An evaluation of dark field microscopy, culture and commercial serological kits in the diagnosis of leptospirosis

Leptospirosis in India: insights on circulating serovars, research lacunae and proposed strategies to control through one health approach

Leptospirosis is one of the most neglected zoonotic infections of public health concern worldwide and a remerging infection in tropical countries such as India. The infection least explored disease and the epidemiological and other critical data are scarce for the disease rate reported and to control the infection. Leptospirosis as sapronosis is as underrated as the infection itself, and this article aims to explore the significance of this aspect of the disease. The research review aimed at the epidemiological understanding of the infection to control the negative impact of the disease. A mixed review and analysis were carried out to understand the knowledge published on the critical and understudied areas like epidemiology, transmission, diagnosis, treatment, and control of infection. A systematic analysis was carried out to extract information about the reported circulating strains, and research lacunae in India with the published data available in PubMed. The article elaborately discusses crucial inference areas of infection transmission and addresses lacunae in critically unacclaimed areas of infection to control the spread of infection using one health approach (OHA), and strategies to control leptospiral infection are proposed. The article also reviewed how and why Leptospirosis can be best studied and controlled by "One health approach" in India.

Enhancing leptospirosis control with nanosensing technology: A critical analysis

Leptospirosis is a serious health problem in tropical areas; thus, animals shed leptospires in the environment. Humans are accidental hosts infected through exposure to contaminating bacteria in the environment. One health strategy can be applied to protect and eliminate leptospirosis because this cooperates and coordinates activities between doctors, veterinarians, and ecologists. However, conventional methods still have limitations. Therefore, the main challenges of leptospirosis control are the high sensing of detection methods to screen and control the pathogens. Interestingly, nano sensing combined with a leptospirosis detection approach can increase the sensitivity and eliminate some limitations. This article reviews nanomaterial development for an advanced leptospirosis detection method, e.g., latex beads-based agglutination test, magnetic nanoparticles enrichment, and gold-nanoparticles-based immunochromatographic assay. Thus, nanomaterials can be functionalized with biomolecules or sensing molecules utilized in various mechanisms such as biosensors. Over the last decade, many biosensors have been developed for Leptospira spp. pathogen and others. The evolution of biosensors for leptospirosis detection was designed for high efficiency and might be an alternative tool. In addition, the high-sensing fabrications are useful for leptospires screening in very low levels, for example, soil or water from the environment.

A clinical pilot study for the detection of sphingomyelinase in leptospirosis patient's urine at tertiary care hospital

Purpose

Leptospirosis is a perplexing mystification for many clinicians. Clinically often underdiagnosed due to lack of a rapid, sensitive, and specific diagnostic test. Currently available diagnostic tests have their own limitations; therefore, monitoring biomarkers that contribute an essential role in pathogenesis is crucial. Herein, a pilot study was conducted to detect the presence of sphingomyelinase in urine of leptospirosis patients.

Methods

Blood and urine samples were collected from 140 patients having febrile illness. Samples were analyzed through culturing, dark-field microscopy, detecting anti-leptospiral antibodies by MAT, IgM ELISA, Leptocheck-WB and screening for sphingomyelinase using a sphingomyelinase assay kit.

Results

Out of 140 febrile illness patients, 22.14 % were tested leptospirosis, 33.57 % were dengue, 25 % scrub typhus, 18.57 % malaria and 0.71 % co-infection (dengue-leptospirosis). MAT seropositivity of 19.28 % (27/140) was confirmed with the highest agglutinant determined against serovar Icterohaemorrhagiae RGA followed by Autumnalis, Australis, and Pyrogens. IgM ELISA and Leptocheck-WB positivity was 16.42 % and 13.57 % respectively. Whereas culture and dark-field microscopy showed a sensitivity of 4.28 % and 2.1 %, respectively. Out of 31 confirmed cases of leptospirosis, sphingomyelinase was detected in the urine of 25 (80.64 %) patients, MAT positivity was seen in 87.09 % and culture positivity was seen in 12.90 % of cases.

Conclusion

Detection of sphingomyelinase in the urine of a leptospirosis patient and its absence in other febrile illnesses like dengue, malaria and scrub typhus establish evidence of secretion of sphingomyelinase in urine during leptospiral infection. Hence, sphingomyelinase could be used as a potential diagnostic biomarker to detect leptospirosis in a non-invasive way.

