Emergence of novel Leptospira serovars: a need for adjusting vaccination policies for dogs?

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.

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.

Effect of Vaccination against Leptospira on Shelter Asymptomatic Dogs Following a Long-Term Study

(1) Background: Vaccination of dogs against leptospirosis is of paramount importance, as they ideally must provide not only long-term protection, but also against the renal carrier state of leptospires. This study assessed the post-vaccine humoral response against Leptospira in naturally exposed dogs and effects on renal carrier status. (2) Methods: A total of 118 dogs were studied for 365 days, separated into Group A (vaccinated, n = 94) and Group B (non-vaccinated, n = 24). Group A was subdivided into three groups: A1 with 32 dogs immunized with the vaccine #1; A2 by 32 dogs with #2; and A3 30 dogs with #3. Serology (MAT and IgG-ELISA) and urinary PCR were conducted. (3) Results: Seroreactivity increased at D15 post-vaccination and, regardless of vaccine brand, remained high up to D180, with antibody switch to IgG after D30. A total of 46.8% of animals from Group A were PCR-positive at least once, in contrast to 75% in Group B, regardless of vaccine brand (p < 0.05; OR: 0.3). (4) Conclusions: All commercial vaccines succeeded at eliciting a long-term IgG-based response and were partially effective at protecting against kidney infection.

Isolation of Leptospira interrogans Serovar Canicola in a Vaccinated Dog without Clinical Symptoms

More than one million cases of leptospirosis occur across the globe annually, resulting in about 59,000 deaths. Dogs are one of the most important reservoirs of Leptospira species and play an important role in transmitting the pathogen to humans. Many of these infections are controlled by routine vaccination that has reduced the possible reintroduction of leptospiral serovars into the human population. However, it is still not clear how a vaccinated dog can become infected with one or more Leptospira serovars contained in the vaccine formulation and thus against which it should be immunized. Here, we present the case of an asymptomatic dog who developed leptospiral infection despite being vaccinated. This unusual case emphasizes the substantial impact of immunization on mitigating the acute signs of the disease, even while providing limited protection against infection. Further studies will be required to better understand the role of dogs in the environmental circulation of leptospiral serovars in Sardinia. Asymptomatic leptospiral infection in vaccinated dogs should be considered to allow for better diagnosis and management of the infection. This will be essential for preventing Leptospira outbreaks in the future.

Role of Diagnostics in Epidemiology, Management, Surveillance, and Control of Leptospirosis

A One Health approach to the epidemiology, management, surveillance, and control of leptospirosis relies on accessible and accurate diagnostics that can be applied to humans and companion animals and livestock. Diagnosis should be multifaceted and take into account exposure risk, clinical presentation, and multiple direct and/or indirect diagnostic approaches. Methods of direct detection of Leptospira spp. include culture, histopathology and immunostaining of tissues or clinical specimens, and nucleic acid amplification tests (NAATs). Indirect serologic methods to detect leptospiral antibodies include the microscopic agglutination test (MAT), the enzyme-linked immunosorbent assay (ELISA), and lateral flow methods. Rapid diagnostics that can be applied at the point-of-care; NAAT and lateral flow serologic tests are essential for management of acute infection and control of outbreaks. Culture is essential to an understanding of regional knowledge of circulating strains, and we discuss recent improvements in methods for cultivation, genomic sequencing, and serotyping. We review the limitations of NAATs, MAT, and other diagnostic approaches in the context of our expanding understanding of the diversity of pathogenic Leptospira spp. Novel approaches are needed, such as loop mediated isothermal amplification (LAMP) and clustered regularly interspaced short palindromic repeats (CRISPR)-based approaches to leptospiral nucleic acid detection.

Prevalence of leptospirosis in vaccinated working dogs and humans with occupational risk

Introducción.

Los perros de trabajo pueden infectarse con diversas serovariedades de Leptospira que se mantienen en sus túbulos renales e intersticios por mucho tiempo, por lo que se convierten en portadores y fuentes de infección para otros huéspedes.

Objetivo.

Establecer la prevalencia de Leptospira spp. en perros de trabajo vacunados y en población humana con riesgo ocupacional de seis unidades policiales en Colombia.

Materiales y métodos.

