Enzyme-linked immunosorbent assay to diagnose human leptospirosis: a meta-analysis of the published literature

Molecularly imprinted polymers for sensing/depleting human serum albumin (HSA): A critical review of recent advances and current challenges

Human serum albumin (HSA) is an essential biomacromolecule in the blood circulatory system because it carries numerous molecules, including fatty acids (FAs), bilirubin, metal ions, hormones, and different pharmaceuticals, and plays a significant role in regulating blood osmotic pressure. Fluctuations in HSA levels in human biofluids, particularly urine and serum, are associated with several disorders, such as elevated blood pressure, diabetes mellitus (DM), liver dysfunction, and a wide range of renal diseases. Thus, the ability to quickly and accurately measure HSA levels is important for the rapid identification of these disorders in human populations. Molecularly imprinted polymers (MIPs), well known as artificial antibodies (Abs), have been extensively used for the quantitative detection of small molecules and macromolecules, especially HSA, in recent decades. This review highlights major challenges and recent developments in the application of MIPs to detect HSA in artificial and real samples. The fabrication and application of various MIPs for the depletion of HSA are also discussed, as well as different MIP preparation approaches and strategies for overcoming obstacles that hinder the development of MIPs with high efficiency and recognition capability for HSA determination/depletion.

Diagnostic method-based underestimation of leptospirosis in clinical and research settings; an experience from a large prospective study in a high endemic setting

Background

Leptospirosis has globally significant human mortality and morbidity, yet estimating the clinical and public health burden of leptospirosis is challenging because timely diagnosis remains limited. The goal of the present study was to evaluate leptospirosis undercounting by current standard methods in both clinical and epidemiological study settings.

Methodology/Principal findings

A prospective hospital-based study was conducted in multiple hospitals in Sri Lanka from 2016 to 2019. Culture, whole blood, and urine samples were collected from clinically suspected leptospirosis cases and patients with undifferentiated fever. Analysis of biological samples from 1,734 subjects confirmed 591 (34.1%) cases as leptospirosis and 297 (17.1%) were classified as “probable” leptospirosis cases. Whole blood quantitative PCR (qPCR) did identify the most cases (322/540(60%)) but missed 40%. Cases missed by each method include; urine qPCR, 70% (153/220); acute sample microscopic agglutination test (MAT), 80% (409/510); paired serum sample MAT, 58% (98/170); and surveillance clinical case definition, 53% (265/496). qPCR of negative culture samples after six months of observation was of diagnostic value retrospectively with but missed 58% of positives (109/353).

Conclusion

Leptospirosis disease burden estimates should consider the limitations of standard diagnostic tests. qPCR of multiple sample types should be used as a leading standard test for diagnosing acute leptospirosis.

Diagnostics of leptospirosis have not been optimised yet and is considered as a significant limiting factor for estimating the disease burden. This prospective hospital-based study, including 1734 clinically suspected leptospirosis cases and undifferentiated febrile patients, revealed that a minimum of 40% of cases would be missed by using any of the following tests individually. (Whole blood qPCR, single or paired-sample MAT, Urine qPCR, culture, culture qPCR, surveillance case definition). Therefore, we conclude that whole blood qPCR should be the standard test for diagnosing leptospirosis for clinical purposes until day 10 of the reported disease. MAT should be limited to places where the serological diagnosis has an epidemiological interest. qPCR testing of microscopically-negative cultures should be done before discarding to increase the yield in research settings.

Role of Diagnostics in Epidemiology, Management, Surveillance, and Control of Leptospirosis

A One Health approach to the epidemiology, management, surveillance, and control of leptospirosis relies on accessible and accurate diagnostics that can be applied to humans and companion animals and livestock. Diagnosis should be multifaceted and take into account exposure risk, clinical presentation, and multiple direct and/or indirect diagnostic approaches. Methods of direct detection of Leptospira spp. include culture, histopathology and immunostaining of tissues or clinical specimens, and nucleic acid amplification tests (NAATs). Indirect serologic methods to detect leptospiral antibodies include the microscopic agglutination test (MAT), the enzyme-linked immunosorbent assay (ELISA), and lateral flow methods. Rapid diagnostics that can be applied at the point-of-care; NAAT and lateral flow serologic tests are essential for management of acute infection and control of outbreaks. Culture is essential to an understanding of regional knowledge of circulating strains, and we discuss recent improvements in methods for cultivation, genomic sequencing, and serotyping. We review the limitations of NAATs, MAT, and other diagnostic approaches in the context of our expanding understanding of the diversity of pathogenic Leptospira spp. Novel approaches are needed, such as loop mediated isothermal amplification (LAMP) and clustered regularly interspaced short palindromic repeats (CRISPR)-based approaches to leptospiral nucleic acid detection.

