Leptospirosis: current situation and trends of specific laboratory tests

Isolation of Virulent Leptospira Serogroup Australis Field Strains from Symptomatic Dogs for Canine Leptospiral Vaccine Development

Leptospirosis is a widespread zoonosis caused by spirochaetes belonging to the pathogenic species of Leptospira, which are classified into more than 25 serogroups and 250 serovars. Vaccination can prevent the disease in dogs but offers incomplete efficacy because of a lack of cross-protection between serogroups. The aim of this study was to validate a robust recruitment and sampling process, with the objectives of isolating and typing circulating Leptospira pathogenic strains and then selecting those of proven virulence and pathogenicity for vaccine development. Blood and urine samples from dogs with clinical syndromes compatible with acute leptospirosis were sterilely collected and transported to a reference laboratory for a micro-agglutination test (MAT), PCR, and bacterial isolation. Isolated strains underwent molecular typing using RNA16S, variable-number tandem repeat (VNTR), and pulsed-field gel electrophoresis (PFGE). Subtyping was performed using core genome multilocus sequence typing (CgMLST). Among 64 included dogs, 41 had MAT and/or PCR results compatible with Leptospira infection, and 14 Leptospira strains were isolated. Based on molecular typing, 11 isolates were classified as L. interrogans serogroup Australis, serovar Bratislava, and 3 as serogroup Icterohaemorrhagiae, serovar Icterohaemorrhagiae. CgMLST subtyping revealed a diversity of clonal groups (CGs) distributed in several regional clusters. Besides validating a robust recruitment and sampling process, this study outlines the value of combining PCR and serological testing when suspecting leptospirosis and the usefulness of implementing molecular typing methods to identify circulating field strains. It also confirms the epidemiological importance of the Australis serogroup and allows for the collection of different highly pathogenic strains for vaccine development.

Spatiotemporal assessment of pathogenic Leptospira in subtropical coastal watersheds

The World Health Organization classifies leptospirosis as a significant public health concern, predominantly affecting impoverished and unsanitary regions. By using the Pensacola Bay System as a case study, this study examines the underappreciated susceptibility of developed subtropical coastal ecosystems such as the Pensacola Bay System to neglected zoonotic pathogens such as Leptospira. We analyzed 132 water samples collected over 12 months from 44 distinct locations with high levels of Escherichia coli (>410 most probable number/100 mL). Fecal indicator bacteria (FIB) concentrations were assessed using IDEXX Colilert-18 and Enterolert-18, and an analysis of water physiochemical characteristics and rainfall intensity was conducted. The LipL32 gene was used as a quantitative polymerase chain reaction (qPCR) indicator to identify the distribution of Leptospira interrogans. The results revealed 12 instances of the presence of L. interrogans at sites with high FIB over various land cover and aquatic ecosystem types. Independent of specific rainfall events, a seasonal relationship between precipitation and elevated rates of fecal bacteria and leptospirosis was found. These findings highlight qPCR's utility in identifying pathogens in aquatic environments and the widespread conditions where it can be found in natural and developed areas.

The other great imitator among infectious diseases: Leptospirosis

INTRODUCTION

Leptospirosis is a worldwide zoonosis responsible for highly diverse clinical presentations with a wide range of severity. Variable environment exposures to infected urines of rodents have been described.

OBSERVATION

We report five cases of serologically confirmed leptospirosis leading to hospitalization in an intensive care unit (ICU) of a French center. These patients displayed neurological, respiratory, and abdominal presentation of leptospirosis with variable level of severity. Either professional, leisure related, or daily living exposures have been retrieved.

CONCLUSION

These cases underline the diversity of clinical presentation and environmental exposure of this infectious disease. They highlight the interest of an exhaustive anamnesis with collection of professional activity, environmental exposures, and leisure activities.

Laboratory Investigations in Infectious Uveitis

Laboratory investigations can play a significant role in the diagnosis and decision-making of infectious uveitis. Though direct demonstration of the infective organism remains the gold standard of diagnosis, it is not always possible with ocular tissues. Recent advancements in molecular techniques have made it possible to overcome these limitations and to identify the genomic DNA of pathogens associated with infectious uveitis. Techniques such as next-generation sequencing can analyze all DNA-based lifeforms, regardless of whether they are bacteria, fungi, viruses, or parasites and have been used in the laboratory diagnosis of intraocular inflammation. On the other hand, serological tests, though they dominate the diagnostic landscape of various infectious etiologies in uveitis in routine clinical practice, have varied specificities and sensitivities in different infectious uveitis. In this review, we focus on various methods of laboratory diagnosis of infectious uveitis and discuss the recent advances in molecular diagnosis and their role in various infectious clinical entities.

Leptospirosis and characterization of Leptospira isolates from patients in Koprivnica-Križevci County, Croatia from 2000-2004

Introduction

Leptospirosis, caused by spirochetes of the genus Leptospira , is present in the Koprivnica-Križevci County area, Croatia. Clinical manifestation can range from asymptomatic, short-term mild, non-specific febrile disease, to severe forms with high mortality rates.

Aim

The aim of the study was to valuate culture in front of microscopic agglutination test (MAT) for diagnosis of infection, and to evaluate clinical and laboratory features of the disease. Moreover, we want to characterize Leptospira strains involved in infection in Koprivnica-Križevci County, Croatia.

Methods

We included 68 patients with clinical presentation consistent with leptospirosis collected in a 5-year period (2000-2004). Clinical samples (blood, urine and cerebrospinal fluid, CSF) were inoculated in Kolthoff's medium; species of isolated Leptospira strains was determined with Tm of real-time PCR, serogroup/serovar with MAT and NotI-RFLP analysis. Demonstration of specific antibodies in patients' sera was done using microscopic agglutination test.

Results

Leptospira was isolated from the blood of 14/51(27.5 %) patients and the most often identified serogroup/serovar was Icterohaemorrhagiae (8/10, 80%) followed by Grippotyphosa (10%). Regarding to species level, 8/10 isolated belonged to L. interrogans sensu stricto and one to L. kirschneri species. MAT was carried out on 51 patients with suspected leptospirosis, and was positive in 11/51(21.5 %) patients. Most of our patients presented with moderate severe symptoms, were hospitalized from August to October, and were infected mainly during the work or recreation in our county. The frequency of particular clinical features and pathological laboratory findings correlated with the severity of the clinical condition.

Conclusions

Leptospirosis can be confirmed microbiologically, culture and MAT contributed almost equally to the diagnosis of infection. Serovar Icterohaemorrhagiae was found as the dominant one, and L. interrogans sensu stricto as dominant species in our county. Epidemiological data shown that leptospirosis occurs seasonally, affects the rural population, and most commonly is presented with moderate severe clinical course.

