacological treatment.

Quantification of Leishmania infantum DNA by a real-time PCR assay with high sensitivity

A real-time PCR was developed to quantify Leishmania infantum kinetoplast DNA and optimized to reach a sensitivity of 0.0125 parasites/ml of blood. In order to analyze the incidence of heterogeneity and number of minicircles, we performed comparative PCR by using the Leishmania DNA polymerase gene as a reporter. Assays performed in both promastigote and amastigote stages showed variations among different L. infantum and Leishmania donovani strains and the stability of the minicircle numbers for a particular strain. Analysis of blood samples from a patient who presented with Mediterranean visceral leishmaniasis confirmed the reliability of such an assay for Leishmania quantification in biological samples and allowed an estimation of positivity thresholds of classical tests used for direct diagnosis of the disease; positivity thresholds were in the range of 18 to 42, 0.7 to 42, and 0.12 to 22.5 parasites/ml for microscopic examination, culture, and conventional PCR, respectively. At the time of diagnosis, parasitemia could vary by a wide range (32 to 188,700 parasites/ml, with a median of 837 parasites/ml), while in bone marrow, parasite load was more than 100 parasites per 10(6) nucleated human cells. After successful therapy, parasitemia levels remain lower than 1 parasite/ml. In the immunocompromised host, relapses correlate with an increase in the level of parasitemia, sometimes scanty, justifying the need for assays with high sensitivity. Such sensitivity allows the detection of Leishmania DNA in the blood of 21% of patients with no history of leishmaniasis living in the Marseilles area, where leishmaniasis is endemic. This technique may be useful for epidemiologic and diagnostic purposes, especially for the quantification of parasitemia at low levels during posttherapy follow-up.

Comparison of different tissue sampling for PCR-based diagnosis and follow-up of canine visceral leishmaniosis

In this study, different types of tissue sampling for PCR-based diagnosis and follow-up of canine visceral leishmaniosis were compared. Skin, whole blood and lymph node samples were collected from 95 naturally infected dogs living in South Italy, where the disease is endemic. Twenty-nine of these 95 dogs, treated with meglumine administered concurrently with allopurinol for 30 days, and then with allopurinol alone, were monitored during a period of 2 years. The DNA extracted from the clinical specimens was amplified by PCR using as target DNA a 116-bp fragment in the constant region of the kinetoplast DNA minicircle. PCR analysis was more sensitive than indirect immunofluorescence antibody test in detecting Leishmania infection in symptomatic dogs: 99% of lymph node samples resulted positive, whereas 94% of blood samples and 95% of skin samples gave a positive result. PCR analysis of samples from dogs followed up 2 years showed that: (1) all subjects resulted positive in at least one of the three types of samples; (2) all time the dogs had a relapse, PCR resulted positive in all three types of samples; (3) when dogs were apparently healthy, PCR analysis was positive on skin and lymph node samples, but not always on blood samples. Since lymph node sampling is invasive and sometimes difficult in healthy asymptomatic dogs, our results suggest that, independently from the presence or not of cutaneous lesions, skin biopsy represents a good substratum for PCR-based diagnosis and follow-up of canine visceral leishmaniosis.

Leishmaniose visceral no Brasil: quadro atual, desafios e perspectivas

No Brasil, a importância da leishmaniose visceral reside não somente na sua alta incidência e ampla distribuição, mas também na possibilidade de assumir formas graves e letais quando associada ao quadro de má nutrição e infecções concomitantes. A crescente urbanização da doença ocorrida nos últimos 20 anos coloca em pauta a discussão das estratégias de controle empregadas. Neste artigo foram analisados os principais aspectos biológicos, ambientais e sociais que influenciaram no processo de expansão e urbanização dos focos da doença. Os métodos disponíveis para o diagnóstico e tratamento não apresentam a eficácia e aplicabilidade desejadas, embora avanços promissores tenham sido alcançados com as pesquisas de novos testes diagnósticos e drogas terapêuticas. As medidas de controle da doença até agora implementadas foram incapazes de eliminar a transmissão e impedir a ocorrência de novas epidemias. É feita uma breve análise destas medidas e dos desafios a serem enfrentados. A prevenção da doença nos cães através da imunoprofilaxia aparece como uma alternativa para o controle. Uma nova vacina para cães, já testada em campo, está sendo industrializada e será comercializada no Brasil a partir de 2004. Apesar da existência de inúmeros estudos sobre a leishmaniose visceral humana e canina, muitas lacunas ainda precisam ser preenchidas.

