Diagnosis Of Visceral Leishmaniasis Research Articles

Leishmanial Lymphadenopathy in a Native Patient from the Nonendemic Region of Himachal Pradesh, India

A case of leishmanial lymphadenopathy in an immunocompetent native from a nonendemic area of the Ravi River valley area (altitude 996 m above the mean sea level) of Chamba, Himachal Pradesh, India, is reported. Diagnosis of visceral leishmaniasis by demonstration of Leishman–Donovan bodies in lymph nodes by fine-needle aspiration cytology has been rarely reported.

Bayesian latent class models for identifying canine visceral leishmaniosis using diagnostic tests in the absence of a gold standard.

Like many infectious diseases, there is no practical gold standard for diagnosing clinical visceral leishmaniasis (VL). Latent class modeling has been proposed to estimate a latent gold standard for identifying disease. These proposed models for VL have leveraged information from diagnostic tests with dichotomous serological and PCR assays, but have not employed continuous diagnostic test information. In this paper, we employ Bayesian latent class models to improve the identification of canine visceral leishmaniasis using the dichotomous PCR assay and the Dual Path Platform (DPP) serology test. The DPP test has historically been used as a dichotomous assay, but can also yield numerical information via the DPP reader. Using data collected from a cohort of hunting dogs across the United States, which were identified as having either negative or symptomatic disease, we evaluate the impact of including numerical DPP reader information as a proxy for immune response. We find that inclusion of DPP reader information allows us to illustrate changes in immune response as a function of age. Utilization of continuous DPP reader information can improve the correct discrimination between individuals that are negative for disease and those with clinical VL. These models provide a promising avenue for diagnostic testing in contexts with multiple, imperfect diagnostic tests. Specifically, they can easily be applied to human visceral leishmaniasis when diagnostic test results are available. Also, appropriate diagnosis of canine visceral leishmaniasis has important consequences for curtailing spread of disease to humans.

Diagnosis of Visceral Leishmaniasis in an Elimination Setting: A Validation Study of the Diagnostic Algorithm in India.

Visceral leishmaniasis (VL) is on the verge of elimination on the Indian subcontinent. Nonetheless, the currently low VL-incidence setting brings along new challenges, one of which is the validity of the diagnostic algorithm, based on a combination of suggestive clinical symptoms in combination with a positive rK39 Rapid Diagnostic Test (RDT). With this study, we aimed to assess the positive predictive value of the diagnostic algorithm in the current low-endemic setting in India by re-assessing newly diagnosed VL patients with a qPCR analysis on venous blood as the reference test. In addition, we evaluated the specificity of the rK39 RDT by testing non-VL cases with the rK39 RDT. Participants were recruited in Bihar and Uttar Pradesh, India. VL patients diagnosed based on the diagnostic algorithm were recruited through six primary health care centers (PHCs); non-VL cases were identified through a door-to-door survey in currently endemic, previously endemic, and non-endemic clusters, and tested with rK39 RDT, as well as—if positive—with qPCR on peripheral blood. We found that 95% (70/74; 95% CI 87–99%) of incident VL cases diagnosed at the PHC level using the current diagnostic algorithm were confirmed by qPCR. Among 15,422 non-VL cases, 39 were rK39 RDT positive, reflecting a specificity of the test of 99.7% (95% CI 99.7–99.8%). The current diagnostic algorithm combining suggestive clinical features with a positive rK39 RDT still seems valid in the current low-endemic setting in India.

Visceral leishmaniasis in a recent transmission region: 27.4% infectivity rate among seronegative dogs.

American visceral leishmaniasis (VL) is a parasitic disease whose main domestic reservoir in the urban environment is dog and is considered one of the most important zoonoses in the context of public health. Serological tests are typically used for the diagnostic screening of the disease. This study aimed to analyse the performance of different methodologies used in the diagnosis of VL in dogs sampled from a recent transmission area. The sample consisted of 52 dogs separated into groups based on the absence and presence of clinical signs of VL. The following serological techniques were carried out: the DPP® rapid test (RT), the ALERE® RT and an RT and immunoenzymatic assay with a recently developed protein (rKDDR-plus). In addition, molecular techniques were carried out with conjunctival swabs, and bone marrow aspirate samples and parasitological samples were obtained directly from bone marrow aspirates. It was concluded that 27.4% of seronegative dogs were infected, but the serological tests, used as screening tests, showed unsatisfactory sensitivity results (average: 51.2%) for dogs without clinical signs. It was suggested that polymerase chain reaction with conjunctival swabbing be used as a screening test for dogs without clinical signs, as this is a non-invasive collection technique with high-sensitivity values.

