Leptospirosis

Cleavage of cell junction proteins as a host invasion strategy in leptospirosis

Infection and invasion are the prerequisites for developing the disease symptoms in a host. While the probable mechanism of host invasion and pathogenesis is known in many pathogens, very little information is available on Leptospira invasion/pathogenesis. For causing systemic infection Leptospira must transmigrate across epithelial barriers, which is the most critical and challenging step. Extracellular and membrane-bound proteases play a crucial role in the invasion process. An extensive search for the proteins experimentally proven to be involved in the invasion process through cell junction cleavage in other pathogens has resulted in identifying 26 proteins. The similarity searches on the Leptospira genome for counterparts of these 26 pathogenesis-related proteins identified at least 12 probable coding sequences. The proteins were either extracellular or membrane-bound with a proteolytic domain to cleave the cell junction proteins. This review will emphasize our current understanding of the pathogenic aspects of host cell junction-pathogenic protein interactions involved in the invasion process. Further, potential candidate proteins with cell junction cleavage properties that may be exploited in the diagnostic/therapeutic aspects of leptospirosis will also be discussed. KEY POINTS: • The review focussed on the cell junction cleavage proteins in bacterial pathogenesis • Cell junction disruptors from Leptospira genome are identified using bioinformatics • The review provides insights into the therapeutic/diagnostic interventions possible.

Leptospiral LipL45 lipoprotein undergoes processing and shares structural similarities with bacterial sigma regulators

Leptospirosis is a widespread zoonotic infectious disease of human and veterinary concern caused by pathogenic spirochetes of the genus Leptospira. To date, little progress towards understanding leptospiral pathogenesis and identification of virulence factors has been made, which is the main bottleneck for developing effective measures against the disease. Some leptospiral proteins, including LipL32, Lig proteins, LipL45, and LipL21, are being considered as potential virulence factors or vaccine candidates. However, their function remains to be established. LipL45 is the most expressed membrane lipoprotein in leptospires, upregulated when the bacteria are transferred to temperatures resembling the host, expressed during infection, suppressed after culture attenuation, and known to suffer processing in vivo and in vitro, generating fragments. Based on body of evidence, we hypothesized that the LipL45 processing might occur by an auto-cleavage event, deriving two fragments. The results presented here, based on bioinformatics, structure modeling analysis, and experimental data, corroborate that LipL45 processing probably includes a self-catalyzed non-proteolytic event and suggest the participation of LipL45 in cell-surface signaling pathways, as the protein shares structural similarities with bacterial sigma regulators. Our data indicate that LipL45 might play an important role in response to environmental conditions, with possible function in the adaptation to the host.

Seroprevalence of leptospirosis among stray dogs in Bosnia and Herzegovina

Leptospirosis is a (re) emerging zoonosis that occurs worldwide. This study aimed to assess seroprevalence of leptospirosis and to identify the most common reactive serovars and risk factors for seropositivity in apparently healthy stray dogs of unknown vaccination status in the Sarajevo region of Bosnia and Herzegovina. Positive microscopic agglutination test titres (≥ 1:25) were detected in 3.87% (156/4028) of samples and most of the sera reacted against one serovar (85.9%). Dogs were most commonly reactive to Canicola (40.4%) and Hardjo (33.3%), followed by Pomona (15.4%) Tarassovi (14.7%), Icterohaemorrhagiae (8.3%), Grippotyphosa (5.8%), Bratislava (1.3%) and Saxkoebing (0.6%). Dogs older than one year had higher odds of seropositivity compared to younger dogs. The seropositivity was higher in spring and autumn than in summer. These results advocate for the need of a control strategy for this zoonosis in the country, which should include sero-surveillance, monitoring, and the inclusion of additional serovars in the testing.

Genetic structure and diversity of the rfb locus of pathogenic species of the genus Leptospira

Leptospirosis is caused by pathogenic strains of the genus Leptospira and is considered the most widespread zoonotic bacterial disease. The genus is characterized by the large number of serology variants, which challenges developing effective serotyping methods and vaccines with a broad spectrum. Because knowledge on the genetic basis of the serological diversity among leptospires is still limited, we aimed to explore the genetic structure and patterns of the rfb locus, which is involved in the biosynthesis of lipopolysaccharides, the major surface antigen that defines the serovar in leptospires. Here, we used genomic data of 722 pathogenic samples and compared the gene composition of their rfb locus by hierarchical clustering. Clustering analysis showed that the rfb locus gene composition is species-independent and strongly associated with the serological classification. The samples were grouped into four well-defined classes, which cluster together samples either belonging to the same serogroup or from different serogroups but sharing serological affinity. Our findings can assist in the development of new strategies based on molecular methods, which can lead to better tools for serological identification in this zoonosis.

Tracking potential Leptospira sources following human cases of leptospirosis: A One Health approach applied to an ecosystem in Brittany, France

Pathogenic Leptospira can cause leptospirosis: a widespread, potentially fatal bacterial zoonosis whose risk is mediated by the soil and water features, animal host distributions, meaning the local ecosystem. When human cases of leptospirosis occur, it is challenging to track down their source because ecosystem-level epidemiological knowledge on Leptospira is needed. Between 2016 and 2019 in a focal riparian ecosystem, the human population experienced an outbreak and successive cases of leptospirosis attributable to L. kirschneri and L. interrogans. The epidemiological investigation was carried out using the One Health approach, as described in international health guidelines. As a first step in this process, we investigated leptospiral carriage in the main animal hosts found in the region. We sampled 143 nutrias, 17 muskrats, and 10 Norway rats using convenient trapping. DNA was extracted from their kidneys, lungs, and urine and subjected to real-time PCR (RT-PCR) targeting the Leptospira 16S rDNA and lfb1 genes. In the farms along the river's stretch of interest, we sampled serum from 439 cattle and used a microscopic agglutination test to detect the presence of antibodies against Leptospira. Urine samples were concomitantly obtained from 145 cattle and were used in two analyses: RT-PCR targeting the Leptospira 16S rDNA gene and Leptospira culturing. We found th, wt rodents were the most likely source of the L. interrogans behind the human cases. The cattle tested negative for Leptospira DNA but positive for antibodies against the serogroups implicated in the human cases. We failed to identify the potential source of the L. kirschneri responsible for several human cases of leptospirosis. Our results call for further clarification of the Leptospira maintenance community, which may comprise known maintenance hosts, such as rodents, as well as taxa not commonly considered to be maintenance hosts but that can still spread Leptospira. The resulting research network will collaboratively conduct future eco-epidemiological surveys to illuminate the leptospirosis risks faced by humans and animals within ecosystems.

Acute pancreatitis as a rare complication of leptospirosis: A case report and literature review

Leptospirosis is a zoonotic disease. We present a case of acute pancreatitis associated with leptospirosis. An 88-year-old woman was admitted to the hospital with high fever and severe myalgia of the lower extremities. Based on the clinical presentation, hepatic dysfunction with a mild increase in bilirubin, renal dysfunction, and life history, the possibility of leptospirosis was considered. Plain computed tomography of the trunk on admission revealed no special findings. Appropriate antimicrobial therapy was administered at an early stage. After treatment initiation, the clinical symptoms and blood test abnormalities began to improve, and the patient appeared to be doing well. Although no abdominal or back pain was consistently noted during hospitalization, the serum amylase level increased over time; therefore, the patient underwent another computed tomography scan on the ninth day. Acute pancreatitis, which was absent upon admission, was noted. Appropriate treatment for pancreatitis was administered, and the patient was discharged. A subsequent serum antibody test confirmed the diagnosis of leptospirosis. Herein, we also summarized previous cases of acute pancreatitis associated with leptospirosis. The time of onset for pancreatitis was inconsistent, and there were a few cases of pancreatitis without abdominal or back pain. In contrast, serum amylase or lipase levels were elevated in all patients, which could be an important trigger for suspected complications of pancreatitis. When leptospirosis is suspected, complications of pancreatitis should always be considered, even in the absence of apparent abdominal pain. Regular monitoring of pancreatic enzymes such as amylase and lipase is recommended.

Objectification of evaluation criteria in microscopic agglutination test using deep learning

We aim to objectify the evaluation criteria of agglutination rate estimation in the Microscopic Agglutination Test (MAT). This study proposes a deep learning method that extracts free leptospires from dark-field microscopic images and calculates the agglutination rate. The experiments show the effect of objectification with real pictures.

Leptospira-specific immunoglobulin Y (IgY) is protective in infected hamsters

Leptospirosis, a globally significant zoonotic disease caused by pathogenic Leptospira, continues to threaten the health and public safety of both humans and animals. Current clinical treatment of leptospirosis mainly relies on antibiotics but their efficacy in severe cases is controversial. Passive immunization has a protective effect in the treatment of infectious diseases. In addition, chicken egg yolk antibody (IgY) has gained increasing attention as a safe passive immunization agent. This study aimed to investigate whether hens produce specific IgY after immunization with inactivated Leptospira and the protective effect of specific IgY against leptospirosis. First, it was demonstrated that specific IgY could be extracted from the eggs of hens vaccinated with inactivated Leptospira and that specific IgY can specifically recognize and bind homotypic Leptospira with a high titre, as shown by MAT and ELISA. Next, we tested the therapeutic effects of IgY in early and late leptospirosis using a hamster model. The results showed that early specific IgY treatment increased the survival rate of hamsters to 100%, alleviated pathological damage to the liver, kidney, and lung, reduced leptospiral burden, and restored haematological indices as well as functional indicators of the liver and kidney. The therapeutic effect of early specific IgY was comparable to that of doxycycline. Late IgY treatment also enhanced the survival rate of hamsters and improved the symptoms of leptospirosis similar to early IgY treatment. However, the therapeutic effect of late IgY treatment was better when combined with doxycycline. Furthermore, no Leptospira colonization was observed in the kidneys, livers, or lungs of the surviving hamsters treated with specific IgY. Mechanistically, IgY was found to inhibit the growth and adhesion to cells of Leptospira. In conclusion, passive immunotherapy with specific IgY can be considered an effective treatment for leptospirosis, and may replace antibiotics regarding its therapeutic effects.