Comparison of two widely used PCR primer systems for detection of toxoplasma in amniotic fluid, blood, and tissues

The PCR diagnosis of toxoplasmosis suffers from lack of standardization. Interlaboratory comparative studies of PCR methods have been performed, but intralaboratory comparisons are scarce. Here, we optimized and compared the technical performances of two PCR primer systems widely used for Toxoplasma detection. The differences between the two methods were visible only at low parasite concentrations (< or = 1 Toxoplasma genome per reaction tube). Nevertheless, when clinical samples were tested, both methods significantly differed in their technical sensitivities and specificities. Only one method appeared adequate for samples containing blood or tissue.

PCR diagnosis and characterization of Leishmania in local and imported clinical samples

Leishmaniasis diagnosis in regions where multiple species exist should identify each species directly in the clinical sample without parasite culturing. The sensitivity of two PCR approaches which amplify part of the ssu rRNA gene and the ribosomal internal transcribed spacer (ITS), respectively, was determined using human and dog blood seeded with Leishmania promastigotes. ssu-rDNA-PCR was more sensitive than ITS1-PCR, however species identification was not possible by the former approach. When a nested ITS1-PCR was used its sensitivity equaled the ssu-rDNA-PCR. Digestion of ITS1 amplicon with the restriction enzyme HaeIII distinguished all medically relevant Leishmania species. ITS1-PCR was used to diagnose 162 local and imported suspected cases of leishmaniasis in Israel, the Palestinian Authority and Germany. 113 cases (69.7%) were positive by PCR and species identification was possible in 110 samples. Leishmania DNA was also amplified and identified at the species level from archived non-stained and Giemsa stained microscope slides.

Detection of circulating Leishmania chagasi DNA for the non-invasive diagnosis of human infection

A polymerase chain reaction (PCR) assay for the detection of Leishmania spp. DNA in peripheral blood was optimized and evaluated for the diagnosis of human visceral leishmaniasis (VL) in Brazil during May 2001 to December 2002. Optimization of the technique resulted in a detection limit of 1.65 fg of purified L. (L.) chagasi DNA, equivalent to 1.65 x 10(-2) parasites. Leishmania DNA was detected in the blood of 48 of 53 patients with parasitologically-confirmed VL, which corresponds to a sensitivity of 91%. No DNA was detected in the peripheral blood of 15 healthy, non-exposed volunteers, giving a specificity of 100%. We conclude that detection of parasite DNA in peripheral blood offers a non-invasive, sensitive and rapid method for the detection of VL caused by L. (L.) chagasi.

Evaluation of PCR as a diagnostic mass-screening tool to detect Leishmania (Viannia) spp. in domestic dogs (Canis familiaris)

Several studies have suggested that the PCR could be used in epidemiological mass-screening surveys to detect Leishmania (Viannia) spp. infection in human and animal hosts. Dogs from an area of Leishmania braziliensis and Leishmania peruviana endemicity were screened for American cutaneous leishmaniasis (ACL) infection by established PCR-based and enzyme-linked immunosorbent antibody test (ELISA) protocols. PCR detected Leishmania (Viannia) infection in a total of 90 of 1,066 (8.4%) dogs: 32 of 368 (8.7%), 65 of 769 (8.5%), and 7 of 42 (16.7%) dogs were PCR positive by testing of whole blood, buffy coat, and bone marrow aspirates, respectively. ELISA detected infection in 221 of 1,059 (20.9%) tested dogs. The high prevalence of Leishmania (Viannia) detected by PCR and ELISA in both asymptomatic (7.5 and 19.2%, respectively) and symptomatic (32 and 62.5%, respectively) dogs is further circumstantial evidence for their suspected role as reservoir hosts of ACL. However, the low sensitivity of PCR (31%) compared to ELISA (81%) indicates that PCR cannot be used for mass screening of samples in ACL epidemiological studies. Unless more-sensitive PCR protocols were to be developed, its use should be restricted to the diagnosis of active (canine and human) cases and to the parasitological monitoring of patients after chemotherapy.

