Severity markers in severe leptospirosis: a cohort study

Weil's Disease-Immunopathogenesis, Multiple Organ Failure, and Potential Role of Gut Microbiota

Leptospirosis is an important zoonotic disease, causing about 60,000 deaths annually. In this review, we have described in detail the immunopathogenesis of leptospirosis, the influence of cytokines, genetic susceptibility on the course of the disease, and the evasion of the immune response. These data are combined with information about immunological and pathomorphological changes in the kidneys, liver, and lungs, which are most affected by Weil's disease. The review also suggests a possible role of the gut microbiota in the clinical course of leptospirosis, the main mechanisms of the influence of gut dysbiosis on damage in the liver, kidneys, and lungs through several axes, i.e., gut-liver, gut-kidney, and gut-lungs. Modulation of gut microbiota by probiotics and/or fecal microbiota transplantation in leptospirosis may become an important area of scientific research.

Pulmonary haemorrhage as the earliest sign of severe leptospirosis in hamster model challenged with Leptospira interrogans strain HP358

Background

Severe leptospirosis is challenging as it could evolve rapidly and potentially fatal if appropriate management is not performed. An understanding of the progression and pathophysiology of Leptospira infection is important to determine the early changes that could be potentially used to predict the severe occurrence of leptospirosis. This study aimed to understand the kinetics pathogenesis of Leptospira interrogans strain HP358 in the hamster model and identify the early parameters that could be used as biomarkers to predict severe leptospirosis.

Methodology/Principal findings

Male Syrian hamsters were infected with Leptospira interrogans strain HP358 and euthanized after 24 hours, 3, 4, 5, 6 and 7 days post-infection. Blood, lungs, liver and kidneys were collected for leptospiral detection, haematology, serum biochemistry and differential expression of pro- and anti-inflammatory markers. Macroscopic and microscopic organ damages were investigated. Leptospira interrogans strain HP358 was highly pathogenic and killed hamsters within 6–7 days post-infection. Pulmonary haemorrhage and blood vessel congestion in organs were noticed as the earliest pathological changes. The damages in organs and changes in biochemistry value were preceded by changes in haematology and immune gene expression.

Conclusion/Significance

This study deciphered haemorrhage as the earliest manifestation of severe leptospirosis and high levels of IL-1β, CXCL10/IP-10, CCL3/MIP-α, neutrophils and low levels of lymphocytes and platelets serve as a cumulative panel of biomarkers in severe leptospirosis.

As the severe form of leptospirosis could progress rapidly and be potentially fatal if not treated earlier, deciphering the pathophysiology kinetics of infection is crucial to determine the parameters of disease severity. To understand this, we challenged hamsters with the highly virulent Leptospira interrogans strain HP358. Pulmonary haemorrhage was observed as the earliest pathological change followed by liver and kidneys damages. The increased expression of IL-1β, CXCL10/IP-10, CCL3/MIP-α, high neutrophils and low lymphocytes and platelets production observed in the present study indicate that these parameters could serve as a cumulative panel of biomarkers in severe leptospirosis.

Clinical spectrum of endemic leptospirosis in relation to cytokine response

OBJECTIVES

To describe the clinical spectrum and the cytokine response of leptospirosis patients in an endemic setting of Sri Lanka.

METHODS

Patients presenting to the university teaching hospital, Anuradhapura, Sri Lanka with a leptospirosis-compatible illness were recruited over a period of 12 months starting from June 2012. Daily clinical and biochemical parameters of the patients were prospectively assessed with a follow-up of 14 days after discharge. A magnetic bead-based multiplex cytokine kit was used to detect 17 cytokines.

RESULTS

Of the 142 clinically suspected leptospirosis patients recruited, 47 were confirmed and, 29 cases were labeled as "probable." Thrombocytopenia and leukocytosis were observed at least once during the hospital stay among 76(54%) and 39(28%) patients, respectively. Acute kidney injury was observed in 31 patients (22%) and it was significantly higher among confirmed and probable cases. Hu TNF-α and IL-1β were detected only in patients without complications. Hu MIP-1b levels were significantly higher among patients with complications. During the convalescence period, all tested serum cytokine levels were lower compared to the acute sample, except for IL-8. The cytokine response during the acute phase clustered in four different groups. High serum creatinine was associated GM-CSF, high IL-5 and IL-6 level were correlates with lung involvement and saturation drop. The patients with high billirubin (direct)>7 mmol/l had high IL-13 levels.