Palma F, Santana R, Nery N, C. Quintero-Vélez J, Zeppelini CG, Almeida do Sacramento G, Cruz JS, Lustosa R, Santana Ferreira I, Carvalho-Pereira T, Diggle PJ, Wunder EA, I. Ko A, Alzate Lopez Y, Begon M, G. Reis M, Costa F. Factors associated with differential seropositivity to Leptospira interrogans and Leptospira kirschneri in a high transmission urban setting for leptospirosis in Brazil

BACKGROUND

Leptospirosis is a zoonosis caused by pathogenic species of bacteria belonging to the genus Leptospira. Most studies infer the epidemiological patterns of a single serogroup or aggregate all serogroups to estimate overall seropositivity, thus not exploring the risks of exposure to distinct serogroups. The present study aims to delineate the demographic, socioeconomic and environmental factors associated with seropositivity of Leptospira serogroup Icterohaemorraghiae and serogroup Cynopteri in an urban high transmission setting for leptospirosis in Brazil.

METHODS/PRINCIPAL FINDINGS

We performed a cross-sectional serological study in five informal urban communities in the city of Salvador, Brazil. During the years 2018, 2020 2021, we recruited 2.808 residents and collected blood samples for serological analysis using microagglutination assays. We used a fixed-effect multinomial logistic regression model to identify risk factors associated with seropositivity for each serogroup. Seropositivity to Cynopteri increased with each year of age (OR 1.03; 95% CI 1.01-1.06) and was higher in those living in houses with unplastered walls (exposed brick) (OR 1.68; 95% CI 1.09-2.59) and where cats were present near the household (OR 2.00; 95% CI 1.03-3.88). Seropositivity to Icterohaemorrhagiae also increased with each year of age (OR 1.02; 95% CI 1.01-1.03) and was higher in males (OR 1.51; 95% CI 1.09-2.10), in those with work-related exposures (OR 1.71; 95% CI 1.10-2.66) or who had contact with sewage (OR 1.42; 95% CI 1.00-2.03). Spatial analysis showed differences in distribution of seropositivity to serogroups Icterohaemorrhagiae and Cynopteri within the five districts where study communities were situated.

CONCLUSIONS/SIGNIFICANCE

Our data suggest distinct epidemiological patterns associated with the Icterohaemorrhagiae and Cynopteri serogroups in the urban environment at high risk for leptospirosis and with differences in spatial niches. We emphasize the need for studies that accurately identify the different pathogenic serogroups that circulate and infect residents of low-income areas.

Use of Advanced Diagnostics for Timely Identification of Travel-associated Leptospira santarosai Infection in Four Adolescents Through Plasma Microbial Cell-free DNA Sequencing With the Karius Test

BACKGROUND

Leptospirosis is an important zoonotic infection worldwide. Diagnosis of leptospirosis is challenging given its nonspecific clinical symptoms that overlap with other acute febrile illnesses and limitations with conventional diagnostic testing. Alternative advanced diagnostics, such as microbial cell-free DNA (mcfDNA), are increasingly being used to aid in the diagnosis of infections and can be applied to pathogens with public health importance such as Leptospira , a nationally notifiable disease.

METHODS

The Karius Test uses plasma mcfDNA sequencing to detect and quantify DNA-based pathogens. This test offered through the Karius lab detected 4 cases of Leptospira santarosai during a 5-month period across the United States in 2021 and were clinically reviewed.

RESULTS

In our case series, 4 adolescents with recent travel to Central America (Costa Rica, n = 3 and Belize, n = 1) from April to August 2021 were diagnosed with leptospirosis. While a large workup was performed in all cases, mcfDNA testing was the first test to detect L. santarosai as the microbiological diagnosis in all cases.

CONCLUSIONS

Results of the Karius Test enabled rapid, noninvasive diagnosis of leptospirosis allowing for targeted therapy. Use of mcfDNA can be utilized for diagnosis of pathogens where conventional testing is challenging or limited. This in turn can enable quick diagnosis for targeted treatment and potentially aid in supporting case definitions of reportable diseases of public health concern.

Efficacy and safety of antibiotics for treatment of leptospirosis: a systematic review and network meta-analysis

BACKGROUND

Leptospirosis, an important zoonotic bacterial disease, commonly affects resource-poor populations and results in significant morbidity and mortality worldwide. The value of antibiotics in leptospirosis remains unclear, as evidenced by the conflicting opinions published.

METHODS

We conducted a search in the PubMed, Web of Science, and Cochrane Library databases for studies. These studies included clinical trials and retrospective studies that evaluated the efficacy or safety of antibiotics for leptospirosis treatment. The primary outcomes assessed were defervescence time, mortality rate, and hospital stays. Subgroup analyses were performed based on whether there were cases involving children and whether there were cases of severe jaundice. Safety was defined as the prevalence of adverse events associated with the use of antibiotics. p scores were utilized to rank the efficacy of the antibiotics.

RESULTS

There are included 9 randomized controlled trials (RCTs), 1 control trial (CT), and 3 retrospective studies (RS) involving 920 patients and 8 antibiotics. Six antibiotics resulted in significantly shorter defervescence times compared to the control, namely cefotaxime (MD, - 1.88; 95% CI =  - 2.60 to - 1.15), azithromycin (MD, - 1.74; 95% CI =  - 2.52 to - 0.95), doxycycline (MD, - 1.53; 95% CI =  - 2.05 to - 1.00), ceftriaxone (MD, - 1.22; 95% CI =  - 1.89 to - 0.55), penicillin (MD, - 1.22; 95% CI =  - 1.80 to - 0.64), and penicillin or ampicillin (MD, - 0.08; 95% CI =  - 1.01 to - 0.59). The antibiotics were not effective in reducing the mortality and hospital stays. Common adverse reactions to antibiotics included Jarisch-Herxheimer reaction, rash, headache, and digestive reactions (nausea, vomiting, diarrhea, abdominal pain, and others).

CONCLUSIONS

Findings recommend that leptospirosis patients be treated with antibiotics, which significantly reduced the leptospirosis defervescence time. Cephalosporins, doxycycline, and penicillin are suggested, and azithromycin may be a suitable alternative for drug-resistant cases.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42022354938.

Global proteome of the saprophytic strain Leptospira biflexa and comparative analysis with pathogenic strain Leptospira interrogans uncover new pathogenesis mechanisms

Leptospira is a genus of bacteria that includes free-living saprophytic species found in water or soil, and pathogenic species, which are the etiologic agents of leptospirosis. Besides all the efforts, there are only a few proteins described as virulence factors in the pathogenic strain L. interrogans. This work aims to perform L. biflexa serovar Patoc1 strain Paris global proteome and to compare with the proteome database of pathogenic L. interrogans serovar Copenhageni strain Fiocruz L1-130. We identified a total of 2327 expressed proteins of L. biflexa by mass spectrometry. Using the Get Homologues software with the global proteome of L. biflexa and L. interrogans, we found orthologous proteins classified into conserved, low conserved, and specific proteins. Comparative bioinformatic analyses were performed to understand the biological functions of the proteins, subcellular localization, the presence of signal peptide, structural domains, and motifs using public softwares. These results lead to the selection of 182 low conserved within the saprophyte, and 176 specific proteins of L. interrogans. It is anticipated that these findings will indicate further studies to uncover virulence factors in the pathogenic strain. This work presents for the first time the global proteome of saprophytic strain L. biflexa serovar Patoc, strain Patoc1. SIGNIFICANCE: The comparative analysis established an array of specific proteins in pathogenic strain that will narrow down the identification of immune protective proteins that will help fight leptospirosis.

Prevalence, genetic diversity and eco-epidemiology of pathogenic Leptospira species in small mammal communities in urban parks Lyon city, France

Rodents are recognized as the main reservoirs of Leptospira spp. Rats, in particular, serve as hosts for the widely predominant Leptospira interrogans serovar Icterohaemorrhagiae, found worldwide. Several studies have shown the importance of other reservoirs, such as mice or hedgehogs, which harbor other leptospires' serovars. Nevertheless, our knowledge of circulating Leptospira spp. in reservoirs other than rats remains limited. In this context, we proposed an eco-health approach to assess the health hazard associated with leptospires in urban green spaces, where contacts between human/small mammals and domestic animals are likely. We studied the prevalence, the diversity of circulating strains, and epidemiology of pathogenic Leptospira species in small terrestrial mammal communities (rodents and shrews), between 2020-2022, in two parks in Lyon metropolis, France. Our study showed a significant carriage of Leptospira spp. in small terrestrial mammals in these parks and unveiled a global prevalence rate of 11.4%. Significant variations of prevalence were observed among the small mammal species (from 0 to 26.1%), with Rattus norvegicus exhibiting the highest infection levels (26.1%). We also observed strong spatio-temporal variations in Leptospira spp. circulation in its reservoirs. Prevalence seems to be higher in the peri-urban park and in autumn in 2021 and 2022. This is potentially due to differences in landscape, abiotic conditions and small mammal communities' composition. Our study suggests an important public health relevance of rats and in a lesser extent of other rodents (Apodemus spp., Clethrionomys glareolus and Mus musculus) as reservoirs of L. interrogans, with rodent species carrying specific serogroups/serovars. We also emphasize the potential hazard associated between the shrew Crocidura russula and L. kirschneri. Altogether, these results improve our knowledge about the prevalence of leptospirosis in an urban environment, which is an essential prerequisite for the implementation of prevention of associated risks.

Domestic dogs in indigenous Amazonian communities: Key players in Leptospira cycling and transmission?

BACKGROUND

Leptospirosis is the world's most common zoonotic disease. Mitigation and control rely on pathogen identification and understanding the roles of potential reservoirs in cycling and transmission. Underreporting and misdiagnosis obscure the magnitude of the problem and confound efforts to understand key epidemiological components. Difficulties in culturing hamper the use of serological diagnostics and delay the development of DNA detection methods. As a result, especially in complex ecosystems, we know very little about the importance of different mammalian host species in cycling and transmission to humans.