Revealing a Novel Antigen Repressor of Differentiation Kinase 2 for Diagnosis of Human Visceral Leishmaniasis in India.

Visceral leishmaniasis (VL) is one of the major global health concerns due to its association with morbidity and mortality. All available diagnostic tools have been, until now, unable to provide a very specific and cost-effective mode of detection for VL globally. Therefore, the design of robust, specific, and commercially translatable diagnostic tests is urgently required. Currently, we are attempting to identify and explore the diagnostic potential of a novel parasite antigen. Repressor of differentiation kinase 2 (RDK2), a serine/threonine kinase, has a versatile role in parasite life cycle progression. However, its role as a diagnostic candidate for VL has not been investigated. Herein, we cloned and over-expressed LdRDK2 and studied the recombinant RDK2 for the diagnosis of human VL using serum and urine samples. In silico analysis predicted that RDK2 is conserved among Leishmania species with the least conservation in humans. RDK2 developed immune-reactive bands with antibodies present in VL patients’ sera, and it demonstrated no cross-reactivity with sera from healthy controls and other diseases. Additionally, RDK2 antigen demonstrated a significant reactivity with IgG antibodies of VL patients’ sera, with 78% sensitivity and 86.67% specificity as compared to healthy controls and other diseases. Furthermore, we evaluated its utility for non-invasive diagnosis of VL using patients’ urine samples and found 93.8% sensitivity and 85.7% specificity. RDK2 was found to have better sensitivity and treatment response in patients’ urine compared to serum samples, indicating its role as a promising point of care (POC) antigen. In a nutshell, we explored the role of RDK2 as a potential diagnostic marker for VL in both invasive and non-invasive modes as well as its utility as a promising POC antigen for treatment response cases.

Lethality among individuals infected with visceral leishmaniasis in Brazil: a retrospective study (2007-2018).

Visceral leishmaniasis (VL) is a public health problem with a high prevalence and lethality in Brazil. This study aims to estimate the lethality and associated factors in individuals with VL and assess survival time, emphasizing VL/HIV coinfection. This retrospective study has 37,583 individuals notified and confirmed with VL in the Sistema de Informação de Agravos de Notificação (SINAN) between 2007 and 2018 (Brazil). Lethality was evaluated considering VL deaths, deaths from other causes (OC), and non-deaths. We performed a multinomial logistic regression, with non-death as the benchmark category. We conducted a survival analysis (Kaplan-Meier method), emphasizing VL/HIV coinfection. Most individuals were young, male, mixed race, low schooling level, and urban dwellers. The lethality rate was 10.2% (VL and OC deaths) and 7.8% (VL deaths). The prevalence of HIV infection was 8.81%. A higher likelihood of VL and OC deaths was observed in older age groups, females, and with a higher number of symptoms. A higher likelihood of OC deaths was identified in individuals with HIV. A lower likelihood of VL and OC deaths was observed for individuals on VL therapy. The mean survival time was longer for VL/HIV individuals, who had a lower survival rate than those with VL. The data point to the need for attention to the timely diagnosis of VL and HIV and adequate pharmacological treatment in this population.

Strengthening Visceral Leishmaniasis Diagnosis Capacity to Improve Access to Care in Kenya: The Example of Marsabit County

