Direct detection of leptospiral material in human postmortem samples

Fatal acute undifferentiated febrile illness among clinically suspected leptospirosis cases in Colombia, 2016-2019

BACKGROUND

Acute undifferentiated febrile illness is a common challenge for clinicians, especially in tropical and subtropical countries. Incorrect or delayed diagnosis of febrile patients may result in medical complications or preventable deaths. Common causes of acute undifferentiated febrile illness in Colombia include leptospirosis, rickettsioses, dengue fever, malaria, chikungunya, and Zika virus infection. In this study, we described the acute undifferentiated febrile illness in postmortem patients reported as suspected cases of leptospirosis through the national leptospirosis surveillance in Colombia, 2016-2019.

METHODOLOGY/PRINCIPAL FINDINGS

We retrospectively analyze human fresh and formalin-fixed tissue samples from fatal suspected leptospirosis cases reported by the Public Health Laboratories in Colombia. Leptospirosis confirmation was made by immunohistochemistry, real-time polymerase chain reaction (PCR) in the tissue samples. In some cases, the serum sample was used for confirmation by Microagglutination test (MAT). Simultaneously, tissue samples were tested by PCR for the most common viral (dengue, Zika, and chikungunya), bacterial (Brucella spp., and Rickettsia spp.), and parasitic (malaria). Fresh tissue samples from 92 fatal suspected leptospirosis cases were reported to the National Reference Laboratory from 22/32 departments in Colombia. We confirmed leptospirosis in 27% (25/92) of cases. Other pathogens identified by real-time PCR were Brucella spp. (10.9%), Rickettsia spp. (14.1%), and dengue (2.2%). Dengue (6.9%), hepatitis (3.5%), and Yellow Fever cases (2.2%) were detected by the pathology. All patients were negative for chikungunya and Plasmodium spp. Most cases were classified as undifferentiated febrile illnesses (45.7%; 42/92).

CONCLUSIONS/SIGNIFICANCE

This study underscores the importance of early and accurate recognition of leptospirosis to prevent mortalities. Moreover, it draws attention to the existence of other febrile syndromes in Colombia, including rickettsiosis and brucellosis, that currently lack sufficient human surveillance and regular reporting. Expanding laboratory surveillance to include viruses such as Hantavirus, Mayaro virus, Oropouche virus, and West Nile virus is crucial.

Leptospiral Infection, Pathogenesis and Its Diagnosis-A Review

Leptospirosis is a perplexing conundrum for many. In the existing literature, the pathophysiological mechanisms pertaining to leptospirosis is still not understood in full. Considered as a neglected tropical zoonotic disease, leptospirosis is culminating as a serious problem worldwide, seemingly existing as co-infections with various other unrelated diseases, including dengue and malaria. Misdiagnosis is also common as non-specific symptoms are documented extensively in the literature. This can easily lead to death, as the severe form of leptospirosis (Weil's disease) manifests as a complex of systemic complications, especially renal failure. The virulence of Leptospira sp. is usually attributed to the outer membrane proteins, including LipL32. With an armament of virulence factors at their disposal, their ability to easily adhere, invade and replicate within cells calls for a swift refinement in research progress to establish their exact pathophysiological framework. As an effort to reconstitute the current knowledge on leptospirosis, the basis of leptospiral infection, including its risk factors, classification, morphology, transmission, pathogenesis, co-infections and clinical manifestations are highlighted in this review. The various diagnostic techniques are also outlined with emphasis on their respective pros and cons.