A Promising Tool in Serological Diagnosis: Current Research Progress of Antigenic Epitopes in Infectious Diseases

Infectious diseases, caused by various pathogens in the clinic, threaten the safety of human life, are harmful to physical and mental health, and also increase economic burdens on society. Infections are a complex mechanism of interaction between pathogenic microorganisms and their host. Identification of the causative agent of the infection is vital for the diagnosis and treatment of diseases. Etiological laboratory diagnostic tests are therefore essential to identify pathogens. However, due to its rapidity and automation, the serological diagnostic test is among the methods of great significance for the diagnosis of infections with the basis of detecting antigens or antibodies in body fluids clinically. Epitopes, as a special chemical group that determines the specificity of antigens and the basic unit of inducing immune responses, play an important role in the study of immune responses. Identifying the epitopes of a pathogen may contribute to the development of a vaccine to prevent disease, the diagnosis of the corresponding disease, and the determination of different stages of the disease. Moreover, both the preparation of neutralizing antibodies based on useful epitopes and the assembly of several associated epitopes can be used in the treatment of disease. Epitopes can be divided into B cell epitopes and T cell epitopes; B cell epitopes stimulate the body to produce antibodies and are therefore commonly used as targets for the design of serological diagnostic experiments. Meanwhile, epitopes can fall into two possible categories: linear and conformational. This article reviews the role of B cell epitopes in the clinical diagnosis of infectious diseases.

Genetic basis underlying the serological affinity of leptospiral serovars from serogroups Sejroe, Mini and Hebdomadis

Leptospirosis is a widely distributed zoonosis caused by pathogenic strains of bacteria of the genus Leptospira (Phylum Spirochaetes). Its agents are commonly classified based on their antigenic characteristics into serogroups and serovars, which are relevant for epidemiologic studies and vaccine development. Serological tests are considered laborious and require a specialized infrastructure. Some molecular methods have been proposed to accelerate these procedures, but they still can not replace the immunological tests, thus requiring a further understanding of the genetic basis underlying the serological classification. In this work, we focused on elucidating the genetic factors determinant for the serogroup Sejroe, which is one of the most prevalent serogroups in livestock. For this, we conducted a comparative analysis using >700 leptospiral genomic samples available in the public database. The analysis showed that the genes comprising the rfb locus are the main genetic factors associated with the serological classification. Samples from the serogroup Sejroe have an rfb locus with a conserved gene composition that differs from most other serogroups. Hebdomadis and Mini were the only serogroups whose samples have an rfb locus with similar gene composition to those from serogroup Sejroe, corroborating with the serological affinity shared by them. Finally, we could determine a small region in the rfb locus in which each of those three serogroups can be distinguished by its gene composition. This is the first work that uses an extensive repertoire of genomic data of leptospiral samples to elucidate the molecular basis of the serological classification and open the road to more reliable strategies based on molecular methods for serodiagnosis.

Molecular Diagnostic Methods For The Detection of Leptospirosis

Leptospirosis is a widespread infectious disease caused by the spirochete Leptospira. The clinical features of leptospirosis are fever, headache, vomiting, jaundice, and the acute form of the disease is commonly called Weil’s disease. The microscopic agglutination test (MAT) is a gold standard method used to detect leptospirosis. However, it requires 14 days of time and skilled personnel to detect leptospirosis. Various molecular methods were developed for the rapid detection process, including polymerase chain reaction (PCR), multiplex PCR, nested PCR, real-time PCR, and Loop-mediated isothermal amplification (LAMP). Other immuno-based biosensor kits are readily available for the diagnosis of leptospirosis. Though these methods claim to be highly sensitive and specific, each method has its drawbacks. This review discusses the different molecular diagnostic techniques applied for the diagnosis of leptospirosis; elaborating on each method’s sensitivity, specificity, and detection time and the different samples of water, blood, and urine used.

Enzyme immunoassays (EIA) for serodiagnosis of human leptospirosis: specific IgG3/IgG1 isotyping may further inform diagnosis of acute disease

The laborious microscopic agglutination test (MAT) is the gold standard serologic test for laboratory diagnosis of leptospirosis. We developed EIA based serologic assays using recombinant proteins (rLigA, rLigB, rLipL32) and whole-cell extracts from eight Leptospira serovars as antigen and assessed the diagnostic performance of the new assay within each class, against MAT positive (MAT+) human sera panels from Portugal/PT (n = 143) and Angola/AO (n = 100). We found that a combination of recombinant proteins rLigA, rLigB and rLipL32 correctly identified antigen-specific IgG from patients with clinical and laboratory confirmed leptospirosis (MAT+) with 92% sensitivity and ~ 97% specificity (AUC 0.974) in serum from the provinces of Luanda (LDA) and Huambo (HBO) in Angola. A combination of whole cell extracts of L. interrogans sv Copenhageni (LiC), L. kirschneri Mozdok (LkM), L. borgpetersenii Arborea (LbA) and L. biflexa Patoc (LbP) accurately identified patients with clinical and laboratory confirmed leptospirosis (MAT+) with 100% sensitivity and ~ 98% specificity for all provinces of Angola and Portugal (AUC: 0.997 for AO/LDA/HBO, 1.000 for AO/HLA, 0.999 for PT/AZ and 1.000 for PT/LIS). Interestingly, we found that MAT+ IgG+ serum from Angola had a significantly higher presence of IgD and that IgG3/IgG1 isotypes were significantly increased in the MAT+ IgG+ serum from Portugal. Given that IgM/IgD class and IgG3/IgG1 specific isotypes are produced in the earliest course of infection, immunoglobulin G isotyping may be used to inform diagnosis of acute leptospirosis. The speed, ease of use and accuracy of EIA tests make them excellent alternatives to the laborious and expensive MAT for screening acute infection in areas where circulating serovars of pathogenic Leptospira are well defined.

Evaluation of a genus-specific rGroEL1-524 IgM-ELISA and commercial ELISA kits during the course of leptospirosis in Thailand

In the present study, we developed a genus-specific rGroEL_1-524 IgM-ELISA assay for use in screening diagnosis of suspected leptospirosis among acute undifferentiated febrile illness patients during acute fever. The diagnostic accuracies of the rGroEL_1–524 IgM-ELISA, commercial Panbio IgM-ELISA, and Virion-Serion Classic IgG-ELISA were evaluated using 133 Thai leptospirosis sera and 210 controls. Sensitivities were 91.7%, 59.6%, and 17.7% for acute infection, and the specificities were 92.6%, 90.2%, and 88.3% for the non-leptospirosis control, respectively. The rGroEL_1-524 IgM-ELISA had high sensitivity, at 92.3% and 91.7%, among culture-positive and MAT-negative cases at 1–3 days post-onset of symptoms (DPO1–3), respectively. Impaired specificity on scrub typhus was found, possibly from antibody cross-reaction to ortholog GroEL. Commercial Panbio IgM-ELISA had sensitivities at DPO1–3 of 30.8% and 41.7% for culture-positive and MAT-negative cases whereas Virion-Serion IgG-ELISA showed sensitivities of 5.9% and 13.3%, respectively. The rGroEL_1-524 IgM-ELISA could be useful as a screening test for early diagnosis. The performance of the commercial ELISA suggests the applicability of IgM-ELISA for diagnosis, while IgG-ELISA is useful for seroprevalence surveys. However, confirmation by reference tests is recommended.