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.

Resistance-Based Lateral Flow Immunosensor with a NFC-Enabled Smartphone for Rapid Diagnosis of Leptospirosis in Clinical Samples

Leptospirosis is one of the most life-threatening tropical diseases caused by pathogenic Leptospira. To date, a diagnostic device that offers rapid and sensitive detection of leptospires has been still in demand for proper treatment to reduce the mortality rate. Herein, we create a resistance-based lateral flow immunosensor diagnosis device (R-LFI) that integrates near-field communication (NFC) with a portable smartphone for leptospiral detection in clinical samples. A specific monoclonal antibody against the pathogen was coated on a nitrocellulose membrane (NCM) where the test line was collocated. Two electrodes with a sandwich-like configuration were installed employing a conductive double-sided adhesive tape and connected with a NFC smartphone-based detection system. A half-sandwich immunocomplex formation induced high proton conduction, resulting in a considerable decrement in resistive response. The performance of the R-LFI sensor was evaluated using recombinant LipL32 (rLipL32), Leptospira interrogans, and clinical samples. The R-LFI device exhibited linear responses toward rLipL32 protein in phosphate buffer and L. interrogans-spiked healthy human serum samples within the concentration ranging from 1 to 1000 ng mL^-1 (limit of detection (LOD): 0.29 ng mL^-1) and from 10⁴ to 10⁶ cell mL^-1 (LOD: 4.89 × 10³ cell mL^-1), respectively. Our R-LFI sensor successfully detected L. interrogans-positive clinical samples as confirmed by polymerase chain reaction (PCR). This platform offers high specificity, selectivity, simplicity, miniscule sample volume, and no labeling element requirement. These desirable features make it particularly suitable for countries where medical facilities and resources are limited.

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.

Rapid diagnostic test (Leptocheck-WB) for detection of acute leptospirosis: a meta-analysis of diagnostic accuracy

The majority of leptospirosis is subclinical or mild self-limiting systemic illness. A rapid and accurate diagnostic test for the detection of leptospirosis is essential to prevent disease progression from acute non-severe illness to potentially fatal infection. Rapid diagnostic tests (RDTs) recognized as point-of-care (PoC) tests may support clinical decision-making in resource-poor settings. We aimed to assess the accuracy of PoC (Leptocheck-WB) for the detection of acute leptospirosis by meta-analysis of data from eligible studies. This study adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis for Diagnostic Test Accuracy (PRISMA-DTA) guideline. The pooling of data was done only when there were two or more studies that used a particular type of reference test. A total of ten studies (n = 5369) were identified. The majority (70%) were from the Asian region. Using microscopic agglutination test (MAT) as reference test, the pooled sensitivity (0.75, 95% CI: 0.64 to 0.84, 10 studies, I²: 85.9%) and specificity (0.87, 95% CI: 0.77 to 0.94, 10 studies, I²: 97.37%) of Leptocheck-WB in the detection of leptospirosis were moderate. With the use of enzyme-linked immunosorbent assay (ELISA) reference test, the pooled sensitivity 0.85 (95% CI: 0.79 to 0.9, 4 studies, I²: 27.49%) and specificity 0.79 (95% CI: 0.71 to 0.85, 4 studies, I²: 58.9%) of Leptocheck-WB were also moderate. Diagnostic odds ratio of Leptocheck-WB with MAT (21, 95% CI: 10-44) or with ELISA as reference test (21, 95% CI: 9-46) showed an acceptable level of accuracy. Meta-regression analysis showed methodological quality of studies (p: 0.06) and study design (p: 0.09) were potential factors that affected the accuracy of Leptocheck-WB test. Findings suggest that Leptocheck-WB has a moderate level of acceptance for detection of acute leptospirosis. Further confirmation with large-sampled, prospectively designed studies using the same samples for evaluating test accuracy is recommended.