Dissemination kinetics and pathology of canine Leptospira icterohaemorrhagiae isolate in a guinea pig infection model

Despite significant progress made in elucidating the mechanism of acute human leptospirosis in different organs, there is a paucity of information in organs such as the heart, pancreas, brain, and adrenal gland. This study was designed to establish leptospire dissemination kinetics and patho-morphological changes associated with these orangs in the guinea pig infection model using cultural isolation (CI), polymerase chain reaction (PCR), Warthin Starry silver stain (WSss), immunohistochemistry (IH), and transmission electron microscopy (TEM). Twenty guinea pigs were inoculated intra-peritoneally with a low dosage of 1 × 10⁷ Leptospira interrogans serovar Icterohaemorrhagiae and 10 as control using distilled water. The guinea pigs were sacrificed at post-infection day (p.i.d.) ½, 1, 3, 5, and 7 followed by the harvest of the brain, pancreas, adrenal gland, heart, lungs, liver, kidneys, and spleen for CI, PCR, HE, WSss, IH, and TEM evaluations. The study revealed early dissemination of Leptospira organism in the brain, heart, pancreas, and adrenal gland and exerted various histopathological changes that were not explicitly elucidated in previous studies. This study revealed that the virulent pathogenic isolate of Leptospira organism obtained from clinically infected dog mimicked the same clinical manifestations, gross and histopathological changes especially in organs that were not previously evaluated.

Diagnostic accuracy of genetic markers and nucleic acid techniques for the detection of Leptospira in clinical samples: A meta-analysis

BACKGROUND

Leptospirosis is often difficult to diagnose because of its nonspecific symptoms. The drawbacks of direct isolation and serological tests have led to the increased development of nucleic acid-based assays, which are more rapid and accurate. A meta-analysis was performed to evaluate the diagnostic accuracy of genetic markers for the detection of Leptospira in clinical samples.

METHODOLOGY AND PRINCIPLE FINDINGS

A literature search was performed in Scopus, PubMed, MEDLINE and non-indexed citations (via Ovid) by using suitable keyword combinations. Studies evaluating the performance of nucleic acid assays targeting leptospire genes in human or animal clinical samples against a reference test were included. Of the 1645 articles identified, 42 eligible studies involving 7414 samples were included in the analysis. The diagnostic performance of nucleic acid assays targeting the rrs, lipL32, secY and flaB genes was pooled and analyzed. Among the genetic markers analyzed, the secY gene showed the highest diagnostic accuracy measures, with a pooled sensitivity of 0.56 (95% CI: 0.50-0.63), a specificity of 0.98 (95% CI: 0.97-0.98), a diagnostic odds ratio of 46.16 (95% CI: 6.20-343.49), and an area under the curve of summary receiver operating characteristics curves of 0.94. Nevertheless, a high degree of heterogeneity was observed in this meta-analysis. Therefore, the present findings here should be interpreted with caution.

CONCLUSION

The diagnostic accuracies of the studies examined for each genetic marker showed a significant heterogeneity. The secY gene exhibited higher diagnostic accuracy measures compared with other genetic markers, such as lipL32, flaB, and rrs, but the difference was not significant. Thus, these genetic markers had no significant difference in diagnostic accuracy for leptospirosis. Further research into these genetic markers is warranted.

Three Leptospira Strains From Western Indian Ocean Wildlife Show Highly Distinct Virulence Phenotypes Through Hamster Experimental Infection

Leptospirosis is one of the most widespread zoonoses worldwide, with highest incidence reported on tropical islands. Recent investigations carried out in a One-Health framework have revealed a wide diversity of pathogenic Leptospira lineages on the different islands of Western Indian Ocean carried out by a large diversity of mammal reservoirs, including domestic and wild fauna. Using golden Syrian hamsters as a model of acute infection, we studied the virulence of Leptospira interrogans, L. mayottensis, and L. borgpetersenii isolates obtained from rats, tenrecs, and bats, respectively. Hamsters were inoculated with 2.10⁸ bacterial cells and monitored for 1 month. The L. interrogans isolate proved to be the most pathogenic while L. mayottensis and L. borgpetersenii isolates induced no clinical symptoms in the infected hamsters. High leptospiral DNA amounts were also detected in the urine and organs of hamsters infected with the L. interrogans isolate while L. mayottensis and L. borgpetersenii isolates mostly failed to disseminate into the organism. In addition, histological damage was more pronounced in the kidneys and lungs of hamsters infected with the L. interrogans isolate. Altogether, these data support that Leptospira strains shed by mammals endemic to this insular ecosystem (L. mayottensis and L. borgpetersenii isolates) are less pathogenic than the L. interrogans rat-borne isolate. These results may provide a relevant framework for understanding the contrasting epidemiology of human leptospirosis observed among Western Indian Ocean islands.