Sef fimbria operon construction, expression, and function for direct rapid detection of Salmonella Enteritidis

Salmonella Enteritidis (SE) causes both horizontal and vertical transmission of diseases in poultry industry and is also one of the main causes of human food poisoning. Sequence analysis of the sef operon of poultry-derived Salmonella serotypes showed the presence of an entire sef operon in SE, whereas only sef pseudogenes were found in Salmonella Gallinarum and Salmonella Pullorum. Subsequently, the sef operon of SE was cloned into the pBR322 plasmid and expressed in a modified Escherichia coli strain SE5000. sef operon expression was demonstrated using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, western blot, agglutination assay, and transmission electron microscopy. The results showed that SE5000+Sef, but not SE5000+pBR322, could specifically react with SE-positive chicken serum in an agglutination assay, which could be clearly visualized by the naked eye within less than 2 min. In contrast, SE5000+Sef could not be recognized in Salmonella Gallinarum- and Salmonella Pullorum-positive chicken sera. Next, taking advantage of the exclusive presence of an entire sef operon in SE, we set up an agglutination-based detection system to monitor the dynamics of Sef-targeted antibody from SE-infected chicks for 47 days. Using the proposed detection method, SE was readily detectable starting from 2 weeks post-infection. Finally, we compared the proposed SE5000+Sef-based detection system with commercially available agglutination antigen using the classical bacterial isolation and identification procedure as reference. The results showed that the SE5000+Sef system was more consistent with the results of bacterial isolation and identification with almost 100% accuracy. We established a simple, sensitive, and cheap agglutination method for rapid and specific detection of SE-infected chickens, which can facilitate epidemiological investigation and eradication of SE infections. KEY POINTS: • Only the Salmonella Enteritidis serotype expressed Sef fimbriae in chicken infected with SE. • A rapid, large-scale method of detection by the naked eye of detection of SE-infected chicken is presented.

Equine leptospirosis: Experimental challenge of Leptospira interrogans serovar Bratislava fails to establish infection in naïve horses

BACKGROUND

Little information is available about experimental inoculation of leptospirosis in horses and the pathogenicity of Leptospira interrogans serovar Bratislava in this host.

OBJECTIVES

To determine the serological, clinical, pathological and haematological responses of horses to L. interrogans serovar Bratislava strain PigK151.

STUDY DESIGN

Randomised controlled in vivo experiment.

METHODS

Ten seronegative female foals were divided into 2 groups, control (n = 4) and challenged (n = 6). The challenged group received 1 × 10⁹ leptospires divided equally between topical ocular and intraperitoneal injections. Blood and urine samples were analysed. The temperature was recorded daily for the first 9 days, then weekly. Sera were tested by microscopic agglutination test (MAT). Automated complete blood count, differential and chemistry panel were performed. Histopathological analysis was performed on sections of liver, kidney, urinary bladder, uterine body and pineal gland. Sample culturing was performed from blood, urine, liver, kidney, reproductive tract and vitreous humour.

RESULTS

No pyrexia was noted. PCR and culture were negative from all samples. Differences between groups were found in CBC, differential counts and serum biochemistry panel (or profile), suggesting that leptospiral challenge triggered an inflammatory response. No evidence of leptospirosis was found from histopathological analysis. All challenged foals developed a humoral response. The MAT allowed the confirmation of the infecting serovar at a later stage, but it also revealed cross-reactive results that were further explained by genomic analysis.

MAIN LIMITATIONS

This experimental challenge had two main limitations: (a) the results might have varied if another strain from the same serovar had been used and (b) the use of another route of infection and a higher bacterial dose might have achieved colonisation.

CONCLUSIONS

Based on these findings, it may suggest that L. interrogans serovar Bratislava is neither pathogenic nor host-adapted serovar for horses, although these results might have varied if another strain from the same serovar had been used instead.

Evaluation of new leptospiral antigens for the diagnosis of equine leptospirosis: An approach using pan-genomic analysis, reverse vaccinology and antigenic selection

BACKGROUND

The current gold standard diagnostic test for leptospirosis is the microscopic agglutination test (MAT), which has many drawbacks; therefore, the development of a better and easier serological test for leptospirosis is needed.

OBJECTIVES

To apply reverse vaccinology (RV) and antigenic selection on the assortment of leptospiral targets and evaluate their potential for use as reagents for the diagnosis of equine leptospirosis.

STUDY DESIGN

Cross-sectional study.

METHODS

The antigenic selection parameters were: proteins with antigenicity score ≥0.5 (VaxiJen), at least one B cell epitope and size between 10 and 275 KDa. New leptospiral proteins were cloned, expressed and serologically screened against equine sera (n = 128) on a single analysis and comparative combinations. Sensitivity (Se) and specificity (Sp), accuracy, positive predictive value (PPV) and negative predictive value (NPV) were calculated. A BLAST with nucleotide and protein sequences was used to identify the serovar or species specificity.

MAIN LIMITATIONS

This cross-sectional analysis had three main limitations: (a) The equine sera used in these tests were limited to sera submitted to the Animal Health Diagnosis Center and were only tested against seven serovars; (b) MAT results were considered being 'perfect', and the highest titre presented was considered being the infecting serovar, which may not hold true; (c) The strains used to represent the serovars and the limited number of different serovars and species included in the genetic analysis, which leads to the possibility that these proteins might be present in different species or serovars that perhaps would be seroprevalent in another geographic region.

CONCLUSIONS

The new leptospiral antigens described in this research could increase the sensitivity and specificity of ELISA for detection of Leptospira exposure and the detection of leptospirosis in horses along with support from other clinical signs. Some of these new antigens might be used to improve the detection of infecting serovar.

Molecular Detection and Typing of Pathogenic Leptospira in Febrile Patients and Phylogenetic Comparison with Leptospira Detected among Animals in Tanzania

Molecular data are required to improve our understanding of the epidemiology of leptospirosis in Africa and to identify sources of human infection. We applied molecular methods to identify the infecting Leptospira species and genotypes among patients hospitalized with fever in Tanzania and compared these with Leptospira genotypes detected among animals in Tanzania to infer potential sources of human infection. We performed lipL32 real-time PCR to detect the presence of pathogenic Leptospira in acute-phase plasma, serum, and urine samples obtained from study participants with serologically confirmed leptospirosis and participants who had died with febrile illness. Leptospira blood culture was also performed. In positive specimens, we performed species-specific PCR and compared participant Leptospira secY sequences with Leptospira reference sequences and sequences previously obtained from animals in Tanzania. We detected Leptospira DNA in four (3.6%) of 111 participant blood samples. We detected Leptospira borgpetersenii (one participant, 25.0%), Leptospira interrogans (one participant, 25.0%), and Leptospira kirschneri (one participant, 25.0%) (one [25%] undetermined). Phylogenetic comparison of secY sequence from the L. borgpetersenii and L. kirschneri genotypes detected from participants was closely related to but distinct from genotypes detected among local livestock species. Our results indicate that a diverse range of Leptospira species is causing human infection. Although our analysis suggests a close relationship between Leptospira genotypes found in people and livestock, continued efforts are needed to obtain more Leptospira genetic material from human leptospirosis cases to help prioritize Leptospira species and genotypes for control.