Mediante tres instrumentos estructurados, se evaluaron 92 perros de trabajo con inmunización previa contra Leptospira spp. (65 machos y 27 hembras) y 69 personas de seis unidades policiales de los municipios de Manizales, Pereira, Armenia, Ibagué, Tuluá y Cali. Se obtuvieron muestras sanguíneas de las personas y de los perros, las cuales se evaluaron mediante la prueba de microaglutinación (Microscopic Agglutination Test, MAT) en 24 serogrupos. Se hizo un examen clínico de los perros y se obtuvieron muestras de orina para urocultivo.

Resultados.

La seroprevalencia de leptospirosis en las personas fue de 2,9 % (n=2) y en los perros de 57,61 % (n=53). Los serogrupos más prevalentes en los perros fueron Leptospira canicola y L. panama. El urocultivo fue positivo en 58,7 % (54/92) de las muestras y se encontró asociación estadísticamente significativa entre la edad de los perros (≥10 años; p=0,043) y la ubicación de la unidad policial (p=0,016).

Conclusión.

Las características epidemiológicas de la leptospirosis en los perros sugieren una presentación endémica de la infección. Se requieren algoritmos diagnósticos sensibles y específicos para investigar la leptospirosis canina y diferenciar los anticuerpos vacunales de la infección natural.

Identification of σE-Dependent Promoter Upstream of clpB from the Pathogenic Spirochaete Leptospira interrogans by Applying an E. coli Two-Plasmid System

There is limited information on gene expression in the pathogenic spirochaete Leptospira interrogans and genetic mechanisms controlling its virulence. Transcription is the first step in gene expression that is often determined by environmental effects, including infection-induced stresses. Alterations in the environment result in significant changes in the transcription of many genes, allowing effective adaptation of Leptospira to mammalian hosts. Thus, promoter and transcriptional start site identification are crucial for determining gene expression regulation and for the understanding of genetic regulatory mechanisms existing in Leptospira. Here, we characterized the promoter region of the L. interrogans clpB gene (clpB_Li) encoding an AAA⁺ molecular chaperone ClpB essential for the survival of this spirochaete under thermal and oxidative stresses, and also during infection of the host. Primer extension analysis demonstrated that transcription of clpB in L. interrogans initiates at a cytidine located 41 bp upstream of the ATG initiation codon, and, to a lesser extent, at an adenine located 2 bp downstream of the identified site. Transcription of both transcripts was heat-inducible. Determination of clpB_Li transcription start site, combined with promoter transcriptional activity assays using a modified two-plasmid system in E. coli, revealed that clpB_Li transcription is controlled by the ECF σ^E factor. Of the ten L. interrogans ECF σ factors, the factor encoded by LIC_12757 (LA0876) is most likely to be the key regulator of clpB gene expression in Leptospira cells, especially under thermal stress. Furthermore, clpB expression may be mediated by ppGpp in Leptospira.

Leptospira seroprevalence in owned dogs from Spain

Leptospira is a widespread zoonosis that has been linked to transmission between dogs and humans. The main purposes were to determine the seroprevalence of anti-Leptospira serum antibody and to identify the most common serovars in dogs in Spain. This is a cross-sectional study with 1,310 records of canine Leptospira testing data from Spain since 2015 to 2017. Inclusion criteria were individual cases with MAT test results for 8 serovars (Bratislava, Icterohaemorrhagiae, Australis, Pomona, Grippotyphosa, Autumnalis, Canicola and Saxkoebing) and to have the zip code data. Three hundred and thirty-eight samples (25.8%; 95%CI 23.6–28.4) were seropositive (≥1:100). According to geographic areas, North had the highest seroprevalence (38.0%; 95%CI 28.9–47.1) followed by South (29.4%; 95%CI 20.1–38.8), Center (28.6%; 95%CI 24.3–33.0), Mediterranean (22.3%; 95%CI 19.1–25.6) and Northwest (22.2%; 95%CI 7.9–36.4). Seropositivity (MAT ≥1:100) was most common to serovars Icterohaemorrhagiae (19.4%; 95%CI 17.2–21.5) and Bratislava (8.5%; 95%CI 7.0–10.0), followed by Grippotyphosa (7.2%; 95%CI 5.8–8.6), Australis (6.4%; 95%CI 5.0–7.7), Autumnalis (5.0%; 95%CI 3.8–6.2), Pomona (4.5%; 95%CI 3.3–5.6), Canicola (3.4%; 95%CI 2.4–4.4) and Saxkoebing (0.8%; 95%CI 0.3–1.3). An association was found between positivity (MAT ≥1:100) and males (P = 0.003) and dogs that were 6 years old or older were at higher risk of exposure (P = 0.001; OR 4.61; 95%CI 1.86–11.43). This study has shown that dogs in Spain are commonly exposed to Leptospira infection and points out the necessity to control the prevalence of this severe widespread zoonosis in dogs and humans.