METHODOLOGY/PRINCIPAL FINDINGS

We sampled dogs from five indigenous Kichwa communities living in the Yasuní National Park in the Ecuadorian Amazon basin. Blood and urine samples from domestic dogs were collected to assess the exposure of these animals to Leptospira and to identify the circulating species. Microscopic Agglutination Tests with a panel of 22 different serovars showed anti-leptospira antibodies in 36 sampled dogs (75%), and 7 serogroups were detected. Two DNA-based detection assays revealed pathogenic Leptospira DNA in 18 of 19 dog urine samples (94.7%). Amplicon sequencing and phylogenetic analysis of 16S rRNA and SecY genes from 15 urine samples revealed genetic diversity within two of three different Leptospira species: noguchii (n = 7), santarosai (n = 7), and interrogans (n = 1).

CONCLUSIONS/SIGNIFICANCE

The high prevalence of antibodies and Leptospira DNA provides strong evidence for high rates of past and current infections. Such high prevalence has not been previously reported for dogs. These dogs live in the peridomestic environment in close contact with humans, yet they are free-ranging animals that interact with wildlife. This complex web of interactions may explain the diverse types of pathogenic Leptospira observed in this study. Our results suggest that domestic dogs are likely to play an important role in the cycling and transmission of Leptospira. Future studies in areas with complex ecoepidemiology will enable better parsing of the significance of genotypic, environmental, and host characteristics.

Climate-driven models of leptospirosis dynamics in tropical islands from three oceanic basins

BACKGROUND

Leptospirosis is a neglected zoonosis which remains poorly known despite its epidemic potential, especially in tropical islands where outdoor lifestyle, vulnerability to invasive reservoir species and hot and rainy climate constitute higher risks for infections. Burden remains poorly documented while outbreaks can easily overflow health systems of these isolated and poorly populated areas. Identification of generic patterns driving leptospirosis dynamics across tropical islands would help understand its epidemiology for better preparedness of communities. In this study, we aim to model leptospirosis seasonality and outbreaks in tropical islands based on precipitation and temperature indicators.

METHODOLOGY/PRINCIPAL FINDINGS

We adjusted machine learning models on leptospirosis surveillance data from seven tropical islands (Guadeloupe, Reunion Island, Fiji, Futuna, New Caledonia, and Tahiti) to investigate 1) the effect of climate on the disease's seasonal dynamic, i.e., the centered seasonal profile and 2) inter-annual anomalies, i.e., the incidence deviations from the seasonal profile. The model was then used to estimate seasonal dynamics of leptospirosis in Vanuatu and Puerto Rico where disease incidence data were not available. A robust model, validated across different islands with leave-island-out cross-validation and based on current and 2-month lagged precipitation and current and 1-month lagged temperature, can be constructed to estimate the seasonal dynamic of leptospirosis. In opposition, climate determinants and their importance in estimating inter-annual anomalies highly differed across islands.

CONCLUSIONS/SIGNIFICANCE

Climate appears as a strong determinant of leptospirosis seasonality in tropical islands regardless of the diversity of the considered environments and the different lifestyles across the islands. However, predictive and expandable abilities from climate indicators weaken when estimating inter-annual outbreaks and emphasize the importance of these local characteristics in the occurrence of outbreaks.

[Overview on utility of in-house tests for detection of systemic infectious diseases in dogs]

For detection of infectious diseases, several point-of-care (POC) tests are on the market in addition to methods performed in commercial laboratories. These POC tests are based on enzyme-linked immunosorbent assay (ELISA) or other immunochromatographic technologies and present results within few minutes in veterinary practice. This article gives an overview of the utility of numerous POC tests of different manufacturers for detection of parvovirus antigen in feces, Dirofilaria (D.) immitis antigen in blood as well as antibodies against Borrelia (B.) burgdorferi, Anaplasma (A.) spp., Ehrlichia (E.) spp., Leptospira (L.) spp. and Leishmania (L.) infantum in blood (single or in different combinations). Sensitivity and specificity of these tests are important for their usefulness in veterinary practice. Furthermore, presence of antibodies or detection of antigen has to correlate with the presence of clinical signs. POC tests for detection of canine parvovirus antigen have a very high specificity, the sensitivity of all evaluated POC tests, however, is very low. POC tests for detection of D. immitis antigen have a very high sensitivity and specificity. As they detect antigen from the uterus of female adult parasites, test results are negative when only very few female or only male adults are present. POC tests for detection of antibodies against B. burgdorferi only indicate contact with Borrelia spp. and do not prove clinical Lyme disease, as the infection only extremely rarely causes clinical signs. POC tests for detection of antibodies against A. phagocytophilum are also not suitable for diagnosis of clinical anaplasmosis. Infections with A. phagocytophilum only lead to clinical disease in very rare cases and in these, clinical signs occur before the development of antibodies. POC tests for detection of antibodies against E. canis have a very high sensitivity as well as specificity. POC tests for detection of antibodies against L. infantum and Leptospira species (spp.) show a very high specificity and a high sensitivity. However, Leptospira spp. antibody-positive results may occur following vaccination, as the POC tests cannot distinguish between field and vaccination strains.

Investigation of anti-Leptospira spp. antibodies and leptospiruria in cats attended to a veterinary teaching hospital in southern Brazil

Leptospirosis is a bacterial zoonosis that affects both humans and animals worldwide. Currently, it is known that cats may be susceptible to infection. This study aims to investigate the presence of anti-Leptospira spp. antibodies and leptospiruria in cats, using Microscopic Agglutination Test (MAT) and Real-time Polymerase Chain Reaction (PCR) techniques, respectively. A total of 76 cats, undergoing comprehensive anamnesis, general physical examination, and complementary exams were included in the investigation. Among the 76 cats tested, 9.2% (7/76) exhibited the presence of anti-Leptospira spp. antibodies, while Leptospira spp. DNA was detected in at 1.3% (1/76) of the evaluated urine samples. No significant associations were observed between the serological and molecular diagnostic results and the assessed variables, including clinical data and laboratory results of cats testing positive. This study provides insight into the occurrence of Leptospira spp. infection and leptospiruria in cats treated at a veterinary teaching hospital in southern Brazil.

Pathogenic Leptospira contamination in the environment: a systematic review

Background

The pathogenic Leptospira is maintained in renal tubules of certain animals, mostly rodents, and excreted in the urine which can contaminate the environment. It is necessary to detect pathogenic Leptospira in environmental samples. Knowing the survival of Leptospira in the environment (water and soil) can provide an overview of where and how they can be transmitted to humans.

Objective

Therefore, this study aimed to provide a systematic overview of pathogenic Leptospira presence in water and soil environment, the various species of pathogenic Leptospira that are harmful for human, and the ability to survive using a systematic review method.

Methods

The search process used four databases: PubMed, Science Direct, Scopus, and ProQuest. Furthermore, the articles sought were published from 2000 to July 2021, and 38 were analysed.

Results

The pathogenic Leptospira contamination in water was higher in urban areas, while soil samples were higher in rural areas. Various pathogenic Leptospira detected in the environment were L. alstonii, L. kmetyi, L. noguchii, and L. interrogans. Those pathogenic Leptospira can survive in water at 4-30°C and at pH < 7; in soil, it can survive at a humidity of < 20% and a pH < 6.

Conclusion

Urban and rural areas have the same risk for leptospirosis disease because pathogenic Leptospira (P1).

Detection of pathogenic Leptospira with rapid extraction followed by recombinase polymerase amplification (RPA) and quantitative polymerase chain reaction (qPCR) assay-A comprehensive study from Sri Lanka

Leptospirosis is the most widespread zoonosis in the world. The disease is more prevalent in tropical regions where the majority of developing countries are located. Leptospirosis is considered a protean manifestation zoonosis with severity of the disease ranging from a mild febrile illness to a severe and life-threatening illness. Clinical symptoms of leptospirosis overlap with other tropical febrile illnesses. Early, rapid, and definitive diagnosis is important for effective patient management. Since Polymerase Chain Reaction (PCR)-based assays are not readily available in most clinical settings, there is a need for an affordable, simple, and rapid diagnostic test. Quantitative PCR (qPCR) and Recombinase Polymerase Amplification (RPA) were implemented at the Faculty of Medicine, University of Kelaniya, and a prospective study to evaluate RPA for diagnosis of acute phase of leptospirosis was conducted. Results indicate that RPA and qPCR were positive in 81% (98/121) of the total positive and acute clinical samples. Of the 81 positive MAT confirmed patients 60 (74%) and 53 (65%) were positive with qPCR and RPA respectively. Retrospective evaluation revealed a high diagnostic accuracy (sensitivity-70% and specificity-87%) of RPA compared to MAT as the reference gold standard. Results further suggest that there is no significant difference between the two assays, qPCR and RPA-SwiftX (P = 0.40). Laboratory procedures for the extraction and detection by qPCR in the laboratory have been optimized to obtain results within 6 hours. However, the RPA-SwiftX method under field conditions took 35 minutes. The RPA-SwiftX method could replace the qPCR which shows similar sensitivity and specificity. Therefore, RPA established under the current study presents a powerful tool for the early and rapid diagnosis of leptospirosis at point-of-care.

Antibiotics for treatment of leptospirosis

BACKGROUND

Leptospirosis is a disease transmitted from animals to humans through water, soil, or food contaminated with the urine of infected animals, caused by pathogenic Leptospira species. Antibiotics are commonly prescribed for the management of leptospirosis. Despite the widespread use of antibiotic treatment for leptospirosis, there seems to be insufficient evidence to determine its effectiveness or to recommend antibiotic use as a standard practice. This updated systematic review evaluated the available evidence regarding the use of antibiotics in treating leptospirosis, building upon a previously published Cochrane review.

OBJECTIVES

To evaluate the benefits and harms of antibiotics versus placebo, no intervention, or another antibiotic for the treatment of people with leptospirosis.

SEARCH METHODS

We identified randomised clinical trials following standard Cochrane procedures. The date of the last search was 27 March 2023.

SELECTION CRITERIA

We searched for randomised clinical trials of various designs that examined the use of antibiotics for treating leptospirosis. We did not impose any restrictions based on the age, sex, occupation, or comorbidities of the participants involved in the trials. Our search encompassed trials that evaluated antibiotics, regardless of the method of administration, dosage, and schedule, and compared them with placebo or no intervention, or compared different antibiotics. We included trials regardless of the outcomes reported.

