Meta-analysis of risk factors for canine leptospirosis

Seroprevalence of Leptospira antibodies in dogs and cats from Santa Fe, a city in East-Central Argentina endemic for leptospirosis

This study examines household pets as potential epidemiological links between environments contaminated with pathogenic leptospires and humans in Santa Fe, Argentina. The aims of our study were: (a) to characterize the habits and exposure to environmental sources of leptospirosis in the population of dogs and cats attending to municipal spay and neutering campaigns in Santa Fe, Argentina, (b) to assess the seroprevalence of anti-Leptospira antibodies in asymptomatic dogs and cats, (c) to evaluate factors that could increase seropositivity, and (d) to identify spatial clusters of seropositive dogs and cats in the capital city of Santa Fe. From May to November 2022, a cross-sectional serosurvey was conducted during municipal spaying/neutering campaigns. Eligible household dogs and cats were over 6 months old, apparently healthy, and not vaccinated against leptospirosis in the past 6 months. We used microagglutination test (MAT) to assess anti-Leptospira antibodies using a panel of 10 reference strains. We used generalized linear mixed effects models (GLMM) to examine individual and census tract-level risk factors for seropositivity, and local Moran's I statistic for spatial clusters. Results showed higher leptospiral antibody prevalence in dogs (18.2 %) than cats (3.6 %, p = 0.002). Dogs with street access had higher likelihood of being seropositive (OR: 3.8, 95 % CI: 1.2; 11.9), and areas with chronic poverty showed an elevated risk of presenting seropositive animals (RR: 4.0, 95 % CI: 1.1; 14.4). Spatial analysis didn't reveal significant seropositivity clusters among census tracts. These findings shed light on widespread Leptospira seropositivity in pets in this endemic region. Understanding seroprevalence and risk factors can guide public and veterinary health strategies, emphasizing increased leptospirosis vaccination for dogs in vulnerable areas and promoting responsible pet care.

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.

Seroprevalence of leptospirosis among stray dogs in Bosnia and Herzegovina

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

Seroprevalence of pathogenic Leptospira serogroups in asymptomatic domestic dogs and cats: systematic review and meta-analysis

Leptospirosis is a neglected zoonotic disease transmitted by contact with the urine of animals infected with pathogenic species of the bacteria Leptospira or by contact with environments contaminated with the bacteria. Domestic dogs and cats may act as reservoirs or as sentinels of environmental contamination with leptospires, posing a public health concern. There is a great diversity of leptospires, and one common way to classify them is into serogroups that provide some information on the host species they are associated with. The aims of this study were: (1) to quantitatively summarize the overall prevalence and serogroup-specific prevalence of antibodies against pathogenic leptospires in asymptomatic dogs and cats and (2) to identify environmental and host characteristics that may affect the prevalence. Three electronic databases and the reference lists of eligible articles were screened, for epidemiological studies conducted between the years 2012-2022. We estimated overall and serogroup-specific prevalence using three-level meta-analysis models and assessed potential sources of heterogeneity by moderator analysis and meta-regression. Eighty-four studies met the inclusion criteria (dog studies 66.7%, cat studies 26.2%, and both species 7.1%). There were significant differences between dogs and cats in the overall prevalence model (P < 0.001), but not in the serogroup-specific model (P>0.05). In dogs, the prevalence of Leptospira interrogans serogroup Canicola was significantly higher than the other pathogenic serogroups (P < 0.001), while in cats there were no significant differences among serogroups (P = 0.373). Moderator analysis showed that the prevalence of L. kirschneri serogroup Grippotyphosa was significantly higher in stray/sheltered dogs than in domiciled dogs (P = 0.028). These results suggest that pathogenic serogroups associated with small mammals are circulating among asymptomatic pets and should be taken into account in the transmission cycle of leptospires, as well as in the standard MAT panel for diagnosis in dogs and cats. It also highlights the importance of including both dogs and cats as potential reservoirs when conducting eco-epidemiological studies in different geographical and ecological areas.

Acute human leptospirosis in a Caribbean region of Colombia: From classic to emerging risk factors

BACKGROUND

Leptospirosis is a zoonosis of worldwide incidence, with a broad spectrum of health risk factors.

