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

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.

Diagnosis of human leptospirosis: systematic review and meta-analysis of the diagnostic accuracy of the Leptospira microscopic agglutination test, PCR targeting Lfb1, and IgM ELISA to Leptospira fainei serovar Hurstbridge

BACKGROUND

Leptospirosis is an underdiagnosed infectious disease with non-specific clinical presentation that requires laboratory confirmation for diagnosis. The serologic reference standard remains the microscopic agglutination test (MAT) on paired serum samples. However, reported estimates of MAT's sensitivity vary. We evaluated the accuracy of four index tests, MAT on paired samples as well as alternative standards for leptospirosis diagnosis: MAT on single acute-phase samples, polymerase chain reaction (PCR) with the target gene Lfb1, and ELISA IgM with Leptospira fainei serovar Hurstbridge as an antigen.

METHODS

We performed a systematic review of studies reporting results of leptospirosis diagnostic tests. We searched eight electronic databases and selected studies that tested human blood samples and compared index tests with blood culture and/or PCR and/or MAT (comparator tests). For MAT selection criteria we defined a threshold for single acute-phase samples according to a national classification of leptospirosis endemicity. We used a Bayesian random-effect meta-analysis to estimate the sensitivity and specificity of MAT in single acute-phase and paired samples separately, and assessed risk of bias using the Quality Assessment of Studies of Diagnostic Accuracy Approach- 2 (QUADAS-2) tool.

RESULTS

For the MAT accuracy evaluation, 15 studies were included, 11 with single acute-phase serum, and 12 with paired sera. Two included studies used PCR targeting the Lfb1 gene, and one included study used IgM ELISA with Leptospira fainei serovar Hurstbridge as antigen. For MAT in single acute-phase samples, the pooled sensitivity and specificity were 14% (95% credible interval [CrI] 3-38%) and 86% (95% CrI 59-96%), respectively, and the predicted sensitivity and specificity were 14% (95% CrI 0-90%) and 86% (95% CrI 9-100%). Among paired MAT samples, the pooled sensitivity and specificity were 68% (95% CrI 32-92%) and 75% (95% CrI 45-93%) respectively, and the predicted sensitivity and specificity were 69% (95% CrI 2-100%) and 75% (2-100%).

CONCLUSIONS

Based on our analysis, the accuracy of MAT in paired samples was not high, but it remains the reference standard until a more accurate diagnostic test is developed. Future studies that include larger numbers of participants with paired samples will improve the certainty of accuracy estimates.

The combination of RPA-CRISPR/Cas12a and Leptospira IgM RDT enhances the early detection of leptospirosis

BACKGROUND

Lack of available sensitive point-of-care testing is one of the primary obstacles to the rapid diagnosis of leptospirosis. The purpose of this study was to test the performance of two point-of-care tests, a clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 12a (CRISPR/Cas12a) fluorescence-based diagnostic assay (FBDA), a Leptospira immunoglobulin M (IgM) rapid diagnostic test (RDT), and the two tests combined.

METHODOLOGY/PRINCIPAL FINDINGS

For the diagnosis of 171 clinical samples, a recombinase polymerase amplification (RPA)-CRISPR/Cas12a FBDA for whole blood and Leptospira IgM RDT (Medical Science Public Health, Thailand) for serum were used. The confirmed cases were determined by using any positive qPCR, microscopic agglutination test (MAT), and culture results. Diagnostic accuracy was assessed on the first day of enrollment and stratified by the day after symptom onset. The overall sensitivity of the Leptospira IgM RDT and RPA-CRISPR/Cas12a FBDA was 55.66% and 60.38%, respectively. When the two tests were combined, the sensitivity rose to 84.91%. The specificity of each test was 63.08% and 100%, respectively, and 63.08% when combined. The sensitivity of the Leptospira IgM RDT rose on days 4-6 after the onset of fever, while the RPA-CRISPR/Cas12a FBDA continued to decrease. When the two tests were combined, the sensitivity was over 80% at different days post-onset of fever.

CONCLUSIONS/SIGNIFICANCE

The combination of Leptospira IgM RDT and RPA-CRISPR/Cas12 FBDA exhibited significant sensitivity for the detection of leptospires at various days after the onset of fever, thereby reducing the likelihood of misdiagnosis. The combination of these assays may be suitable for early leptospirosis screening in situations with limited resources.