DATA COLLECTION AND ANALYSIS

During the preparation of this review, we adhered to the Cochrane methodology and used Review Manager. The primary outcomes were all-cause mortality and serious adverse events (nosocomial infection). Our secondary outcomes were quality of life, proportion of people with adverse events considered non-serious, and days of hospitalisation. To assess the risk of bias of the included trials, we used the RoB 2 tool, and for evaluating the certainty of evidence we used GRADEpro GDT software. We presented dichotomous outcomes as risk ratios (RR) and continuous outcomes as mean differences (MD), both accompanied by their corresponding 95% confidence intervals (CI). We used the random-effects model for all our main analyses and the fixed-effect model for sensitivity analyses. For our primary outcome analyses, we included trial data from the longest follow-up period.

MAIN RESULTS

We identified nine randomised clinical trials comprising 1019 participants. Seven trials compared two intervention groups and two trials compared three intervention groups. Amongst the trials comparing antibiotics versus placebos, four trials assessed penicillin and one trial assessed doxycycline. In the trials comparing different antibiotics, one trial evaluated doxycycline versus azithromycin, one trial assessed penicillin versus doxycycline versus cefotaxime, and one trial evaluated ceftriaxone versus penicillin. One trial assessed penicillin with chloramphenicol and no intervention. Apart from two trials that recruited military personnel stationed in endemic areas or military personnel returning from training courses in endemic areas, the remaining trials recruited people from the general population presenting to the hospital with fever in an endemic area. The participants' ages in the included trials was 13 to 92 years. The treatment duration was seven days for penicillin, doxycycline, and cephalosporins; five days for chloramphenicol; and three days for azithromycin. The follow-up durations varied across trials, with three trials not specifying their follow-up periods. Three trials were excluded from quantitative synthesis; one reported zero events for a prespecified outcome, and two did not provide data for any prespecified outcomes. Antibiotics versus placebo or no intervention The evidence is very uncertain about the effect of penicillin versus placebo on all-cause mortality (RR 1.57, 95% CI 0.65 to 3.79; I2 = 8%; 3 trials, 367 participants; very low-certainty evidence). The evidence is very uncertain about the effect of penicillin or chloramphenicol versus placebo on adverse events considered non-serious (RR 1.05, 95% CI 0.35 to 3.17; I2 = 0%; 2 trials, 162 participants; very low-certainty evidence). None of the included trials assessed serious adverse events. Antibiotics versus another antibiotic The evidence is very uncertain about the effect of penicillin versus cephalosporin on all-cause mortality (RR 1.38, 95% CI 0.47 to 4.04; I2 = 0%; 2 trials, 348 participants; very low-certainty evidence), or versus doxycycline (RR 0.93, 95% CI 0.13 to 6.46; 1 trial, 168 participants; very low-certainty evidence). The evidence is very uncertain about the effect of cefotaxime versus doxycycline on all-cause mortality (RR 0.18, 95% CI 0.01 to 3.78; 1 trial, 169 participants; very low-certainty evidence). The evidence is very uncertain about the effect of penicillin versus doxycycline on serious adverse events (nosocomial infection) (RR 0.62, 95% CI 0.11 to 3.62; 1 trial, 168 participants; very low-certainty evidence) or versus cefotaxime (RR 1.01, 95% CI 0.15 to 7.02; 1 trial, 175 participants; very low-certainty evidence). The evidence is very uncertain about the effect of doxycycline versus cefotaxime on serious adverse events (nosocomial infection) (RR 1.01, 95% CI 0.15 to 7.02; 1 trial, 175 participants; very low-certainty evidence). The evidence is very uncertain about the effect of penicillin versus cefotaxime (RR 3.03, 95% CI 0.13 to 73.47; 1 trial, 175 participants; very low-certainty evidence), versus doxycycline (RR 2.80, 95% CI 0.12 to 67.66; 1 trial, 175 participants; very low-certainty evidence), or versus chloramphenicol on adverse events considered non-serious (RR 0.74, 95% CI 0.15 to 3.67; 1 trial, 52 participants; very low-certainty evidence). Funding Six of the nine trials included statements disclosing their funding/supporting sources and three trials did not mention funding source. Four of the six trials mentioning sources received funds from public or governmental sources or from international charitable sources, and the remaining two, in addition to public or governmental sources, received support in the form of trial drug supply directly from pharmaceutical companies.

AUTHORS' CONCLUSIONS

As the certainty of evidence is very low, we do not know if antibiotics provide little to no effect on all-cause mortality, serious adverse events, or adverse events considered non-serious. There is a lack of definitive rigorous data from randomised trials to support the use of antibiotics for treating leptospirosis infection, and the absence of trials reporting data on clinically relevant outcomes further adds to this limitation.

Antibiotic prophylaxis for leptospirosis

BACKGROUND

Leptospirosis is a global zoonotic and waterborne disease caused by pathogenic Leptospira species. Antibiotics are used as a strategy for prevention of leptospirosis, in particular in travellers and high-risk groups. However, the clinical benefits are unknown, especially when considering possible treatment-associated adverse effects. This review assesses the use of antibiotic prophylaxis in leptospirosis and is an update of a previously published review in the Cochrane Library (2009, Issue 3).

OBJECTIVES

To evaluate the benefits and harms of antibiotic prophylaxis for human leptospirosis.

SEARCH METHODS

We identified randomised clinical trials through electronic searches of the Cochrane Hepato-Biliary Group Controlled Trials Register, CENTRAL, MEDLINE, Embase, LILACS, Science Citation Index Expanded, and other resources. We searched online clinical trial registries to identify unpublished or ongoing trials. We checked reference lists of the retrieved studies for further trials. The last date of search was 17 April 2023.

SELECTION CRITERIA

We included ⁠⁠randomised clinical trials of any trial design, assessing antibiotics for prevention of leptospirosis, and with no restrictions on age, sex, occupation, or comorbidity of trial participants. We looked for trials assessing antibiotics irrespective of route of administration, dosage, and schedule versus placebo or no intervention. We also included trials assessing antibiotics versus other antibiotics using these criteria, or the same antibiotic but with another dose or schedule.

DATA COLLECTION AND ANALYSIS

We followed Cochrane methodology. The primary outcomes were all-cause mortality, laboratory-confirmed leptospirosis regardless of the presence of an identified clinical syndrome (inclusive of asymptomatic cases), clinical diagnosis of leptospirosis regardless of the presence of laboratory confirmation, clinical diagnosis of leptospirosis confirmed by laboratory diagnosis (exclusive of asymptomatic cases), and serious adverse events. The secondary outcomes were quality of life and the proportion of people with non-serious adverse events. We assessed the risk of bias of the included trials using the RoB 2 tool and the certainty of evidence using GRADE. We presented dichotomous outcomes as risk ratios (RR) and continuous outcomes as mean difference (MD), with their 95% confidence intervals (CI). We used a random-effects model for our main analyses and the fixed-effect model for sensitivity analyses. Our primary outcome analyses included trial data at the longest follow-up.

MAIN RESULTS

We identified five randomised clinical trials comprising 2593 participants that compared antibiotics (doxycycline, azithromycin, or penicillin) with placebo, or one antibiotic compared with another. Four trials assessed doxycycline with different durations, one trial assessed azithromycin, and one trial assessed penicillin. One trial had three intervention groups: doxycycline, azithromycin, and placebo. Three trials assessed pre-exposure prophylaxis, one trial assessed postexposure prophylaxis, and one did not report this clearly. Four trials recruited residents in endemic areas, and one trial recruited soldiers who experienced limited time exposure. The participants' ages in the included trials were 10 to 80 years. Follow-up ranged from one to three months. Antibiotics versus placebo Doxycycline compared with placebo may result in little to no difference in all-cause mortality (RR 0.15, 95% CI 0.01 to 2.83; 1 trial, 782 participants; low-certainty evidence). Prophylactic antibiotics may have little to no effect on laboratory-confirmed leptospirosis, but the evidence is very uncertain (RR 0.56, 95% CI 0.25 to 1.26; 5 trials, 2593 participants; very low-certainty evidence). Antibiotics may result in little to no difference in the clinical diagnosis of leptospirosis regardless of laboratory confirmation (RR 0.76, 95% CI 0.53 to 1.08; 4 trials, 1653 participants; low-certainty evidence) and the clinical diagnosis of leptospirosis with laboratory confirmation (RR 0.57, 95% CI 0.26 to 1.26; 4 trials, 1653 participants; low-certainty evidence). Antibiotics compared with placebo may increase non-serious adverse events, but the evidence is very uncertain (RR 10.13, 95% CI 2.40 to 42.71; 3 trials, 1909 participants; very low-certainty evidence). One antibiotic versus another antibiotic One trial assessed doxycycline versus azithromycin but did not report mortality. Compared to azithromycin, doxycycline may have little to no effect on laboratory-confirmed leptospirosis regardless of the presence of an identified clinical syndrome (RR 1.49, 95% CI 0.51 to 4.32; 1 trial, 137 participants), on the clinical diagnosis of leptospirosis regardless of the presence of laboratory confirmation (RR 4.18, 95% CI 0.94 to 18.66; 1 trial, 137 participants), on the clinical diagnosis of leptospirosis confirmed by laboratory diagnosis (RR 4.18, 95% CI 0.94 to 18.66; 1 trial, 137 participants), and on non-serious adverse events (RR 1.12, 95% CI 0.36 to 3.48; 1 trial, 137 participants), but the evidence is very uncertain. The certainty of evidence for all the outcomes was very low. None of the five included trials reported serious adverse events or assessed quality of life. One study is awaiting classification. Funding Four of the five trials included statements disclosing their funding/supporting sources, and the remaining trial did not include this. Three of the four trials that disclosed their supporting sources received the supply of trial drugs directly from the same pharmaceutical company, and the remaining trial received financial support from a governmental source.

AUTHORS' CONCLUSIONS

We do not know if antibiotics versus placebo or another antibiotic has little or have no effect on all-cause mortality or leptospirosis infection because the certainty of evidence is low or very low. We do not know if antibiotics versus placebo may increase the overall risk of non-serious adverse events because of very low-certainty evidence. We lack definitive rigorous data from randomised trials to support the use of antibiotics for the prophylaxis of leptospirosis infection. We lack trials reporting data on clinically relevant outcomes.

