Diagnosis of acute canine leptospirosis using multiple laboratory tests and characterization of the isolated strains

Current knowledge on leptospirosis in cats: A systematic review with metanalysis on direct detection, serological response, and clinical data

Leptospirosis is a neglected bacterial zoonosis that affects a wide range of mammals, with important implications from a One Health perspective. Over the past years feline leptospirosis has gained increased attention in the scientific community. Here we describe a systematic review with meta-analysis that followed the PRISMA guidelines, with an additional PROSPERO registration. The study provides global seropositivity, urinary shedding rates, global serogroup distribution, descriptive data of leptospires that had been isolated from cats and clinical and laboratory features presented by symptomatic cats with acute disease. The search was carried out in six different databases, with the identification of 79 reports describing leptospiral infection in cats. The pooled frequency of seroreactive cats was 11% (95% CI: 9%-13%), with Javanica and Pomona as the most frequent serogroups found. Frequency for urinary shedding was 8% (95% CI: 5%-10%), with L. interrogans identified in most samples. A total of 16 isolates were isolated from cats, with Bataviae as the most frequent serogroup. Twenty symptomatic cats with confirmed leptospiral infection were identified. Anorexia, lethargy, polydipsia, and bleeding disorders were the clinical signs most frequently reported. The results suggest that cats from some locations are exposed to leptospires and may act as urinary shedders of this pathogen, thus indicating a possible role of this species in disease transmission. Clinical data indicates that acute infection is mostly atypical when compared to dogs, and due to difficulties to define an archetypal clinical presentation in cats, feline leptospirosis is likely to be underdiagnosed disease in this species.

Occurrence of serological reactions for Leptospira spp. in donkeys and mules from Minas Gerais, Brazil

Research concerning leptospirosis in donkeys and mules has been neglected around the world. Therefore, the aim of this study was to investigate the epidemiological situation of the prevalence of anti-Leptospira spp. antibodies in donkeys and mules from the state of Minas Gerais, Brazil. Blood serum samples were collected from 180 animals (109 donkeys and 71 mules) in two rural properties from the state of Minas Gerais, Brazil, and then submitted to a microscopic agglutination test (MAT). Urea and creatinine values were also quantified. Epidemiological variables such as age, breeding system, contact with other animal species, source of water and food, vaccination against leptospirosis, presence of reproductive alterations, and rodent control were also investigated. From 180 samples collected, 39 (21.67%) showed positive results in the MAT, at a dilution ≥ 1:100. Some animals were reactive for more than one serovar. The serovar Tarassovi was the most frequent (14.07%), followed by Hardjo (11.85%) and Wolffi (11.11%). There was a statistically significant difference between animals from 0 to 3 years of age reactive in the MAT in comparison to the other age groups. Most of the animals had urea and creatinine concentrations within the acceptable reference limit; however, there was a significant increase in creatinine levels in some of the test animals. The studied properties showed differences in some epidemiological aspects such as vaccination of the animals, presence of reproductive problems in the herd, and rodent control. Such aspects pointed as risk factors that may influence the frequency of positive serological results in property 1. The present study demonstrated that the prevalence of leptospirosis in donkeys and mules is high and several serovars are being maintained by these animals, representing a potential public health risk.

TaqMan real-time PCR for detection of pathogenic Leptospira spp. in canine clinical samples

Introduction

Canine leptospirosis has always been a differential diagnosis in dogs presenting with clinical signs and blood profiles associated with kidney and/or liver disease. The conventional polymerase chain reaction (PCR) provides diagnoses, but real-time PCR-based tests provide earlier confirmation and determine the severity of infection, especially in the acute stage, allowing early detection for immediate treatment decisions. To our knowledge, real-time PCR has not been routinely adopted for clinical investigation in Malaysia. This study evaluated TaqMan real-time PCR (qPCR) assays diagnosing leptospirosis and compared their applicability to clinical samples from dogs with kidney and/or liver disease against a conventional PCR reference.

Material and Methods

The qPCR assays were validated using existing leptospiral isolates. Whole blood and urine samples were analysed using a conventional PCR, LipL32(1) and LipL32(2) qPCRs and a microscopic agglutination test. The sensitivity and specificity of the qPCRs were determined.

Results

The LipL32(1) qPCR assay had more diagnostic value than the LipL32(2) qPCR assay. Further evaluation of this assay revealed that it could detect as low as five DNA copies per reaction with high specificity for the tested leptospiral strains. No cross-amplification was observed with other organisms. Analysing the clinical samples, the LipL32(1) qPCR assay had 100.0% sensitivity and >75.0% specificity.

Conclusion

The LipL32(1) qPCR assay is sensitive, specific and has the potential to be applied in future studies.

Spatial Owner-Dog Seroprevalence of Leptospira spp. Antibodies in Oceanic Islands and Costal Mainland of Southern Brazil

Leptospirosis has been described as a disease neglected worldwide. Affecting humans and animals, the disease is often related to poor environmental conditions such as lack of sanitation and presence of synanthropic rodents. Despite being considered as a One Health issue, no study has focused on comparing owner-dog seroprevalence between islands and seashore mainland. Accordingly, the present study assessed anti-Leptospira spp. antibodies by applying microscopic agglutination test (MAT) methods to Leptospira and assessing associated risk factors via univariate and multivariate logistic regression analysis of owners and their dogs in islands and seashore mainland of southern Brazil. No anti-Leptospira spp. Seropositivity was found in 330 owner serum samples, while dogs presented an overall seroprevalence of 5.9%. All seropositive dogs reacted to serogroups of Leptospira interrogans, including 66.7% of Pyrogenes, 44.4% Canicola, 22.2% Icterohaemorrhagiae, 16.7% Australis; six reacted to more than one serogroup. No association was found among seropositivity and epidemiological variables, except that neighborhood dogs were less likely to be seropositive. Although no seropositivity was observed in owners, seropositivity in dogs had the potential to indicate such species as being sentinels for environmental exposure and potential human risk of infection.