AIM

The objective was to determine risk factors associated with acute human leptospirosis and to explore predictive variables of risk to human leptospirosis.

METHODS

The study was carried out in the Department of Córdoba, in the north of Colombia. We conducted a longitudinal prospective descriptive study with non-probabilistic sampling, which included 339 patients suspected of leptospirosis. Positive cases were confirmed by MAT and PCR. The determination of social and environmental risk factors was done with a survey on epidemiological and environmental variables to establish an association between cases of leptospirosis and risk factors as well as predictive variables.

RESULTS

We found 19.8% (67/339) cases of acute leptospirosis, and the seroprevalence was 27.1% (92/339). The most frequent serogroups were Sejroe, Australis, Pomona, Batavie, Pyrogenes and Grippotyphosa. We identified the following risk factors: age between 10 and 19 years (OR = 2.571; 95% CI); pig ownership (OR = 2.019; 95% CI); bathing or recreational activities in lake/lagoon (OR = 3.85; 95% CI) and in dams (OR = 3.0; 95% CI); floodings 30 days before the onset of symptoms (OR = 2.019; 95% CI), and a mean temperature of 28°C (p 0.044; 95%CI). As significant predictor variables, we identified age (10-19 years), bathing or recreational activities in the lake/lagoon, and flooding 30 days before symptoms were again evidenced. This region presents classic risk factors (pig ownership) and emerging environmental risk factors (recreational practice or bathing in a lake/lagoon and flooding 30 days before the onset of symptoms), and demographic factors such as young age (10-19 years).

CONCLUSIONS

These factors are also predictors of human cases of acute leptospirosis and provide contextual information on environmental and public health that should be considered for epidemiological surveillance in this endemic area.

One Health Approach to Leptospirosis: Dogs as Environmental Sentinels for Identification and Monitoring of Human Risk Areas in Southern Brazil

Leptospirosis has been a neglected, widespread and reemerging zoonotic disease of global importance. The One Health holistic approach combining human, animal and environmental health has been important for control and prevention of zoonotic disease. An urban municipality in Southern Brazil with a high prevalence of leptospirosis was selected by convenience, with asymptomatic human and canine individuals serologically tested using MAT against 30 Leptospira spp. serovars. Epidemiological questionnaires were assessed along with the historical national database, with associated risk factors to dog and human seropositivity analyzed using multiple logistic regression. The spatial distribution of retrospective human leptospirosis cases was analyzed using a Kernel map and overlapped dog seropositivity and historical flooding areas, demonstrating that domestic and asymptomatic dogs may be important environmental sentinels for leptospirosis in such urban areas, even in the absence of human seropositivity and low canine seropositivity. Associated risk factors for leptospirosis in dogs and humans according to multiple regression included healthy dogs (p = 0.02, odds ratio-OR = 0.17, confidence interval of 95%CI 0.03-0.71) with indoor access (p = 0.059, OR = 5.12, 95%CI 1.10-37.7) and human males (p = 0.042, OR = 2.44, 95%CI 1.08-6.11) with presenting calf pain (p = 0.005, OR = 3.14, 95%CI 1.46-7. 14), jaundice (p < 0.001, OR = 4.61, 95%CI 2.11-10.10) and renal failure (p = 0.008, OR = 4.49, 95%CI 1.49-13.76). The greater the rain precipitation (above 3 mm of average annual precipitation), the higher the number of leptospirosis cases in humans. In conclusion, dog active serosurvey and rain precipitation should be systematically reported and plotted altogether as a basis for the early detection and monitoring of human risk areas. Such findings may serve as a basis for public health policies in Brazil and other endemic countries worldwide.

One Health Approach to Leptospirosis: Human-Dog Seroprevalence Associated to Socioeconomic and Environmental Risk Factors in Brazil over a 20-Year Period (2001-2020)

Despite being considered a neglected, re-emerging and the most widespread zoonotic disease worldwide, human-dog leptospirosis has not been subjected to One Health approach, and neither were its socioeconomic and environmental risk factors, as well as concomitant spatial analysis over time. Accordingly, notified human leptospirosis cases, incidence rate and urban hotspot areas, in addition to a systematic review of dog leptospirosis cases, were performed nationwide from 2001 to 2020 in Brazil. Data on Gross Domestic Product (GDP), flooding and study areas were also assessed and tabulated. Human-dog leptospirosis cases were simultaneously mapped with overlapping flooding areas, along with the main circulant serovars. Comparative outcome has shown that dogs may be exposed similarly to humans, becoming important sentinels and/or reservoirs for human leptospirosis in larger geographic areas. Moreover, the study herein can help in the decision and implementation of public policies in Brazil and may serve as a model for other tropical countries worldwide.