Relevance of Polymerase Chain Reaction in Early Diagnosis of Leptospirosis

Aim and background

Leptospirosis is common in India, especially in the southern states. Mortality is high among untreated cases. Diagnosis of leptospirosis remains a challenge in India as polymerase chain reaction (PCR), which is more sensitive than Immunoglobulin M (IgM) is not widely available. This study aimed to find out the difference in diagnostic yield with PCR and IgM in early leptospirosis.

Materials and methods

This retrospective, single-center study included 67 adults with laboratory-confirmed leptospirosis (IgM, PCR, or both) who presented within 7 days of symptom onset and were admitted to the intensive care unit (ICU). The difference in the diagnostic yield with PCR and IgM ELISA was studied.

Results

About 77.6% of the patients tested positive by PCR and 55.2% tested positive by IgM. There was a statistically significant difference in the detection of leptospirosis by PCR and IgM (p-value = 0.036). In the subgroup of patients who presented within 3 days of onset of symptoms, PCR positivity was 90.32% whereas IgM positivity was only 25.8%.

Conclusion

Our study showed that the sensitivity of leptospira PCR is significantly higher than IgM in the first week of illness. It also showed that among the subset of patients who died, a majority were detected only by PCR. Since PCR is not widely available, leptospirosis remains underdiagnosed and mortality from the same is underestimated. Polymerase chain reaction, if routinely done along with IgM for all suspected cases of leptospirosis that present within the first week of illness helps in prompt diagnosis and treatment.

How to cite this article

Sreevalsan TV, Chandra R. Relevance of Polymerase Chain Reaction in Early Diagnosis of Leptospirosis. Indian J Crit Care Med 2024;28(3):290-293.

A Fatal Case of Presumptive Diagnosis of Leptospirosis Involving the Central Nervous System

Leptospirosis is a reemerging zooanthroponosis with a worldwide distribution, though it has a higher incidence in areas with tropical climate. A characteristic finding of the disease is its wide spectrum of symptoms and organ involvement, as it can appear either with very mild flu-like manifestations or with multiorgan failure, affecting the central nervous system (CNS) with a concomitant hepatorenal dysfunction (Weil's syndrome) and significant high mortality rate. We report herein a fatal case of a 25 years old female, previously healthy, with impaired neurological status. She had high fever and severe multiorgan failure. The clinical data and the epidemiological factors were not conclusive for the diagnosis, and the first serology test from the cerebrospinal fluid (CSF) and sera samples were negative. When the repetition of the blood test showed elevated IgM antibodies, Leptospirosis was the presumptive diagnosis. Although CNS involvement is rare, the diagnosis should be considered when there is an elevated risk of exposure. The diagnostic protocol should encompass direct evidence of the bacterium and indirect measurement of antibodies. Timely detection and management are imperative to forestall complications and fatality associated with the disease.

First isolation and genotyping of pathogenic Leptospira spp. from Austria

Leptospirosis is a globally distributed zoonotic disease. The standard serological test, known as Microscopic Agglutination Test (MAT), requires the use of live Leptospira strains. To enhance its sensitivity and specificity, the usage of locally circulating strains is recommended. However, to date, no local strain is available from Austria. This study aimed to isolate circulating Leptospira strains from cattle in Austria to enhance the performances of the routine serological test for both humans and animals. We used a statistical approach combined with a comprehensive literature search to profile cattle with greater risk of leptospirosis infection and implemented a targeted sampling between November 2021 and October 2022. Urine and/or kidney tissue were sampled from 410 cattle considered at higher risk of infection. Samples were inoculated into EMJH-STAFF culture media within 2-6 h and a real-time PCR targeting the lipL32 gene was used to confirm the presence/absence of pathogenic Leptospira in each sample. Isolates were further characterised by core genome multilocus sequence typing (cgMLST). Nine out of 429 samples tested positive by PCR, from which three isolates were successfully cultured and identified as Leptospira borgpetersenii serogroup Sejroe serovar Hardjobovis, cgMLST cluster 40. This is the first report on the isolation and genotyping of local zoonotic Leptospira in Austria, which holds the potential for a significant improvement in diagnostic performance in the country. Although the local strain was identified as a cattle-adapted serovar, it possesses significant zoonotic implications. Furthermore, this study contributes to a better understanding of the epidemiology of leptospirosis in Europe.

Fulminant Leptospirosis Presenting with Rapidly Developing Acute Renal Failure and Multiorgan Failure

Leptospirosis, caused by pathogenic spirochetes of the Leptospira genus, is a common zoonosis in tropical and subtropical regions and can lead to an epidemic following heavy rainfall or flooding. The primary reservoirs of Leptospira include rodents, wild animals, dogs, cats, amphibians, and others, but the brown rat (Rattus norvegicus) remains the main source of human Leptospirosis. Humans are often accidental hosts and they can be infected through cuts, abrasions, mucosa, conjunctiva, or by ingesting contaminated water. The clinical manifestation of leptospirosis can vary from mild, nonspecific symptoms to a fatal outcome involving liver and renal failure, pulmonary hemorrhage, meningitis, and septic shock. The severity of fatal outcomes is likely to be due to virulence factors, host susceptibility, and epidemiological conditions. L. interrogans are associated with high-risk individuals, particularly patients older than 60 years of age in clinical settings. The current case study showed a foreign worker who presented with rapidly deteriorating clinical signs of fever, jaundice, impaired consciousness, and oliguric acute renal failure. Drawing from our experience, it is advisable to consider the possibility of leptospirosis diagnosis in patients who show clinical symptoms such as fever, hepatic failure with jaundice, and acute renal failure. This is particularly important for those individuals with a prior history of pathogen exposure. This case study had a strong suspicion of leptospirosis, which was confirmed by the microscopic agglutination test (MAT) and, later, the patient's recovery following treatment.

Non-purulent myositis caused by direct invasion of skeletal muscle tissue by Leptospira in a hamster model

Myalgia is a common symptom of Leptospira infection in humans. Autopsies have reported that muscle tissue shows degeneration and necrosis of the myofibers and infiltration of inflammatory cells composed mainly of macrophages and lymphocytes. It remains unclear whether Leptospira directly infects the muscle and how the infiltrating inflammatory cells are involved in muscle fiber destruction. This study evaluated the relationship between histopathological changes and leptospiral localization in the muscle tissue of a hamster model. The influence of macrophages in skeletal muscle injury was also investigated, using selective depletion of macrophages by administration of liposomal clodronate. Hamsters infected subcutaneously with Leptospira interrogans serovar Manilae strain UP-MMC-SM showed myositis of the thighs adjacent to the inoculated area beginning at 6 days post-infection. The myositis was non-purulent and showed sporadic degeneration and necrosis of muscle fibers. The degeneration of myofibers was accompanied by aggregations of macrophages. Immunofluorescence staining revealed leptospires surrounding the damaged muscle fibers. Subcutaneous injection of formalin-killed Leptospira or intraperitoneal injection of live Leptospira caused no myositis in hamster thighs. Liposomal clodronate treatment in infected hamsters reduced macrophage infiltration in muscle tissue without impacting bacterial clearance. Muscle necrosis was still observed in the infected hamsters treated with liposomal clodronate, and there was no significant change in serum creatine kinase levels compared to those in animals treated with liposomes alone. Our findings suggest that leptospiral invasion of muscle tissue from an inoculation site leads to the destruction of muscle fibers and causes non-purulent myositis, whereas the infiltrating macrophages contribute less to muscle destruction.

Detection of Antibodies for Pathogenic Leptospira in Wild Mammals and Birds from Southern Chile-First Record of Seropositivity in a Guiña (Leopardus guigna)

Leptospirosis is a neglected bacterial zoonotic disease of worldwide distribution that is present in different animal species. This epidemiological study determined the seroprevalence of pathogenic Leptospira spp. in animals at a wildlife rehabilitation center in Puerto Montt, southern Chile, by sampling 60 animals belonging to three classes (birds, mammals, and reptiles). Diagnosis was performed using the microscopic agglutination test with a panel of eight serovars and serogroups. The results showed that 15 animals had anti-Leptospira antibodies, obtaining a seroprevalence of 25.00%, with Leptospira borgpetersenii serogroup Tarassovi presenting reactivity in 13 of the seropositive animals. Among the classes of mammals, chilla foxes (Lycalopex griseus) and pudus (Pudu puda) were seropositive. A guiña (Leopardus guigna) was also seropositive, which was described for the first time in mammals. Among the classes of birds, choroy parrots (Enicognathus leptorhynchus), bandurrias (Theristicus melanopis), and Magellanic penguins (Spheniscus magellanicus) were seropositive. Routine examinations to diagnose leptospirosis, perform epidemiological surveillance, and apply prevention and control measures are necessary, and additional research focusing on the One Health approach to explore the epidemiological role of different wild animal species in the maintenance and transmission of leptospirosis at the local and global levels are recommended.

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.

Canine Staphylococcaceae circulating in a Kenyan animal shelter

Animal shelters, especially in resource-poor countries, bring together pets from different regions and with different backgrounds. The crowding of such animals often results in infectious diseases, such as respiratory infections. This study characterized Staphylococcaceae from diseased and apparently healthy dogs housed in an animal shelter in Kenya, to determine their antibiotic resistance profiles, their genetic relatedness, and the presence of dominant clones. Therefore, bacteria were collected from all 167 dogs present in the shelter in June 2015 and screened for Staphylococcaceae using standard cultivation techniques. In all, 92 strains were isolated from 85 dogs and subsequently sequenced by PacBio long-read sequencing. Strains encompassed nine validated species, while S. aureus (n = 47), S. pseudintermedius (n = 21), and Mammaliicoccus (M.) sciuri (n = 16) were the three most dominant species. Two S. aureus clones of ST15 (CC15) and ST1292 (CC1) were isolated from 7 and 37 dogs, respectively. All 92 strains isolated were tested for their antimicrobial susceptibility by determining the minimum inhibitory concentrations. In all, 86 strains had resistance-associated minimal inhibitory concentrations to at least one of the following antimicrobials: tetracycline, benzylpenicillin, oxacillin, erythromycin, clindamycin, trimethoprim, kanamycin/gentamicin, or streptomycin. Many virulence-encoding genes were detected in the S. aureus strains, other Staphylococcaceae contained a different set of homologs of such genes. The presence of mobile genetic elements, such as plasmids and prophages, known to facilitate the dissemination of virulence- and resistance-encoding genes, was also assessed. The unsuspected high presence of two S. aureus clones in about 50% of dogs suggests dissemination within the shelter and a human source.IMPORTANCEMicrobiological data from sub-Saharan Africa are scarce compared to data from North America, Europe, or Asia, and data derived from dogs, the man's best friend, kept in sub-Saharan Africa are largely missing. This work presents data on Staphylococcaceae mainly isolated from the nasal cavity of dogs stationed at a Kenyan shelter in 2015. We characterized 92 strains isolated from 85 dogs, diseased and apparently healthy ones. The strains isolated covered nine validated species and we determined their phenotypic resistance and characterized their complete genomes. Interestingly, Staphylococcus aureus of two predominant genetic lineages, likely to be acquired from humans, colonized many dogs. We also detected 15 novel sequence types of Mammaliicoccus sciuri and S. pseudintermedius indicating sub-Saharan-specific phylogenetic lineages. The data presented are baseline data that guide antimicrobial treatment for dogs in the region.