[Diagnosis of leptospirosis in dogs]

Rapid confirmation of the diagnosis leptospirosis is important in order to apply appropriate treatment; in addition, infected dogs are a zoonotic risk. Culture and isolation of living leptospires from blood, urine, or tissues is considered the reference standard of diagnosis. However, sensitivity are low, and leptospires require weeks to months to grow. Therefore, diagnosis of leptospirosis is most commonly based on antibody testing or the detection of Leptospira spp. DNA by PCR. Microscopic agglutination test (MAT) is currently still the recommended confirmatory test for canine leptospirosis, despite its numerous limitations (e. g., negative results in early infection, positive results due to vaccine-associated antibodies). ELISA can differentiate between IgG and IgM antibodies and thus, discriminate current infections from previous vaccination or exposure. Point-of-care tests and in-house-PCR tests have recently been developed for use in private practice allowing easy and immediate diagnosis. However, only few data on sensitivity and specificity of these tests exist so far. A reliable diagnosis can only be established in case of a positive PCR result or a fourfold titre increase in MAT.

Real-Time PCR Reveals Rapid Dissemination of Leptospira interrogans after Intraperitoneal and Conjunctival Inoculation of Hamsters

The pathogen Leptospira interrogans is a highly motile spirochete that causes acute and fulminant infections in humans and other accidental hosts. Hematogenous dissemination is important for infection by the pathogen but remains poorly understood because few animal model studies have used sensitive tools to quantify the bacteria. We evaluated the kinetics of leptospiral infection in Golden Syrian hamsters by a sensitive quantitative real-time PCR (TaqMan) with lipl32 as the target gene. The dissemination and bacterial burden were measured after intraperitoneal infection with a high dose (10(8)) or low dose (2.5 × 10(2)) of leptospires. We also examined the conjunctival challenge route to mimic the natural history of infection. Quantification of leptospires in perfused animals revealed that pathogens were detected in all organs of intraperitoneally infected hamsters, including the eye and brain, within 1 h after inoculation of 10(8) virulent L. interrogans bacteria. Peaks of 10(5) to 10(8) leptospires per gram or per milliliter were achieved in blood and all tissues between day 4 and day 8 after intraperitoneal inoculation of high- and low-dose challenges, respectively, coinciding with macroscopic and histological changes. The conjunctival route resulted in a delay in the time to peak organ burden in comparison to intraperitoneal infection, indicating that although infection could be established, penetration efficiency was low across this epithelial barrier. Surprisingly, infection with a large inoculum of high-passage-number attenuated L. interrogans strains resulted in dissemination to all organs in the first 4 days postinfection, albeit with a lower burden, followed by clearance from the blood and organs 7 days postinfection and survival of all animals. These results demonstrate that leptospiral dissemination and tissue invasion occur. In contrast, development of a critical level of tissue burden and pathology are dependent on the virulence of the infecting strain.

High sensitive PCR method for detection of pathogenic Leptospira spp. in paraffin-embedded tissues

This study describes the development and application of a new PCR assay for the specific detection of pathogenic leptospires and its comparison with a previously reported PCR protocol. New primers were designed for PCR optimization and evaluation in artificially-infected paraffin-embedded tissues. PCR was then applied to post-mortem, paraffin-embedded samples, followed by amplicon sequencing. The PCR was more efficient than the reported protocol, allowing the amplification of expected DNA fragment from the artificially infected samples and from 44% of the post-mortem samples. The sequences of PCR amplicons from different patients showed >99% homology with pathogenic leptospires DNA sequences. The applicability of a highly sensitive and specific tool to screen histological specimens for the detection of pathogenic Leptospira spp. would facilitate a better assessment of the prevalence and epidemiology of leptospirosis, which constitutes a health problem in many countries.