The value of pre-exposure prophylaxis: A case series of US Marines infected with leptospirosis

BACKGROUND

Leptospirosis is an ever-present threat found in the freshwater areas in many tropical and sub-tropical regions throughout the world and travelers to these areas are at increased risk of infection. This study describes a case series of 47 US Marines who experienced a single point leptospirosis exposure in 2014 and were admitted to a military treatment facility.

METHODS

Descriptive statistics were conducted for patient demographics, symptoms, laboratory results, and outcomes. Hypothesis tests were conducted to identify significant outcomes (length of hospitalization, severity of infection, intensive care unit (ICU) admission, and cholecystectomy). Patient data was applied to five leptospirosis scoring models to assess their accuracy in the context of this population.

RESULTS

The patients were all male (n = 47, 100%), had a median age of 22 (range 19-37), a mean body mass index of 24.3 (SD 2.5), and most were taking antibiotic prophylaxis (n = 40, 85.1%). Most patients experienced thrombocytopenia (n = 37, 78.7%), proteinuria (n = 35, 74.5%), and transaminitis (n = 37, 78.7%). Correct classification of infection varied among the models from 42.6% (n = 20) to 10.6% (n = 5). Not taking pre-exposure prophylaxis was significantly correlated with severe infection (p = 0.02), undergoing a cholecystectomy (p = 0.01), and being admitted to the ICU (p < 0.01). No other results were found to be both clinically and statistically significant.

CONCLUSIONS

Leptospirosis diagnostic models currently in use may be less effective in predicting disease severity in young and healthy populations who are taking antibiotic prophylaxis. The use of pre-exposure prophylaxis significantly correlates with less severe health outcomes.

Going Micro in Leptospirosis Kidney Disease

Leptospirosis is a zoonotic and waterborne disease worldwide. It is a neglected infectious disease caused by Leptospira spp., as well as a reemerging disease and global public health problem with respect to morbidity and mortality both in humans and animals. Leptospirosis emerges as a leading cause of acute febrile illness along with hepatorenal injury in many countries, including Thailand. While most affected persons are symptomatic in acute disease, which is always difficult to differentiate from other tropical diseases, there is growing evidence of subtle manifestations that cause unrecognized chronic symptoms. The kidney is one of the common organs affected by Leptospires. Although acute kidney injury in the spectrum of interstitial nephritis is a well-described characteristic in severe leptospirosis, chronic kidney disease from leptospirosis is widely discussed. Early recognition of severe leptospirosis leads to reduce morbidity and mortality. Thus, in this review, we highlight the spectrum of characteristics involved in leptospirosis kidney disease and the use of serologic and molecular methods, as well as the treatments of severe leptospirosis.

Clinical Evaluation of the Modified Faine Criteria in Patients Admitted with Suspected Leptospirosis to the Territorial Hospital, New Caledonia, 2018 to 2019

Leptospirosis is endemic in New Caledonia. Clinical diagnosis is often difficult and its evolution can be fatal. Leptospirosis requires specific management before biological confirmation. Modified Faine criteria (Faine Score) have been suggested to diagnose leptospirosis on epidemiological (parts A and B) and biological (part C) criteria. The main objective of our study was to assess the relevance of the epidemiological-clinical modified Faine score, parts A and B (MF A + B), in patients with suspected leptospirosis in New Caledonia. A monocentric case-control study was conducted in suspect patients for whom a Leptospira polymerase chain reaction (PCR) test was done within the first 7 days of signs onset at the tertiary hospital from January 2018 to January 2019. Cases and control subjects were matched 1:2 in the gender and age categories. Bivariate, and then multivariable, analyses studied the association between the MF A + B score and a positive Leptospira PCR test, adjusted on the variables retained. In all, 35 cases and 70 control subjects matched for age and gender were analyzed. Multivariable analysis by logistic regression found a significant association between an MF A + B score taken from the categories "possible leptospirosis" (score, 20-25) and "presumed leptospirosis" (score, > 26), and the case or control subject status (P < 0.0001). Model performance was high, with an area under the curve value of 99.27%, 93.55% sensitivity, and 96.36% specificity, which classified subjects correctly in 95.35% of cases. Our study suggests using the MF A + B score to identify possible cases of leptospirosis and initiate antibiotic therapy before biological confirmation in New Caledonia. This score should be evaluated in areas where more differential diagnoses exist and where PCR is not widely available.