CONCLUSIONS

Results of this study confirms that the knowledge on cytokine response in leptospirosis could be more complex than other similar tropical disease, and biosignatures that provide diagnostic and prognostic information for human leptospirosis remain to be discovered.

The role of leptospiremia and specific immune response in severe leptospirosis

Leptospirosis can cause a high mortality rate, especially in severe cases. This multicenter cross-sectional study aimed to examine both host and pathogen factors that might contribute to the disease severity. A total of 217 leptospirosis patients were recruited and divided into two groups of non-severe and severe. Severe leptospirosis was defined by a modified sequential organ failure assessment (mSOFA) score of more than two or needed for mechanical ventilation support or had pulmonary hemorrhage or death. We found that leptospiremia, plasma neutrophil gelatinase-associated lipocalin (pNGAL), and interleukin 6 (IL-6) at the first day of enrollment (day 1) and microscopic agglutination test (MAT) titer at 7 days after enrollment (days 7) were significantly higher in the severe group than in the non-severe group. After adjustment for age, gender, and the days of fever, there were statistically significant associations of baseline leptospiremia level (OR 1.70, 95% CI 1.23–2.34, p = 0.001), pNGAL (OR 9.46, 95% CI 4.20–21.33, p < 0.001), and IL-6 (OR 2.82, 95% CI 1.96–4.07, p < 0.001) with the severity. In conclusion, a high leptospiremia, pNGAL, and IL-6 level at baseline were associated with severe leptospirosis.

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.

Cytokine response in human leptospirosis with different clinical outcomes: a systematic review

Background

Leptospirosis is a neglected zoonotic disease which is a major challenge for clinicians and public health professionals in tropical countries. The cytokine storm during the second (immune) phase is thought to be a major contributory factor for the leptospirosis disease severity. We aim to summarize evidence for cytokine response in leptospirosis at different clinical outcomes.

Methods

A systematic review was carried out to examine the cytokine response in leptospirosis patients using relevant scientific databases. Reference lists of the selected articles were also screened. Quality of the selected studies was assessed by using the National Institutes of Health Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies.

Results

Of the 239 articles retrieved in the initial search, 18 studies fulfilled the selection criteria. India and Thailand have produced the highest number of studies (17% each, n = 3). The majority were comparative cross-sectional studies (72%, n = 13). Overall the quality of the selected studies was fair regardless of few drawbacks such as reporting of sample size and the lack of adjustment for confounders. Microscopic agglutination test (67% - 12/18) and enzyme-linked immunosorbent assay (50% - 9/18) were commonly used for the confirmation of leptospirosis and the measurement of cytokines respectively. IL-1b, IL-2, IL-4, IL-6, IL-8, IL-10 and TNF-α levels were found to be significantly higher in severe than in mild leptospirosis. There were equivocal findings on the association between IL-1β, TNF-α and IL-10/TNF-α ratio and disease severity.

Conclusions

Leptospirosis had a wide-range of elevated cytokines. However, prospective studies in-relation to the onset of the symptom are required to better understand the pathophysiology of cytokine response in leptospirosis.

Elevated levels of IL-8 in fatal leptospirosis

Leptospirosis causes a wide range of clinical outcomes, including organ failure and death. Early treatment significantly increases the chances of cure. Interleukin-8 (IL-8) is a chemoattractant cytokine for neutrophil and is associated with multiple organ failure. Research has indicated IL-8 to be raised in severe and fatal cases of leptospirosis, but its suitability as a prognostic biomarker has yet to be confirmed. This study aimed to evaluate the significance of IL-8 with the clinical outcomes of leptospirosis patients. Plasma IL-8 was measured in fifty-two samples from hospitalized patients and nineteen healthy controls. The comparisons were made between mild, severe-survived and fatal groups identified by clinical or laboratory findings. IL-8 was significantly higher in fatal (p = 0.01) compared to mild cases. IL-8 was also significantly higher in fatal (p = 0.02) when compared to survived cases of leptospirosis. IL-8 levels in the plasma of fatal leptospirosis cases were significantly elevated compared to survived cases and may serve as a potential prognostic biomarker in determining the possible outcome of leptospirosis patients.