Leptospirosis: current situation and trends of specific laboratory tests

Leptospirosis is re-emerging as a worldwide zoonosis and is caused by bacteria of the genus Leptospira. Human leptospirosis is associated with high temperature and humidity. Laboratory tests are indispensible for the early diagnosis and proper disease management. The demand for suitable leptospirosis point-of-care diagnostic tests grows with the awareness and number of incidences. Confirmation is achieved by the microscopic agglutination test, bacterial cultivation, PCR or histopathologic methods. However, high costs, poor standardization and/or elaborate sample preparation prevent routine use at the point of care. Cost-efficient, but insensitive serological methods dominate the diagnostic landscape and, likewise, urgently need improvement toward greater compliance with some of the point-of-care criteria. Combined application of antigen and antibody detection methods increases accuracy, but also new development or transfer of diagnostic technologies should be considered useful. Nano- and microparticle technology may play a key role in improving future antigen detection methods.

Comparison of two PCR methods for detection of Leptospira interrogans in formalin-fixed and paraffin-embedded tissues

In this study we compared two polymerase chain reaction (PCR) methods using either 16S ribosomal RNA (rRNA) or 23S rRNA gene primers for the detection of different Leptospira interrogans serovars. The performance of these two methods was assessed using DNA extracted from bovine tissues previously inoculated with several bacterial suspensions. PCR was performed on the same tissues before and after the formalin-fixed, paraffin-embedding procedure (FFPE tissues). The 23S rDNA PCR detected all fresh and FFPE positive tissues while the 16S rDNA-based protocol detected primarily the positive fresh tissues. Both methods are specific for pathogenic L. interrogans. The 23S-based PCR method successfully detected Leptospira in four dubious cases of human leptospirosis from archival tissue specimens and one leptospirosis-positive canine specimen. A sensitive method for leptospirosis identification in FFPE tissues would be a useful tool to screen histological specimen archives and gain a better assessment of human leptospirosis prevalence, especially in tropical countries, where large outbreaks can occur following the rainy season.

Outpatient follow-up of patients hospitalized for acute leptospirosis

OBJECTIVE

The outcome of leptospirosis after the resolution of acute disease, either spontaneously or after treatment, is not well described. The aim of this study was to assess the possible sequelae of acute leptospirosis after hospital discharge.

METHODS

We report here a prospective study carried out in São Paulo, Brazil in which patients hospitalized for leptospirosis were followed in the outpatient setting.

RESULTS

Forty-seven patients were serially assessed: 32 severe and 15 mild cases. Early and late complications were not common in either group, but subjective complaints were common in the first few weeks after hospital discharge (53% of severe cases, 40% of mild cases). Two patients had continuing complaints: one had profound general malaise and the other developed new onset panic disorder. The sample analyzed represented 26% of the patients hospitalized with leptospirosis in the city of São Paulo during the study period. The duration of follow-up was an average of approximately 20 days at the first visit, and approximately 40 days at the second visit. Forty-seven patients came for one follow-up visit and 22 of the same patients had two follow-up visits.

CONCLUSIONS

While two of 47 patients reported continuing symptoms after hospitalization for acute leptospirosis, no definitive, objective evidence of chronic sequelae due to this infection was proven. While preliminary, these observations point to the need for a prospective, rigorous and systematic study to definitively determine and characterize late complications and chronic disease after acute leptospirosis.

An emerging pulmonary haemorrhagic syndrome in dogs: similar to the human leptospiral pulmonary haemorrhagic syndrome?