Microscopic detection of Leptospira bacterial organisms in urine sediment from a young dog with leptospirosis and a review of the pathobiology and diagnosis of canine leptospirosis

Samples collected from an 11-month-old Dachshund-mix dog with a history of acute azotemia, fever, and enlarged and irregular kidneys were received at the Colorado State Veterinary Diagnostic Laboratory (CSU VDL). The submitting veterinarians were concerned about lymphoma versus acute nephritis/pyelonephritis. The CSU clinical pathology laboratory received urine for urinalysis and kidney aspirates for cytologic evaluation. Urine had also been submitted for aerobic culture and Leptospirosis PCR, and serum was submitted for Lepto-5 microscopic agglutination testing (MAT). Upon examination of a wet mount of the urine sediment, technical staff noted "vibrating" clumps of granular-appearing material throughout the slide, which prompted the preparation of a stained sediment slide for pathologist review. Very small, faintly staining organisms were observed, and an attempt was made to picture-match these with published reports of Leptospira in dog urine, but none could be found. In addition, some references claimed that Leptospira organisms are not seen in urine with light microscopy. The suspicion that these organisms were Leptospira sp. was supported by the MAT results and later confirmed by PCR. The organisms subsequently exhibited strong positive immunolabeling for the Leptospira antigen. This case report provides a searchable record of Leptospira organisms visualized by routine light microscopy in dog urine during natural infection and a review of canine leptospirosis pathobiology and diagnosis.

Serological and Molecular Evidence of Pathogenic Leptospira spp. in Stray Dogs and Cats of Sicily (South Italy), 2017-2021

Leptospirosis is a zoonosis of public health concern. Its prevalence in stray animals in the South of Italy is unknown. This study aimed to investigate Leptospira spp. prevalence in 1009 stray animals. Out of them, 749 were alive animals, including 358 dogs (316 from Palermo and 42 from Ragusa) and 391 cats (359 from Palermo and 32 from Ragusa), and 260 were corpses (216 dogs and 44 cats) randomly collected in Sicily. Dogs and cats underwent a serological screening by Microscopic Agglutination Test and a molecular investigation by Real-Time PCR targeting lipL32. Corpses were subjected to Real-Time PCR. Serological analyses showed a prevalence of 1.12% (4/358) for dogs and 0.26% (1/391) for cats, with the only positive cat coming from Palermo. Serogroup Icterohaemorrhagiae serovar Icterohaemorrhagiae or Copenhageni, followed by Canicola and Bratislava, were the most spread among dogs, while the serological positive cat reacted with Hardjo serogroup. Two urine (2/32, 6.25%) and one blood (1/391, 0.26%) samples of cats, all from Ragusa, were positive at Real-Time PCR for pathogenic Leptospira spp. Sequencing analyses showed the presence of L. interrogans serogroup Icterohaemorrhagiae serovar Icterohaemorrhagiae or Copenhageni in one of the positive urine samples and in the positive blood sample. Analyses on corpses showed a prevalence of 1.85% (4/216) in Sicilian dog kidney samples, while all corpses of cats resulted in negative. Genotyping analysis showed a genetic relatedness between cat and human isolates. Results show Leptospira spp. circulation among Sicilian stray animals. The genetic relatedness between cat and human isolates suggests a possible common infection source.

Pathogenesis and Genomic Analysis of a Virulent Leptospira Interrogans Serovar Copenhageni Isolated from a Dog with Lethal Infection

Dogs are highly susceptible to leptospirosis and are a public health concern due to their important role as a source of spreading disease, particularly in urban settings. In this study, we present the pathogenesis, serological characterization, and complete genome sequencing of a virulent Brazilian strain (NEG7) of L. interrogans serovar Copenhageni isolated from the urine of a dog that died due to acute leptospirosis. Clinical investigation showed that the dog was presented with icteric mucous membranes, weakness, dehydration, anorexia, and kidney and liver failures. Necropsy followed by histopathological evaluation revealed lesions compatible with liver and kidney leptospirosis. The leptospires recovered from the urine were further characterized by genome analysis, which confirmed that the isolate belonged to L. interrogans serogroup icterohaemorrhagiae serovar Copenhageni. Multiple bioinformatics tools were used to characterize the genomic features, and comparisons with other available Copenhageni strains were performed. Characterization based on absence of an INDEL in the gene lic12008, associated with phylogenetic and ANI (99.99% identity) analyses, confirmed the genetic relatedness of the isolate with L. interrogans serovar Copenhageni. A better understanding of the diversity of the pathogenic Leptospira isolates could help in identifying genotypes responsible for severe infections. Moreover, it can be used to develop control and prevention strategies for Leptospira serovars associated with particular animal reservoirs.