Biochemical parameters of blood in cows in latent course of leptospirosis

Changes in the biochemical parameters of blood in cows in the latent course of leptospirosis have been studied by the results of the reaction of microagglutination (RMA). The dynamics of biochemical blood parameters is manifested by hyperproteinemia, dysproteinemia, hemolytic anemia, hyperbilirubinemia, intra- and extrahepatic cholestasis, hyperfermentemia, mineral metabolism disorders, in particular hypocalcemia, hypophosphatemia, indicating the development of hepatopathy which should be classified as hepatocholangitis. It was determined that the pathological process is manifested in all animals for the titer of antibodies to one or another Leptospira serovar. Significant changes from the side of the hepatobiliary system in infested cows for the antibody titer kabura equaling 1:100, polonica 1:200, ballum 1:100, szvajzak 1:100–1:200, bratislava 1:800 and in animals for the titers kabura of 1:100–1:200; polonium 1:100; szvajzak 1:100–1:200; ballum 1:100; bratislava 1:100–1:200. At leptospirosis caused by bratislava and ballum serovars, a disorder of the functional state of the hepatobiliary system, characterized by an increase in the level of total protein, bilirubin, AST, GGTP and ALP activity was diagnosed as the urea, calcium and phosphorus levels in blood decreased. In the case of the latent course of the disease caused by kabura, polonica, szvajzak, ballumand bratislava serovars, a probably higher concentration of bilirubin, activity of aminotransferases (AST and ALAT), GGTP and ALP was determined in comparison to clinically healthy animals. In cows, in the presence of antibody titers kabura 1:100, polonica 1:200, ballum 1:100, szvajzak 1:100–1:200; bratislava 1:800, in 22.2% of cases, we recorded increase in the total protein against the background of dysproteinemia in 50.0–88.9% of animals, and increase in bilirubin in 78.6%, and increase in the activity of blood serum enzymes (AST, ALAT, GGTP, ALP), and also hypocalcemia and hypophosphatemia in 33.3–100.0%. The conducted studies indicate that in latent leptospirosis in cows, in addition to etiotropic therapy, one should include in the protocol the pharmacological correction preparations, which would contribute to the restoration of the functional state of the hepatobiliary system.

Hepatic leptospiral infections in dogs without obvious renal involvement

Background

Reports of chronic hepatitis in dogs caused by Leptospira spp. are confined to small case series. Fluorescence in situ hybridization (FISH) allows the identification of spirochetes in liver samples. Consequently, this technique may help elucidate the role of Leptospira spp. in cases of chronic hepatitis.

Objectives

To describe cases of hepatic leptospirosis in dogs diagnosed by FISH and subsequent polymerase chain reaction (PCR) speciation, with the absence of clinically relevant renal involvement.

Animals

Ten client‐owned dogs.

Methods

Retrospective case series from the University of Cambridge presented between 2013 and 2016 or cases consulted by telephone advice during this time period. Cases were selected based on histopathologically confirmed granulomatous hepatitis and leptospiral organisms identified by FISH and PCR speciation (Leptospira interrogans/kirschneri).

Results

All cases had increased liver enzyme activities, and FISH in combination with PCR speciation‐confirmed infection with L. interrogans/kirschneri. Four dogs underwent repeat liver biopsy, FISH and PCR speciation 4‐15 months after initial presentation and doxycycline treatment with 1 dog undergoing repeat sampling at necropsy. Three dogs that underwent repeat biopsy remained positive for L. interrogans/kirschneri infection. Six dogs were alive at the time of manuscript preparation and 4 dogs were euthanized as a result of progressive liver disease.