Severe pulmonary haemorrhage is a rare necropsy finding in dogs but the leptospiral pulmonary haemorrhagic syndrome (LPHS) is a well recognized disease in humans. Here we report a pulmonary haemorrhagic syndrome in dogs that closely resembles the human disease. All 15 dogs had massive, pulmonary haemorrhage affecting all lung lobes while haemorrhage in other organs was minimal. Histologically, pulmonary lesions were characterized by acute, alveolar haemorrhage without identifiable vascular lesions. Seven dogs had mild alveolar wall necrosis with hyaline membranes and minimal intraalveolar fibrin. In addition, eight dogs had acute renal tubular necrosis. Six dogs had a clinical diagnosis of leptospirosis based on renal and hepatic failure, positive microscopic agglutination test (MAT) and/or positive blood/urine Leptospira-specific PCR. Leptospira could not be cultured post mortem from the lungs or kidneys. However, Leptospira-specific PCR was positive in lung, liver or kidneys of three dogs. In summary, a novel pulmonary haemorrhagic syndrome was identified in dogs but the mechanism of the massive pulmonary erythrocyte extravasation remains elusive. The lack of a consistent post mortem identification of Leptospira spp. in dogs with pulmonary haemorrhage raise questions as to whether additional factors besides Leptospira may cause this as yet unrecognized entity in dogs.

Inactivation of a putative flagellar motor switch protein FliG1 prevents Borrelia burgdorferi from swimming in highly viscous media and blocks its infectivity

The flagellar motor switch complex protein FliG plays an essential role in flagella biosynthesis and motility. In most motile bacteria, only one fliG homologue is present in the genome. However, several spirochete species have two putative fliG genes (referred to as fliG1 and fliG2) and their roles in flagella assembly and motility remain unknown. In this report, the Lyme disease spirochete Borrelia burgdorferi was used as a genetic model to investigate the roles of these two fliG homologues. It was found that fliG2 encodes a typical motor switch complex protein that is required for the flagellation and motility of B. burgdorferi. In contrast, the function of fliG1 is quite unique. Disruption of fliG1 did not affect flagellation and the mutant was still motile but failed to translate in highly viscous media. GFP-fusion and motion tracking analyses revealed that FliG1 asymmetrically locates at one end of cells and the loss of fliG1 somehow impacted one bundle of flagella rotation. In addition, animal studies demonstrated that the fliG1- mutant was quickly cleared after inoculation into the murine host, which highlights the importance of the ability to swim in highly viscous media in the infectivity of B. burgdorferi and probably other pathogenic spirochetes.

Use of quantitative real-time PCR for studying the dissemination of Leptospira interrogans in the guinea pig infection model of leptospirosis

The dynamics of leptospirosis infection have been poorly studied. The purpose of this study was to determine the LD50, rate of bacterial dissemination, histopathology and antibody responses against leptospira following inoculation with the highly virulent Leptospira interrogans Fiocruz L1-130 strain in a guinea pig model of leptospirosis. Three routes of infection (intraperitoneal, conjunctival and subcutaneous inoculation) were used to establish disease in guinea pigs. The size and kinetics of leptospiral burdens in the blood and tissues of infected animals were determined over a 1 week course of infection using quantitative real-time PCR (qPCR). Bacteraemia peaked at day 5 post-infection reaching more than 5×104 leptospires ml−1. The highest spirochaetal load was found in the liver and kidneys, and was associated with alterations in organ tissues and a decline in liver and kidney functions. In contrast, lesions and bacteria were not detected in guinea pigs infected with an avirulent strain derived from a high-passage-number in vitro-passaged variant of the Fiocruz L1-130 strain. The use of qPCR supports the findings of earlier studies and provides an easy and reliable method for the quantification of L. interrogans in the tissues of infected animals. qPCR will be used in future studies to evaluate the efficacy of vaccine candidates against leptospirosis and the virulence of selected L. interrogans mutants relative to the parental strain.