Update on molecular diagnosis of human leptospirosis

Background

Leptospirosis, caused by pathogenic Leptospira spp., is a widespread zoonotic disease worldwide. Early diagnosis is required for proper patient management and reducing leptospirosis morbidity and mortality.

Objective

To summarize current literature regarding commonly used and new promising molecular approaches to Leptospira detection and diagnostic tests of human leptospirosis.

Method

The relevant articles in Leptospira and leptospirosis were retrieved from MEDLINE (PubMed) and Scopus.

Results

Several molecular techniques have been developed for diagnosis of human leptospirosis. Polymerase chain reaction-based techniques targeting on either lipL32 or 16S rRNA (rrs) gene are most commonly used to detect leptospiral DNA in various clinical specimens. Whole blood and urine are recommended specimens for suspected cases in the first (acute) and the second (immune) phases, respectively. Isothermal amplification with less expensive instrument is an alternative DNA detection technique that may be suitable for resource-limited laboratories.

Conclusion

Detection of leptospiral DNA in clinical specimens using molecular techniques enhances sensitivity for diagnosis of leptospirosis. The efficient and robust molecular detection especially in the early leptospiremic phase may prompt early and appropriate treatment leading to reduced morbidity and mortality of patients with leptospirosis.

A Case of Fusobacterium necrophorum without Lemierre’s Syndrome Mimicking Acute Leptospirosis

Jaundice, conjunctival hyperemia, and acute kidney injury (AKI) are the characteristics of leptospirosis. However, it is not well known that Fusobacterium necrophorum infection can have a clinical picture similar to that of leptospirosis. A 38-year-old man was admitted with jaundice, conjunctival hyperemia, and AKI for 7 days. Chest CT scan showed multiple pulmonary nodules, atypical for leptospirosis. We started treatment with IV piperacillin-tazobactam and minocycline. He became anuric and was urgently started on hemodialysis on the second hospital day. Later on, blood cultures grew Fusobacterium necrophorum and other anaerobic bacteria. Antibody and PCR assays for Leptospira were negative. We narrowed the antibiotics to IV ceftriaxone and metronidazole. He responded well to the treatment and was discharged on the 18th hospital day. F. necrophorum infection is known to cause mixed infection with other anaerobic bacteria. The resistance of many anaerobic bacteria continues to progress, and F. necrophorum itself sometimes produces β-lactamase. This case highlights the potential risks of using penicillin before diagnosis of leptospirosis.

Development of multiplex PCR for neglected infectious diseases

Scrub typhus, murine typhus, and leptospirosis are widely neglected infectious diseases caused by Orientia tsutsugamushi, Rickettsia typhi, and pathogenic Leptospira spp., respectively. Patients usually present with non-specific symptoms and therefore are commonly diagnosed with acute undifferentiated febrile illness. Consequently, patients face delayed treatment and increased mortality. Antibody-based serological test currently used as gold standard has limitations due to insufficient antibody titers, especially in the early phase of infection. In this study, we aimed to develop multiplex PCR to combine 3 primer pairs that target specific genes encoding 56-kDa TSA of O. tsutsugamushi, 17-kDa antigen of R. typhi, and LipL32 of L. Interrogans and evaluate its performance in comparison to the standard serological tests. Using EDTA blood samples of known patients, the sensitivity and specificity of our multiplex PCR was 100% and 70%, respectively. In addition, the assay was able to diagnose the co-infection of scrub typhus and leptospirosis. The assay may be useful in identifying causative agents during the early phase of these diseases, enabling prompt and appropriate treatment.

Scrub typhus, murine typhus, and leptospirosis are diagnosed as acute undifferentiated febrile illness. Diagnostic tests for these diseases depend on antibody detection. However, antibody detection is still limited by its tendency to return negative results during the early phase of aforementioned diseases. In this study, a novel multiplex PCR has been developed for detecting Orientia tsutsugamushi, Rickettsia typhi, and Leptospira interrogans that are simultaneously amplified in a single tube. The results have shown that multiplex PCR could be used as a diagnostic tool for detecting bacteria during the early phase of scrub typhus, murine typhus, and leptospirosis, allowing for administration of appropriate treatment.

Risk Factors and Prediction of Leptospiral Seropositivity Among Dogs and Dog Handlers in Malaysia

This study determined the potential risk factors that may contribute to seropositivity among dogs and dog handlers from working dog and dog shelter institutions. Data was collected from dogs (n = 266) and dog handlers (n = 161) using a standardised guided questionnaire. Serum obtained from the dogs and dog handlers was tested using the microscopic agglutination test (MAT). A logistic regression analysis was used to predict leptospiral seropositivity of dogs and dog handlers based on potential risk factors. A total of 22.2% of dogs and 21.7% of dog handlers were seropositive. The significant predictors for the dogs' seropositivity were presence of rats (OR = 4.61 (95% CI: 1.05, 20.33), p = 0.043) and shared common area (OR = 5.12 (95% CI: 1.94, 13.46), p = 0.001) within the organisation. Significant predictor for dog handler seropositivity was contact time with the dogs of more than six hours/day (OR = 3.28 (95% CI: 1.28, 8.40), p = 0.013) after controlling for the effect of other risk factors such as small mammal contact, rat infestation at home, flooding at housing area (within three months) and urban locality. The exposure to various disease sources identified poses risk to dogs and dog handlers. Risk could be reduced with adequate application of protection at work while handling dogs and thus limiting contact with these sources and reducing exposure to infection.

Spatial epidemiological approaches to inform leptospirosis surveillance and control: A systematic review and critical appraisal of methods

Leptospirosis is a global zoonotic disease that the transmission is driven by complex geographical and temporal variation in demographics, animal hosts and socioecological factors. This results in complex challenges for the identification of high-risk areas. Spatial and temporal epidemiological tools could be used to support leptospirosis control programs, but the adequacy of its application has not been evaluated. We searched literature in six databases including PubMed, Web of Science, EMBASE, Scopus, SciELO and Zoological Record to systematically review and critically assess the use of spatial and temporal analytical tools for leptospirosis and to provide general framework for its application in future studies. We reviewed 115 articles published between 1930 and October 2018 from 41 different countries. Of these, 65 (56.52%) articles were on human leptospirosis, 39 (33.91%) on animal leptospirosis and 11 (9.5%) used data from both human and animal leptospirosis. Spatial analytical (n = 106) tools were used to describe the distribution of incidence/prevalence at various geographical scales (96.5%) and to explored spatial patterns to detect clustering and hot spots (33%). A total of 51 studies modelled the relationships of various variables on the risk of human (n = 31), animal (n = 17) and both human and animal infection (n = 3). Among those modelling studies, few studies had generated spatially structured models and predictive maps of human (n = 2/31) and animal leptospirosis (n = 1/17). In addition, nine studies applied time-series analytical tools to predict leptospirosis incidence. Spatial and temporal analytical tools have been greatly utilized to improve our understanding on leptospirosis epidemiology. Yet the quality of the epidemiological data, the selection of covariates and spatial analytical techniques should be carefully considered in future studies to improve usefulness of evidence as tools to support leptospirosis control. A general framework for the application of spatial analytical tools for leptospirosis was proposed.