Conclusions and Clinical Importance

The presence of hepatic leptospiral organisms may be associated with chronic granulomatous hepatitis without clinical evidence of renal involvement. Further studies are necessary to elucidate the etiological role of these organisms in the disease.

MAT cross-reactions or vaccine cross-protection: retrospective study of 863 leptospirosis canine cases

Dogs are naturally exposed to numerous pathogenic serogroups. Leptospirosis vaccines are claimed to afford a clinical protection restricted to the serogroups of which they are composed.

Objectives

Dogs exhibiting liver and kidney injury were suspected of having leptospirosis. The purpose of this study was to compare the microscopic agglutination test (MAT) results in naive and vaccinated dogs experiencing leptospirosis outcomes. Only MAT-positive animals were included in the study.

Methods

Over five years, 3 512 dogs were suspected of having leptospirosis. For each case, biochemical parameter results were recorded. Leptospirosis involvement was investigated by MAT performed against 6 major serogroups (Icterohaemorrhagiae, Canicola, Australis, Autumnalis, Grippotyphosa and Sejroë). MAT-positive results confirmed leptospirosis cases in 147 naïve dogs and in 580 fully vaccinated dogs. Serological titres of agglutinating antibodies were related to the severity of liver and kidney failure.

Results

The most prevalent outcome of leptospirosis in unvaccinated dogs was liver failure (57.8%) compared to 51.7% for kidney disease, but the most severe onset (90.8%) was found among the cases of acute kidney injury compared to the severe (42.3%) hepatitis cases. In dogs vaccinated by bivalent Icterohaemorrhagiae and Canicola bacterins, hepatitis decreased from 57.8 to 46.5% and acute kidney injury from 51.7 to 21.6%. The decrease was shown in leptospirosis cases induced by field strains belonging to the six most prevalent serogroups, including the 4 serogroups heterologous to the vaccine.

Conclusion

Common vaccination was efficient in decreasing hepatitis and kidney failure induced by field Leptospira spp infection regardless of the MAT-prominent serogroup and limited the disease severity in the remaining cases.

Orchitis and balanoposthitis in a dog with Leptospira interrogans serovar Canicola in Southern California

Leptospirosis is a disease caused by bacteria Leptospira. It can infect multiple species of mammals, including humans, dogs, rats, mice, raccoons, skunks, opossums, cows and pigs. Once infected, mammals may present with a variety of clinical manifestations. While the classical presentation of the disease is easily recognised by experienced clinicians practising in endemic regions, atypical systemic manifestations can be missed. In this case report, we describe the atypical manifestations of orchitis and balanoposthitis in a five-year-old male intact dog from Los Angeles County, California with confirmed leptospirosis. The dog was infected with serovar Canicola, which is uncommon for this region. Awareness of these atypical manifestations would hopefully guide clinicians towards early diagnosis.

Isolation and Identification of Putative Protein Substrates of the AAA+ Molecular Chaperone ClpB from the Pathogenic Spirochaete Leptospira interrogans

Bacterial ClpB is an ATP-dependent Hsp100 chaperone that reactivates aggregated proteins in cooperation with the DnaK chaperone system and promotes survival of bacteria under stress conditions. A large number of publications also indicate that ClpB supports the virulence of bacteria, including a pathogenic spirochaete Leptospira interrogans responsible for leptospirosis in both animals and humans. However, the exact role of ClpB in bacterial pathogenicity remains poorly characterized. It can be assumed that ClpB, due to its role as the molecular chaperone, mediates refolding of essential bacterial proteins, including the known virulence factors, which may become prone to aggregation under infection-induced stresses. In this study, we identified putative substrates of ClpB from L. interrogans (ClpB_Li). For this purpose, we used a proteomic approach combining the ClpB-Trap affinity pull-down assays, Liquid chromatography-tandem mass spectrometry (LC-MS-MS/MS), and bioinformatics analyses. Most of the identified proteins were enzymes predominantly associated with major metabolic pathways like the tricarboxylic acid (TCA) cycle, glycolysis–gluconeogenesis and amino acid and fatty acid metabolism. Based on our proteomic study, we suggest that ClpB can support the virulence of L.interrogans by protecting the conformational integrity and catalytic activity of multiple metabolic enzymes, thus maintaining energy homeostasis in pathogen cells.