Unraveling the leptospirosis epidemic: tales from the Philippine outbreak - a short communication

Leptospirosis, also known as Weil's disease, is an emerging zoonotic infection that occurs worldwide but is particularly common in the tropics. There has been an increasing trend of leptospirosis in the Philippines since the outbreak occurred in 2020. The number of reported cases was 182 in 2020, 1661 in 2021, and 2794 in 2022. This present article aimed to access previously published studies on the prevalence, implications, and efforts to combat leptospirosis worldwide, with a particular focus on the Philippines from 2001 to 2023. In writing this article, we conducted a thorough search of databases such as PubMed, Researchgate, Web of Science, Scopus, and Google Scholar within 20 years. This present article found that more than 810 cases were reported from 1 January to 4 March 2023. The Cagayan Valley Region has 103 cases, the Zamboanga Peninsula has 77 cases, and the Western Visayas Region has 176 cases, making them the worst-hit areas. The increase in leptospirosis cases in the Philippines is primarily attributed to several factors. Firstly, the country is prone to natural disasters such as typhoons, floods, and landslides, which increase the risk of water sources and the environment being contaminated with Leptospira bacteria. To address the menace of leptospirosis in the Philippines, we urge the Philippine government to focus on improving healthcare infrastructure, providing swift, reliable, and effective treatments, implementing safety regulations, supplying personal protective equipment to medical authorities, and taking strict actions to improve water sanitation.

A rare case of anti-DPPX encephalitis combined with neuroleptospirosis

BACKGROUND

Neuroleptospirosis and anti-dipeptidyl-peptidase-like protein 6 (DPPX) encephalitis are both very rare and have only been reported in the form of respective case reports. There are no reports of anti-DPPX encephalitis combined with neuroleptospirosis in the literature. We reported the first case of neuroleptospirosis combined with elevated DPPX antibodies in serum and cerebrospinal fluid (CSF).

CASE PRESENTATION

A previously healthy 53-year-old Chinese male farmer with a history of drinking raw stream water and flood sewage exposure was brought to the hospital due to an acute onset of neuropsychiatric symptoms. No fever or meningeal irritation signs were detected on physical examination. Routine laboratory investigations, including infection indicators, leukocyte and protein in CSF, electroencephalogram and gadolinium-enhanced magnetic resonance imaging of the brain, all revealed normal. While metagenomic next-generation sequencing (mNGS) identified the DNA genome of Leptospira interrogans in the CSF. Anti-DPPX antibody was detected both in blood and in CSF. A diagnosis of neuroleptospirosis combined with autoimmune encephalitis associated with DPPX-Ab was eventually made. He resolved completely after adequate amount of penicillin combined with immunotherapy.

CONCLUSION

We highlight that in patients with acute or subacute behavioral changes, even in the absence of fever, if the most recent freshwater exposure is clear, physicians should pay attention to leptospirosis. Due to the low sensitivity of routine microscopy, culture, polymerase chain reaction and antibody testing, mNGS may have more advantages in diagnosing neuroleptospirosis. As autoimmune encephalitis can be triggered by various infections, neuroleptospirosis may be one of the causes of autoimmune encephalitis. Since neuronal antibody measurements themselves are not that common in neuroleptospirosis, future studies are needed to determine whether the detection of anti-DPPX antibodies is a rare event in leptospirosis. Early identification of autoimmune encephalitis and timely administration of immunotherapy may lead to a better outcome.

Structural investigation of vitamin K epoxide reductase domain-containing protein in Leptospira species: a potential target for the development of new leptospirosis treatments as an alternative to antibiotics

Leptospirosis is a worldwide zoonosis caused by the motile bacterium Leptospira. This disease can cause hemorrhagic symptoms, multi-visceral and renal failures, resulting in one million cases and approximately 60,000 deaths each year. The motility of Leptospira is highly involved in its virulence and is ensured by the presence of two flagella in the periplasm. Several proteins that require the formation of disulfide bridges are essential for flagellar function. In Leptospira, these redox reactions are catalysed by the vitamin K epoxide reductase domain-containing protein (VKORdcp). The aim of the present work was to study the conservation of VKORdcp among Leptospira species and its interactions with putative substrates and inhibitor. Our results evidenced the presence of ten amino acids specific to either pathogenic or saprophytic species. Furthermore, structural studies revealed a higher affinity of the enzyme for vitamin K1 quinone, compared to ubiquinone. Finally, characterisation of the binding of a potential inhibitor revealed the involvement of some VKORdcp amino acids that have not been present in the human enzyme, in particular the polar residue D114. Our study thus paves the way for the future development of Leptospira VKORdcp inhibitors, capable of blocking bacterial motility. Such molecules could therefore offer a promising therapeutic alternative to antibiotics, especially in the event of the emergence of antibiotic-resistant strains.Communicated by Ramaswamy H. Sarma.

Infections and Influencing Factors of Pathogens in Rattus norvegicus along the Zengjiang River in Guangzhou, China

Background: Rattus norvegicus can carry and transmit various zoonotic pathogens. Some studies were conducted to investigate a few zoonotic pathogens in Guangzhou, China, but no coinfections were investigated or specifically mentioned. Studies on the infections and the influencing factors of various zoonotic pathogens in R. norvegicus along the Zengjiang River in Guangzhou have not been carried out. Materials and Methods: In this study, R. norvegicus was captured in November 2020 and September 2021 along the Zengjiang River, and was tested for Bartonella spp., Leptospira spp., Orientia tsutsugamushi, Borrelia burgdorferi, Hantavirus (HV), Ehrlichia spp., and severe fever with thrombocytopenia syndrome virus (SFTSV) by the RT-PCR. Logistic regression analysis was used to determine the impact of habitat and demographic factors on the infections and coinfections of the surveyed pathogens. Results: In 119 R. norvegicus, the detection rates of Bartonella spp., Leptospira spp., O. tsutsugamushi, B. burgdorferi, and HV were 46.2%, 31.9%, 5%, 0.8%, and 18.5%, respectively. Ehrlichia spp. and SFTSV were negative. The triple coinfection rate of Bartonella spp., Leptospira spp., and HV was 11.8%. In addition, the coinfection of Bartonella spp., Leptospira spp., and B. burgdorferi was 0.8%. Dual coinfection of Bartonella spp. and Leptospira spp., Leptospira spp. and HV, Bartonella spp. and O. tsutsugamushi, Leptospira spp. and O. tsutsugamushi, and HV and O. tsutsugamushi was 9.2%, 3.4%, 1.7%, 1.7%, and 0.8%, respectively. Infections of these pathogens in R. norvegicus were found in habitats of banana plantation, grassland, and bush. Weight affected the infection of Bartonella spp., Leptospira spp., or HV in R. norvegicus. Conclusions: R. norvegicus along the Zengjiang River not only carried various potentially zoonotic pathogens but also had a variety of coinfections. Surveillance of the density and pathogens in R. norvegicus should be strengthened to reduce the incidence of relevant zoonotic diseases.

Leptospirosis and Dengue Coinfection-Associated Multi-Organ Dysfunction Syndrome: A Case Report

Dengue and leptospirosis are frequently discussed separately, with dengue causing rash and leptospirosis causing jaundice. Currently, there are more and more reports of coinfections. The comparable clinical symptoms of both infections make it challenging to distinguish between leptospirosis and dengue. Differentiating between leptospirosis and dengue is crucial since leptospirosis has a more favorable prognosis with early antibiotic therapy, whereas dengue does not have a specific treatment, although early detection is essential for close monitoring and cautious fluid management. Here, we highlight a case of dengue virus and leptospirosis coinfection in a female who presented with acute febrile illness, dyspnea, and altered sensorium, which progressed to multiorgan dysfunction syndrome, involving the neurological, respiratory, hepatic, and hematological systems.

Enhancing leptospirosis control with nanosensing technology: A critical analysis

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

A case of leptospirosis in transcarpathia complicated with Jarisch-Herxheimer reaction

A case report of Jarisch-Herxheimer (JHR) reaction on a 10th day of Leptospirosis caused by Leptospira Pomona. JHR occurs as a complication of an antibiotic treatment of various spirochetes and may lead to respiratory distress syndrome, renal failure, hepatic insufficiency, and multiple organ failure. This case represents a skin and cardio-vascular form of JHR with no lung involvement. The patient was treated with benzylpenicillin and low dexamethasone doses for 5th day of the disease with a shift to ceftriaxone and high doses of methylprednisolone. The fastest diagnosis of a sporadic zoonotic disease, early start of antibiotic therapy, and adequate doses of corticosteroids are key to the successful treatment of leptospirosis.