Leptospirosis as a cause of fever associated with jaundice in the Democratic Republic of the Congo

Background

Fever with jaundice is a common symptom of some infectious diseases. In public health surveillance within the Democratic Republic of the Congo (DRC), yellow fever is the only recognized cause of fever with jaundice. However, only 5% of the surveillance cases are positive for yellow fever and thus indicate the involvement of other pathogens. Leptospira spp. are the causative agents of leptospirosis, a widespread bacterial zoonosis, a known cause of fever with jaundice. This study aimed to determine the seropositivity of anti-Leptospira antibodies among suspected yellow fever cases and map the geographical distribution of possible leptospirosis in the DRC.

Methods

We conducted a retrospective study using 1,300 samples from yellow fever surveillance in the DRC from January 2017 to December 2018. Serum samples were screened for the presence of IgM against Leptospira spp. by a whole cell-based IgM ELISA (Patoc-IgM ELISA) at the Institut National de Recherche Biomedicale in Kinshasa (INRB) according to World Health Organization (WHO) guidance. Exploratory univariable and multivariable logistic regression analyses were undertaken to assess associations between socio-demographic factors and the presence of Leptospira IgM.

Results

Of the 1,300 serum samples screened, 88 (7%) showed evidence of IgM against Leptospira spp. Most positive cases (34%) were young adult males in the 20–29-year group. There were statistically significant associations between having Leptospira IgM antibodies, age, sex, and living area. Observed positive cases were mostly located in urban settings, and the majority lived in the province of Kinshasa. There was a statistically significant association between seasonality and IgM Leptospira spp. positivity amongst those living in Kinshasa, where most of the positive cases occurred during the rainy season.

Conclusions

This study showed that leptospirosis is likely an overlooked cause of unexplained cases of fever with jaundice in the DRC and highlights the need to consider leptospirosis in the differential diagnosis of fever with jaundice, particularly in young adult males. Further studies are needed to identify animal reservoirs, associated risk factors, and the burden of human leptospirosis in the DRC.

Leptospirosis is an important bacterial zoonosis with a worldwide distribution. Each year there are an estimated one million cases, with about 60,000 deaths. The true burden of the disease, however, is unknown. The burden of leptospirosis is probably underestimated due to the lack of specific clinical symptoms and diagnostic techniques that are not readily available. Clinical diagnosis of leptospirosis is difficult because of the diversity of symptoms, ranging from asymptomatic forms to severe multivisceral icteric states. Differential diagnoses with infections presenting with fever or fever and jaundice are numerous and may mislead the clinician. Leptospirosis is considered endemic in sub-Saharan Africa and is known to cause fever with jaundice in African countries; however, for most countries, available epidemiologic data are scarce, including in the Democratic Republic of Congo (DRC). An improved understanding of the epidemiology of leptospirosis will improve clinical management, lead to policy formulation, and have implications for national surveillance of infectious diseases in these countries. We conducted a retrospective seroepidemiological study to extend the description of the pathogens responsible for fever with jaundice in the DRC and to clarify the circulation of possible leptospirosis in the country. This study showed that leptospirosis is a likely cause of fever with jaundice in the DRC.

Laboratory Diagnosis of Leptospirosis

The diagnosis of leptospirosis depends on specific laboratory tests because nonspecific and diverse clinical manifestations make clinical diagnosis difficult and it is easily confused with other infectious diseases in the tropics. Suitable laboratory diagnostic tests vary depending on the stage of the disease, requiring the combination of diagnostic tests using appropriate specimens at each disease stage.