First Isolation and Molecular Typing of Pathogenic and Intermediate Leptospira Species from Urine of Symptomatic Dogs

Aim of this study was to evaluate, the presence and diversity of Leptospira spp. in blood and urine samples collected from 175 owned-dogs from Sardinia, Italy. After determination of leptospiral infection by microscopic agglutination test (MAT), urine from MAT-positive dogs were examined by real-time polymerase chain reaction (lipL32 rt-PCR) and then isolated by culture. In order to characterize obtained serovars, positive cultures were then subjected to 16S rRNA and secY sequencing, phylogenetic analysis and Multilocus Sequence Typing (MLST). Results showed that seven dogs (4%; 95% CI: 0-55) had Leptospira DNAs in their urine and five strains were isolated from urine cultures. The three different sequence types (ST17, ST198 and ST24) belonging to Leptospira interrogans genomospecies identified by MLST analyses in this study, confirmed that the leptospiral infection was widespread in Sardinian dogs. We also reported the first characterization of a new Leptospira spp. isolated from urine of one dog living in the study area. Whole genome sequencing and phylogenetic analysis, confirmed that this genospecies was closely related to Leptospira hovindhougenii, an intermediate Leptospira spp. with unknown pathogenicity previously isolated from a rat in Denmark. Further studies are required to clarify whether healthy dogs that shed leptospires in their urine could represent a zoonotic risk for humans in this region.

Leptospirosis: a neglected tropical zoonotic infection of public health importance-an updated review

Leptospirosis is a zoonotic and waterborne disease worldwide. It is a neglected, reemerging disease of global public health importance with respect to morbidity and mortality both in humans and animals. Due to negligence, rapid, unplanned urbanization, and poor sanitation, leptospirosis emerges as a leading cause of acute febrile illness in many of the developing countries. Every individual has a risk of getting infected as domestic and wild animals carry leptospires; the at-risk population varies from the healthcare professionals, animal caretakers, farmers and agricultural workers, fishermen, rodent catchers, water sports people, National Disaster Response Force (NDRF) personnel, people who volunteer rescue operations in flood-affected areas, sanitary workers, sewage workers, etc. The clinical manifestations of leptospirosis range from flu-like illness to acute kidney failure (AKF), pneumonia, jaundice, pulmonary hemorrhages, etc. But many rare and uncommon clinical manifestations are being reported worldwide. This review will cover all possible updates in leptospirosis from occurrence, transmission, rare clinical manifestations, diagnosis, treatment, and prophylactic measures that are currently available, their advantages and the future perspectives, elaborately. There are less or very few reviews on leptospirosis in recent years. Thus, this work will serve as background knowledge for the current understanding of leptospirosis for researchers. This will provide a detailed analysis of leptospirosis and also help in finding research gaps and areas to focus on regarding future research perspectives.

Serological evidence of human leptospirosis in patients with acute undifferentiated febrile illness from Uttarakhand, India: A pilot study

CONTEXT:

To the best of our knowledge, there are no reports of serological evidence of human leptospirosis from Uttarakhand state in India.

AIMS:

The aim of this study was to screen for serological evidence of leptospirosis in patients with acute undifferentiated febrile illness at a tertiary care teaching hospital in Uttarakhand.

SETTINGS AND DESIGN:

A pilot study was conducted from March to November 2017.

SUBJECTS AND METHODS:

Fifty-three adult patients who presented in Medicine outpatient Department with a history of fever of ≥7 up to 14 days duration with or without other associated symptoms such as a headache, rashes, myalgia, arthralgia, and conjunctival suffusion were enrolled in the study using convenience sampling technique. Blood samples of these patients were collected and subjected to peripheral smear examination for malaria parasites, dengue immunoglobulin M (IgM) immunochromatographic card test, IgM Typhidot, Leptospira and Scrub typhus IgM ELISA, respectively. Aerobic blood culture was performed in 24 cases. Relevant clinico-epidemiological details were obtained as per the pro forma formulated in accordance with the modified Faine's criteria.

STATISTICAL ANALYSIS USED:

Descriptive statistics.

RESULTS:

The study population consisted of 50.94% of males and 49.06% of females with a mean age ± standard deviation of 34.2 ± 15.2 years. Fifty febrile patients had additional symptoms of which myalgia was the most common (81.1%) followed by arthralgia (22.6%). Peripheral smears of all patients were negative for malaria parasites. Dengue and Typhidot IgM positivity was observed in two and eight patients, respectively. Six and five patients were tested positive by leptospira and scrub typhus IgM ELISA, respectively. Salmonella Typhi was isolated from blood sample of only one patient. Serum samples of two patients showed dual positivity. All six leptospira seropositive patients satisfied modified Faine's criteria.

CONCLUSIONS:

Leptospirosis is a seemingly unexplored infection in Uttarakhand and should be considered as a differential diagnosis in patients with acute undifferentiated febrile illness.