Identification of the most effective serovars to be included in the MAT antigen panel to optimize the serodiagnosis of Leptospira infection in Northern Italy

The microscopic agglutination test (MAT) assay is adopted as a world-wide reference test for the serodiagnosis of leptospirosis in humans and animals. One of the main limitations of MAT is the lack of sensitivity and serodiagnostic antigens should be periodically updated with locally circulating serovars in order to optimise its performance. The aim of this study was to determine the need to implement the antigen panel currently adopted in Northern Italy for the diagnosis of Leptospira infection in dogs. For this purpose, a group of 288 dogs with and without clinical signs potentially consistent with Leptospira infection or found to have an increased C-reactive protein (CRP) serum concentration, sampled in 2013-2016 in Northern Italy, were tested by MAT comparing the results obtained with a nine antigens panel (Australis-Bratislava, Ballum-Ballum, Canicola-Canicola, Grippotyphosa-Grippotyphosa, Icterohaemorrhagiae-Copenhageni, Icterohaemorrhagiae-Icterohaemorrhagiae, Sejroe-Hardjo, Pomona-Pomona and Tarassovi-Tarassovi serovars) routinely adopted and a panel expanded to 27 antigens. In general, the antigen panel currently adopted in Northern Italy for the routine MAT assay resulted adequate for the diagnosis of Leptospira infection in dogs. The main exception concerns the Sejroe serogroup, with the Saxkoebing and Sejroe serovars that were more effective than Hardjo for diagnosis in dogs and whose inclusion in the antigen panel is recommended. Among other antigens evaluated in this study, Cynopteri serovar was detected with high frequency but its pathogenic role in dogs and as public health threat deserve further investigation.

A systematic review on leptospirosis in cattle: A European perspective

Leptospirosis is a zoonotic disease which is globally distributed and represents a classic One Health issue that demands a comprehensive understanding of the hosts, transmission paths, and risk factors of transmission. Bovine leptospirosis often results in economic losses through its severe impact on reproduction performance while it threatens human health at human-cattle-environment interfaces. However, a clear analysis of the disease characteristics in European cattle is currently lacking. The objective of this review was to summarise the current knowledge on the epidemiology of bovine leptospirosis in Europe. We conducted a systematic literature review, screening four electronic databases, and filtered articles published between 2001 and 2021, in English, German, and French. Sixty-two articles were ultimately included in the review. The seroprevalence of leptospirosis in cattle was remarkably variable among studies, probably reflecting local variations but also heterogeneity in the study designs, laboratory methods, and sample sizes. Risk factors positively associated with the disease were diverse, related to local, environmental, and climatic parameters as well as farming practices. The most reported circulating Leptospira serogroups in European cattle were Sejroe (58.5%), Australis (41.5%), Grippotyphosa (41.5%), Icterohaemorrhagiae (37.7%), and Pomona (26.4%), which have also been associated with human infections worldwide. Abortion (58.6%) and fertility disorders (24.1%) were the most frequently reported signs of leptospirosis in European cattle and were generally associated with chronic infections. This work highlights several research gaps, including a lack of harmonisation in diagnostic methods, a lack of large-scale studies, and a lack of molecular investigations. Given that predictions regarding the climatic suitability for leptospirosis in Europe suggest an increase of leptospirosis risk it is important to raise awareness among stakeholders and motivate an integrated One Health approach to the prevention and control of this zoonotic disease in cattle and humans.

Diagnosis of leptospira by metagenomics next-generation sequencing with extracorporeal membrane oxygenation support: a case report

BACKGROUND

Leptospirosis is an infectious disease caused by pathogenic Leptospira spp., which could result in severe illnesses. Indirect contact with these pathogens is more common. Individuals could contract this disease through contact with contaminated water or during floods. In this case, we present the details of a 40-year-old male pig farmer who suffered from severe pulmonary hemorrhagic leptospirosis and multiple organ failure. The diagnosis of leptospirosis was confirmed through metagenomics next-generation sequencing (mNGS) while the patient received extracorporeal membrane oxygenation (ECMO) support, and antibiotic treatment was adjusted accordingly. The patient underwent comprehensive treatment and rehabilitation in the intensive care unit.

CONCLUSION

This case illustrates the importance of early diagnosis and treatment of leptospirosis. While obtaining the epidemiological history, second-generation metagenomics sequencing was utilized to confirm the etiology. The prompt initiation of ECMO therapy provided a crucial window of opportunity for addressing the underlying cause. This case report offers valuable insights for diagnosing patients with similar symptoms.

Modeling the dynamics of leptospirosis in India

Leptospirosis, a formidable zoonotic threat spawned by Leptospira, plagues tropical and subtropical realms. This study delves deep into tropical Indian states, namely, Kerala, Gujarat, Karnataka, Maharashtra, and Tamil Nadu, unraveling the dynamics of leptospirosis through a comprehensive mathematical model that embraces temperature-driven growth rates of Leptospira. Sensitivity analysis and parameter estimation techniques fortified the model's accuracy, unraveling the factors shaping leptospirosis transmission. Notably, the numerical results highlight the significant impact of rainfall, fishing, climate, mining, agriculture, and cattle farming on leptospirosis prevalence in the endemic states of India. Finally, our study urges resolute preventive action to control and combat leptospirosis in India. Strengthening surveillance, impactful awareness campaigns, targeted interventions, and improved hygiene practices among high-risk individuals are vital. Embracing these proactive strategies will alleviate the burden of leptospirosis and enhance public health in India and beyond.

Updated ACVIM consensus statement on leptospirosis in dogs

Since publication of the last consensus statement on leptospirosis in dogs, there has been revision of leptospiral taxonomy and advancements in typing methods, widespread use of new diagnostic tests and vaccines, and improved understanding of the epidemiology and pathophysiology of the disease. Leptospirosis continues to be prevalent in dogs, including in small breed dogs from urban areas, puppies as young as 11 weeks of age, geriatric dogs, dogs in rural areas, and dogs that have been inadequately vaccinated for leptospirosis (including dogs vaccinated with 2-serovar Leptospira vaccines in some regions). In 2021, the American College of Veterinary Internal Medicine (ACVIM) Board of Regents voted to approve the topic for a revised Consensus Statement. After identification of core panelists, a multidisciplinary group of 6 experts from the fields of veterinary medicine, human medicine, and public health was assembled to vote on the recommendations using the Delphi method. A draft was presented at the 2023 ACVIM Forum, and a written draft posted on the ACVIM website for comment by the membership before submission to the editors of the Journal of Veterinary Internal Medicine. This revised document provides guidance for veterinary practitioners on disease in dogs as well as cats. The level of agreement among the 12 voting members (including core panelists) is provided in association with each recommendation. A denominator lower than 12 reflects abstention of ≥1 panelists either because they considered the recommendation to be outside their scope of expertise or because there was a perceived conflict of interest.

Impaired functions of human monocyte-derived dendritic cells and induction of regulatory T cells by pathogenic Leptospira

Leptospirosis is a global zoonosis caused by pathogenic Leptospira. The disease outcome is influenced by the interplay between innate and adaptive immune responses. Dendritic cells (DCs) play a crucial role in shaping the adaptive immune response. A recent study revealed that pathogenic Leptospira limited the activation of human monocyte-derived dendritic cells (MoDCs) compared to non-pathogenic Leptospira, but their impact on T-cell responses has not been investigated. Our study is the first to explore how viable pathogenic and non-pathogenic Leptospira affect the interaction between human MoDCs and T cells. We found that MoDCs infected with pathogenic leptospires (L. interrogans serovar Pomona and a clinical isolate, MoDCs-P) exhibited lower levels of CD80 and CD83 expression, suggesting partially impaired MoDC maturation, induced regulatory T cells (Tregs) while failing to induce CD4+ T cell proliferation, compared to MoDCs infected with non-pathogenic leptospires (L. biflexa serovar Patoc and L. meyeri serovar Ranarum, MoDCs-NP). In contrast, non-pathogenic leptospires enhanced MoDC maturation and induced higher T cell proliferation including IFN-γ-producing CD4+ T cells, indicative of a Th1-type response. Furthermore, pathogenic leptospires induced higher MoDC apoptosis through a cysteine aspartic acid-specific protease-3 (caspase-3)-dependent pathway and upregulated expression of the prostaglandin-endoperoxide synthase 2 (PTGS2) gene. Notably, prostaglandin E2 (PGE2), a product of the PTGS2 pathway, was found at higher levels in the sera of patients with acute leptospirosis and in the supernatant of MoDCs-P, possibly contributing to Treg induction, compared to those of healthy donors and MoDCs-NP, respectively. In conclusion, this study reveals a novel immunosuppressive strategy employed by pathogenic Leptospira to evade host immunity by partially impairing MoDC maturation and inducing Tregs. These findings deepen our understanding of leptospirosis pathogenesis in humans and may provide a novel strategy to modulate DCs for the prevention and treatment of the disease.

Phylogenomics of Leptospira santarosai, a prevalent pathogenic species in the Americas

BACKGROUND

Leptospirosis is a complex zoonotic disease mostly caused by a group of eight pathogenic species (L. interrogans, L. borgpetersenii, L. kirschneri, L. mayottensis, L. noguchii, L. santarosai, L. weilii, L. alexanderi), with a wide spectrum of animal reservoirs and patient outcomes. Leptospira interrogans is considered as the leading causative agent of leptospirosis worldwide and it is the most studied species. However, the genomic features and phylogeography of other Leptospira pathogenic species remain to be determined.

METHODOLOGY/PRINCIPAL FINDINGS

Here we investigated the genome diversity of the main pathogenic Leptospira species based on a collection of 914 genomes from strains isolated around the world. Genome analyses revealed species-specific genome size and GC content, and an open pangenome in the pathogenic species, except for L. mayottensis. Taking advantage of a new set of genomes of L. santarosai strains isolated from patients in Costa Rica, we took a closer look at this species. L. santarosai strains are largely distributed in America, including the Caribbean islands, with over 96% of the available genomes originating from this continent. Phylogenetic analysis showed high genetic diversity within L. santarosai, and the clonal groups identified by cgMLST were strongly associated with geographical areas. Serotype identification based on serogrouping and/or analysis of the O-antigen biosynthesis gene loci further confirmed the great diversity of strains within the species.

CONCLUSIONS/SIGNIFICANCE

In conclusion, we report a comprehensive genome analysis of pathogenic Leptospira species with a focus on L. santarosai. Our study sheds new light onto the genomic diversity, evolutionary history, and epidemiology of leptospirosis in America and globally. Our findings also expand our knowledge of the genes driving O-antigen diversity. In addition, our work provides a framework for understanding the virulence and spread of L. santarosai and for improving its surveillance in both humans and animals.