Rapid and sensitive point-of-care detection of Leptospira by RPA-CRISPR/Cas12a targeting lipL32

Background

One of the key barriers preventing rapid diagnosis of leptospirosis is the lack of available sensitive point-of-care testing. This study aimed to develop and validate a clustered regularly-interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 12a (CRISPR/Cas12a) platform combined with isothermal amplification to detect leptospires from extracted patient DNA samples.

Methodology/Principal findings

A Recombinase Polymerase Amplification (RPA)-CRISPR/Cas12a-fluorescence assay was designed to detect the lipL32 gene of pathogenic Leptospira spp. The assays demonstrated a limit of detection (LOD) of 100 cells/mL, with no cross-reactivity against several other acute febrile illnesses. The clinical performance of the assay was validated with DNA extracted from 110 clinical specimens and then compared to results from qPCR detection of Leptospira spp. The RPA-CRISPR/Cas12a assay showed 85.2% sensitivity, 100% specificity, and 92.7% accuracy. The sensitivity increased on days 4–6 after the fever onset and decreased after day 7. The specificity was consistent for several days after the onset of fever. The overall performance of the RPA-CRISPR/Cas12a platform was better than the commercial rapid diagnostic test (RDT). We also developed a lateral flow detection assay (LFDA) combined with RPA-CRISPR/Cas12a to make the test more accessible and easier to interpret. The combined LFDA showed a similar LOD of 100 cells/mL and could correctly distinguish between known positive and negative clinical samples in a pilot study.

Conclusions/Significance

The RPA-CRISPR/Cas12 targeting the lipL32 gene demonstrated acceptable sensitivity and excellent specificity for detection of leptospires. This assay might be an appropriate test for acute leptospirosis screening in limited-resource settings.

Clinical signs and symptoms of leptospirosis are similar to those of other infectious diseases such as dengue, sepsis, and malaria, making it difficult to diagnose. In this study, we developed an RPA-CRISPR/Cas12a -based detection platform to identify the lipL32 gene of pathogenic Leptospira spp. The results showed that the limit of detection (LOD) was approximately 10² cells/mL without cross-reactivity against other infectious diseases. The platform was validated using 110 patients from 15 hospitals in Sisaket province, Thailand. The sensitivity, specificity, and accuracy was found to be 85.2%, 100% and 92.7%, respectively, for the diagnosis of leptospirosis. Assay sensitivity increased at 4–6 d post-onset of fever, with a consistent specificity every day after the onset of fever. We also developed a lateral flow detection assay combined with RPA-CRISPR/Cas12a, which also had a LOD of 10² cells/mL and could correctly distinguish known positive and negative clinical samples in a pilot study. Findings from this study demonstrate the potential effectiveness of the RPA-CRISPR/Cas12a platform in improving speed and accuracy of leptospirosis diagnosis especially in limited-resource settings.

Identification and validation of circulating miRNAs as potential new biomarkers for severe liver disease in patients with leptospirosis

Background

Leptospirosis, a global zoonotic infectious disease, has various clinical manifestations ranging from mild self-limiting illness to life-threatening with multi-organ damage, including liver involvement. This study was aimed at identifying circulating microRNAs (miRNAs) as novel biomarkers for predicting severe liver involvement in patients with leptospirosis.

Methods

In a discovery set, 12 serum samples of patients with anicteric and icteric leptospirosis at initial clinical presentation were used for miRNA profiling by a NanoString nCounter miRNA assay. In a validated cohort, top candidate miRNAs were selected and further tested by qRT-PCR in serum samples of 81 and 16 individuals with anicteric and icteric leptospirosis, respectively.

Results

The discovery set identified 38 significantly differential expression miRNAs between the two groups. Among these, miR-601 and miR-630 were selected as the top two candidates significantly up-regulated expressed in the icteric group. The enriched KEGG pathway showed that these miRNAs were mainly involved in immune responses and inflammation. In the validated cohort, miR-601 and miR-630 levels were significantly higher in the icteric group compared with the anicteric group. Additionally, these two miRNAs displayed good predictors of subsequent acute liver failure with a high sensitivity of 100%. On regression analysis, elevated miR-601 and miR-630 expression were also predictive of multi-organ failures and poor overall survival.