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.

Risk factors for human acute leptospirosis in northern Tanzania

INTRODUCTION

Leptospirosis is a major cause of febrile illness in Africa but little is known about risk factors for human infection. We conducted a cross-sectional study to investigate risk factors for acute leptospirosis and Leptospira seropositivity among patients with fever attending referral hospitals in northern Tanzania.

METHODS

We enrolled patients with fever from two referral hospitals in Moshi, Tanzania, 2012-2014, and performed Leptospira microscopic agglutination testing on acute and convalescent serum. Cases of acute leptospirosis were participants with a four-fold rise in antibody titers, or a single reciprocal titer ≥800. Seropositive participants required a single titer ≥100, and controls had titers <100 in both acute and convalescent samples. We administered a questionnaire to assess risk behaviors over the preceding 30 days. We created cumulative scales of exposure to livestock urine, rodents, and surface water, and calculated odds ratios (OR) for individual behaviors and for cumulative exposure variables.

RESULTS

We identified 24 acute cases, 252 seropositive participants, and 592 controls. Rice farming (OR 14.6), cleaning cattle waste (OR 4.3), feeding cattle (OR 3.9), farm work (OR 3.3), and an increasing cattle urine exposure score (OR 1.2 per point) were associated with acute leptospirosis.

CONCLUSIONS

In our population, exposure to cattle and rice farming were risk factors for acute leptospirosis. Although further data is needed, these results suggest that cattle may be an important source of human leptospirosis. Further investigation is needed to explore the potential for control of livestock Leptospira infection to reduce human disease.

A systematic review of human and animal leptospirosis in the Pacific Islands reveals pathogen and reservoir diversity

BACKGROUND

The Pacific Islands have environmental conditions highly favourable for transmission of leptospirosis, a neglected zoonosis with highest incidence in the tropics, and Oceania in particular. Recent reports confirm the emergence and outbreaks of leptospirosis in the Pacific Islands, but the epidemiology and drivers of transmission of human and animal leptospirosis are poorly documented, especially in the more isolated and less developed islands.

METHODOLOGY/PRINCIPAL FINDINGS

We conducted a systematic review of human and animal leptospirosis within 25 Pacific Islands (PIs) in Polynesia, Melanesia, Micronesia, as well as Easter Island and Hawaii. We performed a literature search using four international databases for articles published between January 1947 and June 2017. We further included grey literature available on the internet. We identified 148 studies describing leptospirosis epidemiology, but the number of studies varied significantly between PIs. No data were available from four PIs. Human leptospirosis has been reported from 13 PIs, with 63% of all studies conducted in Hawaii, French Polynesia and New Caledonia. Animal leptospirosis has been investigated in 19 PIs and from 14 host species, mainly pigs (18% of studies), cattle (16%) and dogs (11%). Only 13 studies provided information on both human and animal leptospirosis from the same location. Serology results were highly diverse in the region, both in humans and animals.

CONCLUSIONS/SIGNIFICANCE

Our study suggests that, as in other tropical regions, leptospirosis is widespread in the PIs while showing some epidemiological heterogeneity. Data are scarce or absent from many PIs. Rodents, cattle, pigs and dogs are all likely to be important carriers, but the relative importance of each animal species in human infection needs to be clarified. Epidemiological surveys with appropriate sampling design, pathogen typing and data analysis are needed to improve our understanding of transmission patterns and to develop effective intervention strategies.

Thai-Lepto-on-admission probability (THAI-LEPTO) score as an early tool for initial diagnosis of leptospirosis: Result from Thai-Lepto AKI study group

Background

Leptospirosis is one of the most important zoonosis in the tropics. Currently, specific laboratory diagnostic test for leptospirosis such as polymerase chain reaction (PCR) or direct culture cannot be applied at the primary care setting especially in the resource- limited countries. Therefore, clinical presentation and laboratory examination are still the primary diagnostic tools for leptospirosis.

Objectives

To detect clinical factors for predicting leptospirosis in suspected cases, and to create a clinical prediction score (THAI-LEPTO) that is practical and easy to use in general practice while awaiting laboratory results.

Materials and methods

We performed a prospective multicenter study with a development and a validation cohort of patients presenting with clinical suspicion of leptospirosis as per the WHO clinical criteria. The development cohort was conducted at 11 centers in 8 provinces around Thailand. The validation cohort was conducted at 4 centers in 1 province from the Northeastern part of Thailand. Leptospirosis confirmed cases were defined if any one of the tests were positive: microscopic agglutination test, direct culture, or PCR technique. Multivariable logistic regression was used to identify predictors of leptospirosis. The clinical prediction score was derived from the regression coefficients (original) or from the odds ratio values (simplified). We used receiver operating characteristic (ROC) curve analysis to evaluate the diagnostic ability of our score and to find the optimal cutoff values of the score. We used a validation cohort to evaluate the accuracy of our methods.

Results

In the development cohort, we enrolled 221 leptospirosis suspected cases and analyzed 211. Among those, 105 (50%) were leptospirosis confirmed cases. In logistic regression adjusted for age, gender, day of fever, and one clinical factor at a time, leptospirosis group had more hypotension OR = 2.76 (95% CI 1.07–7.10), jaundice OR = 3.40 (95%CI 1.48–8.44), muscle pain OR = 2.12 (95%CI 1.06–4.26), acute kidney injury (AKI) OR = 2.90 (95%CI 1.31–6.15), low hemoglobin OR = 3.48 (95%CI 1.72–7.04), and hypokalemia with hyponatremia OR = 3.56 (95%CI 1.17–10.84) than non-leptospirosis group. The abovementioned factors along with neutrophilia and pulmonary opacity were used in the development of the score. The simplified score with 7 variables was the summation of the odds ratio values as follows: hypotension 3, jaundice 2, muscle pain 2, AKI 1.5, low hemoglobin 3, hypokalemia with hyponatremia 3, and neutrophilia 1. The score showed the highest discriminatory power with area under the curve (AUC) 0.82 (95%CI 0.67–0.97) on fever day 3–4. In the validation cohort we enrolled 96 leptospirosis suspected cases and analyzed 92. Of those, 69 (75%) were leptospirosis confirmed cases. The performance of the simplified score with 7 variables at a cutoff of 4 was AUC 0.78 (95%CI 0.68–0.89); sensitivity 73.5; specificity 73.7; positive predictive value 87.8; negative predictive value 58.3.

Conclusions

THAI-LEPTO score is a newly developed diagnostic tool for early presumptive diagnosis of leptospirosis in patients presenting with severe clinical suspicion of the disease. The score can easily be applied at the point of care while awaiting confirmatory laboratory results. Each predictor used has been supported by evidence of clinical and pathophysiological correlation.

Leptospirosis is an important zoonosis in the tropics. However, there is still a major barrier of early diagnosis of leptospirosis due to a lack of specific and sensitive testing. Moreover, in resource-limited countries with small budgets, a simple and cheap diagnostic test is essential for the diagnosis of leptospirosis. The THAI-LEPTO score has been developed and validated based on the relevant clinical history and related laboratory test. This score will help the physician in early diagnosis and prompt treatment leptospirosis as a point of care test. Finally, we aim that this scoring system can be one of the key parts of diagnostic algorithm and improve leptospirosis patients’ outcome.