Severe mononeuritis multiplex as a rare case of neuro leptospirosis: A case report

Leptospirosis is a zoonotic bacterial disease caused by infection of spirochetes of the genus Leptospira. While typically self-limiting and non-fatal, severe manifestations can arise, including various neurological complications that are often overlooked. This case study presents a 59-year-old man with serologically positive Leptospirosis, who subsequently developed asymmetrical progressive leg weakness, severe back pain, and overflow incontinence suggestive of mononeuritis multiplex. Doxycycline treatment was started and intended to last for seven days. The patient had ongoing paraparesis, but all other problems were disappeared. The present case emphasizes the significance of identifying and treating neurological problems brought on by leptospirosis. To improve suitable treatment plans and patient outcomes, more research on these problems is necessary.

Quantifying the relationship between climatic indicators and leptospirosis incidence in Fiji: A modelling study

Leptospirosis, a global zoonotic disease, is prevalent in tropical and subtropical regions, including Fiji where it's endemic with year-round cases and sporadic outbreaks coinciding with heavy rainfall. However, the relationship between climate and leptospirosis has not yet been well characterised in the South Pacific. In this study, we quantify the effects of different climatic indicators on leptospirosis incidence in Fiji, using a time series of weekly case data between 2006 and 2017. We used a Bayesian hierarchical mixed-model framework to explore the impact of different precipitation, temperature, and El Niño Southern Oscillation (ENSO) indicators on leptospirosis cases over a 12-year period. We found that total precipitation from the previous six weeks (lagged by one week) was the best precipitation indicator, with increased total precipitation leading to increased leptospirosis incidence (0.24 [95% CrI 0.15-0.33]). Negative values of the Niño 3.4 index (indicative of La Niña conditions) lagged by four weeks were associated with increased leptospirosis risk (-0.2 [95% CrI -0.29 --0.11]). Finally, minimum temperature (lagged by one week) when included with the other variables was positively associated with leptospirosis risk (0.15 [95% CrI 0.01-0.30]). We found that the final model was better able to capture the outbreak peaks compared with the baseline model (which included seasonal and inter-annual random effects), particularly in the Western and Northern division, with climate indicators improving predictions 58.1% of the time. This study identified key climatic factors influencing leptospirosis risk in Fiji. Combining these results with demographic and spatial factors can support a precision public health framework allowing for more effective public health preparedness and response which targets interventions to the right population, place, and time. This study further highlights the need for enhanced surveillance data and is a necessary first step towards the development of a climate-based early warning system.

Seroprevalence and associated risk factors of leptospirosis in bovine dairy farms in Telangana state, India

The current cross-sectional study aimed to determine the seroprevalence of Leptospira infection in bovine dairy farms in the Telangana state of India, as well as the associated risk factors, in order to implement effective preventive measures for disease control. A total of 469 blood samples were collected from 67 herds/farms in different areas, covering 20 administrative districts in the state. These samples consisted of 253 from cattle and 216 from buffaloes. Questionnaires were used to collect data on host and epidemiological factors. The collected sera were tested using the gold standard serological test, the Microscopic Agglutination Test (MAT), which employed a panel of 18 reference serovars for Leptospira exposure. The statistical analysis of epidemiological data was carried out to identify the risk factors associated with Leptospira exposure. The overall observed seroprevalence at the animal and farm levels was 41.4% and 77.6%, respectively. The most prevalent anti-leptospiral antibodies were observed against the serogroups Icterohaemorrhagiae (32.4%), Pomona (22.2%), Javanica (19.1%), Australis (17.0%), Bataviae (15.5%), Autumnalis (12.9%), Hebdomadis (12.9%), and others, in the total reacting samples. At the animal level, the significant risk factors associated with exposure to Leptospira species were breed (p = 0.03) and health status (p = 0.03). Furthermore, the multivariate statistical analysis of farm factors revealed that farm size (p = 0.05), presence of dogs (p = 0.04) and rodents (p = 0.01) on the farm, use of fodder from wet soils (p = 0.04), and proximity to water bodies (p = 0.04) were significantly associated with exposure to Leptospira in the studied region. This study provides the first report from India highlighting the important risk factors at the herd/farm and animal level associated with Leptospira infections in cattle and buffaloes. The findings contribute to strengthening the one-health strategy by facilitating the design and planning of appropriate control measures to alleviate the burden of leptospirosis in bovines.

Prevalence and Risk Factors of Leptospira spp. Infection in Backyard Pigs in the State of Paraná, Brazil

Leptospirosis is a zoonotic disease that poses a significant threat to human and animal health worldwide. Among different animal species, pigs are known to play a crucial role in the transmission of the pathogenic Leptospira spp. This study aimed to investigate the prevalence of Leptospira spp. infection and associated risk factors in backyard pigs in the state of Paraná, Brazil. A set of 1393 blood samples were collected from pigs on 188 subsistence properties from 136 different municipalities of the Paraná state and tested using the microscopic agglutination test (MAT) to detect antibodies against 24 different Leptospira spp. serovars. The results revealed an overall seroprevalence of 15.87% (221/1393; 95% CI: 13.95-17.78%) for Leptospira spp. antibodies, with Icterohaemorrhagiae, Butembo, and Pomona being the most commonly detected in serovar levels. The lack of rodent control (OR 1.12, 95% CI: 0.63-1.98, p = 0.02) was the only variable associated with disease incidence and was identified as a significant risk factor for Leptospira spp. infection in this context. These findings highlight the urgent need to implement effective control measures, such as improved housing conditions, rodent control, and veterinary assistance, to prevent the spread of this zoonotic disease in backyard pigs in Paraná, Brazil.

An investigation of geographical clusters of leptospirosis during the outbreak in Pangandaran, West Java, Indonesia

Leptospirosis is neglected in many tropical developing countries, including Indonesia. Our research on this zoonotic disease aimed to investigate epidemiological features and spatial clustering of recent leptospirosis outbreaks in Pangandaran, West Java. The study analysed data on leptospirosis notifications between September 2022 and May 2023. Global Moran I and local indicator for spatial association (LISA) were applied. Comparative analysis was performed to characterise the identified hotspots of leptospirosis relative to its neighbourhoods. A total of 172 reported leptospirosis in 40 villages from 9 sub-districts in Pangandaran District were analysed. Of these, 132 cases (76.7%) were male. The median age was 49 years (interquartile range [IQR]: 34-59 years). Severe outcomes including renal failure, lung failure, and hepatic necrosis were reported in up to 5% of the cases. A total of 30 patients died, resulting in the case fatality rate (CFR) of 17.4%. Moran's I analysis showed significant spatial autocorrelation (I=0.293; p=0.002) and LISA results identified 7 High-High clusters (hotspots) in the Southwest, with the total population at risk at 26,184 people. The hotspots had more cases among older individuals (median age: 51, IQR: 36-61 years; p<0.001), more farmers (79%, p=0.001) and more evidence of the presence of rats (p=0.02). A comprehensive One Health intervention should be targeted towards these high-risk areas to control the transmission of leptospirosis. More empirical evidence is needed to understand the role of climate, animals and sociodemographic characteristics on the transmission of leptospirosis in the area studied.

Case Report: Relapsing Leptospirosis in an Immunocompromised Host

Leptospirosis is typically a self-limited febrile illness; when it occurs, meningitis usually develops early in the course. Here, we describe a patient who had engaged in freshwater activities in Kauai that was immunocompromised due to a history of mantle cell lymphoma, autologous hematopoietic cell transplant, and hypogammaglobulinemia. He developed leptospiral meningoencephalitis 11 weeks after illness onset and persistently detectable Leptospira DNA in blood and cerebrospinal fluid along with ongoing clinical illness, despite appropriate treatment.

Pulmonary haemorrhage as a frequent cause of death among patients with severe complicated Leptospirosis in Southern Sri Lanka

BACKGROUND

Leptospirosis is a tropical disease associated with life threatening complications. Identifying clinical and investigation-based parameters that predict mortality and morbidity is vital to provide optimal supportive care.

METHODS

We conducted an observational study in an endemic setting, in the southern Sri Lanka. Consecutive patients having complicated leptospirosis were recruited over 18 months. Clinical, investigational and treatment data were collected and the predictors of mortality were analysed.

RESULTS

Out of 88 patients having complicated leptospirosis, 89% were male. Mean age was 47yrs (±16.0). Among the total major complications 94.3% had acute kidney injury, 38.6% pulmonary haemorrhages, 12.5% fulminant hepatic failure, 60.2% hemodynamic instability and 33% myocarditis. An acute significant reduction of haemoglobin (Hb) was observed in 79.4% of patients with pulmonary haemorrhage. The mean of the highest haemoglobin reduction in patients with pulmonary haemorrhage was 3.1g/dL. The presence of pulmonary haemorrhage (PH) and hemodynamic instability within first 48 hours of admission significantly predicted mortality (p<0.05) in severe leptospirosis. Additionally, within first 48 hours of admission, elevated SGOT (AST), presence of atrial fibrillation, presence of significant haemoglobin reduction, higher number of inotropes used, prolonged shock, invasive ventilation and admission to ICU significantly predicted mortality. Out of major complications during the first week after admission, pulmonary haemorrhage and fulminant hepatic failure (FHF) combination had significant adjusted odds of mortality (OR = 6.5 and 4.8, p<0.05). Six patients with severe respiratory failure due to PH underwent ECMO and four survived. The overall mortality in complicated leptospirosis was 17%. In PH and FHF, the mortality rate was higher reaching 35.4% and 54.5%, respectively.

CONCLUSIONS

Within first 48 hours of admission, major complications such as pulmonary haemorrhage and haemodynamic instability and other parameters such as atrial fibrillation, acute haemoglobin reduction, elevated SGOT level could be used as early parameters predictive of mortality in severe leptospirosis. PH and FHF during the first week of admission in leptospirosis are associated with high morbidity and mortality requiring prolonged ICU care and hospitalisation. Above parameters could be used as parameters indicating severity for triaging and intensifying treatment. Using ECMO is a plausible treatment option in patients with severe pulmonary haemorrhage.