Raised levels of Il-6, Il-17a, and Il-22 in fatal leptospirosis

Clinical manifestations of leptospirosis range from mild, common cold-like illness, to a life-threatening condition. The host immune response has been hypothesized to play a major role in leptospirosis outcome. Increased levels of inflammatory mediators, such as cytokines, may promote tissue damage that lead to increased disease severity. The question is whether cytokines levels may predict the outcome of leptospirosis and guide patient management. This study aimed to assess the association between Th1-, Th2-, and Th17-related cytokines with the clinical outcome of patients with leptospirosis. Different cytokine levels were measured in fifty-two plasma samples of hospitalized patients diagnosed with leptospirosis in Malaysia (January 2016-December 2017). Patients were divided into two separate categories: survived (n = 40) and fatal outcome (n = 12). Nineteen plasma samples from healthy individuals were obtained as controls. Cytokine quantification was performed using Simple Plex™ assays from ProteinSimple (San Jose, CA, USA). Measurements were done in triplicate and statistical analysis was performed using GraphPad software and SPSS v20. IL-6 (p = 0.033), IL-17A (p = 0.022), and IL-22 (p = 0.046) were significantly elevated in fatal cases. IL-17A concentration (OR 1.115; 95% CI 1.010-1.231) appeared to be an independent predictor of fatality of leptospirosis. Significantly higher levels of TNF-α (p ≤ 0.0001), IL-6 (p ≤ 0.0001), IL-10 (p ≤ 0.0001), IL-12 (p ≤ 0.0001), IL17A (p ≤ 0.0001), and IL-18 (p ≤ 0.0001) were observed among leptospirosis patients in comparison with healthy controls. Our study shows that certain cytokine levels may serve as possible prognostic biomarkers in leptospirosis patients.

Identifying factors associated with treatment delay in leptospirosis: A retrospective study of patients admitted to hospital in Reunion (Indian Ocean) between 2014 and 2015

BACKGROUND

Leptospirosis is a life-threatening zoonotic disease for which delayed treatment onset has been associated to poor prognosis. The purpose of the study was to identify the determinants of therapeutic delay in hospitalized leptospirosis cases.

PATIENTS AND METHODS

We carried out a retrospective multicenter study in the 4 public hospitals of Reunion Island, South Western Indian Ocean. Medical records of confirmed leptospirosis cases occurring in 2014-2015 were reviewed for socio-economic, demographic, geographic and medical data. The primary outcome measure was the therapeutic delay, defined as the time elapsed between the onset of symptoms and initiation of antibiotics.

RESULTS

Of the 117 patients included, 107 were men, with an average age of 44.9±15years. The median therapeutic delay was 4 days (interquartile: 2-5 days) and this delay was not found to be associated with severity. The following were found to be at increased risk of having a longer therapeutic delay: cases occurring outside the epidemic period, or rainy season (OR 2.8 [1.08-7.3], P=0.04) and cases with first medical evaluation in primary health care (OR 4.63 [1.43-14.93]; P=0.01) instead of emergency unit. No socio-economic or geographic characteristics were found to be linked to a longer therapeutic delay.

CONCLUSION

Although delayed treatment was not associated to disease severity, our results indicate that leptospirosis awareness is needed all year in the subtropical area of Reunion Island and particularly in primary care.

Leptospirosis in French Historical Medical Literature: Weil's Disease or Kelsch's Disease?

Early names for leptospirosis often indicate occupational or environmental exposure. Leptospirosis is hard to identify in the tropical setting because of co-circulating diseases. This is not the case in the temperate setting, such as Europe, where the few historical differential diagnoses were malaria, typhoid, and viral hepatitis. Leptospirosis presumably caused community epidemics in Europe before 1900 and military epidemiologists carefully documented outbreaks in "constrained settings." Achille Kelsch (1841-1911) synthesized available military data and epidemiological perspectives to define "epidemic jaundice" as a nosological continuum, caused by an infectious agent found in muds and water. He viewed Weil's disease as being only one form of that now well-identified disease continuum. The causative pathogen and epidemiological determinants were identified years later. The role of soils and muds as intermediate reservoirs, as suggested by Kelsch, deserves further investigation.