A surfactant-mediated sol-gel method for the preparation of molecularly imprinted polymers and its application in a biomimetic immunoassay for the detection of protein

Molecularly imprinted polymers have demonstrated tremendous potential in the immunoassay as alternatives to biological antibodies. However, the production of molecularly imprinted polymers for protein remains great challenges because of structural complexity and organic solvent instability. In addition, non-specific binding sites in the molecularly imprinted polymers debase the feasibility of it as alternative to antibodies for immunoassay. Here, a surfactant-mediated sol-gel system in an aqueous environment was designed to produce the molecularly imprinted polymers for protein. A blocked strategy was introduced to decrease non-specific cross-reactivity and to improve the selectivity. The developed products were characterized by infrared spectroscopy, scanning electron microscope, transmission electron microscope, X-ray photoelectron spectroscopy, and vibrating sample magnetometer, respectively. The obtained molecularly imprinted polymers exhibited desirable specific recognition towards the target and a biomimetic immunoassay method was developed. The method exhibited a good linear response to human serum albumin in a concentration range of 1-100 μg mL^-1. The limit of detection of this method was 0.3 μg mL^-1 (3s/K), and good recoveries ranging from 85.4-104.5% were achieved. This study demonstrated that the molecularly imprinted polymers prepared by the surfactant-mediated sol-gel method can produce high selectivity materials, which had great potential to replace antibodies in a biomimetic immunoassay.

Seroprevalence of Leptospirosis among High-Risk Individuals in Morocco

Background

Leptospirosis is an anthropozoonotic reemerging neglected infectious disease underreported in most developing countries. A cross-sectional study was performed between 17 and 23 February 2014 to estimate the seroprevalence of leptospirosis among high-risk populations in Casablanca (Morocco).

Methods

A total of 490 human serum samples (97.6% males) were collected in 3 high-risk occupational sites including the biggest meat slaughterhouse (n = 208), a poultry market (n = 121), and the fish market (n = 161). A total of 125 human blood samples were also collected from the general population and used in this study as a control group. To detect the presence of anti-Leptospira, sera were screened with in-house IgG and IgM enzyme-linked immunosorbent assay (ELISA). Positive samples were tested by Microscopic Agglutination Technique (MAT) using a panel of 24 serovar cultures and cut point of 1 : 25.

Results

Seroprevalence of leptospirosis among the control group was 10.4% (13/125). A high seropositivity among the overall seroprevalence of 24.1% (118/490) was observed in the high-risk groups of which 7.3% (36/490), 13.7% (67/490), and 3.1% (15/490) were for anti-Leptospira IgM, IgG, and both IgG and IgM antibodies, respectively. Most of the positive individuals were occupationally involved in poultry (37.2%), followed by the market fish (26.1%) and the meat slaughterhouse (14.9%) workers. Among all ELISA-positive serum samples, 20.3% (n = 24) had positive MAT responses, of which the Icterohaemorrhagiae (n = 7) is the most common infecting serogroup followed by Javanica (4), Australis (2), and Sejroe, Mini, and Panama (one in each). In the remaining 8 MAT-positive sera, MAT showed equal titers against more than one serogroup.

Conclusion

Individuals engaged in risk activities are often exposed to leptospiral infection. Therefore, control and prevention policies toward these populations are necessary.

An unusual case of fulminant leptospiral myocarditis: a case report

Background

Fulminant myocarditis secondary to leptospirosis is rare and associated with poor outcomes.

Case summary

We describe a 60-year-old gentleman with fulminant leptospiral myocarditis and profound cardiogenic shock requiring veno-arterial extracorporeal membrane oxygenator (VA-ECMO) support. He was given high-dose pulse steroids early on post-VA-ECMO implantation and achieved full recovery. To our knowledge, this is the first reported case of leptospiral myocarditis with multiorgan dysfunction successfully managed by VA-ECMO and high-dose pulse steroids.

Discussion

This case report highlights the potential benefits of steroids in the management of leptospiral myocarditis which requires further validation. Early aggressive supportive management with ECMO should be considered in patients with fulminant leptospiral myocarditis.

Diagnostic accuracy of leptospirosis whole-cell lateral flow assays: a systematic review and meta-analysis

BACKGROUND

Leptospirosis is under-diagnosed by clinicians in many high-incidence countries, because reference diagnostic tests are largely unavailable. Lateral flow assays (LFA) that use antigen derived from heat-treated whole cell Leptospira biflexa serovar Patoc have the potential to improve leptospirosis diagnosis in resource-limited settings.

OBJECTIVES

We sought to summarize estimates of sensitivity and specificity of LFA by conducting a systematic review and meta-analysis of evaluations of the accuracy of LFA to diagnose human leptospirosis.

DATA SOURCES

On 4 July 2017 we searched three medical databases. Study eligibility criteriaArticles were included if they were a study of LFA sensitivity and specificity.

PARTICIPANTS

Patients with suspected leptospirosis.

INTERVENTIONS

Nil.