Isolation and characterization of pathogenic leptospires associated with cattle

Pathogenic leptospires colonize the renal tubules of reservoir hosts of infection, including cattle, and are excreted via urine. In order to identify circulating serovars of pathogenic leptospires in beef cattle, and their associated rates of urinary excretion, a cross sectional study was performed. Fifty urine samples were collected one day each month over 12 consecutive months (N = 600), directly from the bladder of beef cattle at a single slaughter facility and assessed for the presence of leptospires by culture and the fluorescent antibody test (FAT). Where possible, a matched serum sample was also collected for the microscopic agglutination test (MAT). Forty-three urine samples were either culture positive or FAT positive, indicating that 7.2% of sampled beef cattle were actively excreting leptospires in urine. Twenty-three urine samples were culture positive. Sequence analysis of 16S ribosomal DNA and secY indicated that all isolates were Leptospira borgpetersenii. Typing by serology indicated that all isolates were serogroup Sejroe. An overall seroprevalence of 20% (MAT ≥ 1:25) was determined; positive bovine sera was most reactive to serogroup Sejroe (serovar Hardjo) (8.1%), and serogroup Australis (serovar Bratislava) (6.7%). There was poor correlation between seroprevalence and excretion of leptospires since 18/43 (41.9%) cattle, which were positive by culture or FAT, were seronegative. The virulence of two selected isolates of L. borgpetersenii was confirmed by experimental infection in small animal models of infection. Results confirm that L. borgpetesenii continues to circulate in beef cattle and that multiple diagnostic assays are required to detect active shedding. These findings also highlight beef cattle as a reservoir host for the potential zoonotic transmission of leptospires.

Seroprevalence of Leptospirosis in Working Dogs

Working dogs are canine animals that have been trained to assist human beings in carrying out various tasks. They help in guarding property, performing rescues, assisting the visually impaired or physically handicapped, searching for drugs, explosives, and others. Leptospirosis is one of the most widespread zoonotic diseases in the world and a commonly occurring disease of the tropics and subtropics. In Malaysia, all working dogs are normally vaccinated with serovars, Pomona, Icterohaemorrhagiae, Canicola, and Grippotyphosa based on protocols recommended from other countries. The duration of immunity in vaccinated dogs for Leptospira can last up to 13 months; however, there is no full crossprotection between the different serovars. Five representative canine units from different government agencies in Malaysia (n = 96 dogs) were recruited in this study. For detection, the microscopic agglutination test was performed by incubating the serum from dogs with various serovars of leptospires, namely, Icterohaemorrhagiae, Canicola, Pomona, Grippotyphosa, Australis, Bataviae, Javanica, Tarassovi, Hebdomadis, Lai, and Pyrogenes. The plasma obtained was used for polymerase chain reaction (PCR) analysis, for the detection of 16S rRNA, and lipL 32 genes of Leptospira. Out of the 96 dogs sampled, only 3 dogs were positive toward serovars, Australis, Bataviae, and Javanica, based on the cutoff point at 1:80. The seroprevalence of canine leptospirosis in this population was 3.1% (n = 3/96). However, all 96 blood samples of working dogs tested negative for both pathogenic and nonpathogenic Leptospira genes. The results revealed that, by vaccination alone, working dogs were not fully protected against leptospirosis and could pose a risk to dog handlers. A preventative and control protocol for leptospirosis is warranted, and its implementation should be monitored and improved accordingly from time to time, in order to maintain a healthy condition in both working dogs and their handlers.