Evaluation of protective immunity of Leptospira immunoglobulin like protein A (LigA) DNA vaccine against challenge in hamsters

We demonstrated earlier that immunization with recombinant Leptospira immunoglobulin like protein A (LigA) induced significant protection against virulent Leptospira interrogans serovar Pomona challenge in hamsters. However, the protective immune mechanism remains unclear. In the present study we demonstrated the protective efficacy of a LigA DNA vaccine and evaluated the immune mechanism underlying the protection against leptospirosis in hamsters. The LigA DNA vaccine was constructed in two truncated forms as the conserved portion (LigAcon) and a variable portion (LigAvar). Four-week-old hamsters were immunized three times at two-week intervals with vector alone or an equal amount of a recombinant construct containing either LigAcon or LigAvar. All animals were challenged intraperitoneally 2 weeks after the last immunization with a dose (LD50=10(8)) of virulent L. interrogans serovar Pomona. Prior to challenge, four animals were sacrificed, the spleen was removed aseptically, and splenocytes were assayed for lymphocyte proliferation and cytokine profiles in response to recall antigen. The protective efficacy was evaluated on the basis of survival and histopathological lesions in the kidney. The immuno-protective mechanism was assessed on the basis of Th1/Th2 profile of cytokines in immunized animals. Our results indicate that immunization with LigA DNA vaccine provides significant protection against leptospirosis. We suggest that immuno-protection is conferred by both humoral and cellular immunity as revealed by an increase in antibody titers during subsequent boosters, significant proliferation of lymphocytes and enhancement of both Th1 and Th2 cytokines. Taken together, the present study suggests that a LigA DNA vaccine is a promising candidate for prevention of leptospirosis.

Molecular detection of Leptospira interrogans in human tissues and environmental samples in a lethal case of leptospirosis

A forensic case of suspected Leptospirosis with fatal course was resolved by the molecular detection of Leptospira interrogans in postmortem human tissues and in environmental samples. Polymerase chain reaction analysis and DNA sequencing confirmed the clinical diagnosis of Weil syndrome, and the death was considered to be an occupational accident with all the legal implications.

Leptospirosis: pathogenesis, immunity, and diagnosis

PURPOSE OF REVIEW

Leptospirosis is among the most important zoonotic diseases worldwide. Completion of the genomic sequences of leptospires has facilitated advances in diagnosis and prevention of the disease, and yielded insight into its pathogenesis. This article reviews this research, emphasizing recent progress.

RECENT FINDINGS

Leptospirosis is caused by a group of highly invasive spiral bacteria (spirochetes) that can infect both people and animals. Spirochetes can survive in the environment and host, and therefore outer membrane and secretory proteins that interact with the host are of considerable interest in leptospire research. The genetic approach to studying pathogenesis is hindered by fastidious growth of pathogenic leptospires. Integrated genomic and proteomic approaches, however, have yielded enhanced understanding of the pathogenesis of leptospirosis. Furthermore, studies of innate immune response to the organism have enhanced our understanding of host susceptibility and resistance to infection. In-silico analysis and high-throughput cloning and expression have had major impacts on efforts to develop vaccine candidates and diagnostic reagents.

SUMMARY

In the future, we must effectively utilize the wealth of genetic information to combat the disease. More studies into genetics, immune mechanisms that may be exploited to prevent leptospirosis, and pathogenesis of the disease are necessary.

Polymerase chain reaction in comparison with serological tests for early diagnosis of human leptospirosis