Immunodominance of LipL3293-272 peptides revealed by leptospirosis sera and therapeutic monoclonal antibodies

BACKGROUND/PURPOSE

Leptospirosis is a neglected zoonosis, imposing significant human and veterinary public health burdens. In this study, recombinant LipL32_93-147 and LipL32_148-184 middle domain of LipL32_93-184, and LipL32_171-214, and LipL32_215-272 of c-terminal LipL32_171-272 truncations were defined for immunodominance of the molecule during Leptospira infections revealed by leptospirosis sera.

RESULTS

IgM-dominant was directed to highly surface accessible LipL32_148-184 and Lipl32_171-214. IgG dominance of LipL32_148-184 revealed by rabbit anti-Leptospira sera and convalescent leptospirosis paired sera were mapped to highly accessible surface of middle LipL32_148-184 truncation whereas two LipL32_148-184 and LipL32_215-272 truncations were IgG-dominant when revealed by single leptospirosis sera. The IgM-dominant of LipL32_148-214 and IgG-dominant LipL32_148-184 peptides have highly conserved amino acids of 70% identity among pathogenic and intermediate Leptospira species and were mapped to the highly surface accessible area of LipL32 molecule that mediated interaction of host components. IgG dominance of two therapeutic epitopes located at LipL32_243-253 and LipL32_122-130 of mAbLPF1 and mAbLPF2, respectively has been shown less IgG-dominant (<30%), located outside IgG-dominant regions characterized by leptospirosis paired sera.

CONCLUSION

The IgM- and IgG-dominant LipL32 could be further perspectives for immunodominant LipL32-based serodiagnosis and LipL32 epitope-based vaccine.

Epidemiological and clinical features of leptospirosis in a highly endemic area over three time periods

OBJECTIVES

To present the features of human leptospirosis over three time periods (1970-1975; 2000-2005; 2010-2015), to compare the collected data and to determine whether the incidence, seasonal and spatial distribution, prevalence of presumptive infective serogroups and clinical features have changed over the last 50 years.

METHODS

Epidemiological and clinical data obtained from patients hospitalised and treated in a well-known endemic focus of leptospirosis, Koprivnica-Križevci County in Croatia, were analysed.

RESULTS

We observed a steady decline in the overall incidence of leptospirosis and a change in the patient age distribution, with the age ratio changing in favour of middle-aged and older patients. Although leptospirosis was most frequently diagnosed in August in all time periods, the number of cases increased in autumn. The most prevalent serogroup during the first and the second time period was Icterohaemorrhagiae, while in the third time period, the serogroup Australis prevailed. We also noted an increase in the number of severe clinical manifestations.

CONCLUSIONS

This retrospective research demonstrates a continuous decline in the incidence of human leptospirosis in Croatia. The pattern of disease has changed from predominantly mild clinical forms observed in children to more severe clinical forms observed in middle-aged to older patients, especially those working in agriculture. Additional epidemiological changes included an increase in the number of cases during the autumn months and changes in prevailing serogroups. Statistical analysis revealed a significant relationship between the severity of the clinical picture, patient age and presumed sources of infection.

Rapid, actionable diagnosis of urban epidemic leptospirosis using a pathogenic Leptospira lipL32-based real-time PCR assay

Background

With a conservatively estimated 1 million cases of leptospirosis worldwide and a 5–10% fatality rate, the rapid diagnosis of leptospirosis leading to effective clinical and public health decision making is of high importance, and yet remains a challenge.

Methodology

Based on parallel, population-based studies in two leptospirosis-endemic regions in Brazil, a real-time PCR assay which detects lipL32, a gene specifically present in pathogenic Leptospira, was assessed for the diagnostic effectiveness and accuracy. Patients identified by active hospital-based surveillance in Salvador and Curitiba during large urban leptospirosis epidemics were tested. Real-time PCR reactions were performed with DNA-extracted samples obtained from 127 confirmed and 23 unconfirmed cases suspected of leptospirosis, 122 patients with an acute febrile illness other than leptospirosis, and 60 healthy blood donors.

Principal findings

The PCR assay had a limit of detection of 280 Leptospira genomic equivalents/mL. Sensitivity for confirmed cases was 61% for whole blood and 29% for serum samples. Sensitivity was higher (86%) for samples collected within the first 6 days after onset of illness compared to those collected after 7 days (34%). The real-time PCR assay was able to detect leptospiral DNA in blood from 56% of serological non-confirmed cases. The overall specificity of the assay was 99%.

Conclusions

These findings indicate that real-time PCR may be a reliable tool for early diagnosis of leptospirosis, which is decisive for clinical management of severe and life-threatening cases and for public health decision making.

In this study, we describe the performance testing and diagnostic accuracy assessment of a previously described real-time PCR assay aiming at the validation for early diagnosis of human leptospirosis. We found that diagnostic sensitivity was higher for EDTA whole blood samples (61%) than for serum samples (29%). We demonstrated that the molecular diagnosis was optimal when performed with EDTA whole samples collected within the first 6 days with symptoms, condition in which the sensitivity was 86%. The real-time PCR assay was able to detect leptospiral DNA in EDTA whole blood from 56% of serological non-confirmed cases for whom a convalescent sample was not available. The test overall specificity was 99%. Our findings demonstrate that real-time PCR is a reliable diagnostic tool suited for early diagnosis, and its results could support early medical interventions that could have a decisive impact on clinical outcome and thus decrease both the severity and fatality of cases.

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.

A patient who made an impact on how I practice: Severe leptospirosis presenting as ARDS in the ICU

Severe leptospirosis can be a rare cause of acute respiratory distress syndrome (ARDS) and multiorgan failure. A patient who made an impact on how I practice was a case of severe leptospirosis (Weil's disease) that presented as ARDS in the ICU. Leptospirosis is an under-reported infectious disease worldwide and should be considered as a cause of ARDS especially in patients with exposure history complicated with diffuse alveolar bleeding (DAH), icteric hepatitis and renal deterioration. Empiric treatment should be recommended before confirmation of laboratory tests as serological diagnosis is time consuming.

Utility of Loop-mediated Isothermal Amplification Assay, Polymerase Chain Reaction, and ELISA for Diagnosis of Leptospirosis in South Indian Patients

BACKGROUND

Leptospirosis is a zoonotic disease which requires laboratory diagnosis for confirmation.

MATERIALS AND METHODS

In this study serum samples from adults with acute undifferentiated fever (duration ≤15 days) were tested for IgM antibodies to Leptospira by ELISA, PCR for rrs gene and loop-mediated isothermal amplification (LAMP) assay for LipL32 and LipL41.

RESULTS

Among the 150 sera tested, three were positive by PCR, LAMP and IgM ELISA/modified Faines' criteria, two by only PCR; seven only by LAMP assay and forty fulfilled modified Faine's criteria (illness clinically compatible and IgM ELISA positive for leptospirosis). Clinical correlation revealed renal compromise, low platelet count and severe jaundice were significantly related to leptospirosis (P < 0.05).