BackgroundVisceral leishmaniasis (VL), also known as kala-azar, is a neglected tropical disease (NTD) that is fatal if not treated early. The WHO targets the elimination of VL as a public health problem in its 2030 NTD road map. However, improving access to VL diagnosis and treatment remains a major challenge in many VL-endemic countries. Kenya is endemic for VL and is among the top 6 high-disease burden countries in the world.MethodsFIND, through its activities in improving the diagnosis of VL and supporting the elimination of the disease in Kenya, has worked with various county ministries of health (MOH) and central MOH over the last couple of years. FIND’s activities in Marsabit county started in 2018. In this work, we present the implementation of activities and the impacts in Marsabit county. We reviewed the data for 2017 and 2019 outbreaks (before and after the implementation of FIND’s activities) and assessed the importance of improving access and community sensitization to VL diagnosis. We assessed the contribution of each facility to the total distance traveled from a perspective of location optimization.ResultsThere was a sharp increase in the number of people tested in the 2017 outbreak compared to the 2019 outbreak. In 2017, 437 people were tested compared to 2,338 in 2019. The county reported 234 and 688 VL cases in 2017 and 2019, respectively. The data revealed a shift in the demographic structures of cases toward the younger population (mean age in 2017 was 17.6 years and 15.3 years in 2019), with more female cases reported in 2019 compared to 2017. In 2017, 44.4% were 10 years of age or under. In 2019, the proportion 10 years or below was 52.2%. The addition of two new diagnosis facilities in 2018 resulted in a decrease in the distance traveled by confirmed VL cases from 28.1 km in 2017 to 10.8 km in 2019. Assessing the impact of facility placement indicated the most optimal facilities to provide VL diagnostic services and minimize the distance traveled by patients. Adding new facilities reduces the travel distance until a point where the addition of a new facility provides no additional impact.ConclusionThe results from this study indicate the need to carefully consider the placement of health facilities in improving access to VL diagnosis and treatment and could serve as an investment case in deciding when to stop adding new facilities in a particular setting. Extending the activities in Kenya to other VL-endemic countries in East Africa will contribute significantly toward the elimination of the disease, addressing the needs of marginalized populations and leaving no one behind.

Utility of smear examination, culture, and serological tests in the diagnosis of visceral leishmaniasis/post-kala-azar dermal leishmaniasis at National Centre for Disease Control, Delhi.

Introduction:A range of assays have been developed to detect specific antileishmanial antibody, such as rK 39 immunochromatographic test (ICT), KE 16 ICT, ELISA test, and indirect immunofluorescent antibody test (IFAT), which play a crucial role in serological diagnosis of visceral leishmaniasis (VL). However, limited published reports are available on the utility of serological test (IFAT test/rk 39), smear examination, and culture in the diagnosis of VL and post-kala-azar dermal leishmaniasis (PKDL) in our country.Materials and Methods:We present utility of serological test (IFAT test/rK 39), smear examination for Leishmania donovani (LD) bodies, and culture in 2589 samples from 2294 VL/PKDL suspected patients (January 2009–December 2019) tested in Centre for Arboviral and Zoonotic diseases, National Centre for Disease Control, New Delhi, India, for laboratory diagnosis of VL/PKDL.Results:A total of 80/553 (14.4%) cases were confirmed of VL (74/522 cases by demonstration of LD bodies in bone marrow smear examination, 5/12 in splenic smear examination 1/19 by culture) and 4/21 (19.0%) cases were confirmed of PKDL (demonstration of LD bodies in slit skin smear examination. In our study 197/1368 (14.4%) cases were diagnosed positive by IFAT, 34/646 (5.2%) cases by rk 39 ICT for VL/PKDL by demonstration of specific antileishmanial antibodies.Conclusion:As the goal of elimination of VL as a public health problem is approaching, apart from serological tests such as rk 39 and IFAT, direct methods of detection such as (parasitic demonstration in BM smear, culture, and molecular tests) for Leishmania may play a crucial role for achieving a correct diagnosis and treatment. We also concluded that IFAT though not field-friendly, its optimal use as an adjunct test with BM smear in all stages of infections may be required. Further rk39 is a simple, reliable, noninvasive, and field-friendly test for diagnosis VL, especially in endemic areas.

Cytodiagnosis of Visceral Leishmaniasis in Lymph Node Aspirate: A Rare Case Report

Leishmaniasis is a parasitic disease caused by leishmania species. There are three main forms of the disease: Cutaneous, Mucocutaneous and Visceral Leishmaniasis (VL). VL with lymphadenitis is an uncommon presentation. Visceral leishmaniasis is usually diagnosed by identification of parasite Leishman Donovan (LD) bodies in bone marrow aspirates but cytological diagnosis of VL on lymph node aspirates has rarely been reported. This is a case report of a 37-year-old male presenting with multiple isolated cervical lymphadenopathy for three months. The lymphadenopathy was initially suspected to be tubercular in nature which is highly prevalent in India and lymphadenopathy is its common presenting feature, but on Fine Needle Aspiration Cytology (FNAC) of the node, multiple leishmania parasites were identified. Lymphadenopathy due to leishmaniasis is rare in India and most of the previous cases reported have association of leishmaniasis with Human Immunodeficiency Virus (HIV) infection. But this case is unusual as it is not associated with HIV infection. Thus, leishmaniasis should be included in the differential diagnosis of lymphadenopathy, especially in patients coming from endemic region. Cytology can be very helpful in such cases for early diagnosis and further management.