Seroprevalence of pathogenic Leptospira spp. in domestic dogs from southern Chile and risk factors associated with different environments

Leptospirosis is a neglected and severe zoonotic bacterial disease that affects canine populations worldwide, and it is present in animals from different settings, such as urban and rural environments. Therefore, a cross-sectional study was conducted on owned domestic dogs from urban and rural origins in southern Chile. The study aimed: 1) to estimate the true prevalence of pathogenic Leptospira in dogs from urban and rural environments in southern Chile, 2) to determine the serovars circulating in an endemic area of Chile, 3) to assess potential risk factors associated with seropositivity in dogs from urban and rural environments. Blood samples from 706 canines were collected, and the serum was tested with Micro-Agglutination-Test (MAT), using a panel of 13 serovars. A Bayesian approach was applied to estimate True prevalence (TP). In addition, dog owners answered a questionnaire that had prompts regarding dog characteristics and potential risk factors. The effect of these factors on the risk of being infected was analysed using a logistic regression model. The TP for urban dogs was 9.4% and 9.1% for rural animals. However, seroprevalence was higher in dogs with different individual, lifestyle, and habitat characteristics regarding their origin. For example, in urban animals, those living in places with rodents roaming near houses and dogs with rodent hunting habits had decreased risk for the seropositivity in MAT. On the other hand, in rural dogs, those of a recognized breed, with contact with cattle and sheep, living with more than one cat at home and living in places close to natural water sources have more risk to seropositivity in MAT. The presence of anti-Leptospira antibodies is widespread in pet dogs in urban and rural environments in southern Chile, and individual, lifestyle and habitat characteristics of the animals, according to the origin, are associated with the seropositivity in MAT. Therefore, the adoption of preventive measures is urgent, in addition to increase the awareness either in public health institutions, practitioners and companion animals' owners, considering the zoonotic potential of Leptospira infection and the close contact between people and their pets.

Comparison of Two Leptospira Type Strains of Serovar Grippotyphosa in Microscopic Agglutination Test (MAT) Diagnostics for the Detection of Infections with Leptospires in Horses, Dogs and Pigs

Simple Summary

Leptospires are bacteria of major health concern as they can cause severe systemic diseases in humans and animals alike. In routine diagnostics, the detection of a leptospirosis heavily relies on the analysis of specific antibodies that were generated by the immune system of an infected species. The most widely used test for the detection of such antibodies is the microscopic agglutination test which itself depends on defined types of laboratory grown Leptospires, so-called serovars. A good judgment of the behaviour of these serovars is vital for interpreting test results and clearly defining what type of Leptospires the patient is infected with as this may have implications for therapy and prognosis. In the following, a study on the reaction pattern of a certain type of serovars named ‘Grippotyphosa’ that itself can be divided into two differently reacting subtypes was conducted. It turned out that, depending on the animal species sampled, a differing reaction patterns to the two Grippotyphosa subtypes in the diagnostic test reflected different distribution of these subtypes in the respective populations. In the future, these insights will further improve test performance and assessment or results.

Abstract

The MAT test is of great importance in the diagnosis of leptospiral infections. Based on various differences, the serovar Grippotyphosa has been divided into two types, Moskva V and Duyster. Differences or similarities of the two type strains in the context of leptospiral diagnostics have not yet been elucidated in more detail; therefore both strains were analysed in MAT diagnostics for the detection of leptospiral infections in pigs, dogs and horses. Serum samples from 2996 pigs, 55 dogs and 35 horses, as well as vitreous and/or aqueous fluid samples from these and 13 additional horses were analysed by MAT; available supplementary samples were tested for leptospires by PCR. In pigs, 92.6% of the samples with both strains received an identical titre result in the MAT test, whereas in dogs and horses only 53.0% and 43.6% had concordant results. Since infections with the serovar Grippotyphosa occur more frequently in dogs and horses overall, more differences were observed here. In the case of discrepant serological results, supplementary samples and PCR examinations were not able to add information on the true status. Further analyses of follow-up studies or at least serum pairs from dogs and horses infected with the serovar Grippotyphosa are necessary.

The Evaluation of the Diagnostic Value of a PCR Assay When Compared to a Serologic Micro-Agglutination Test for Canine Leptospirosis

Objective

To evaluate PCR assay sensitivity and specificity compared to that of microscopic agglutination test (MAT) for diagnosis of canine leptospirosis. Electronic records search was performed to identify dogs with results for both PCR and MAT testing for leptospirosis.

Methods

All dogs were clinically ill. Diagnosis of leptospirosis was defined as an unvaccinated dog with a positive MAT titer of ≥1:800 or a vaccinated dog or dog with an unknown vaccination status with a positive MAT titer of ≥1:1,600. Diagnosis of leptospirosis was excluded based on MAT titer <1:800 on both the initial and convalescent samples or an initial MAT titer <1:800 and an alternative definitive diagnosis.

Results

Forty-nine samples (urine, n = 39; blood, n = 10) were evaluated. Leptospirosis was diagnosed in 17 dogs and excluded in 26 dogs. Urine PCR assay demonstrated sensitivity of 69.2%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 86.6%. Blood PCR assay demonstrated sensitivity of 25%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 25%. Overall PCR sensitivity was 52.4%, specificity was 100%, positive predictive value was 100%, and negative predictive value was 73.7%.

Conclusions

PCR assay performed on urine or blood has high specificity and positive predictive value when compared to MAT for diagnosis of clinical canine leptospirosis. Sensitivity and negative predictive value are moderate to low, so PCR testing should be performed in conjunction with paired MAT testing for canine leptospirosis. Prior antibiotic therapy does not preclude the use of the PCR test.

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.