METHODS

For included articles, we assessed study quality, characteristics of participants and diagnostic testing methods. We estimated sensitivity and specificity for each study against the study-defined case definition as the reference standard, and performed a meta-analysis using a random-effects bivariate model.

RESULTS

Our search identified 225 unique reports, of which we included nine (4%) published reports containing 11 studies. We classified one (9%) study as high quality. Nine (82%) studies used reference tests with considerable risk of misclassification. Our pooled estimates of sensitivity and specificity were 79% (95% CI 70%-86%) and 92% (95% CI 85%-96%), respectively.

CONCLUSIONS

As the evidence base for determining the accuracy of LFA is small and at risk of bias, pooled estimates of sensitivity and specificity should be interpreted with caution. Further studies should use either reference tests with high sensitivity and specificity or statistical techniques that account for an imperfect reference standard.

Development and validation of pan-Leptospira Taqman qPCR for the detection of Leptospira spp. in clinical specimens

BACKGROUND

Early diagnosis of leptospirosis is important for ensuring better clinical management and achieving better outcomes. Currently, serological assays suffer from inconsistent performance and are less useful for early diagnosis of leptospirosis. As an alternative, qPCR is more sensitive, specific and able to detect the presence of leptospiral DNA during the acute phase of the infection. Meanwhile, most molecular assays do not detect the non-pathogenic group of Leptospira, even though these groups may also infect humans, although less frequently and less severely.

METHODS

A set of primers and probe targeting rrs genes of 22 Leptospira spp. were designed and evaluated on 31 Leptospira isolates, 41 other organisms and 65 clinical samples from suspected patients.

RESULTS

The developed assay was able to detect as low as 20 fg Leptospira DNA per reaction (equivalent to approximately 4 copies) and showed high specificity against the tested leptospiral strains. No cross amplification was observed with the other organisms. During the evaluation of the confirmed clinical specimens, the developed assay was able to correctly identify all positive samples (n = 10/10). One amplification was observed in a negative sample (n = 1/55). The sequencing of the PCR product of the discordant sample revealed that the sequences were similar to those of L. interrogans and L. kirschneri.

CONCLUSION

The findings suggest that the developed Taqman qPCR assay is sensitive, specific and has potential to be applied in a larger subsequent study.

IgM ELISA for leptospirosis diagnosis: a systematic review and meta-analysis

Abstract A systematic review with meta-analysis was performed to estimate the accuracy of IgM ELISA for Leptospirosis diagnosis. A search of Medline, Lilacs, Embase, Cochrane Central Register of Controlled Trials and Grey literature (Google Scholar and British Library) was conducted. The medical subject headings (MeSHs) and the words “leptospirosis”, “human leptospirosis” and “IgM ELISA” were used. Fifty-two studies were analyzed, which included 10,775 samples. The pooled sensitivity of all the studies was 86% (CI 95%, 85%-87%) and specificity was 90% (CI 95%, 89%-91%). In studies of the acute phase, the sensitivity and specificity were 84% (CI 95%, 82%-85%) and 91% (CI 95%, 90%-91%), respectively. In conclusion, IgM ELISA is sensitive for use as an initial screen for leptospiral infections.

Evaluation of different serological assays for early diagnosis of leptospirosis in Martinique (French West Indies)

BACKGROUND

Leptospirosis is a potentially life-threatening but curable zoonosis whose prognosis depends on accurate and timely diagnosis. Because of its non-specific clinical presentation, laboratory testing is essential to confirm the diagnosis. Here, we aimed to assess the performance of two enzyme-linked immunosorbent assays (ELISAs) (ELISA Serion and ELISA-Hb Pasteur) and one immunodot (GenBio) using quantitative PCR (qPCR) as gold standard, instead of the traditional microscopic agglutination test, for the diagnosis of acute leptospirosis in an endemic area.