Characterization of the molecular chaperone ClpB from the pathogenic spirochaete Leptospira interrogans

Leptospira interrogans is a spirochaete responsible for leptospirosis in mammals. The molecular mechanisms of the Leptospira virulence remain mostly unknown. Recently, it has been demonstrated that an AAA+ chaperone ClpB (a member of the Hsp100 family) from L. interrogans (ClpBLi) is not only essential for survival of Leptospira under the thermal and oxidative stresses, but also during infection of a host. The aim of this study was to provide further insight into the role of ClpB in the pathogenic spirochaetes and explore its biochemical properties. We found that a non-hydrolysable ATP analogue, ATPγS, but not AMP-PNP induces the formation of ClpBLi hexamers and stabilizes the associated form of the chaperone. ADP also induces structural changes in ClpBLi and promotes its self-assembly, but does not produce full association into the hexamers. We also demonstrated that ClpBLi exhibits a weak ATPase activity that is stimulated by κ-casein and poly-lysine, and may mediate protein disaggregation independently from the DnaK chaperone system. Unexpectedly, the presence of E. coli DnaK/DnaJ/GrpE did not significantly affect the disaggregation activity of ClpBLi and ClpBLi did not substitute for the ClpBEc function in the clpB-null E. coli strain. This result underscores the species-specificity of the ClpB cooperation with the co-chaperones and is most likely due to a loss of interactions between the ClpBLi middle domain and the E. coli DnaK. We also found that ClpBLi interacts more efficiently with the aggregated G6PDH in the presence of ATPγS rather than ATP. Our results indicate that ClpB's importance during infection might be due to its role as a molecular chaperone involved in reactivation of protein aggregates.

New trends in human and animal leptospirosis in Croatia, 2009-2014

Leptospirosis is a geographically widespread and globally underestimated zoonosis that affects humans and variety of animals. To identify trends and possible risk factors, joined medical and veterinary teams investigated epidemiology and epizootiology of leptospirosis in Croatia. Retrospective analysis of data obtained from referent diagnostic laboratories included a total of 1917 human and 123964 animal sera tested in the period from 2009 to 2014. We found high human leptospirosis average incidence rate of 1.53/100000 with clear predominance of male patients older than 40 years (sex ratio M/F:3.2; median age 51±15.1years). Statistical analysis revealed seasonal and annual variations of incidence in humans that were primarily associated with favourable weather conditions (temperature 10-19, 9°C and precipitation above 100mm/m²). Majority of infections in humans were caused by serogroups Sejroe, Australis and Icterohaemorrhagiae. Notable variations in seroprevalence and changing trends in prevailing serogroups were recorded in most of the domestic animals and during the entire period of investigation. All of the observed findings underline leptospirosis as a significant human and veterinary public health threat and emphasize the importance of continuous multidisciplinary surveillance. We also argue that only input from both professions improves our overall knowledge on leptospirosis and leads to better and more efficient prevention and control strategies.

First report of Leptospira infections in red deer, roe deer, and fallow deer in Poland

Introduction: Recently in Europe an increase in the population of red deer (Cervus elaphus), roe deer (Capreolus capreolus), and fallow deer (Dama dama) has been observed. Research on the prevalence of Leptospira infections in Polish cervids has been performed for the first time.

Material and Methods: During 2014/2015 hunting season, 147 blood samples from red deer, roe deer, and fallow deer were collected. The animals originated from different geographical regions across Poland. Serum samples were tested by microscopic agglutination test (MAT) for the presence of specific antibodies to the following Leptospira serovars: Icterohaemorrhagiae, Grippotyphosa, Sejroe, Tarassovi, Pomona, Canicola, Bratislava, Hardjo, Ballum, Zanoni, Hebdomadis, and Poi.

Results: Serum antibody titres specific to Grippotyphosa, Pomona, and Zanoni serovars were found; none of the sera were positive for any of the other serovars. Out of 147 serum samples only 7 were positive, which gave an overall prevalence of 4.8% in the tested animal population.

Conclusion: The low Leptospira antibody titres along with the low number of positive serum samples in deer indicate that these animals may not act as significant reservoirs of Leptospira for either humans or animals in Poland.

Immunoreactivity of the AAA+ chaperone ClpB from Leptospira interrogans with sera from Leptospira-infected animals

Background

Leptospira interrogans is a spirochaete responsible for leptospirosis in mammals. The molecular mechanisms of the Leptospira virulence remain mostly unknown. Recently, it has been demonstrated that L. interrogans ClpB (ClpB_Li) is essential for bacterial survival under stressful conditions and also during infection. The aim of this study was to provide further insight into the role of ClpB in L. interrogans and answer the question whether ClpB_Li as a potential virulence factor may be a target of the humoral immune response during leptospiral infections in mammals.