Time for change? A systematic review with meta-analysis of leptospires infecting dogs to assess vaccine compatibility in Brazil

Dogs are thought to be highly exposed to environmental pathogenic leptospires, possibly acting as potential sources of infection for zoonotic transmission. Vaccination stands as the cornerstone strategy to prevent disease and urinary shedding in dogs, yet the success of vaccination is highly dependent on the correspondence of leptospires circulating locally with those used in vaccine compositions. To provide evidence for vaccine compatibility, and to assess whether there are regional differences on serogroup distribution, we conducted a systematic review with meta-analysis on serological data, characterization of leptospiral isolates and risk factors for seropositivity in dogs from Brazil. Studies reporting canine leptospirosis within the Brazilian territory were eligible for inclusion, and methodology was validated by PROSPERO under registration CRD42020204187. Six electronic databases were searched, and data regarding population, methods, and outcomes were extracted. Sixty-one studies were included to access serogroup distribution and risk factors, with a pooled positivity rate of 19.7% in dog population. Serological evidence indicates that Canicola, Icterohaemorrhagiae and Autumnalis are the most frequently found serogroups. Twenty-eight records were included to access leptospiral strains isolated in Brazil, with n = 56 strains characterized as serogroups Canicola, n = 37 as Icterohaemorrhagiae, n = 2 as Pomona, and n = 1 strain as Australis and Sejroe each. Risk factor analysis revealed that stray dogs, puppies or elderly dogs, male dogs and dogs kept by tutors with poor social and economic conditions are at high risk for infection. The present study revealed overall good compatibility of leptospiral strains circulating locally with those used in vaccines against canine leptospirosis in Brazil. The circulation of serovars Pomona and Grippotyphosa has not been consistently demonstrated, and the inclusion of these serovars in local vaccines cannot be supported by our results. The results also provided serological evidence for the circulation of Serogroup Autumnalis among the studied populations.

Leptospiral infection in domestic cats: Systematic review with meta-analysis

The role of domestic cats in the transmission of Leptospira is controversial, being considered either as a protective factor or a potential source of infection for humans. The aims of this study were to obtain an integrated estimate of the prevalence of leptospiral infection in domestic cats, and to characterize those individuals most susceptible to infection. For this systematic review and meta-analysis, five electronic databases, as well as the reference lists of eligible reports were screened for observational studies published during 1979-2022. The overall prevalence of leptospiral antibodies and of pathogenic Leptospira in kidney/urine was estimated using three-level meta-analysis models. To investigate potential sources of heterogeneity, moderator analyses was performed using the sampling year, health status, living environment, and origin of the cats. The odds-ratio (OR) of potential risk factors was estimated using random-effects meta-analysis models for binary outcomes. The literature search identified 61 eligible publications, containing 114 effect estimates. The overall seroprevalence was 11.7 % (95 % CI: 9.3-14.6 %), the prevalence of leptospires in urine was 3.7 % (95 % CI: 1.7-8.1 %), and the prevalence of leptospires in kidney tissue was 12.8 % (95 % CI: 3.2-39.9 %). There were no significant differences in the estimated prevalence after removing articles with medium risk of bias. Seroprevalence was higher in Europe when compared to Latin America and the Caribbean (P = 0.047) and showed a mild decrease over time (P = 0.023). Outdoor cats had almost three times greater probabilities of infection with Leptospira (OR: 2.74, 95 % CI: 1.10-6.84). No other significant effect was detected among the tested moderators or potential risk factors (P > 0.05). Results suggest that feline leptospirosis should receive particular attention in veterinary care, as exposure to leptospires can occur in approximately 1 in every 10 cats, and more frequently in cats with street access. Domestic cats should be considered as potential Leptospira carriers when designing public health strategies for the control and prevention of leptospirosis. Further investigation is required to improve knowledge of the role of these animals in the environmental transmission cycle.