Leptospirosis Pathophysiology: Into the Storm of Cytokines

Leptospirosis is a neglected tropical zoonosis caused by pathogenic spirochetes of the genus Leptospira. Infected reservoir animals, typically mice and rats, are asymptomatic, carry the pathogen in their renal tubules, and shed pathogenic spirochetes in their urine, contaminating the environment. Humans are accidental hosts of pathogenic Leptospira. Most human infections are mild or asymptomatic. However, 10% of human leptospirosis cases develop into severe forms, including high leptospiremia, multi-organ injuries, and a dramatically increased mortality rate, which can relate to a sepsis-like phenotype. During infection, the triggering of the inflammatory response, especially through the production of cytokines, is essential for the early elimination of pathogens. However, uncontrolled cytokine production can result in a cytokine storm process, followed by a state of immunoparalysis, which can lead to sepsis and associated organ failures. In this review, the involvement of cytokine storm and subsequent immunoparalysis in the development of severe leptospirosis in susceptible hosts will be discussed. The potential contribution of major pro-inflammatory cytokines in the development of tissue lesions and systemic inflammatory response, as well as the role of anti-inflammatory cytokines in contributing to the onset of a deleterious immunosuppressive cascade will also be examined. Data from studies comparing susceptible and resistant mouse models will be included. Lastly, a concise discussion on the use of cytokines for therapeutic purposes or as biomarkers of leptospirosis severity will be provided.

Leptospirosis in human: Biomarkers in host immune responses

Leptospirosis remains one of the most widespread zoonotic diseases caused by spirochetes of the genus Leptospira, which accounts for high morbidity and mortality globally. Leptospiral infections are often found in tropical and subtropical regions, with people exposed to contaminated environments or animal reservoirs are at high risk of getting the infection. Leptospirosis has a wide range of clinical manifestations with non-specific signs and symptoms and often misdiagnosed with other acute febrile illnesses at early stage of infection. Despite being one of the leading causes of zoonotic morbidity worldwide, there is still a gap between pathogenesis and human immune responses during leptospiral infection. It still remains obscure whether the severity of the infection is caused by the pathogenic properties of the Leptospira itself, or it is a consequence of imbalance host immune factors. Hence, in this review, we seek to summarize the past and present milestone findings on the biomarkers of host immune response aspects during human leptospiral infection, including cytokine and other immune mediators. A profound understanding of the interlink between virulence factors and host immune responses during human leptospirosis is imperative to identify potential biomarkers for diagnostic and prognostic applications as well as designing novel immunotherapeutic strategies in future.

Molecular diagnostics for human leptospirosis

PURPOSE OF REVIEW

The definitive diagnosis of leptospirosis, which results from infection with spirochetes of the genus Leptospira, currently relies on the use of culture, serological testing (microscopic agglutination testing), and molecular detection. The purpose of this review is to describe new molecular diagnostics for Leptospira and discuss advancements in the use of available methods.

RECENT FINDINGS

Efforts have been focused on improving the clinical sensitivity of Leptospira detection using molecular methods. In this review, we describe a reoptimized pathogenic species-specific real-time PCR (targeting lipL32) that has demonstrated improved sensitivity, findings by two groups that real-time reverse-transcription PCR assays targeting the 16S rrs gene can improve detection, and two new loop-mediated amplification techniques. Quantitation of leptospiremia, detection in different specimen types, and the complementary roles played by molecular detection and microscopic agglutination testing will be discussed. Finally, a protocol for Leptospira strain subtyping using variable number tandem repeat targets and high-resolution melting will be described.

SUMMARY

Molecular diagnostics have an established role for the diagnosis of leptospirosis and provide an actionable diagnosis in the acute setting. The use of real-time reverse-transcription PCR for testing serum/plasma and cerebrospinal fluid, when available, may improve the detection of Leptospira without decreasing clinical specificity.

Changing patterns in leptospirosis: a three-decade study in Brazil

BACKGROUND

This study was conducted to investigate changes in the clinical pattern of leptospirosis over time, analyzing its clinical and laboratory presentations in a metropolitan city of Brazil.

METHOD

This was a retrospective study including all patients with leptospirosis admitted to tertiary care hospitals in Fortaleza in the northeast of Brazil, between 1985 and 2015. Patients were divided into three groups according to the year of hospital admission: group I for the years 1985-1995, group II for 1996-2005, and group III for 2006-2015. Demographic, clinical, and laboratory data were compared between the groups.