Results

ClpB_Li consists of 860 amino acid residues with a predicted molecular mass of 96.3 kDa and shows multi-domain organization similar to that of the well-characterized ClpB from Escherichia coli. The amino acid sequence identity between ClpB_Li and E. coli ClpB is 52 %. The coding sequence of the clpB_Li gene was cloned and expressed in E. coli BL21(DE3) strain. Immunoreactivity of the recombinant ClpB_Li protein was assessed with the sera collected from Leptospira-infected animals and uninfected healthy controls. Western blotting and ELISA analysis demonstrated that ClpB_Li activates the host immune system, as evidenced by an increased level of antibodies against ClpB_Li in the sera from infected animals, as compared to the control group. Additionally, ClpB_Li was found in kidney tissues of Leptospira-infected hamsters.

Conclusions

ClpB_Li is both synthesized and immunogenic during the infectious process, further supporting its involvement in the pathogenicity of Leptospira. In addition, the immunological properties of ClpB_Li point to its potential value as a diagnostic antigen for the detection of leptospirosis.

Leptospira interrogans serovars Bratislava and Muenchen animal infections: Implications for epidemiology and control

Strains of Leptospira interrogans belonging to two very closely related serovars - Bratislava and Muenchen - have been associated with disease in domestic animals, in particular pigs, but also in horses and dogs. Similar strains have also been recovered from various wildlife species. Their epidemiology is poorly understood. Two hundred and forty seven such isolates, from UK domestic animal and wildlife species, were examined by restriction endonuclease analysis in an attempt to elucidate their epidemiology. A representative sub-sample of 65 of these isolates was further examined by multiple-locus variable-number tandem repeat analysis and 22 by secY sequencing. Ten restriction pattern types were identified. The majority of isolates fell into one of three restriction endonuclease analysis pattern types designated B2a, B2b and M2a. B2a was ubiquitous and was isolated from 10 species and represented the majority of the horse and all dog isolates. B2b was very different, being isolated only from pigs, indicating that this type was maintained by pigs. The pattern M2a was reported for the majority of isolates from pigs but also was common in small rodents isolates. Five restriction pattern types were found only in wildlife suggesting that they are unlikely to pose a disease threat to domestic animals. Multiple-locus variable-number tandem repeat analysis identified six clusters. The REA types B2a and B2b were all found in one MLVA cluster while the majority of the M2a strains examined occurred in another cluster. The secY sequencing detected only one sequence type, clustered with other serovars of Leptospira interrogans.

European consensus statement on leptospirosis in dogs and cats

Leptospirosis is a zoonotic disease with a worldwide distribution affecting most mammalian species. Clinical leptospirosis is common in dogs but appears to be rare in cats. Both dogs and cats, however, can shed leptospires in the urine. This is problematic as it can lead to exposure of humans. The control of leptospirosis, therefore, is important not only from an animal but also from a public health perspective. The aim of this consensus statement is to raise awareness of leptospirosis and to outline the current knowledge on the epidemiology, clinical features, diagnostic tools, prevention and treatment measures relevant to canine and feline leptospirosis in Europe.

Prevalence of antileptospiral serum antibodies in dogs in Ireland

A total of 474 serum samples from client owned Irish dogs were tested for the presence of antibodies to serovars Canicola, Icterohaemorrhagiae, Bratislava, Autumnalis, Pomona, Altodouro, Grippotyphosa, Mozdok, Hardjobovis and Ballum. Six per cent of dogs presented to veterinary practitioners for problems unrelated to leptospirosis showed evidence of prior exposure to leptospiral serovars belonging to the serogropus Ballum, Australis, Pomona and Sejroe. One unvaccinated dog suspected to have leptospirosis showed seroconversion to serogroup Icterohaemorrhagiae. Based on these results the authors conclude that canine exposure to serogroup Ballum should be monitored because dogs may serve as sentinels for this serovar in the environment. Vaccination with multivalent vaccines containing serovar Bratislava in addition to serogroups Icterohaemorrhagiae and Canicola is advisable.