Conclusion

Our data indicated that miRNA expression profiles were significantly differentiated between the icteric and anicteric groups. Serum miR-601 and miR-630 at presentation could potentially serve as promising biomarkers for predicting subsequent acute liver failure and overall survival in patients with leptospirosis.

Evaluation of the Panbio Leptospira IgM ELISA among Outpatients Attending Primary Care in Southeast Asia

Despite estimates suggesting Leptospira spp. being endemic in Southeast Asia, evidence remains limited. Diagnostic accuracy evaluations based on Leptospira ELISA mainly rely on hospitalized and severe patients; therefore, studies measuring the pathogen burden may be inaccurate in the community. We evaluated the Panbio Leptospira ELISA IgM among 656 febrile outpatients attending primary care in Chiangrai, Thailand, and Hlaing Tha Yar, Yangon, Myanmar. ELISA demonstrated limited diagnostic accuracy for the detection of acute leptospiral infection using the manufacturer recommended cutoff, with a sensitivity of 71.4% and specificity of 36.4%, and an area under the receiver operator characteristic curve value of 0.65 (95% CI: 0.41-0.89), compared with our reference test, the PCR assay. ELISA also performed poorly as a screening tool for detecting recent exposure to Leptospira spp. compared with the "gold-standard" microscopic agglutination test, with a specificity of 42.7%. We conclude that the utility of the Leptospira IgM ELISA for both serodiagnosis and seroprevalence is limited in our setting.

Clinical characteristics, outcomes, and predictors of leptospirosis in patients admitted to the medical intensive care unit: A retrospective analysis

BACKGROUND

Early diagnosis and detection of clinical deterioration of leptospirosis are challenges to all clinicians. This study aimed to report the characteristics and outcomes of patients admitted to the medical intensive care unit (MICU) for severe leptospirosis and to identify the clinical predictors of MICU admission.

METHODS

This was a 10-year retrospective study that included all patients diagnosed as leptospirosis, based on either serology or a Thai-Lepto score (TLS) of >4. All clinical characteristics and laboratory data were collected and compared between MICU cases and general ward cases. Binary logistic regression was applied to identify the independent factors for MICU admission.

RESULTS

Of the 68 patients who were diagnosed as leptospirosis based on inclusion criteria, 43 serologically-confirmed cases were subsequently analyzed. Fifty percent of the cases were admitted to the MICU and, compared with those admitted to the general ward, had higher Sequential Organ Failure Assessment (SOFA) score [10 (7-13) vs. 5 (2.2-5.6), p < 0.001]; higher TLS [7.5 (6.5-9.25) vs. 5.5 (3.5-6.5), p < 0.001]; lower mean arterial blood pressure (74.7 ± 15 mmHg vs. 84.2 ± 16.3 mmHg, p = 0.04); lower platelet count in ×10³ cell/mm³ [65 (52.8-105.8) vs. 159 (87.3-181.5), p = 0.008); higher total bilirubin level [4.4 (1.5-8.7) mg/dL vs. 1.2 (0.7-2.8) mg/dL, p = 0.01]; and required more inotropes and vasopressors (87% vs. 4.3%, p < 0.001), mechanical ventilator support (91.3% vs. 4.3%, p < 0.001), and renal replacement therapy (39.1% vs. 0%, p < 0.001). TLS, SOFA score, requirement for mechanical ventilation, and use of inotropes and vasopressors were the predictors of MICU admission. TLS > 6 and SOFA score >6 gave similar power to predict MICU admission.

CONCLUSION

Among patients with leptospirosis, TLS, SOFA score, inotrope or vasopressor requirement, and mechanical ventilator support were the independent predictors of MICU admission. TLS > 6 and SOFA score >6 indicated the need for MICU admission.

A systematic literature review of leptospirosis outbreaks worldwide, 1970-2012

Objective.

This review describes the geographic and temporal distribution of, detection methods for, and other epidemiological features of published leptospirosis outbreaks, with the aim of informing efforts to standardize outbreak-reporting practices.

Methods.

We conducted a systematic review of leptospirosis outbreaks reported in the scientific literature and ProMED during 1970–2012. Predefined criteria were used to identify and classify outbreaks and a standard form was used to extract information.