METHODOLOGY/PRINCIPAL FINDINGS

Between January 2011 and December 2012, a total of 122 patients were diagnosed with leptospirosis, as confirmed by qPCR at the University Hospital of Martinique. Among them, 103 had at least one serum sample available for analysis. Performance of each serological assay was evaluated according to days' post onset of symptoms (DPO) and local species diversity (which included L. santarosai, L. interrogans, L. kirschneri, L. borgpetersenii, L. noguchii, and L. kmetyi). Several thresholds were tested to optimize accuracy. When considering the manufacturer's threshold, the sensitivity of ELISA Serion, ELISA-Hb Pasteur and GenBio immunodot was 75%, 67% and 64%, while specificity was 92%, 98% and 100%, respectively. Moreover, the threshold optimization allowed a significant improvement in specificity for the ELISA Serion from 92% to 99% (p<0.05). During the first 5 DPO, sensitivities were 35%, 30% and 42% for ELISA Serion, ELISA-Hb Pasteur and GenBio immunodot, respectively. However, between 6─10 DPO, these sensitivities dramatically increased to reach 86%, 76% and 67%, respectively. Performances of the three assays were not affected by the species studied.

CONCLUSIONS/SIGNIFICANCE

All these serological assays showed the potential for diagnosing leptospirosis after (but not before) 6 days' post onset of symptoms. In a high prevalence setting, where highest specificities are needed, threshold optimizing should be performed for this purpose.

Highly Uniform Gold Nanobipyramids for Ultrasensitive Colorimetric Detection of Influenza Virus

Gold nanoparticles (AuNPs) have been frequently utilized for the construction of diverse colorimetric biosensors. Normally, AuNPs with sharp edges could have better sensitivity. However, the poor monodipersity of AuNPs with sharp edges seriously confines their utility for colorimetric biosensing. Herein, we demonstrate the utility of highly uniform gold nanobipyramids (Au NBPs) for ultrasensitive colorimetric detection of H₅N₁ virus. The proposed method is based on the fact that alkaline phosphatase (ALP) could catalyze the decomposition of 4-aminophenyl phosphate (4-APP) to generate 4-aminophenol (4-AP), which would then reduce silver nitrate to metal silver and then deposited on Au NBPs. The metal silver shell coated on the Au NBPs changed the refractive index of gold and thus resulted in a blue shift of longitudinal localized surface plasmon resonance (LSPR) and accompanied a vivid color change. This method exhibited a higher sensitivity than that of other Au NPs such as gold nanorods due to the high-index-faceted on the tips of the Au NBPs. This method was used to detect the activity of ALP. It exhibited a linear range of 0.1-5 mU/mL with a limit of detection (LOD) of 0.086 mU/mL. Finally, the proposed method was used in immunoassay to detect H₅N₁ virus. The results showed that the corresponding linear range for the detection of H₅N₁ virus antigen was 0.001-2.5 ng/mL, and the LOD was determined to be 1 pg/mL, which is more sensitive than those in most of the colorimetric biosensors reported previously.

Risk factors for leptospirosis seropositivity in slaughterhouse workers in western Kenya

OBJECTIVES

Leptospirosis has been documented in slaughterhouse workers around the world. Risk factors include smoking and drinking at work, and performing tasks such as cleaning offal. This paper examined risk factors for leptospirosis seropositivity in slaughterhouse workers in western Kenya.

METHODS

The study was conducted between May 2011 and October 2012. Questionnaires were used to collect information from workers on demographic data, health and hygiene practices in the slaughterhouse. A commercial ELISA detected antibodies to Leptospira spp. in serum samples and multilevel logistic regression analysis identified factors associated with leptospirosis seropositivity.

RESULTS

A total of 737 workers from 142 slaughterhouses were recruited. The seroprevalence of antibodies to Leptospira spp. was 13.4% (95% CI 11.1% to 16.1%). Risk factors included: having wounds (OR 3.1; 95% CI 1.5 to 6.1); smoking (OR 1.8; 95% CI 1.1 to 2.9); eating at work (OR 2.1; 95% CI 1.2 to 3.6); cleaning the offal (OR 5.1; 95% CI 1.8 to 15.0); and having a borehole for personal water use (OR 2.3; 95% CI 1.1 to 4.7). At the slaughterhouse level, risk factors included having a roof (OR 2.6; 95% CI 1.2 to 5.6) and drawing water from a well (OR 2.2; 95% CI 1.2 to 4.0). Protective factors included working in slaughterhouses where antemortem inspection was conducted (OR 0.6; 95% CI 0.4 to 1.0) and where workers wore protective aprons (OR 0.4; 95% CI 0.2 to 0.7).

CONCLUSIONS

This is the first report of leptospirosis seropositivity in slaughterhouse workers in Kenya. Potential risk factors were identified and this information can be used to educate workers regarding their disease risks and ways to prevent or reduce transmission.