RESULTS

A total of 507 patients were included. Their mean age was 37.3±15.9years and 82.4% were male. The mean time between symptom onset and admission was 7±4 days. There was a linear decrease in the levels of serum urea (190.1±92.7, 135±79.5, and 95.6±73.3mg/dl, respectively, p <0.0001) and creatinine (5.8±2.9, 3.8±2.6, and 3.0±2.5mg/dl, respectively, p <0.0001) in each decade, while levels of hemoglobin (10.31±1.9, 10.8±2.0, and 11.5±2.1g/dl, respectively, p <0.0001) and platelets (57.900±52.650, 80.130±68.836, and 107.101±99.699×10⁹/l, respectively, p<0.0001) increased. There was a tendency towards a linear decrease in mortality (22%, 14%, and 11.6%, respectively, p=0.060).

CONCLUSIONS

Leptospirosis showed significant changes over time in this region. The main changes point to a decrease in disease severity and complications, such as acute kidney injury. Mortality has decreased, being close to 11%.

High level of IL-10 expression in the blood of animal models possibly relates to resistance against leptospirosis

Leptospirosis is a severe zoonosis which immunopathogenesis is poorly understood. We evaluated correlation between acute form of the disease and the ratio of the anti-inflammatory cytokine IL-10 to the pro-inflammatory TNF-α and IL-1β expression during the early phase of infection comparing resistant mice and susceptible hamsters infected with two different species of virulent Leptospira. The IL-10/TNF-α and IL-10/IL-1β expression ratios were higher in mouse compared to hamster independently of the Leptospira strain, suggesting a preponderant role of the host response and notably these cytokines in the clinical expression and survival to leptospirosis. Using an IL-10 neutralization strategy in Leptospira-infected mouse model, we also showed evidence of a possible role of this cytokine on host susceptibility, bacterial clearance and on regulation of cytokine gene expression.

Cytokines in human leptospirosis

BACKGROUND

Leptospirosis is a zoonotic disease with increased public health concern. Cytokines produced in response to the infection with pathogenic leptospires have been proposed to be involved in the pathogenesis of the disease. The aim of the study was to measure and evaluate the levels of 27 cytokines in patients with acute leptospirosis.

METHODS

The levels of 27 cytokines were measured from 42 acute leptospirosis cases; 47 samples were obtained from severe cases. Statistical analysis was performed using SPSS.

RESULTS

IL-6, IL-8, GM-CSF, IP-10, MCP-1, and VEGF levels differed significantly between the severe cases and the control group, while GM-CSF levels differed significantly between the mild cases and the control group (p<0.05). IL-6, IP-10 and MCP-1 were elevated in most cases. IP-10 was significantly higher in severe than in non-severe cases (p<0.05). The high IP-10 levels suggest a cellular immune response, despite the fact that leptospires are not intracellular organisms. IL-1ra, MCP-1, MIP-1b and TNF-α peaked 1-5 days post onset of illness (p.o.i.), IL-1b, IL-6, IL-8, IL-9, GM-CSF, IP-10 and MIP-1a peaked 6-10 days p.o.i., while VEGF peaked later (11-15 days p.o.i.). TNF-α was significantly lower in the severe cases with pulmonary involvement (p<0.05).

CONCLUSIONS

Having a better insight into the host immune response in leptospirosis could be the basis for immunotherapeutic targets, especially for the severe cases in which antibiotic treatment is not enough.

Clinical and laboratory associations of severity in a Sri Lankan cohort of patients with serologically confirmed leptospirosis: a prospective study

BACKGROUND

Leptospirosis results in significant morbidity and mortality. This study elucidates markers of severity in a cohort of Sri Lankan patients.

METHODS

Patients presenting to three healthcare institutions in the Western province of Sri Lanka with leptospirosis serological confirmed by the microscopic agglutination test (MAT) were included. Prospective data regarding demographic, clinical and laboratory parameters was extracted. Univariate associations and subsequent multivariate logistic regression models were constructed.