Case Report of Cardiac Tamponade Due to Acute Chagas Disease after Misdiagnosis of Visceral Leishmaniasis Based on Serology

Protozoan diseases such as Visceral Leishmaniasis (VL) have re-emerged in Northern Brazil and cases of Chagas Disease also occur. This VL increase leads to early therapy for the public. Confirmatory parasitological diagnoses in VL are performed by bone marrow or spleen aspiration, but ELISA, IFA or immunochromatographic tests for antibody detection are easily performed and can be used in the presence of clinical signs as confirmatory for specific therapy. This approach is successful in providing therapy and prevention of death in VL, but there is a chance of confusion with the emerging disease, Chagas Disease (CD), due to cross-reacting and similar clinical pictures, as in this case. Both VL and CD presented many asymptomatic or oligosymptomatic cases, complicating the picture. Our case report emphasizes these aspects. Positive serology, with an IIF titer of 1/160, and epidemiological correlation, suggests the diagnosis of VL and imposes antimony therapy. Despite the unfavorable evolution and signs of cardiac involvement, the presence of pericarditis and cardiac tamponade confirmed by the echocardiogram suggests CD. We reassessed the profiles of a suggested CD serology, the diagnosis was corrected and treatment with CD specific benznidazole. The good evolution started with benznidazole corroborates the diagnosis of CD and discards the hypothesis of double infection.

Spatial Variation in Delayed Diagnosis of Visceral Leishmaniasis in Bihar, India

Spatial Variation in Delayed Diagnosis of Visceral Leishmaniasis in Bihar, India

Performance of rapid rk39 tests for the diagnosis of visceral leishmaniasis in Ethiopia: a systematic review and meta-analysis

BackgroundVisceral Leishmaniasis (VL) is a severely neglected disease affecting millions of people with high mortality if left untreated. In Ethiopia, the primary laboratory diagnosis of VL is by using an antigen from a 39-amino acid sequence repeat of a kinesin-related (rK39) of leishmania donovani complex (L. donovani), rapid diagnostic tests (RDT). Different rk39 RDT brands are available with very variable performance and studies from Ethiopia showed a very wide range of sensitivity and specificity. Therefore, a systematic review and meta-analysis were conducted to determine the pooled sensitivity and specificity of rk39 RDT in Ethiopia.MethodPUBMED, EMBASE, and other sources were searched using predefined search terms to retrieve all relevant articles from 2007 to 2020. Heterogeneity was assessed by visually inspecting summary receiver operating curves (SROC), Spearman correlation coefficient (rs), Cochran Q test statistics, inconsistency square (I2) and subgroup analysis. The presence and statistical significance of publication bias were assessed by Egger's test at p < 0.05, and all the measurements showed the presence of considerable heterogeneity. Quality assessment of diagnostic accuracy studies (QUADAS-2) checklists was used to check the qualities of the study.ResultsA total of 664 articles were retrieved, and of this 12 articles were included in the meta-analysis. Overall pooled sensitivity and specificity of the rk39 RDT to diagnose VL in Ethiopia were 88.0% (95% CI 86.0% to 89.0%) and 84.0% (95% CI 82.0% to 86.0%), respectively. The sensitivity and specificity of the rk39 RDT commercial test kits were DiaMed: 86.9% (95% CI 84.3% to 89.1%) and 82.2% (95% CI 79.3% to 85.0%), and InBios: 80.0% (95% CI 77.0% to 82.8%) and 97.4% (95% CI 95.0% to 98.8%), respectively.ConclusionReferring to our result, rk39 RDT considered an essential rapid diagnostic test for VL diagnosis. Besides to the diagnostic accuracy, the features such as easy to perform, quick (10–20 min), cheap, equipment-free, electric and cold chain free, and result reproducibility, rk39 RDT is advisable to remains in practice as a diagnostic test at least in the remote VL endemic localities till a better test will come.