Absence of serological or molecular evidence of Leptospira infection in farmed swine in the Hong Kong Special Administrative Region

Leptospirosis is an important zoonotic disease with several maintenance host species including swine. A cross sectional survey was undertaken between January to October 2020 to investigate the prevalence of leptospirosis in farmed swine in the Hong Kong Special Administrative Region (HKSAR) of China. Serum samples were collected from swine on seven farms (15 swine per farm; ten multiparous sows and five twelve-week-old weaners), while kidney samples were collected from 64 swine submitted for routine post-mortem (26 farms; average 2.4 swine per farm, range 1-6). Microscopic agglutination tests (MAT) to a panel of 24 Leptospira antigens did not reveal any evidence of seroconversion at a titre of 1:100. Polymerase chain reaction (PCR) testing of the kidney samples for Leptospira DNA did not detect any evidence of infection. Bayesian methods were used to compute the probability that the leptospirosis prevalence in farmed swine in the HKSAR was <3%, given none of the 105 swine sampled were positive on the MAT. The results of this study demonstrate no serological or molecular evidence of leptospirosis in farmed swine in the HKSAR. Subsequent statistical analysis supports the conclusion that the prevalence of leptospirosis in farmed swine in the HKSAR is negligible at present.

Risk and Predictive Factors of Leptospirosis in Dogs Diagnosed with Kidney and/or Liver Disease in Selangor, Malaysia

Simple Summary

Canine leptospirosis is commonly associated with kidney and/or liver disease. The current study identified the potential risk and predictive factors of dogs diagnosed with kidney and/or liver disease due to leptospirosis. A total of 124 client-owned dogs were recruited and the samples collected were directly tested using polymerase chain reaction (PCR) and subsequently inoculated for bacterial isolation. Statistical analyses were descriptively analyzed, and risk analyses were performed using Pearson chi-square tests and logistic regression. The different breeds of dog with history of exposure to rats and those managed outdoors had a greater risk of leptospirosis (p < 0.05). The significant predictors for the dogs’ positivity were presence of rats and acute clinical illness (p < 0.05). Administration of antibiotics and detection of clinical illness at an early stage of the disease improved the survivability of the dogs (p < 0.05).

Abstract

Canine leptospirosis is commonly associated with kidney and/or liver disease. It has been widely reported and causes public health concerns due to its zoonotic potential and its re-emergence, resulting from close contact between humans and dogs. The current study identified potential risk and predictive factors for dogs diagnosed with kidney and/or liver disease due to leptospirosis. A total of 124 client-owned dogs were recruited, and information such as signalment, medical history, management, and clinical findings were documented. Samples collected from the recruited dogs were directly tested using polymerase chain reaction (PCR) and subsequently inoculated for bacterial isolation. Statistical analyses were descriptively analyzed, and risk analyses were performed using Pearson chi-square tests and logistic regression. A total of 53 dogs (42.7%) were positive for leptospiral infection based on PCR, and 10 leptospiral isolates were successfully recovered from eight dogs. The mortality rate of infected dogs was 34.0% (18/53). Medium and large dog breeds, with a history of exposure to rats, and managed outdoors had a greater risk for leptospirosis (p < 0.05). The significant predictors for the dogs’ positivity were the presence of rats and acute clinical illness (p < 0.05). Administration of antibiotics and the detection of clinical illness at an early stage of the disease improved the survivability of the dogs (p < 0.05). Identifying the profile of dogs that are at risk to leptospirosis could be useful in the design of diagnostic and treatment strategies, as well as to increase awareness for prevention of the disease.

Sperm viability, serological, molecular, and modified seminal plasma agglutination tests in the diagnosis of Leptospira in the semen and serum of bovine bulls

The present study investigated the serum microscopic agglutination test (MAT) among 203 bovine bulls with reproduction by natural means, without apparent signs of orchitis or inflammation of accessory reproductive glands. Simultaneously, the semen of all bulls was subjected to sperm viability analysis and PCR based on the 16S rRNA gene. PCR-positive results of semen samples were confirmed by sequencing. A modified seminal plasma agglutination (MSPA) test, replacing the blood serum of all bulls in the MAT with seminal plasma was performed as well. Eight (8/203 = 3.9%) semen samples from bulls were considered nonviable (necrospermia and azoospermia) without relation to the PCR diagnosis. No agglutinin titers were identified in MSPA test. A high frequency (132/203 = 65%) of leptospiral agglutinin titers was identified in the MAT, particularly for the Sejroe serogroup (Hardjo CTG, 100/203 = 49.3%; Wolffi 74/203 = 36.4%; Guaricura 72/203 = 35.5%; and Hardjoprajitno 56/203 = 27.6%). Three (3/203 = 1.5%) semen samples of bulls were positive in the PCR, but these results were not confirmed by sequencing. The high frequency of serovars from the Sejroe serogroup typically adapted to bovines indicates the need for measures for the prophylaxis/control of the pathogen on the sampled farms. Discrepancies among the MAT, sperm viability, and molecular detection of leptospires in semen highlight the need for a combination of methods to diagnose leptospirosis in bovine bulls. To our knowledge, modified seminal plasma agglutination is described for the first time here to investigate anti-Leptospira antibodies produced locally in the genital tract in the diagnosis of bovine leptospirosis among bulls that reproduce by natural means.