RESULTS

The study included 232 patients, with 68.5% (159) demonstrating severe disease. Significant associations of severe disease at a significance level of p<0.05 were fever >38.8°C on presentation, age >40 years, muscle tenderness, tachycardia on admission, highest white cell count >12 350/mm(3) and <7900/mm(3), highest neutrophil percentage >84%, haemoglobin >11.2 g/dL and <10.2 g/dL, packed cell volume (PCV) >33.8% and <29.8%, lowest platelet count <63 500/mm(3), highest alanine transaminase (ALT) >70 IU/L and hyponatremia with sodium <131 mEq/L. On multivariate analysis, PCV <29.8% (p=0.011; OR 3.750; CI: 1.394-10.423), ALT >70 IU/L (p=0.044; OR 2.639; CI: 1.028-6.774) and hyponatremia <131 mEq/L (p=0.019; OR 6.413; CI: 1.353-30.388) were independent associations of severe disease.

CONCLUSIONS

Severity associations were demonstrated with both clinical and laboratory parameters. There is a need for novel biomarkers for prediction of severity in leptospirosis.

Cytokine levels as biomarkers for leptospirosis patients

Inflammatory mediators were suggested to be biomarkers for prediction of disease severity. In this study, we investigated the levels of IL-6, IL-8, IL-10 and TNF-α in leptospirosis patients with mild or severe illnesses. Sera samples were divided into two groups. The OI group and NOI groups included sera from patients with and without organ involvement, respectively. Each group consisted of 20 pairs of sera. Twenty-five sera from healthy individuals were included as controls. Cytokine levels were compared. Although IL-6, IL-8 and IL-10 levels in acute sera from the OI group were significantly higher than NOI group, only IL-8 level was significantly higher in the OI group when cytokine levels in convalescent sera were compared. TNF-α, an inflammatory cytokine widely studied in leptospirosis was not significantly different between two groups of patients. Our data suggested that IL-6, IL-8 and IL-10 were involved in disease severity. However, time of specimen collection could affect the significant levels of cytokines especially as biomarkers for monitoring disease severity.

Leptospirosis: a report on a series of five autochthonous cases in a Greek region

Leptospirosis is a worldwide zoonotic disease difficult to diagnose both to the clinic and the laboratory. Many risk factors have been involved, such as planting, hunting, harvesting and butchering or sports, such as rafting. We reported our experience through a period of 20  months and we tried to investigate prognostic factors predicting clinical outcomes. Five male patients were admitted to our Department with a median age of 40  years. Overall, three out of five patients presented to other hospital and were transferred to ours with a wrong or delayed diagnosis. In terms of clinical signs and symptoms, all presented with fever, myalgia, headache and jaundice, whereas conjunctival suffusion was present in 80% of them. Acute renal injury and liver deficiency were diagnosed in all subjects. Acute renal failure management required dialysis in 3/5 patients, whereas renal recovery was achieved soon after clinical improvement. However, clinical awareness and serology are the most important tools for accurate and quick diagnosis in order to administer the appropriate therapy.

Specific CD4+ T-Cell Reactivity and Cytokine Release in Different Clinical Presentations of Leptospirosis

Clinical manifestations of leptospirosis are highly variable: from asymptomatic to severe and potentially fatal. The outcome of the disease is usually determined in the immunological phase, beginning in the second week of symptoms. The underlying mechanisms, predictive factors, and individual immune responses that contribute to clinical variations are not well understood. The aim of this study was to determine the specifics of CD4(+) T-cell reactivity and cytokine release after stimulation with leptospiral antigens in patients with leptospirosis of different disease severities (patients with mild and severe symptoms) and in control subjects (with and without proven exposure to Leptospira). Whole-blood specimens were stimulated with Leptospira antigens in vitro. Subsequently, intracellular staining of cytokines was performed, and flow cytometry was used to assess the expression of CD40 ligand (CD40L) and the production of gamma interferon (IFN-γ), interleukin-10 (IL-10), IL-2, and tumor necrosis factor alpha (TNF-α) by CD4(+) T cells. The production of inflammatory cytokines such as TNF-α by CD4(+) T cells after stimulation with leptospiral antigens was highest in patients with severe disease. In contrast, the ratio of IL-10 production to TNF-α production was higher in exposed subjects than in patients with mild and severe disease. Levels of proinflammatory cytokines such as TNF-α may be useful markers of the severity of the immunological phase of leptospirosis. IL-10 production by T cells after antigen-specific stimulation may indicate a more successful downregulation of the inflammatory response and may contribute to an asymptomatic course of the disease.