Metabolic characterization and biomarkers screening for visceral leishmaniasis in golden hamsters

A better understanding of the changes in metabolic molecules during visceral leishmaniasis (VL) is essential to develop new strategies for diagnosis and treatment. Previous metabolomics studies on Leishmania have increased our knowledge of leishmaniasis and its causative pathogen. As these studies were mainly carried out in vitro, to go further, we conducted this global metabolomics analysis on the serum of golden hamsters. Serum samples were detected over a time course of 2, 4, 8 and 12 weeks post infection. Our results revealed that under extensively disturbed metabolomes between the infection group and controls, glycerophospholipid (GPL) metabolism was most affected over the infection time, followed by α-linoleic acid metabolism and arachidonic acid metabolism. Within GPLs, phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were found to be significantly increased, while their enzyme-catalysed metabolites lysophosphatidylcholine (LPC) and lysophosphatidylethanolamine (LPE) showed no significant changes. Moreover, eight differential metabolites were selected. The ability of these metabolites to be used as a diagnostic biomarker panel was supported by receiver operating characteristic (ROC) analysis. Our findings revealed that GPL metabolism might play an important role in the response of the host to Leishmania infection. The metabolism of PC and PE might be crucial in the in vivo progression of VL. The panel of eight potential biomarkers might contribute to the diagnosis of VL.

ChimLeish, a new recombinant chimeric protein evaluated as a diagnostic and prognostic marker for visceral leishmaniasis and human immunodeficiency virus coinfection.

Visceral leishmaniasis (VL) is a neglected tropical disease of global importance caused by parasites of the genus Leishmania, and coinfection with human immunodeficiency virus (HIV) is common in countries where both diseases are endemic. In particular, widely used immunological tests for VL diagnosis have impaired sensitivity (Se) and specificity (Sp) in VL/HIV coinfected patients and there is also cross-reactivity with other endemic diseases, e.g., Chagas disease, malaria, and tuberculosis. To develop new antigens to improve the diagnosis of VL and VL/HIV coinfection, we predicted eight specific B-cell epitopes of four Leishmania infantum antigens and constructed a recombinant polypeptide chimera antigen called ChimLeish. A serological panel of 195 serum samples was used to compare the diagnostic capabilities of ChimLeish alongside the individual synthetic peptides. ChimLeish reacted with sera from all VL and VL/HIV coinfected patients [Se = 100%; Sp = 100%; area under the curve (AUC) = 1.0]. Peptides showed lower reactivities (Se = 76.8 to 99.2%; Sp = 67.1 to 95.7%; AUC between 0.87 and 0.98) as did a L. infantum antigenic preparation used as an antigen control (Se = 56.8%; Sp = 69.5%: AUC = 0.45). Notably, ChimLeish demonstrated a significant reduction (p < 0.05) of anti-ChimLeish antibodies after treatment and cure of a small number of patients. Although only a limited serological panel was tested, preliminary data suggest that ChimLeish should be evaluated in larger sample studies for the diagnosis of VL and VL/HIV coinfection.

Assessment of a New Antigen Detection Test for the Diagnosis of Canine Visceral Leishmaniasis.

Canine visceral leishmaniasis (CVL) is a serious zoonotic disease in Brazil and Southern Europe. CVL is primarily caused by Leishmania infantum and its diagnosis relies largely on detection of parasites in bone marrow or lymph node aspirates by microscopic observation of the parasites in stained smears, parasite culture, or polymerase chain reaction (PCR). Serological tests exist but they do not distinguish active disease from simple exposure to parasite antigens. Here, we have assessed the utility of a new monoclonal antibody--based antigen (protein) detection test for the diagnosis of CVL. The test was positive in 70% of beagle dogs experimentally infected with L. infantum. In contrast, culture of the parasites from bone marrow aspirates was positive in only 40% of the infected animals. These preliminary results suggest that this antigen detection test, which we have recently described for the diagnosis of human VL, has the potential to be a useful diagnostic tool for CVL.

The increased presence of repetitive motifs in the KDDR-plus recombinant protein, a kinesin-derived antigen from Leishmania infantum, improves the diagnostic performance of serological tests for human and canine visceral leishmaniasis.