Evaluation of two immunodiagnostic tests for early rapid diagnosis of leptospirosis in Sri Lanka: a preliminary study

BACKGROUND

Leptospirosis is often treated based on clinical diagnosis. There is a need for rapid laboratory diagnosis for this condition. The aim of this study was to compare the diagnostic accuracy of two rapid IgM based immunodiagnostic assays with the microscopic agglutination test (MAT), in acute leptospirosis infection.

METHODS

MAT, IgM based immunochromatographic test (Leptocheck-WB) and IgM ELISA were performed using acute sera of patients clinically suspected to have leptospirosis (n = 83). Bayesian latent class modeling was used to compare the accuracy of these tests.

RESULTS

Percentage positivity for MAT, Leptocheck-WB, and IgM ELISA were 48.1, 55.3, and 45.7 % respectively. Bayesian latent class modeling showed a combined positivity rate of leptospirosis of 44.7 %. The sensitivity of MAT, Leptocheck-WB and IgM ELISA were 91.4, 95 and 81.1 %, and specificity were 86.7, 76.4 and 83.1 %, respectively.

CONCLUSIONS

Leptocheck-WB has high sensitivity, and, because it is quick and easy to perform, would be a good screening test for acute leptospirosis infection. IgM ELISA has good specificity, and is comparable with MAT; given that it is easier to perform and more widely available than MAT, it would be a more appropriate confirmatory test for use in hospitals with limited access to a specialized laboratory.

Current immunological and molecular tools for leptospirosis: diagnostics, vaccine design, and biomarkers for predicting severity

Leptospirosis is a zoonotic spirochaetal illness that is endemic in many tropical countries. The research base on leptospirosis is not as strong as other tropical infections such as malaria. However, it is a lethal infection that can attack many vital organs in its severe form, leading to multi-organ dysfunction syndrome and death. There are many gaps in knowledge regarding the pathophysiology of leptospirosis and the role of host immunity in causing symptoms. This hinders essential steps in combating disease, such as developing a potential vaccine. Another major problem with leptospirosis is the lack of an easy to perform, accurate diagnostic tests. Many clinicians in resource limited settings resort to clinical judgment in diagnosing leptospirosis. This is unfortunate, as many other diseases such as dengue, hanta virus, rickettsial infections, and even severe bacterial sepsis, can mimic leptospirosis. Another interesting problem is the prediction of disease severity at the onset of the illness. The majority of patients recover from leptospirosis with only a mild febrile illness, while a few others have severe illness with multi-organ failure. Clinical features are poor predictors of potential severity of infection, and therefore the search is on for potential biomarkers that can serve as early warnings for severe disease. This review concentrates on these three important aspects of this neglected tropical disease: diagnostics, developing a vaccine, and potential biomarkers to predict disease severity.

Leptospirosis in humans

Leptospirosis is a widespread and potentially fatal zoonosis that is endemic in many tropical regions and causes large epidemics after heavy rainfall and flooding. Infection results from direct or indirect exposure to infected reservoir host animals that carry the pathogen in their renal tubules and shed pathogenic leptospires in their urine. Although many wild and domestic animals can serve as reservoir hosts, the brown rat (Rattus norvegicus) is the most important source of human infections. Individuals living in urban slum environments characterized by inadequate sanitation and poor housing are at high risk of rat exposure and leptospirosis. The global burden of leptospirosis is expected to rise with demographic shifts that favor increases in the number of urban poor in tropical regions subject to worsening storms and urban flooding due to climate change. Data emerging from prospective surveillance studies suggest that most human leptospiral infections in endemic areas are mild or asymptomatic. Development of more severe outcomes likely depends on three factors: epidemiological conditions, host susceptibility, and pathogen virulence (Fig. 1). Mortality increases with age, particularly in patients older than 60 years of age. High levels of bacteremia are associated with poor clinical outcomes and, based on animal model and in vitro studies, are related in part to poor recognition of leptospiral LPS by human TLR4. Patients with severe leptospirosis experience a cytokine storm characterized by high levels of IL-6, TNF-alpha, and IL-10. Patients with the HLA DQ6 allele are at higher risk of disease, suggesting a role for lymphocyte stimulation by a leptospiral superantigen. Leptospirosis typically presents as a nonspecific, acute febrile illness characterized by fever, myalgia, and headache and may be confused with other entities such as influenza and dengue fever. Newer diagnostic methods facilitate early diagnosis and antibiotic treatment. Patients progressing to multisystem organ failure have widespread hematogenous dissemination of pathogens. Nonoliguric (high output) renal dysfunction should be supported with fluids and electrolytes. When oliguric renal failure occurs, prompt initiation of dialysis can be life saving. Elevated bilirubin levels are due to hepatocellular damage and disruption of intercellular junctions between hepatocytes, resulting in leaking of bilirubin out of bile caniliculi. Hemorrhagic complications are common and are associated with coagulation abnormalities. Severe pulmonary hemorrhage syndrome due to extensive alveolar hemorrhage has a fatality rate of >50 %. Readers are referred to earlier, excellent summaries related to this subject (Adler and de la Peña-Moctezuma 2010; Bharti et al. 2003; Hartskeerl et al. 2011; Ko et al. 2009; Levett 2001; McBride et al. 2005).