Leptospira seroprevalence and associated risk factors in healthy Swedish dogs

BACKGROUND

Leptospirosis is an emerging zoonotic infection worldwide and a cause of life-threatening disease in dogs. Seroprevalence in Swedish dogs is unknown. The aims of the present study were to estimate seroprevalence of pathogenic Leptospira in healthy dogs in Sweden using the microagglutination test (MAT) and a rapid point-of-care enzyme-linked immunosorbent assay (ELISA), and to evaluate risk factors of Leptospira exposure in Swedish dogs.

RESULTS

Positive MAT titres (≥ 1:50) were detected in 27/369 (7.3%) of included dogs. Five different serovars were represented of which the Saxkoebing serovar was the most common (64.3%), followed by Copenhagi (14.3%), Bratislava (10.7%), Icterohaemorrhagiae (7.1%), and Canicola (3.6%). The ELISA test (SNAP® Lepto) was positive in 3/316 (0.9%) dogs. Living in urban areas and contact with stagnant water were found to be risk factors for Leptospira seropositivity (p < 0.05) in a multivariable logistic regression model.

CONCLUSION

In this first seroprevalence study of Leptospira in Swedish dogs, it was shown that healthy dogs without recent (24 months) travel history and antileptospira vaccination had been exposed to pathogenic Leptospira interrogans serovars. Contact with stagnant water and living in urban areas were independent risk factors for seropositivity.

2022 AAHA Canine Vaccination Guidelines

These guidelines are an update and extension of previous AAHA peer-reviewed canine vaccination guidelines published in 2017. Vaccination is a cornerstone of canine preventive healthcare and one of the most cost-effective ways of maintaining a dog's health, longevity, and quality of life. Canine vaccination also serves a public health function by forming a barrier against several zoonotic diseases affecting dogs and humans. Canine vaccines are broadly categorized as containing core and noncore immunizing antigens, with administration recommendations based on assessment of individual patient risk factors. The guidelines include a comprehensive table listing canine core and noncore vaccines and a recommended vaccination and revaccination schedule for each vaccine. The guidelines explain the relevance of different vaccine formulations, including those containing modified-live virus, inactivated, and recombinant immunizing agents. Factors that potentially affect vaccine efficacy are addressed, including the patient's prevaccination immune status and vaccine duration of immunity. Because animal shelters are one of the most challenging environments for prevention and control of infectious diseases, the guidelines also provide recommendations for vaccination of dogs presented at or housed in animal shelters, including the appropriate response to an infectious disease outbreak in the shelter setting. The guidelines explain how practitioners can interpret a patient's serological status, including maternally derived antibody titers, as indicators of immune status and suitability for vaccination. Other topics covered include factors associated with postvaccination adverse events, vaccine storage and handling to preserve product efficacy, interpreting product labeling to ensure proper vaccine use, and using client education and healthcare team training to raise awareness of the importance of vaccinations.

Canine leptospirosis in Canada, test-positive proportion and risk factors (2009 to 2018): A cross-sectional study

Over the past decade, there has been an apparent increased frequency and widened distribution of canine leptospirosis in Canada, however, this has been minimally investigated. Availability and clinical uptake of Leptospira polymerase chain reaction (PCR)-based testing of dogs in Canada may provide important insight into the epidemiology of this canine and zoonotic infectious disease. Study objectives were to evaluate clinical canine Leptospira PCR test results from a large commercial laboratory to determine temporal and spatial distribution in Canada and identify dog, geographic and temporal risk factors for test-positive dogs. This cross-sectional study analyzed data obtained from IDEXX Laboratories, Inc. on 10,437 canine Leptospira PCR tests (blood and/or urine) submitted by Canada-based veterinarians (July 2009 to May 2018). Multivariable logistic regression was used to identify risk factors for test-positive dogs. Test-positive proportion varied widely annually (4.8–14.0%) and by location. Provinces with the highest test-positive proportion over the study period were Nova Scotia (18.5%) and Ontario (9.6%), with the prairie provinces (Manitoba and Alberta combined) having the lowest proportion (1.0%); the northern territories could not be evaluated due to limited testing. In the final model, dog age, sex, breed, month, and year test performed, and location (urban/rural, province) of the practice submitting the sample were significant predictors of a positive Leptospira PCR test. Dogs less than one year of age (OR = 2.1; 95% CI: 1.6–2.9), male sex (OR = 1.3; 1.1–1.5), toy breed (OR = 3.3; 2.5–4.4), and samples submitted from an urban practice (OR = 1.3; 1.0–1.8) had the greatest odds of a positive Leptospira PCR test as compared to referent groups. Significant two-way interactions between province-month and year-month highlight the complex spatial and temporal influences on leptospirosis occurrence in this region. Our work suggests a high incidence of canine leptospirosis regionally within Canada. Identifiable dog and location factors may assist in future targeted prevention efforts.