Results.

During 1970–2012, we identified 318 outbreaks (average: 7 outbreaks/year; range: 1–19). Most outbreaks were reported in the Latin America and the Caribbean region (36%), followed by Southern Asia (13%), and North America (11%). Most outbreaks were located in tropical and subtropical ecoregions (55%). Quality classification showed that there was clear description of laboratory-confirmed cases in 40% of outbreaks. Among those, the average outbreak size was 82 cases overall (range: 2–2 259) but reached 253 cases in tropical/subtropical ecoregions. Common risk factors included outdoor work activities (25%), exposure to floodwaters (23%), and recreational exposure to water (22%). Epidemiologic investigation was conducted in 80% of outbreaks, mainly as case interviews. Case fatality was 5% overall (range: 0%–60%).

Conclusions.

Outbreak reporting increased over the study period with outbreaks covering tropical and non-tropical regions. Outbreaks varied by size, setting, and risk factors; however, data reviewed often had limited information regarding diagnosis and epidemiology. Guidelines are recommended to develop standardized procedures for diagnostic and epidemiological investigations during an outbreak and for reporting.

Significant Clinical Presentation of Leptospirosis in Relation to Sociodemographic and Risk Factors in a Tertiary Hospital, Malaysia

Introduction: Incidence of leptospirosis has increased within the past few years in many countries. Its clinical presentations were generally nonspecific, making it difficult to assist in the diagnosis. Besides the determination of the common clinical features, the sociodemographic background is essential to identify high-risk populations to assist in prevention. Methods: Data for this study were obtained from electronic medical records among patients clinically diagnosed with leptospirosis at a tertiary hospital in Malaysia from the years 2011 to 2015 and were recorded using standard pro forma. Associations between clinical features and sociodemographics were performed using bivariate analysis and logistic regression. Results: Data were collected from 283 patients. Their mean age was 30.71 years old. Out of 283 patients, 206 (72.8%) were male. Involvement in outdoor events and water activities was the highest risk factor of acquiring leptospirosis in 64 (22.7%) patients followed by 59 (20.8%) patients who were staying in crowded housing areas with poor sanitation. Although fever was the main clinical presentation in 274 (96.8%) patients with leptospirosis, gastrointestinal (GIT) symptoms were the second most frequent in 159 (56.2%) patients followed by pulmonary symptoms, myalgia, headache, and jaundice. From the total number of 283 patients, only 21 (92.6%) presented with severe leptospirosis. GIT symptoms were a significant predictor for leptospirosis severity, while the age group was the significant sociodemographic factor toward GIT presentation in leptospirosis. The relationship between GIT symptoms and crowded housing areas with poor sanitation was also significant. Multivariable logistic regression showed that crowded housing areas with poor sanitation (odds ratio [OR] = 3.570, p < 0.001) and age between 20 and 40 years old (OR = 2.056, p = 0.014) were more likely to have GIT symptoms. Conclusions: Information regarding the clinical features of leptospirosis to the public is necessary, while targeted prevention by educational outreach among 20-40 year olds especially those participating in outdoor water activities are crucial to decrease the incidence and complications of leptospirosis.

Development and Validation of a simple score for diagnosis of Leptospirosis at outpatient departments

Background

Leptospirosis is an important zoonotic disease within the tropics. Diagnosing leptospirosis is a clinical obstacle, as clinical presentations are similar to other tropical infectious diseases. Available serological tests are often insensitive and not cost-effective. Many clinical diagnostic scorings had been developed but most were based on hospitalized patients, and wound not be suitable for use in suspected patients in setting of ambulatory care.

Objectives

To develop and internal validate multivariable diagnostic prediction score of leptospirosis in patients suspicious of leptospirosis at out-patient clinics of community hospitals.

Materials and methods

We performed a prospective, multisite diagnostic prediction research with development of a diagnostic score. The development cohort was based on patients suspicious of leptospirosis who visited five community hospitals in Si Sa Ket province, Thailand during December 2017 to November 2018. Leptospirosis confirmed cases were defined when one of the three standard confirmatory tests was positive. Multivariable logistic regression was used for score derivation. Test of AuROC equality was done to compare diagnostic performance of the newly derived score and conventional WHO score.