Diagnostic Accuracy of Recombinant Immunoglobulin-like Protein A-Based IgM ELISA for the Early Diagnosis of Leptospirosis in the Philippines

BACKGROUND

Leptospirosis is an important but largely under-recognized public health problem in the tropics. Establishment of highly sensitive and specific laboratory diagnosis is essential to reveal the magnitude of problem and to improve treatment. This study aimed to evaluate the diagnostic accuracy of a recombinant LigA protein based IgM ELISA during outbreaks in the clinical-setting of a highly endemic country.

METHODOLOGY/PRINCIPAL FINDINGS

A prospective study was conducted from October 2011 to September 2013 at a national referral hospital for infectious diseases in Manila, Philippines. Patients who were hospitalized with clinically suspected leptospirosis were enrolled. Plasma and urine were collected on admission and/or at discharge and tested using the LigA-IgM ELISA and a whole cell-based IgM ELISA. Sensitivity and specificity of these tests were evaluated with cases diagnosed by microscopic agglutination test (MAT), culture and LAMP as the composite reference standard and blood bank donors as healthy controls: the mean+3 standard deviation optical density value of healthy controls was used as the cut-off limit (0.062 for the LigA-IgM ELISA and 0.691 for the whole cell-based IgM ELISA). Of 304 patients enrolled in the study, 270 (89.1%) were male and the median age was 30.5 years; 167 (54.9%) were laboratory confirmed. The sensitivity and ROC curve AUC for the LigA-IgM ELISA was significantly greater than the whole cell-based IgM ELISA (69.5% vs. 54.3%, p<0.01; 0.90 vs. 0.82, p<0.01) on admission, but not at discharge. The specificity of LigA-IgM ELISA and whole cell-based IgM ELISA were not significantly different (98% vs. 97%). Among 158 MAT negative patients, 53 and 28 were positive by LigA- and whole cell-based IgM ELISA, respectively; if the laboratory confirmation was re-defined by LigA-IgM ELISA and LAMP, the clinical findings were more characteristic of leptospirosis than the diagnosis based on MAT/culture/LAMP.

CONCLUSIONS/SIGNIFICANCE

The newly developed LigA-IgM ELISA is more sensitive than the whole cell-based IgM based ELISA. Although the final diagnosis must be validated by more specific tests, LigA-IgM ELISA could be a useful diagnostic test in a real clinical-setting, where diagnosis is needed in the early phase of infection.

Identification of leptospiral 3-hydroxyacyl-CoA dehydrogenase released in the urine of infected hamsters

Background

Leptospirosis is a global zoonosis caused by pathogenic Leptospira. The non-specific clinical signs and symptoms of leptospirosis lead to its misdiagnosis. To date, there is still no reliable rapid test kit that can accurately diagnose leptospirosis at bedside or in field. In this research, with the ultimate goal of formulating a rapid and accurate diagnostic tool for leptospirosis, we aimed to identify leptospiral proteins excreted in urine of infected hamsters, which are thought to mimic Weil’s disease.

Results

Hamsters were subcutaneously infected with leptospires, and the general attributes of urine as well as the proteins excreted in it were examined. Some leptospiral proteins were found to be excreted in the urine from the early phase of infection. The most important finding of this study was the detection of the lipid-metabolizing enzyme, 3-hydroxyacyl-CoA dehydrogenase (HADH), before the onset of illness, when leptospires were not yet detected in the urine of infected hamsters.

Conclusions

This is the first report on the detection of leptospiral HADH in the host urine, which may be a possible candidate leptospiral antigen that can be used in the early diagnosis of human and animal leptospirosis.