CONCLUSION

This study suggests that LAMP assay could be useful for diagnosis of leptospirosis during the 1^st week of illness whereas IgM ELISA forms the mainstay of diagnosis from the 2^nd week onward. Further studies especially community based, comparing ELISA, PCR, LAMP, culture and microscopic agglutination test are required to evaluate the veracity of these findings.

Comparison of the Estimated Incidence of Acute Leptospirosis in the Kilimanjaro Region of Tanzania between 2007-08 and 2012-14

Background

The sole report of annual leptospirosis incidence in continental Africa of 75–102 cases per 100,000 population is from a study performed in August 2007 through September 2008 in the Kilimanjaro Region of Tanzania. To evaluate the stability of this estimate over time, we estimated the incidence of acute leptospirosis in Kilimanjaro Region, northern Tanzania for the time period 2012–2014.

Methodology and Principal Findings

Leptospirosis cases were identified among febrile patients at two sentinel hospitals in the Kilimanjaro Region. Leptospirosis was diagnosed by serum microscopic agglutination testing using a panel of 20 Leptospira serovars belonging to 17 separate serogroups. Serum was taken at enrolment and patients were asked to return 4–6 weeks later to provide convalescent serum. Confirmed cases required a 4-fold rise in titre and probable cases required a single titre of ≥800. Findings from a healthcare utilisation survey were used to estimate multipliers to adjust for cases not seen at sentinel hospitals. We identified 19 (1.7%) confirmed or probable cases among 1,115 patients who presented with a febrile illness. Of cases, the predominant reactive serogroups were Australis 8 (42.1%), Sejroe 3 (15.8%), Grippotyphosa 2 (10.5%), Icterohaemorrhagiae 2 (10.5%), Pyrogenes 2 (10.5%), Djasiman 1 (5.3%), Tarassovi 1 (5.3%). We estimated that the annual incidence of leptospirosis was 11–18 cases per 100,000 population. This was a significantly lower incidence than 2007–08 (p<0.001).

Conclusions

We estimated a much lower incidence of acute leptospirosis than previously, with a notable absence of cases due to the previously predominant serogroup Mini. Our findings indicate a dynamic epidemiology of leptospirosis in this area and highlight the value of multi-year surveillance to understand leptospirosis epidemiology.

Leptospirosis is an infectious disease that causes a fever. It can be severe or fatal. Understanding how many people get leptospirosis helps to determine priorities in allocating resources for disease diagnosis, treatment, and prevention. There are few data about leptospirosis incidence in sub-Saharan African countries. The only mainland estimate is from northern Tanzania for the years 2007–08. To see if leptospirosis incidence had changed since 2007–08, we measured leptospirosis incidence in the same location in 2012–2014. To do this, we systematically approached people at two hospitals in the Kilimanjaro Region and tested them for leptospirosis. We adjusted the number of identified cases of leptospirosis found at the hospitals to account for people with fever who did not come to hospital for testing and care. We also adjusted for imperfect testing methods. We found that the number of people who developed leptospirosis annually had dropped from 75–102 cases per 100,000 people during 2007–08 to 11–18 cases per 100,000 people during 2012–14. Also, the subtype of leptospirosis responsible for the most cases during 2007–08 was not present during 2012–14. The number of people developing leptospirosis was not stable, highlighting the value of measuring how commonly leptospirosis occurs over several years.

Leptospirosis: A clinical review of evidence based diagnosis, treatment and prevention

Leptospirosis is a zoonotic disease with worldwide distribution and increasing prevalence. Infection is caused by the spirochete Leptospira, with common exposure being contaminated fresh water. Most infections are asymptomatic, but symptoms range from a mild, self-limiting, non-specific febrile illness to fulminant respiratory and renal failure with a high mortality rate. The combination of jaundice, renal failure, and hemorrhage is known as Weil’s disease and is the most characteristic pattern associated with severe leptospirosis. Clinical suspicion alone may be enough to warrant empiric antibiotic treatment in many cases. Serological methods are the most commonly used means of confirming a diagnosis of leptospirosis. The “gold standard” is the microscopic agglutination test. Typical treatment for mild causes is oral doxycycline, though azithromycin and oral penicillins are reasonable alternatives. Intravenous penicillin G has long been the standard of care for severe cases though limited studies show no benefit compared to third generation cephalosporins. We review the clinical presentation, diagnosis, treatment and prevention of leptospirosis.

Leptospirosis Presenting with Rapidly Progressing Acute Renal Failure and Conjugated Hyperbilirubinemia: A Case Report

Patient: Male, 53

Final Diagnosis: Leptospirosis

Symptoms: —

Medication: —

Clinical Procedure: None

Specialty: Infectious Diseases

Leptospira and leptospirosis in China

PURPOSE OF REVIEW

In this review, we introduce the epidemiological features, clinical types, laboratory diagnosis, and routine surveillance of leptospirosis in China.

RECENT FINDINGS

Leptospirosis has been prevalent sporadically in China in recent years, but its incidence has decreased, probably due to the lower leptospire-carrying rate in pigs. Leptospira interrogans serogroup Icterohaemorrhagiae serovar Lai is the most common pathogen in Chinese leptospirosis patients and Apodemus agrarius is its major animal host. At least 75% of Chinese leptospirosis patients suffer from the mild influenza-like type of leptospirosis that is caused by any serovars of L. interrogans. However, leptospirosis patients with the pulmonary diffuse hemorrhagic type have a high mortality (40-60%). L. interrogans serovar Lai is the causative agent in 75% of the pulmonary diffuse hemorrhagic leptospirosis patients. Several outer membrane protein antigens exist in all the L. interrogans serovars prevailing in China and predominant T- and B-cell combined epitopes in the outer membrane protein antigens have been identified that can be used for developing novel universal leptospirosis vaccines.

SUMMARY

Leptospirosis cases in the Chinese population have gradually decreased in recent years, but it is still an important zoonotic infectious disease. The development of universal vaccines is critical for the prevention and control of leptospirosis.

Neglected bacterial zoonoses

Bacterial zoonoses comprise a group of diseases in humans or animals acquired by direct contact with or by oral consumption of contaminated animal materials, or via arthropod vectors. Among neglected infections, bacterial zoonoses are among the most neglected given emerging data on incidence and prevalence as causes of acute febrile illness, even in areas where recognized neglected tropical diseases occur frequently. Although many other bacterial infections could also be considered in this neglected category, five distinct infections stand out because they are globally distributed, are acute febrile diseases, have high rates of morbidity and case fatality, and are reported as commonly as malaria, typhoid or dengue virus infections in carefully designed studies in which broad-spectrum diagnoses are actively sought. This review will focus attention on leptospirosis, relapsing fever borreliosis and rickettsioses, including scrub typhus, murine typhus and spotted fever group rickettsiosis. Of greatest interest is the lack of distinguishing clinical features among these infections when in humans, which confounds diagnosis where laboratory confirmation is lacking, and in regions where clinical diagnosis is often attributed to one of several perceived more common threats. As diseases such as malaria come under improved control, the real impact of these common and under-recognized infections will become evident, as will the requirement for the strategies and allocation of resources for their control.