Results

A total of 262 leptospirosis suspicious patients were enrolled. Eighty-two patients (31.5%) were leptospirosis confirmed cases. Five final predictors remained within the reduced logistic model which were history of exposure to wet ground at workplace, history of contact water reservoir used by animal, urine protein and urine blood positive from dipstick test, and neutrophil count from CBC ≥80%. The OPD score diagnostic performance was AuROC 0.72 (95%CI 0.65–0.79). Test of equality revealed significant differences of AuROC between the OPD and WHO score (0.72 vs 0.62, p-value 0.014). Patients were categorized into low and high probability of having leptospirosis at score point of 3.5 with sensitivity 72.4% and specificity 61.7%.

Conclusions

This study developed and internal validated the OPD score. This clinical risk score could be one of the important tools for diagnosis of leptospirosis at the outpatient clinic.

Leptospirosis is an important tropical infectious disease. Early diagnosis of leptospirosis in patients with mild and vague clinical syndrome is another clinical obstacle. Most of the diagnostic score developed for diagnosis of leptospirosis are based on patients with flank clinical symptoms, mostly in hospitalized patient. This study developed the OPD score for early diagnosis of undifferentiated fever for patients visiting outpatient care in leptospirosis endemic area. This score can be practically apply to area where health care facilities are limited by asking patients for only two potential risk factors of exposure to Leptospira, taking simple blood and urine samples. We believed that this score could aid physician in early diagnosis and initiation of treatment in early leptospirosis patient which would alleviate disease progression and probably decrease mortality.

Leptospirosis manifested with severe pulmonary haemorrhagic syndrome successfully treated with venovenous extracorporeal membrane oxygenation

Leptospirosis, one of the most important of neglected tropical diseases, is a common zoonosis in the tropics. Recent reports have demonstrated that pulmonary haemorrhage is one of the fatal complications of severe leptospirosis. In this report, we present a case of leptospirosis manifested with severe pulmonary haemorrhagic syndrome successfully treated with venovenous extracorporeal membrane oxygenation (VV-ECMO). A 39-year-old man who lives in Bangkok presented with fever, severe myalgia and haemoptysis. With rapid progression of acute respiratory failure in 6 hours, he was intubated and a litre of fresh blood was suctioned. Chest x-ray showed diffuse alveolar infiltrates compatible with ARDS, then mechanical ventilator with lung protective strategy was used. Diagnosis of leptospirosis with diffuse alveolar haemorrhage was made. Refractory hypoxaemia was not responsive to positive end-expiratory pressure (PEEP); thus, VV-ECMO was initiated on the first day. Other treatments included plasmapheresis, intravenous pulse methylprednisolone and intravenous antibiotics. The outcome of treatment was successful, and this patient was discharged to home on day 14 after admission.

Restructuring the Modified Faine's Criteria for the Diagnosis of Leptospirosis in Monsoon: A Study from South Gujarat

Context:

Clinical and epidemiological variables in the modified Faine's criteria offered low validity in our study setting.

Aims:

Restructuring and validating modified Faine's criteria for leptospirosis to better suit health scenario of south Gujarat.

Subjects and Methods:

Clinical, epidemiological, and laboratory features of derivation cohort (1216 suspected leptospirosis cases) admitted at a tertiary care hospital of south Gujarat (2007–2015) that significantly correlated with confirmed leptospirosis were used in binary logistic regression to derive scoring models and receiver operating characteristic to determine cutoff values. Validity and net reclassification improvement (NRI) were estimated in validation cohort (82 cases, 2016–2017) and algorithm for diagnosis was prepared.

Results:

Screening model consisted of the presence of conjunctival suffusion, calf tenderness, raised serum creatinine, headache with conjunctival suffusion and/or jaundice, and dyspnea/meningism. Area under curve (AUC) for screening model was 0.590 (standard error [SE] ±0.017) and cutoff score ≥9 gave sensitivity 79.16%, specificity 50%. The confirmatory model consisted of laboratory parameters, namely polymerase chain reaction, immunoglobulin M ELISA, and microscopic agglutination test and gave AUC 0.998 (SE ± 0.001), sensitivity 89.58%, specificity 85.29%, positive predictive value 89.58%, and negative predictive value 85.29% at cutoff score ≥100. Net sensitivity of algorithm was 98.27% at the point of screening (screening model and rapid test) and net specificity 87.89% at the point of confirmation (screening followed by confirmatory model) in validation cohort.