Spatio-temporal distribution and agroecological factors associated with canine leptospirosis in Great Britain

Leptospirosis is an important global zoonotic disease that affects a wide range of mammalian species. Canine leptospirosis outbreaks have been reported after metereological events such as flooding (eg. in Brazil and the United States of America) suggesting an environmental association, but there has been no such study in Great Britain (GB). The distribution of cases across GB is also unreported. Objectives of this study were to: (1) assess the spatio-temporal variation of leptospirosis test submissions (2) explore associations between agroecological risk factors and distribution of different canine leptospirosis serogroups in GB, and (3) generate probability of presence maps for the different serogroups. Data analysed comprised laboratory submissions (n = 3986) to IDEXX laboratories between 1st January 2009 and 31st December 2018 for PCR or MAT leptospirosis testing. Spatial and seasonal scan statistics were used to investigate spatial and temporal clustering of positive tests, logistic regression was used to identify significant agroecological risk factors for positive tests, and the Maxent algorithm was used to model the environmental niche of four serogroups. There was an increased risk of a positive test result in the West Midlands of England (relative risk = 2.16) and between October and January (relative risk = 1.54). Logistic regression identified season and region to be significantly associated with a positive diagnosis,with higher odds of a positive test in Autumn (OR = 1.86 95 %CI 1.29-2.69) and Winter (OR = 1.51, 95 %CI 1.02-2.23) and in the East (OR = 2.20, 95 %CI = 1.31-3.71) and West Midlands (OR = 2.32, 95 %CI 1.45-3.71). The increased test-positive proportion in Autumn together with the increased odds of a positive diagnosis in Autumn suggests there may be a seasonal pattern to the canine leptospirosis in GB. The most important variable associated with higher leptospirosis presence in all ecological niche models was higher average annual temperature. The importance and retention of other variables differed between serogroups. Overall, a higher probability of leptospirosis presence was predicted in southern England and a low probability in Scotland and northern England. Although leptospirosis vaccine usage provides protection against the majority of serogroups identified here, one is not represented in the currently licensed vaccine formulations and therefore leptospirosis should remain a differential diagnosis in vaccinated dogs demonstrating consistent clinical signs of the disease.

Shedding and Genetic Diversity of Leptospira spp. From Urban Stray Dogs in Klang Valley, Malaysia

Leptospirosis is an endemic zoonoses of global proportions. Stray dogs have been postulated to play a role in disease transmission; however, supporting information are still limited. Roaming behavior may not only predispose the dogs to infection, but could also contribute to disease spread. In this study, the susceptibility of urban stray dogs in shedding Leptospira spp. was determined. Blood, urine, and tissue samples of kidney and liver were collected from 100 dogs from 2 animal control facilities. Serological testing using microscopic agglutination test (MAT) were performed on blood against 20 leptospiral serovars with a cut-off titre of ≥ 1:100. Samples were cultured onto semi-solid Ellinghausen and McCullough modified by Johnson and Harris (EMJH) media. Isolates were identified using molecular polymerase chain reaction (PCR) using 2 primers (16s rRNA and LipL32) and hyperimmune serum (HIS) MAT. The seroprevalence for the dogs positive for leptospirosis was 32% (n=32/100) with the following detected serovars: Javanica (n=13), Bataviae (n=10), Icterohaemorrhagiae (n=3), Autumnalis (n=2), Canicola (n=1), Pyrogenes (n=1), Copenhageni (n=1), and Australis (n=1). Six Leptospira spp. isolated were procured from urine (n=2), kidney (n=2) and liver (n=2). All 6 isolates belonged to L. interrogans, a pathogenic variant of Leptospira spp. Serotyping and phylogenetic analysis suggested serovar Bataviae (n=5) and serovar Canicola (n=1). Presence of vaccinal serovars (Icterohaemorrhagiae and Canicola) suggested potential post-vaccination antibodies but the predominance of non-vaccinal serovars (Javanica and Bataviae) indicate the possibility of current infection or post-exposure. Isolation of Leptospira spp. directly from urine sample not only suggested an active infection but highlighted the potential shedding capability among these stray dogs. These findings further strengthen speculations that urban stray dogs could play a role in transmission and dissemination of leptospirosis through their constant movement. The urine of infected dogs may contaminate the environment, posing a major public health threat.

Molecular and serological characterization of pathogenic Leptospira spp. isolated from symptomatic dogs in a highly endemic area, Brazil

Abstract

Background

Leptospirosis is an endemic zoonosis in Brazil, with a great impact on human and animal health. Although dogs are frequently infected by pathogenic Leptospira, the current epidemiological understanding of canine leptospirosis is mainly based on serological tests that predict the infecting serogroup/serovar. Thus, the present study aimed at identifying the causative agent for severe cases of canine leptospirosis in a highly endemic area through the isolation and characterization of the isolated strains.

Results

Urine, serum and blood samples were collected from 31 dogs with suspected acute leptospirosis treated at the Veterinary Hospital Service of Santo Amaro University between 2018 and 2019. Acute infection was confirmed in 17 dogs (54.8%) by the associated use of Polymerase Chain Reaction (PCR), Microscopic Agglutination (MAT) and bacteriological culture. Eleven dogs (35.5%) had titers ≥800, with the most frequent serogroups being Autumnalis and Icterohaemorrhagiae (n = 4 each) and Canicola (n = 2). Leptospires were recovered from four dogs, and Multilocus Sequence Analysis (MLSA) revealed infection caused by L. interrogans, which were further characterized as serogroups Canicola (n = 1) and Icterohaemorrhagiae (n = 3).

Conclusion

The identity of the isolates and serological pattern of MAT suggest that dogs are highly exposed to the serogroup Icterohaemorrhagiae and Canicola, also indicating possible circulation of serogroups not yet isolated in Brazil, notably serogroup Autumnalis. Our findings also reinforce the usefulness of using multiple diagnostic approaches to confirm acute canine leptospirosis.