Visceral leishmaniasis (VL) is caused by protozoa belonging to the Leishmania donovani complex and is considered the most serious and fatal form among the different types of leishmaniasis, if not early diagnosed and treated. Among the measures of disease control stand out the management of infected dogs and the early diagnosis and appropriate treatment of human cases. Several antigens have been characterized for use in the VL diagnosis, among them are the recombinant kinesin-derived antigens from L. infantum, as rK39 and rKDDR. The main difference between these antigens is the size of the non-repetitive kinesin region and the number of repetitions of the 39 amino acid degenerate motif (6.5 and 8.5 repeats in rK39 and rKDDR, respectively). This repetitive region has a high antigenicity score. To evaluate the effect of increasing the number of repeats on diagnostic performance, we designed the rKDDR-plus antigen, containing 15.3 repeats of the 39 amino acid degenerate motif, besides the absence of the non-repetitive portion from L. infantum kinesin. Its performance was evaluated by enzyme-linked immunosorbent assay (ELISA) and rapid immunochromatographic test (ICT), and compared with the kinesin-derived antigens (rKDDR and rK39). In ELISA with human sera, all recombinant antigens had a sensitivity of 98%, whereas the specificity for rKDDR-plus, rKDDR and rK39 was 100%, 96% and 71%, respectively. When evaluated canine sera, the ELISA sensitivity was 97% for all antigens, and the specificity for rKDDR-plus, rKDDR and rK39 was 98%, 91% and 83%, respectively. Evaluation of the ICT/rKDDR-plus, using human sera, showed greater diagnostic sensitivity (90%) and specificity (100%), when compared to the IT LEISH (79% and 98%, respectively), which is based on the rK39 antigen. These results suggest that the increased presence of repetitive motifs in the rKDDR-plus protein improves the diagnostic performance of serological tests by increasing the specificity and accuracy of the diagnosis.

Potential of recombinant LiHyQ, a novel Leishmania infantum protein, for the diagnosis of canine visceral leishmaniasis and as a diagnostic and prognostic marker for human leishmaniasis and human immunodeficiency virus co-infection: A preliminary study

Laboratory diagnosis of leishmaniasis shows variable efficacy in detecting infected mammalian hosts and there is a need to identify suitable antigens to improve the accuracy of diagnostic tests. In the present study, a L. infantum hypothetical protein called LiHyQ was evaluated for the diagnosis of tegumentary (TL) and visceral (VL) leishmaniasis using canine and human samples. A collection of dog sera (n=155) were tested and contained samples from asymptomatic (n=20) and symptomatic (n=25) VL animals, from healthy dogs living in endemic (n=25) or non-endemic (n=25) areas of disease, from Leish-Tec® vaccinated dogs (n=20) or from dogs infected with Ehrlichia canis (n=15), Babesia canis (n=10) and Trypanosoma cruzi (n=15). Sensitivity (Se), Specificity (Sp), Positive Predictive Value (PPV) and Negative Predictive Value (NPV) of 100% were observed for rLiHyQ with these samples, whereas the Se, Sp, PPV and NPV values with L. infantum Soluble Leishmania Antigen (SLA) preparation were 60.0%, 99.0%, 96.0% and 86.0%, respectively. A collection of human sera (n=305) were tested and contained samples from TL (n=50) and VL (n=40) patients, from VL/HIV co-infected patients (n=35), from patients infected with HIV alone (n=30), Chagas Disease (n=30), malaria (n=10), tuberculosis (n=10), paracoccidioidomycosis (n=15), leprosy (n=30) or aspergillosis (n=15); and from healthy subjects (n=40). Se, Sp, PPV and NPV values of 100% were observed for rLiHyQ with these samples, whereas the Se, Sp, PPV and NPV values with SLA were 58.0%, 76.0%, 50.0% and 82.0%, respectively. The antibody reactivity against the protein was compared with commercial kits, and the kappa index varied from 0.95 to 1.00 for rLiHyQ, and of 0.55 to 0.82 for the kits. In addition, the serological follow-up of treated patients showed a significant reduction in rLiHyQ-specific IgG antibody levels. All canine and human samples were tested at the same time using the same reagents, in order to reduce experimental variation and interference in data interpretation. In conclusion, our preliminary data suggest a diagnostic and prognostic role for rLiHyQ against leishmaniasis.

Diagnosis and Causative Species of Visceral Leishmaniasis in Southwest Saudi Arabia.