Prevalence of Leptospira antibodies in wild boars (Sus scrofa) from Northern Portugal: risk factor analysis

Leptospirosis is a zoonosis of worldwide distribution, caused by infection with pathogenic spirochaetes of the genus Leptospira. The wild boar (Sus scrofa), an important hunting species in Europe, seems to play a significant role in the epidemiological cycle of leptospirosis. A total of 101 serum samples from wild boar hunted in Northern Portugal were analysed for leptospiral antibodies detection by microscopic agglutination test. Sera were collected during hunting seasons (2011-2013) and tested with 17 different pathogenic serovars of Leptospira. Antibodies against nine serovars were detected in 66 (65·4%) of these sera. Serovars Tarassovi and Altodouro exhibited the highest seroreactivity rates (23·8% and 16·8%, respectively), followed by Autumnalis (7·9%) and Bratislava (6·9%). Age and district of origin were found to be risk factors for the presence of leptospiral antibodies in contrast to gender. From a One Health perspective, this study revealed that wild boar should be considered as a potential source of leptospirosis dissemination for humans and animal species (domestic and wild) in shared environments, particularly in the Trás-os-Montes region.

High-resolution typing of Leptospira interrogans strains by multispacer sequence typing

Leptospirosis is a worldwide zoonosis which is responsible for the typical form of Weil's disease. The epidemiological surveillance of the Leptospira species agent is important for host prevalence control. Although the genotyping methods have progressed, the identification of some serovars remains ambiguous. We investigated the multispacer sequence typing (MST) method for genotyping strains belonging to the species Leptospira interrogans, which is the main agent of leptospirosis worldwide. A total of 33 DNA samples isolated from the reference strains of L. interrogans serogroups Icterohaemorrhagiae, Australis, Canicola, and Grippotyphosa, which are the most prevalent serogroups in France, were analyzed by both the variable-number tandem-repeat (VNTR) and MST methods. An MST database has been constructed from the DNA of these reference strains to define the MST profiles. The MST profiles corroborated with the VNTR results. Moreover, the MST analysis allowed the identification at the serovar level or potentially to the isolate level for strains belonging to L. interrogans serovar Icterohaemorrhagiae, which then results in a higher resolution than VNTR (Hunter-Gaston index of 0.94 versus 0.68). Regarding L. interrogans serogroups Australis, Canicola, and Grippotyphosa, the MST and VNTR methods similarly identified the genotype. The MST method enabled the acquisition of simple and robust results that were based on the nucleotide sequences. The MST identified clinical isolates in correlation with the reference serovar profiles, thus permitting an epidemiological surveillance of circulating L. interrogans strains, especially for the Icterohaemorrhagiae serogroup, which includes the most prevalent strains of public health interest.

Seroprevalence of Leptospiral Antibodies in Canine Population in and around Namakkal

Leptospirosis is a reemerging and a complex zoonotic bacterial disease, caused by pathogenic serovars of Leptospira interrogans. A total of 124 sera samples of dogs belonging to different categories like vaccinated, unvaccinated-semiowned, and stray dogs were subjected to sampling. Microscopic agglutination test (MAT) was conducted by using Leptospira culture. Out of 42 vaccinated dogs, 24 (57%) were positive to one or more serovars. Of the 24, 22 (52.3%), 11 (26.19%), 4 (9.5%), 1 (3%), and 2 (4.7%) were positive to icterohaemorrhagiae, canicola, pomona, grippotyphosa, and autumnalis, respectively. Of the 48 unvaccinated semiowned dogs, 10 (28.8%) showed positive agglutination to one or more serovars. Of the 10 samples, 7 (14.5%), 2 (4.1%), 3 (6.2%), 3 (6.2%), and 5 (10.2%) were positive to icterohaemorrhagiae, canicola, pomona, grippotyphosa, and autumnalis, respectively. Among the 34 stray dogs, 12 showed positive agglutination to one or more leptospiral antibodies. Of the 12 samples, 6 (17.6%) showed positive agglutination to icterohaemorrhagiae, 2 (5.8%) to canicola, 5 (14.7%) to pomona, 7 (20.5%) to grippotyphosa, and 5 (4.7%) to autumnalis. This study emphasized the changing trends in the epidemiology of leptospirosis with higher prevalence of serovar L. grippotyphosa in street dogs.