Current trends in translational research in leptospirosis

PURPOSE OF REVIEW

In the past years, the importance of studying leptospirosis in a translational context has become more evident. This review addresses recent findings in the study of leptospirosis infection, focusing on those applicable to public health, or that will affect management and diagnosis of cases of leptospirosis.

RECENT FINDINGS

We review here recent findings regarding translational aspects of leptospirosis research. Briefly, PCR or a combination of serology and PCR seem to have a higher sensitivity than the current gold standard (microagglutination test). More clinical trials are needed to determine the best treatment for mild and severe leptospirosis. Dendritic cells and γδ T cells seem to have an important role in the immune response to leptospirosis. Environmental assessment is emerging as a very useful tool.

SUMMARY

In order to understand leptospirosis, multiple aspects need to be considered, including host, pathogen and environment. In this review, we will address newer diagnostics, current advances in immunology and treatment and the growing role of environmental assessment.

Rapid tests for diagnosis of leptospirosis: current tools and emerging technologies

Leptospirosis is an emerging zoonosis with a worldwide distribution but is more commonly found in impoverished populations in developing countries and tropical regions with frequent flooding. The rapid detection of leptospirosis is a critical step to effectively manage the disease and to control outbreaks in both human and animal populations. Therefore, there is a need for accurate and rapid diagnostic tests and appropriate surveillance and alert systems to identify outbreaks. This review describes current in-house methods and commercialized tests for the rapid diagnosis of acute leptospirosis. It focuses on diagnostic tests that can be performed with minimal training and limited equipment in less-developed and newly industrialized countries, particularly in resource-limited settings and with results in minutes to less than 4 hours. We also describe recent technological advances in the field of diagnostic tests that could allow for the development of innovative rapid tests in the near future.

Evaluation of an in-house ELISA using the intermediate species Leptospira fainei for diagnosis of leptospirosis

Leptospirosis is recognized as an emerging zoonotic disease generally affecting urban slums in developing countries and tropical regions. A combination of non-specific symptoms, low awareness among the medical community and a lack of readily available diagnostic tests have made leptospirosis an underdiagnosed disease. In this study, we tested an in-house ELISA with formalin-treated and boiled bacteria from the intermediate species Leptospira fainei as an antigen to detect Leptospira-specific IgM antibodies. A total of 819 serum samples, tested by a microscopic agglutination test (MAT) as a reference test, were used to evaluate the ELISA. Compared with positive and negative sera, the ELISA showed 94 % sensitivity and 99 % specificity. Positive and negative likelihood ratios were 94 and 0.06, respectively. No cross-reactivity was observed in sera from subjects with dengue and syphilis infections. The kappa value was 0.92 (95 % confidence interval 0.88-0.96), which indicated excellent agreement between the MAT and ELISA. The overall performance of this in-house ELISA suggests applicability as a rapid screening test for the diagnosis of leptospirosis in resource-limited settings and in hospitals and laboratories where a MAT is not available.

Leptospirosis-persistence of a dilemma: an overview with particular emphasis on trends and recent advances in vaccines and vaccination strategies

Leptospirosis, caused by pathogenic spirochetes of the genus Leptospira, affects both humans and animals and is among the most common but neglected direct zoonotic disease in the world, particularly in untreated or undiagnosed animals as well as humans. Now, it has been considered as a re-emerging disease causing global health problem due to its increasing incidences in developing as well as developed nations. It is a multisystemic disease leading to death. Diagnostic tests of importance are Latex Agglutination Test (LAT), lateral flow and immunoglobulin M (IgM) based ELISA, PCR based assays, Multiple-microscopic Agglutination Test (MAT), Loop-mediated Isothermal Amplification (LAMP) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Molecular tools like PCR-RFLP, real-time PCR, multiplex PCR, qPCR and immunocapture PCR have all been found useful for rapid and confirmatory detection and differentiation of pathogenic and non-pathogenic leptospires. Inactivated/killed and attenuated vaccines are always attempted, since the beginning of vaccine and vaccination story, against all emerging pathogens with mixed success stories. The advanced tools and techniques like recombinant DNA technology, reverse genetics, DNA vaccination, molecular genetics and proteomics approaches are being explored for search of novel antigens, proteins and genes as potential candidates to discover safer, efficient and better vaccines for leptospirosis. The present review highlights the leptospirosis, susceptible population, disease transmission and epidemiology, treatment, trends and advances in diagnosis, vaccines and vaccination strategies in humans and animals with a view to combat this organism having public health significance.