Visceral leishmaniasis (VL) is the most severe clinical form of the disease and has been reported in the Jazan region of southwest Saudi Arabia. This study aimed to diagnose VL by real-time polymerase chain reaction (PCR) and the direct agglutination test (DAT) and to identify the causative Leishmania species. A total of 80 participants, including 30 suspected VL patients, 30 healthy endemic control individuals, and 20 malaria disease controls, were enrolled in this study. Blood samples were collected and tested for Leishmania DNA by real-time PCR and for antibody by the DAT. Sequencing of some amplified PCR products was used to identify the causative Leishmania species. The diagnosis of VL was successfully achieved by both real-time PCR and by DAT with 100% sensitivity. Leishmania donovani and Leishmania infantum species were detected by sequencing both by the kDNA and ITS1 target genes, followed a BLASTn search. The detection of VL antibody by the DAT followed by the confirmatory detection of Leishmania DNA in patient blood by PCR could promote the adoption of the much less invasive and more sensitive methods for the routine diagnosis of VL. Further study with high sample volume to evaluate the PCR and the DAT are needed, to generate more robust evidence. Based on the sequencing results, emerging studies on VL should focus on the causative Leishmania species, reservoirs, and vectors that are important in the study area.

Revisiting the heterogeneous global genomic population structure of Leishmania infantum.

Leishmania infantum is the main causative agent responsible for visceral leishmaniasis (VL), a disease with global distribution. The genomic structure and genetic variation of this species have been widely studied in different parts of the world. However, in some countries, this information is still yet unknown, as is the genomic behaviour of the main antigens used in VL diagnosis (rK39 and rK28), which have demonstrated variable sensitivity and specificity in a manner dependent on the geographic region analysed. The objective of this study was to explore the genomic architecture and diversity of four Colombian L. infantum isolates obtained in this study and to compare these results with the genetic analysis of 183 L. infantum isolates from across the world (obtained from public databases), as well as to analyse the whole rK39 and rK28 antigen sequences in our dataset. The results showed that, at the global level, L. infantum has high genetic homogeneity and extensive aneuploidy. Furthermore, we demonstrated that there are distinct populations of L. infantum circulating in various countries throughout the globe and that populations of distant countries have close genomic relationships. Additionally, this study demonstrated the high genetic variability of the rK28 antigen worldwide. In conclusion, our study allowed us to (i) expand our knowledge of the genomic structure of global L. infantum; (ii) describe the intra-specific genomic variability of this species; and (iii) understand the genomic characteristics of the main antigens used in the diagnosis of VL. Additionally, this is the first study to report whole-genome sequences of Colombian L. infantum isolates.

MM-326: Visceral Leishmaniasis Mimicking Multiple Myeloma

Context Western parts of the Republic of North Macedonia are considered endemic regions for leishmaniasis. Due to the broad spectrum of hematologic manifestations of visceral leishmaniasis (VL), this anthropozoonosis may be occasionally misdiagnosed as a hematological disease. Objective We present here a patient with VL whose initial clinical and laboratory findings mimicked multiple myeloma and led us to series of diagnostic procedures for plasma cell dyscrasia. Patient Case Report A 66-year-old woman presented at our institution with a history of back pain radiating down the legs. Physical examination revealed massive splenomegaly crossing the abdominal midline. Laboratory data showed pancytopenia (Hb 91 g/L; WBC 1.8 x 109/L; PLT 26 x 109/L), and the peripheral blood smear did not show any specific findings. What led us to suspect multiple myeloma was hyperproteinemia (96 g/L) due to hypergammaglobulinemia with IgG monoclonal components (IgG 71.5 g/L). Bone marrow biopsy with bone marrow aspiration was performed, and clusters of atypical plasma cells up to 20% infiltration were noted, further confirming the initial diagnosis. Still, we noted on M-Grunwald-Giemsa-stained bone marrow aspirate smears intra- and extracellular inclusions, resembling leishmaniasis. Additionally, PCR for B-cell gene rearrangement was negative. The diagnosis of VL was reached by a positive leishmania immunofluorescence antibody test. The patient was treated with amphotericin for 10 days with protracted resolution of the symptoms. The complete recovery of the blood counts was noted within three months. Still, monoclonal IgG, although decreased, remained high at the time of last visit (IgG 55 g/L), which is within three months of treatment. Conclusions Although endemic in our country, VL is rarely included in the differential diagnosis for clinicians, especially in cases with atypical clinical presentation. This case underlies the need for hematologists to consider this condition in patients presenting with uncertain yet common hematological abnormalities.