Detection and characterization of Leptospira spp. in dogs diagnosed with kidney and/or liver disease in Selangor, Malaysia

Leptospirosis is a serious bacterial disease that affects both humans and animals. A wide range of symptoms have been described in humans; the disease in dogs is commonly associated with kidney and/or liver disease. In Malaysia, information about the common serovars infecting dogs is limited. Therefore, we investigated the occurrences of leptospirosis in 124 pet dogs diagnosed with kidney and/or liver disease. Blood, urine, abdominal effusion, and/or kidney and liver were collected from the dogs. Based on microscopic agglutination testing, 53 of 124 (42.7%) dogs were seropositive for leptospiral exposure. Sera were frequently positive to serovars Bataviae (n = 12), Javanica (n = 10), and Icterohaemorrhagiae (n = 10). Direct detection using PCR showed that 42 of 124 (33.9%) of the whole blood and 36 of 113 (31.9%) urine samples were positive for pathogenic Leptospira spp. By PCR, 2 of 23 (9.1%) kidney and 2 of 23 (9.1%) liver were positive for pathogenic Leptospira spp. Abdominal effusion from 4 dogs were PCR-positive for pathogenic Leptospira spp. The species detected were L. interrogans, L. borgpetersenii, L. kirschneri, and L. kmetyi by partial 16S rRNA sequencing. We further identified and characterized 11 Leptospira spp. isolates from 8 dogs as serovars Bataviae, Javanica, and Australis. The mortality rate of the Leptospira-infected dogs was high (18 of 53; 34%).

Multidisciplinary approach in the diagnosis of acute leptospirosis in dogs naturally infected by Leptospira interrogans serogroup Icterohaemorrhagiae: A prospective study

Leptospirosis, a zoonotic disease with worldwide distribution, is caused by spirochetes of the genus Leptospira. In dogs, this disease is frequently misdiagnosed. Few studies have attempted to associate the detection of Leptospira spp. infection with clinicopathological and renal histopathological findings using a multidisciplinary approach. The present study isolated and characterized Leptospira spp. obtained from naturally infected dogs and described relevant clinical and histopathological findings. Blood and urine were collected from 57 dogs with clinical symptomatology suggestive of leptospirosis; 38 cases were confirmed by PCR in urine or by culture or microscopic agglutination testing (titers ≥800). A total of 12 strains of pathogenic Leptospira were isolated from the studied dogs (seven in blood, four in urine and one in both blood and urine samples). All isolates were characterized as Leptospira interrogans serogroup Icterohaemorrhagiae. Of the confirmed cases, almost one-third of the animals had been vaccinated. Our analysis of laboratory testing revealed that azotemia and proteinuria were statistically significant predictors of infection. The main histopathological findings seen in kidney tissues were necrosis, degeneration, tubular regeneration, mononuclear inflammatory infiltrate and congestion. A multidisciplinary approach involving clinicopathological and histopathological characterization of renal involvement can aid in the identification of acute leptospirosis infection.

Kidney Injury Molecule-1 in the detection of early kidney injury in dogs with leptospirosis

Renal damage, a common feature in canine leptospirosis, ranges from a subclinical affection to kidney dysfunction and death. Chances of recovery can be improved by early intervention. However, traditional biomarkers (serum urea and creatinine) have limited relevance for precocity. Kidney Injury Molecule-1 (KIM-1) is a transmembrane protein upregulated in early stages of tubular injury. This study evaluated the use of urinary KIM-1 to detect early renal injury in naturally occurring canine leptospirosis. This exploratory research included 30 dogs divided into two groups: (1) dogs with leptospirosis (n = 25) and (2) healthy dogs (n = 5). Leptospira sp. infection was diagnosed through urine PCR and/or direct bacteriologic culture and/or serology (single MAT titters ≥800). Additionally, stage of infection was further characterized in acute and subacute phases based on the onset of clinical symptoms from 3 to 7 days. Urinary KIM-1 (uKIM-1) concentrations were measured in both groups with a commercial canine ELISA kit. uKIM-1 levels were statistically different (P < 0.01) between the studied groups, especially in non-azotemic dogs (P = 0.0042). The biomarker showed 88 % sensibility to diagnosis of kidney injury at> 1.49 ng/mL cut-off. Urine KIM-1 was negatively correlated with urine specific gravity (USG) but accompanied histopathological evidence of renal degeneration, necrosis and regeneration processes, extending information on kidney health. Measurement of KIM-1 in the urine of canine patients was able to detect naturally occurring acute and subacute leptospirosis accompanied by tubular injury in early non-azotemic infections.