Serological survey of anti-Leptospira spp. antibodies in individuals with animal hoarding disorder and their dogs in a major city of Southern Brazil

Background

Individuals with hoarding disorder (HD) presented a persistent difficulty in detaching from objects and/or animals. Unhealthy conditions, frequently found in cases of animal HD (AHD), may favour environmental contamination and the spread of zoonotic pathogens. Despite that, only one study of zoonotic diseases in individuals with AHD and their companion animals has been conducted to date.

Objectives

This study aimed to assess the seroprevalence of anti‐Leptospira spp. antibodies in individuals with AHD and their dogs in a major city of Southern Brazil.

Methods

Blood samples were obtained from 264 dogs (21 households) and 19 individuals with AHD (11 households) and tested by microscopic agglutination test.

Results

All human samples were seronegative. Seropositivity was found in 16/264 (6.1%; CI 95% 3.3–9.6%) dogs from 11/21 (52.38%) households, with titres ranging from 100 up to 400, and Copenhageni (10/16; 62.5%) was the most frequent serovar. Surprisingly, seropositivity of hoarded dogs found herein was among the lowest reportedly observed in other dog populations of Brazil. Two epidemiological variables were significantly associated with seropositivity in dogs: the presence of cat hoarding (p = 0.004) and the report of flood occurrence in the household (p = 0.031).

Conclusions

No individuals with AHD were seropositive, and besides the lower seroprevalence of dogs, they probably had contact with Leptospira spp. at some point in their life. Since dogs can be considered potential sentinels in leptospirosis, public health programs must become aware of the risk of leptospirosis cases in households of individuals with AHD and nearby communities.

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.

SEROSURVEY FOR SELECTED PARASITIC AND BACTERIAL PATHOGENS IN DARWIN'S FOX (LYCALOPEX FULVIPES): NOT ONLY DOG DISEASES ARE A THREAT

The Darwin's fox (Lycalopex fulvipes) is one of the most endangered carnivores worldwide, with the risk of disease spillover from domestic dogs being a major conservation threat. However, lack of epidemiologic information about generalist, non-dog-transmission-dependent protozoal and bacterial pathogens may be a barrier for disease prevention and management. To determine the exposure of some of these agents in Darwin's fox populations, 54 serum samples were collected from 47 Darwin's foxes in Southern Chile during 2013-18 and assessed for the presence of antibodies against Brucella abortus, Brucella canis, Coxiella burnetii, pathogenic Leptospira (serovars Grippotyphosa, Pomona, Canicola, Hardjo, and Copehageni), Toxoplasma gondii, and Neospora caninum. The highest seroprevalence was detected for T. gondii (78%), followed by pathogenic Leptospira (14%). All the studied Leptospira serovars were confirmed in at least one animal. Two foxes seroconverted to Leptospira and one to T. gondii during the study period. No seroconversions were observed for the other pathogens. No risk factors, either intrinsic (sex, age) or extrinsic (season, year, and degree of landscape anthropization), were associated with the probability of being exposed to T. gondii. Our results indicate that T. gondii exposure is widespread in the Darwin's fox population, including in areas with minimal anthropization, and that T. gondii and pathogenic Leptospira might be neglected threats to the species. Further studies identifying the causes of morbidity and mortality in Darwin's fox are needed to determine if these or other pathogens are having individual or population-wide effects in this species.

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.