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.

Recombinant antigens rLipL21, rLoa22, rLipL32 and rLigACon4-8 for serological diagnosis of leptospirosis by enzyme-linked immunosorbent assays in dogs

Animal leptospirosis is one of the most common zoonotic diseases in the United States and around the world. In a previous study, we applied four recombinant antigens, rLipL21, rLoa22, rLipL32 and rLigACon4-8 of Leptospira interrogans (L. interrogans) for the serological diagnosis of equine leptospirosis (Ye et al, Serodiagnosis of equine leptospirosis by ELISA using four recombinant protein markers, Clin. Vaccine. Immunol. 21:478–483). In this study, the same four recombinant antigens were evaluated for their potential to diagnose canine leptospirosis by ELISA. A total of 305 canine sera that were Leptospira microscopic agglutination test (MAT)-negative (n = 102) and MAT-positive (n = 203) to 5 serovars (Pomona, Grippotyphosa, Icterohaemorrhagiae, Canicola and Hardjo) were tested. When individual recombinant antigens were used, the sensitivity and specificity of ELISA were 97.5% and 84.3% for rLigACon4-8; 89.7% and 81.4% for rLoa22; 92.6% and 84.3% for rLipL32 and 99.5% and 84.3% for rLipL21, respectively compared to the MAT. The sensitivity and specificity of ELISA were, 92.6% and 91.2% for rLigACon4-8 and rLipL32, 97.5% and 84.3% for rLigACon4-8 and rLipL21, 89.7% and 87.3% for rLigACon4-8 and rLoa22, 89.7% and 87.3% to rLipL21 and rLoa22, 92.6% and 91.2% for rLipL21 and rLipL32 and 89.2% and 94.1% for rLoa22 and rLipL32 when one of the two antigens was test positive. The use of all four antigens in the ELISA assay was found to be sensitive and specific, easy to perform, and agreed with the results of the standard Leptospira Microscopic Agglutination test (MAT) for the diagnosis of canine leptospirosis.

Development of a real-time PCR for the detection of pathogenic Leptospira spp. in California sea lions

Several real-time PCR assays are currently used for detection of pathogenic Leptospira spp.; however, few methods have been described for the successful evaluation of clinical urine samples. This study reports a rapid assay for the detection of pathogenic Leptospira spp. in California sea lions Zalophus californianus using real-time PCR with primers and a probe targeting the lipL32 gene. The PCR assay had high analytic sensitivity-the limit of detection was 3 genome copies per PCR volume using L. interrogans serovar Pomona DNA and 100% analytic specificity; it detected all pathogenic leptospiral serovars tested and none of the non-pathogenic Leptospira species (L. biflexa and L. meyeri serovar Semaranga), the intermediate species L. inadai, or the non-Leptospira pathogens tested. Our assay had an amplification efficiency of 1.00. Comparisons between the real-time PCR assay and culture isolation for detection of pathogenic Leptospira spp. in urine and kidney tissue samples from California sea lions showed that samples were more often positive by real-time PCR than by culture methods. Inclusion of an internal amplification control in the real-time PCR assay showed no inhibitory effects in PCR negative samples. These studies indicated that our real-time PCR assay has high analytic sensitivity and specificity for the rapid detection of pathogenic Leptospira species in urine and kidney tissue samples.

Serodiagnosis of equine leptospirosis by enzyme-linked immunosorbent assay using four recombinant protein markers

Leptospirosis, caused by Leptospira spp., is one of the most common zoonotic diseases in the world. We tested four recombinant proteins of Leptospira interrogans, namely, rLipL21, rLoa22, rLipL32, and rLigACon4-8, to evaluate their potential for use as antigens for the diagnosis of equine leptospirosis. We employed equine sera (n = 130) that were microscopic agglutination test (MAT) negative and sera (n = 176) that were MAT positive for the 5 serovars that most commonly cause equine leptospirosis. The sensitivity and specificity of ELISA compared to MAT were 82.39% and 86.15%, respectively, for LigACon4-8, 77.84% and 92.31%, respectively, for Loa22, 77.84% and 86.15%, respectively, for LipL32, and 84.66% and 83.85%, respectively, for LipL21. When one of the two antigens was test positive, the sensitivity and specificity of ELISA were 93.75% and 78.46%, respectively, for rLigACon4-8 and LipL32, 93.18% and 76.15%, respectively, for rLigACon4-8 and LipL21, 89.77% and 80.77%, respectively, for rLigACon4-8 and Loa22, 91.48% and 78.46%, respectively, for LipL21 and Loa22, 93.75% and 76.92%, respectively, for LipL21 and LipL32, and 90.34% and 80.77%, respectively, for Loa22 and LipL32. In conclusion, we have developed an indirect ELISA utilizing rLigACon4-8, rLoa22, rLipL32, and rLipL21 as diagnostic antigens for equine leptospirosis. The use of four antigens in the ELISA was found to be sensitive and specific, the assay was easy to perform, and the results concurred with the results of the standard Leptospira MAT.

A comparative study on microscopic agglutination test and counterimmunoelectrop- horesis for early detection of human leptospirosis

BACKGROUND AND OBJECTIVES

Leptospirosis is a potentially fatal bacterial disease that mimics many diseases; therefore, laboratory confirmation is pivotal. Though microscopic agglutination test (MAT) is accepted as World Health Organisation (WHO) reference test, it has got many pitfalls such as being hazardous, tedious, cumbersome and expensive. Counterimmunoelectrophoresis (CIE) is popularly used for diagnosing many infectious diseases but rarely for Leptospirosis. The aim of this study is to find suitability of CIE for the routine laboratory diagnostic purposes.

MATERIALS AND METHODS

Repeat sampling (paired sera) was possible from 401 subjects of which 181 were in-patients of Salem Government General and Private Hospitals and the remaining 220 MAT negative healthy College students gave their consent for the study. All the 802 sera samples were collected from January 2009 to November 2012 and subjected to the present study. After carrying out MAT and CIE on the suspected and control samples, a comparative evaluation was conducted. McNemars test method was used to find out the significant difference between the two tests in the early diagnosis.

RESULT

The sensitivity, specificity, Positive Predictive value (PPV), Negative Predictive value (NPV) and Efficiency test for CIE were 96.80%, 89.28%, 95.23%, 92.59% and 94.47%, respectively. The corresponding values for MAT were 95.90%, 89.83%, 95.08%, 91.37% and 93.92%, respectively. There was no significant difference between MAT and CIE at 95% and 99% confidence intervals according to McNemars test. P value in the early stage of illness was greater for CIE than MAT when Polymerase Chain Reaction (PCR) was used as Gold Standard of diagnosis.

INTERPRETATION AND CONCLUSION

It was concluded that the CIE could be advantageous over MAT due to its safety, rapidity, simplicity, economic and easy for large number of samples. It can answer little earlier than MAT and found as reliable as that of MAT. Since both the tests had shown similar efficacies in the later stage of the illness, the importance could be given to CIE due to early diagnosis.