Development of a PCR-based method for diagnosis of Leishmania in blood samples

Visceral Leishmaniasis (VL) cases reported in Mediterranean countries and in Northern Europe are becoming increasingly frequent. The past few years several studies have shown Polymerase Chain Reaction to be more effective than the classical methods for the diagnosis of VL in clinical samples. The purpose of this study was the development of a simple, specific and sensitive PCR-based assay for the detection of Leishmania in blood samples. A specific pair of oligonucleotides was designed using conserved sequences of the ssu-rRNA Leishmania infantum gene. Of the 53 blood samples of patients suspected for leishmaniasis that were processed with the newly designed oligonucleotides, 13 were successfully diagnosed positive. The results were confirmed with sequencing and restriction fragment length polymorphism. The lower detection limit of the reported assay was 10 parasites per ml in all seeded samples tested and considered highly satisfactory for diagnosis of Leishmaniasis in blood samples.

Rapid detection of Leishmania infantum infection in dogs: comparative study using an immunochromatographic dipstick test, enzyme-linked immunosorbent assay, and PCR

Current zoonotic visceral leishmaniasis (ZVL) control programs in Brazil include the culling of Leishmania infantum-infected reservoir dogs, a strategy that has failed to prevent a rise of canine and human ZVL cases over the past decade. One of the main reasons this strategy has failed is because of a long delay between sample collection, sample analysis, and control implementation. A rapid, sensitive, and specific diagnostic tool would be highly desirable, because it would allow control interventions to be implemented in situ. We compared an immunochromatographic dipstick test to enzyme-linked immunosorbent assay (ELISA) and PCR for detecting L. infantum infections in dogs from an area of ZVL endemicity in Brazil. The dipstick test was shown to have 61 to 75% specificity and 72 to 77% sensitivity, compared to 100% specificity for both ELISA and PCR and 71 to 88% and 51 to 64% sensitivity for ELISA and PCR, respectively. Of the field samples tested, 92 of 175 (53%), 65 of 175 (37%), and 47 of 175 (27%) were positive by dipstick, ELISA, and PCR, respectively. The positive and negative predictive values for the tested dipstick were 58 to 77% and 75%, respectively. Efforts should be made to develop a more specific dipstick test for diagnosis of leishmaniasis, because they may ultimately prove more cost-effective than currently used diagnostic tests when used in mass-screening surveys.

DNA banking for epidemiologic studies: a review of current practices

To study genetic risk factors for common diseases, researchers have begun collecting DNA specimens in large epidemiologic studies and surveys. However, little information is available to guide researchers in selecting the most appropriate specimens. In an effort to gather the best information for the selection of specimens for these studies, we convened a meeting of scientists engaged in DNA banking for large epidemiologic studies. In this discussion, we review the information presented at that meeting in the context of recent published information. Factors to be considered in choosing the appropriate specimens for epidemiologic studies include quality and quantity of DNA, convenience of collection and storage, cost, and ability to accommodate future needs for genotyping. We focus on four types of specimens that are stored in these banks: (1) whole blood preserved as dried blood spots; (2) whole blood from which genomic DNA is isolated, (3) immortalized lymphocytes from whole blood or separated lymphocytes, prepared immediately or subsequent to cryopreservation; and (4) buccal epithelial cells. Each of the specimens discussed is useful for epidemiologic studies according to specific needs, which we enumerate in our conclusions.

Comparison of six PCR methods using peripheral blood for detection of canine visceral leishmaniasis

The objectives of this study were to compare the sensitivities and reliabilities of different PCR methods for the diagnosis and epidemiological study of canine visceral leishmaniasis (CVL) using dog blood. We chose to work with peripheral blood, as this type of sampling is noninvasive, straightforward, and easy to repeat. Six PCR methods were compared: three primer pairs target genomic DNA, and the other three target kinetoplast (mitochondrial) DNA. Sensitivity, specificity, reproducibility, and ease of interpretation without hybridization were evaluated for each method. The assessment was first performed using artificial samples. All methods could detect less than one parasite per reaction tube. However, the sensitivities varied among the different methods by a factor of 500 on purified cultivated parasites and by a factor of 10,000 on seeded dog blood samples (i.e., from 10 to 10(-3) parasite per ml of blood for the latter). Only four methods were found sufficiently reliable for the diagnosis of CVL. They were tested on 37 dogs living in an area of endemicity and grouped according to clinical status and specific serology. Only the two methods targeting kinetoplast DNA (K13A-K13B and RV1-RV2) could detect the parasite in 100% of symptomatic infected dogs. Similarly, all seropositive dogs were found PCR positive by these methods versus 62% by the genomic-DNA-based methods. Finally, these kinetoplast-based methods proved clearly superior to the others in the detection of Leishmania in asymptomatic dogs. Our data allow the discussion of the advantages and drawbacks of highly sensitive versus moderately sensitive PCR methods in diagnosis and prevalence studies of CVL.