Conclusions:

Simultaneous use of screening model and rapid test gave NRI 81.25% and sequential use of confirmatory test gave NRI 47.18% compared to corresponding parts of the modified Faine's criteria.

The "MICE" scoring system in differentiating the identical twins leptospirosis and hantavirus infection

PURPOSE

To develop a practical scoring system to assist clinicians in differentiating leptospirosis and hantavirus infections, whose epidemiological, clinical, and laboratory characteristics are literally like identical twins.

METHODS

The study population consisted of 162 patients admitted to hospital with a confirmed diagnosis of leptospirosis (LG group, n = 92) and hantavirus infections (HG, group = 70) between January 2000 and January 2019. The two groups were compared in terms of demographic, clinical and laboratory features. Sensitivity, specificity, and positive and negative predictive values were determined from ROC analysis for findings of significance in the diagnosis of leptospirosis, and a scoring system for diagnosis was developed ("MICE" score). During the development of this scoring system, we were careful to employ parameters that would not affect one another statistically, to reflect the involvement of very different systems (such as the hematological, hepatic, renal, and musculoskeletal systems) due to the multisystemic effect of the disease in the organism, and to ensure that the system should be simple to apply and understand. Accordingly, five parameters, serum WBC, creatinine, creatine kinase, total bilirubin, and C-reactive protein, were employed in the "MICE" scoring system.

RESULTS

Three cut-off values were determined using ROC analysis for the five parameters included in the MICE system. Accordingly, scores of 0, 1, or 2 were given based on the values WBC (/μL): ≤ 7500, 7500-15,000, and > 15,000; total bilirubin (mg/dL): ≤ 3, 3-10, and > 10; CRP (mg/dL): ≤ 5, 5-15, and > 15; creatinine (mg/dL): ≤ 1.5, 1.5-3, and > 3; CK (U/L): ≤ 500, 500-1000, > 1000. AUC was calculated as 0.964 at ROC analysis, while the most noteworthy cut-off point was obtained when MICE score was ≥ 3, exhibiting 93.5% sensitivity, 92.9% specificity, PPV 94.5% and NPV 91.5%. A test score ≥ 3 was regarded as positive. In addition, our patients were evaluated using other current scoring systems in addition to "MICE," and our scoring system exhibited a greater diagnostic power in our subjects.

CONCLUSIONS

Leptospirosis and hantavirus infections can be accurately predicted by the MICE scoring system. Early diagnosis and rational treatment will also help to lower the mortality rates in these diseases.

Hypocalcemia, hypochloremia, and eosinopenia as clinical predictors of leptospirosis: A retrospective study

BACKGROUND

Underestimation of leptospirosis cases is happening in many countries. The most common factor of underreporting is misdiagnosis. Considering the limitations of direct detection of pathogen and serological diagnosis for leptospirosis, clinical features and blood tests though non-specific are usually referred in making presumptive diagnosis to decide disease management.

METHODS

In this single-centre retrospective study, comparative analysis on clinical presentations and laboratory findings was performed between confirmed leptospirosis versus non-leptospirosis cases.

RESULTS

In multivariate logistic regression evidenced by a Hosmer-Lemeshow significance value of 0.979 and Nagelkerke R square of 0.426, the predictors of a leptospirosis case are hypocalcemia (calcium <2.10mmol/L), hypochloremia (chloride <98mmol/L), and eosinopenia (absolute eosinophil count <0.040×10⁹/L). The proposed diagnostic scoring model has a discriminatory power with area under the curve (AUC) 0.761 (p<0.001). A score value of 6 reflected a sensitivity of 0.762, specificity of 0.655, a positive predictive value of 0.38, negative predictive value of 0.91, a positive likelihood ratios of 2.21, and a negative likelihood ratios of 0.36.

CONCLUSION

With further validation in clinical settings, implementation of this diagnostic scoring model is helpful to manage presumed leptospirosis especially in the absence of leptospirosis confirmatory tests.