The aim of this study was to compare the sensitivity and specificity of polymerase chain reaction (PCR) using two primer pairs and combined with blood culture, immunoglobulin M enzyme-linked immunosorbent assay (IgM ELISA), microscopic agglutination test (MAT) and slide agglutination test (SAT) in the diagnosis of human leptospirosis. We analysed 124 serum samples: 60 from patients with confirmed leptospirosis, 20 from patients with other diseases and 44 from healthy individuals. Analysing the first serum sample collected during the first 3-8 days of disease, the sensitivities of the four tests MAT, IgM ELISA, SAT and PCR were, respectively, 69.0%, 79.3%, 72.4% and 62%. In subsequent samples, those same sensitivities were, respectively, 95.4%, 100%, 100% and 72.7% in samples collected from days 9 to 14 and 88.9%, 88.9%, 77.8% and 44.4% in those collected from days 15 to 42. The most specific method (at 100%) was PCR and the least specific (at 89.1%) was IgM ELISA. Although we found PCR to be less sensitive than the serological tests over the course of the disease, our data indicate that PCR was the most sensitive in those initial serum samples presenting no specific antibodies detectable by any of the serological methods tested. We also recommend that PCR can be used in combination with serological tests as we found that this improves the sensitivity of the diagnosis of leptospirosis in the first phase of the disease (93.1-96.5%).

NF-kB activation and p38 phosphorilation in microglial cells infected with Leptospira or exposed to partially purified leptospiral lipoproteins

Recently, we have shown a differential susceptibility of non-pathogenic vs. pathogenic leptospires to phagocytosis and killing by microglial cells. Although all ingested to some extent, only the pathogenic strains survived intracellularly while the non-pathogenic ones were killed in a time-dependent manner. By the same infection model, here we demonstrate that microglial cells respond to Leptospira infection with a time- and dose-dependent induction of molecular signals (p38 phosphorilation and NF-kB activation) and the production of soluble factors (cytokines and nitric oxide). Such bio-molecular response is predominantly observed against the pathogenic Leptospira; the phenomenon is reproduced by leptospiral lipoproteins and, to a lower extent, by leptospiral-derived LPS. These data provide initial evidence that Leptospira affects microglial cell response in a different manner depending upon the virulence of the infecting strain; specific bacterial components happen to be involved in the induction of such pathogen-induced immune response.

An outbreak of leptospirosis in seals (Phoca vitulina) in captivity

An outbreak of leptospirosis in seals (Phoca vitulina) in captivity is described. In a zoo in The Netherlands 5 adult seals died within 12 days. At necropsy all animals showed signs of acute septicaemia, consistent with acute leptospirosis. Serological examination of one animal was positive for antibodies against Leptospira interrogans serovar Icterohaemorrhagiae and the serologically closely related serovar Copenhageni. Polymerase chain reaction was positive in one other animal. 8 nutria (Myocastor coypus) were examined, serologically, through bacteriological culture and PCR. 81,8% (9/11) were serologically positive for Leptospira. The seals and nutria were housed in the same water system.

Disproportional exaggerated aspartate transaminase is a useful prognostic parameter in late leptospirosis

AIM: To evaluate the hepatic dysfunction in leptospirosis is usually mild and resolved eventually. However, sequential follow-up of liver biochemical data remained lacking..

METHODS: The biochemistry data and clinical symptoms of 11 sporadic patients were collected and analyzed, focusing on the impacts of leptospirosis upon liver biochemistry tests.

RESULTS: The results disclosed that of the 11 cases, 5 or 45% died. The liver biochemistry data in the beginning of the disease course were only mildly elevated. Nevertheless, late exaggerated aspartate transaminase (AST) elevations were noted in three cases who finally died when compared with the typical course. Besides, significant higher AST/alanine transaminase (ALT) ratios (AARs) of the peak levels for transaminase were also noted in the cases who eventually succumbed. The mean±SD of AARs for the survival group and dead group were 5.652.27 (n = 5) and 1.860.64 (n = 6) respectively (P = 0.006). The ratios of the cases who finally died were all more than 3.0. Conversely, the survival group’s ratios were less than 3.0.

CONCLUSION: Serial follow-up of transaminase might provide evidence to predict some rare evolutions in leptospirosis. If AST elevated progressively without a concomitant change of ALT, it might indicate an acute disease course with ensuing death. Additionally, AAR is another prognostic parameter for leptospirosis. Once the value was higher than 3.0, a grave prognosis is inevitable.