MONITORING OF THE ASSOCIATED COURSE OF LEPTOSPIROSIS AND BABESIOSIS IN DOGS OF THE SUMY REGION OF UKRAINE

Leptospirosis and babesiosis in dogs may be associated. These diseases often have similar symptoms and mask each other, or are asymptomatic, which complicates the diagnosis, significantly worsens the prognosis and reduces the survival of sick animals. Monitoring of the associated course of leptospirosis and babesiosis in dogs makes it possible to study the frequency of this parasitocenosis in dogs and the peculiarities of its course, which is the basis for improving the diagnosis and treatment of sick animals. The aim of the research. Monitor the associated course of leptospirosis and babesiosis in dogs. Methods. The research was conducted in the private veterinary clinic “Vetservice” in Sumy and in the serology department of the Sumy Regional State Laboratory of the Civil Service of Ukraine for Food Safety and Consumer Protection. Blood samples were taken from dogs came for treatment to the “Vetservice” clinic. The diagnosis of babesiosis was established directly in the clinic by the results of erythrocyte microscopy in thin smears of peripheral blood of sick dogs stained by Giemsa. The diagnosis of leptospirosis was established in the serology department of the Sumy Regional State Laboratory based on the results of a study of the serum of sick dogs in the microagglutination reaction. The subjects of the study were clinically ill and suspected dogs with the associated course of leptospirosis and babesiosis, as well as blood samples from these animals. Babesium trophozoites were detected in erythrocytes under an immersion microscope, a magnification of ocular 10 x 90, and the presence of antibodies to leptospira was detected by the presence of agglutination of leptospira in microagglutination reaction. Results. In the study of the incidence of dogs associated with leptospirosis and babesiosis during 2014–2019, according to the clinic “Vetservice” found that the number of reported cases of associated leptospirosis and babesiosis annually varies from 9 to 28 cases. This parasitocenosis is registered all year round with peaks in spring and autumn, moderately in summer and rarely in winter. Purebred animals get sick several times more often than non pedigree ones. During the period from 2016 to 2019, the number of diseases in females and males was approximately the same. During the period from 2014 to 2015, males were more often ill. Conclusions. The prevalence of the associated course of leptospirosis and babesiosis in dogs of the Sumy region of Ukraine was determined with the determination of seasonal, breed and sexual dynamics of this parasitocenosis

Unusual case of polyarthritis and hepatorenal syndrome associated with Leptospira interrogans infection in a dog: A case report

Leptospirosis is a zoonotic disease caused by spirochetal bacterial of the genus Leptospira affecting virtually all mammals. The infection has a broad range of effects, from mild clinical manifestation to multiple organ failure, and ultimately death. A 5-months-old male unvaccinated dog was admitted to the University Veterinary Teaching Hospital presenting dullness, dehydration, jaundiced mucous, bloody diarrhea, vomiting, and hyporexia. Microscopic agglutination test (MAT) detected serological titers of 1:1.600 for serogroup Canicola. After five days of monitoring by the medical team he developed fever and swelling of carpal and tarsal joints, accompanied by functional limitation. Initial antimicrobial treatment was instituted for leptospirosis. Polyarthritis responsiveness to glucocorticoid therapy was observed through decreasing signs of inflammation of the affected joints. The diagnosis of leptospirosis was further confirmed by molecular investigation for Leptospira spp. on blood and synovial fluid samples. Amplification and sequencing of the secY partial gene characterized the infective bacterial as Leptospira interrogans. From the 7th day the respiratory condition worsened and on Day 14 the patient evolved to death, when necropsy and histological evaluation were performed. Prominent anatomopathological findings included: fibrinous polyarthritis, bronchointerstitial pneumonia, intense hepatocyte dissociation, cholestasis, and periportal multifocal hepatitis, diffuse acute tubular necrosis, and significant dystrophic mineralization in the renal parenchyma, lungs, and atrial endocardium. Here, we present a case report of systemic clinical manifestations polyarthritis associated with the presence of leptospiras in the synovial fluid. We highlight the need for richer knowledge about the different clinical manifestations of leptospirosis.

Improvement of Leptospira spp. diagnosis in aborted bovine fetuses by qPCR

Leptospirosis is a disease with major economic impact on livestock industry. The objective of this work was to determine the presence of Leptospira spp. DNA by qPCR in bovine fetuses with presumptive diagnosis of leptospirosis as the cause of abortion. Leptospira spp. DNA was detected by qPCR in 11 out of 34 fetuses. These specimens (10/11) had histopathological findings in hepatic and/or renal tissues compatible with leptospirosis. qPCR detection rate (32.4 %) was higher compared with direct immuno-fluorescence antibody test (DFAT) (11.8 %). The concordance coefficient between both techniques was 0.44. qPCR is a rapid and sensitive technique for the diagnosis of leptospirosis and improved the detection rate in fetal tissues compared with DFAT. Implementation of molecular techniques may increase the accurate detection of leptospirosis as a cause of bovine abortion allowing the application of rapid therapeutic and prophylactics measures in order to reduce the impact of this zoonotic disease.

Detection of New Leptospira Genotypes Infecting Symptomatic Dogs: Is a New Vaccine Formulation Needed?

Leptospirosis in dogs has been largely described worldwide, and epidemiological studies have been mainly based on serological data. This study aims to detect and genotype leptospires affecting symptomatic dogs in Northeast Italy between 2013 and 2019. Overall, 1631 dogs were tested using real-time PCR, and leptospires from 193 dogs were subjected to Multilocus Sequence Typing and a Multiple Loci Variable-number Tandem Repeat Analysis. Leptospires were successfully isolated from 15 symptomatic dogs. Six distinct Sequence Types (STs) were found for 135 leptospires, with 3 STs characterizing Leptospira interrogans (ST17, ST198 and ST24), 2 STs characterizing Leptospira kirschneri (ST117 and ST289) and 1 ST characterizing Leptospira borgpetersenii (ST155), revealing the circulation of the serogroups Icterohaemorrhagiae, Australis, Sejroe and Pomona. The Multiple Loci Variable-number Tandem Repeat Analysis of 17 samples did not result in any additional discrimination. Genotypes were compared with those of strains present in the historical internal database, and possible transmission chains were identified from rat, mouse, hedgehog and pig. This work highlights the importance of molecular methods in revealing and identifying circulating Leptospira strains, and it also encourages the evaluation of the ability of commercially available vaccines to reduce the disease burden among dogs.