Nucleic acid and antigen detection tests for leptospirosis

BACKGROUND

Early diagnosis of leptospirosis may contribute to the effectiveness of antimicrobial therapy and early outbreak recognition. Nucleic acid and antigen detection tests have the potential for early diagnosis of leptospirosis. With this systematic review, we assessed the sensitivity and specificity of nucleic acid and antigen detection tests.

OBJECTIVES

To determine the diagnostic test accuracy of nucleic acid and antigen detection tests for the diagnosis of human symptomatic leptospirosis.

SEARCH METHODS

We searched electronic databases including MEDLINE, Embase, the Cochrane Library, and regional databases from inception to 6 July 2018. We did not apply restrictions to language or time of publication.

SELECTION CRITERIA

We included diagnostic cross-sectional studies and case-control studies of tests that made use of nucleic acid and antigen detection methods in people suspected of systemic leptospirosis. As reference standards, we considered the microscopic agglutination test alone (which detects antibodies against leptospirosis) or in a composite reference standard with culturing or other serological tests. Studies were excluded when the controls were healthy individuals or when there were insufficient data to calculate sensitivity and specificity.

DATA COLLECTION AND ANALYSIS

At least two review authors independently extracted data from each study. We used the revised Quality Assessment of Diagnostic Accuracy Studies tool (QUADAS-2) to assess risk of bias. We calculated study-specific values for sensitivity and specificity with 95% confidence intervals (CI) and pooled the results in a meta-analysis when appropriate. We used the bivariate model for index tests with one positivity threshold, and we used the hierarchical summary receiver operating characteristic model for index tests with multiple positivity thresholds. As possible sources of heterogeneity, we explored: timing of index test, disease prevalence, blood sample type, primers or target genes, and the real-time polymerase chain reaction (PCR) visualisation method. These were added as covariates to the meta-regression models.

MAIN RESULTS

We included 41 studies evaluating nine index tests (conventional PCR (in short: PCR), real-time PCR, nested PCR, PCR performed twice, loop-mediated isothermal amplification, enzyme-linked immunosorbent assay (ELISA), dot-ELISA, immunochromatography-based lateral flow assay, and dipstick assay) with 5981 participants (1834 with and 4147 without leptospirosis). Methodological quality criteria were often not reported, and the risk of bias of the reference standard was generally considered high. The applicability of findings was limited by the frequent use of frozen samples. We conducted meta-analyses for the PCR and the real-time PCR on blood products.The pooled sensitivity of the PCR was 70% (95% CI 37% to 90%) and the pooled specificity was 95% (95% CI 75% to 99%). When studies with a high risk of bias in the reference standard domain were excluded, the pooled sensitivity was 87% (95% CI 44% to 98%) and the pooled specificity was 97% (95% CI 60% to 100%). For the real-time PCR, we estimated a summary receiver operating characteristic curve. To illustrate, a point on the curve with 85% specificity had a sensitivity of 49% (95% CI 30% to 68%). Likewise, at 90% specificity, sensitivity was 40% (95% CI 24% to 59%) and at 95% specificity, sensitivity was 29% (95% CI 15% to 49%). The median specificity of real-time PCR on blood products was 92%. We did not formally compare the diagnostic test accuracy of PCR and real-time PCR, as direct comparison studies were lacking. Three of 15 studies analysing PCR on blood products reported the timing of sample collection in the studies included in the meta-analyses (range 1 to 7 days postonset of symptoms), and nine out of 16 studies analysing real-time PCR on blood products (range 1 to 19 days postonset of symptoms). In PCR studies, specificity was lower in settings with high leptospirosis prevalence. Other investigations of heterogeneity did not identify statistically significant associations. Two studies suggested that PCR and real-time PCR may be more sensitive on blood samples collected early in the disease stage. Results of other index tests were described narratively.

AUTHORS' CONCLUSIONS

The validity of review findings are limited and should be interpreted with caution. There is a substantial between-study variability in the accuracy of PCR and real-time PCR, as well as a substantial variability in the prevalence of leptospirosis. Consequently, the position of PCR and real-time PCR in the clinical pathway depends on regional considerations such as disease prevalence, factors that are likely to influence accuracy, and downstream consequences of test results. There is insufficient evidence to conclude which of the nucleic acid and antigen detection tests is the most accurate. There is preliminary evidence that PCR and real-time PCR are more sensitive on blood samples collected early in the disease stage, but this needs to be confirmed in future studies.