Identification of Serogroups Australis and Icterohaemorrhagiae in Two Dogs with a Severe Form of Acute Leptospirosis in Italy

Leptospirosis is an infectious disease that causes serious illness in dogs. For this reason, epidemiological and clinical studies focusing on disease characterization are widely advocated. The aim of this study was to characterize the leptospires identified in dogs with confirmed symptomatic acute leptospirosis. Leptospira spp. DNA detected in urine, blood, or both samples from nine infected dogs was analyzed using the multi-locus sequence typing (MLST) technique. Leptospires from two dogs were successfully typed: one was identified as belonging to Sequence Type (ST) 17 and one to ST198, both within the L. interrogans species, serogroups Icterohaemorrhagiae and Australis, respectively. Based on the results of routine serologic tests, antibodies reactive toward these serogroups are commonly revealed in dogs in Italy. This study provides the first molecular analysis that identifies infecting Leptospira directly on DNA from biological samples of dogs, showing that serogroup Australis can lead to a severe clinical presentation of leptospirosis in infected dogs.

Genetic diversity of pathogenic leptospires from wild, domestic and captive host species in Portugal

Leptospirosis is a neglected zoonotic disease of worldwide distribution with a significant veterinary and public health impact. It is caused by pathogenic bacteria of the genus Leptospira. The availability of effective tools to accurately identify and type leptospires is of utmost importance for the diagnosis of the disease and for assessing its epidemiology. Several multi-locus sequence typing (MLST) approaches were described for the typing of worldwide isolates of Leptospira but an extensive agreement towards the adoption of a unique consensus scheme for this agent is still lacking. Most genotyped strains originate from Asian and South American countries, with a minority originating from Europe (being most countries represented only by one or a few isolates). The knowledge of the diversity of circulating leptospires is the key to understanding the disease transmission and its zoonotic implications. In this study, we revisited the taxonomy of several isolates of pathogenic Leptospira obtained from domestic, wild and captive animals in Portugal, between 1990 and 2012. A selection of these isolates was genotyped using two previously published MLST schemes. A total of seven distinct sequence types (STs) were detected among the Portuguese isolates with two STs representing L. borgpetersenii (ST149 and ST152), two STs representing L. kirschneri (ST117 and ST100) and three STs representing L. interrogans (ST17, ST24 and ST140). Global widespread (and maybe more virulent) Leptospira genotypes seem to circulate in Portugal, particularly the L. interrogans ST17 isolates which are associated with several outbreaks of leptospirosis among humans and animals in different regions of the world. This study contributes to the enrichment of the global MLST databases with a new set of allele and sequence type information also providing novel data on circulating Leptospira serovars in Portugal.

Outpatient Clinical Trial in Dogs With Leptospirosis Treated With Enrofloxacin Hydrochloride-Dihydrate (ENRO-C)

Pharmacokinetics of enrofloxacin HCl-2H₂O (enro-C) in dogs and Monte-Carlo simulations against Leptospira spp. prompted a clinical study to treat the clinically apparent phase of this disease. Leptospirosis was diagnosed by real-time PCR from blood, micro-agglutination titers (MAT), clinical signs and blood parameters of the liver and kidney. In order to determine the clinical ability of the participants to diagnose leptospirosis on the first exam and establish an early treatment to avoid excessive organ damage, patients were clinically classified as: high-risk or medium-risk. Forty-five dogs were included in this trial (from 2017 to early 2019). The treatment consisted of IM injections of a 5% aqueous enro-C suspension (10 mg/kg/day) for 10 days, and subsequently enro-C was administered orally for another 7 days in gelatin capsules. Thirty-four high-risk and 11 medium-risk dogs were treated, including 6 puppies (4 high-risk with ages between 6 to 10 months and 2 medium-risk dogs with an average age of 6 and 7 months). Other ages ranged from 1 to 5 years. Fifteen cases had a history of having received prior treatment with other antibiotics, including all puppies. The clinical diagnostic error was 13.5% (7/52 cases), and only one of the misdiagnosed dogs had been classified as a high-risk patient. Three to 5 days after finishing treatment with enro-C, 82.2% of the dogs were negative to real-time PCR from urine samples and 100% negativity was observed on day 30 after treatment, when antibody titrations dropped to 1:100–1:200. Based on the absence of clinical signs, real-time PCR, and MAT titers, all treated dogs were considered as successful treatments. Within 6–24 months of clinical follow-up, no relapses were recorded. Adverse effects were inconsequential. This study represents the first report of a successful treatment of canine leptospirosis using a fluoroquinolone, and due to its efficacy, it is suggested that enro-C be considered as a viable option for the treatment of this disease.

Diagnosis of Canine Leptospirosis

Several diagnostic tests are available to aid veterinarians in diagnosis of leptospirosis. Understanding the course of infection is imperative to determining which diagnostic test to order and sample to submit. Diagnostic tests for dogs suspected of having leptospirosis include antibody-based tests and polymerase chain reaction (PCR). Paired acute and convalescent microscopic agglutination test (MAT) are diagnostic for leptospirosis. PCR performed on blood and/or urine can be a valuable tool to aid in diagnosis of leptospirosis. Commercially available rapid point-of-care diagnostics have been validated in dogs and have value early in the course of illness before MAT and PCR results are available.