Signalment changes in canine leptospirosis between 1970 and 2009

Are Pathogenic Leptospira Species Ubiquitous in Urban Recreational Parks in Sydney, Australia?

Leptospirosis is a zoonotic disease caused by the spirochete bacteria Leptospira spp. From December 2017 to December 2023, a total of 34 canine leptospirosis cases were reported in urban Sydney, Australia. During the same spatio-temporal frame, one locally acquired human case was also reported. As it was hypothesised that human residents and companion dogs might both be exposed to pathogenic Leptospira in community green spaces in Sydney, an environmental survey was conducted from December 2023 to January 2024 to detect the presence of pathogenic Leptospira DNA in multipurpose, recreational public parks in the council areas of the Inner West and City of Sydney, Australia. A total of 75 environmental samples were collected from 20 public parks that were easily accessible by human and canine visitors. Quantitative PCR (qPCR) testing targeting pathogenic and intermediate Leptospira spp. was performed, and differences in detection of Leptospira spp. between dog-allowed and dog-prohibited areas were statistically examined. The global Moran's Index was calculated to identify any spatial autocorrelation in the qPCR results. Pathogenic leptospires were detected in all 20 parks, either in water or soil samples (35/75 samples). Cycle threshold (Ct) values were slightly lower for water samples (Ct 28.52-39.10) compared to soil samples (Ct 33.78-39.77). The chi-squared test and Fisher's exact test results were statistically non-significant (p > 0.05 for both water and soil samples), and there was no spatial autocorrelation detected in the qPCR results (p > 0.05 for both sample types). Although further research is now required, our preliminary results indicate the presence of pathogenic Leptospira DNA and its potential ubiquity in recreational parks in Sydney.

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.

Leptospirosis is an emerging infectious disease of pig-hunting dogs and humans in North Queensland

BACKGROUND

Leptospirosis is a zoonotic disease with a worldwide distribution, caused by pathogenic serovars in the genus Leptospira. Feral pigs are known carriers of Leptospira species and pig hunting using dogs is a common recreational activity in Queensland, Australia.

METHODOLOGY AND PRINCIPAL FINDINGS

This study aimed to determine the seroprevalence of Leptospira spp. serovars in pig-hunting dogs above the Tropic of Capricorn in Queensland and by establishing the geographic distribution, serovars and incidence of human cases of leptospirosis in Queensland, identify potential overlap between human and canine exposure. We also explored the knowledge and risk-taking behaviours of pig-hunting dog owners towards zoonotic diseases. Ninety-eight pig-hunting dogs deemed healthy by physical examination and owned by 41 people from Queensland had serum submitted for Microscopic Agglutination Testing (MAT) to determine antibody titres against Leptospira serovars, while 40/41 dog owners completed a survey on their knowledge of diseases relating to pig hunting. Human leptospirosis cases (n = 330) notified to Queensland Health between 2015-2018 were analysed. Approximately one quarter (23/87; 26%) of unvaccinated pig-hunting dogs were seropositive to Leptospira spp. Although harder to interpret, 8/11 (73%) vaccinated dogs were seropositive to Leptospira spp. Pig hunters may be more likely to contract leptospirosis compared with the general Queensland population, based on responses from surveyed hunters. The highest concentration of human leptospirosis was in the wet tropics region of Far North Queensland. There was little overlap between the serovars dogs were exposed to and those infecting humans. The dominant serovar identified in unvaccinated dogs was Australis (13/23; 57%), with serovar Arborea (36/330; 10.9%) responsible for the highest number of human leptospirosis cases. Topaz was the second most common serovar in both humans and dogs and was previously unrecorded in Australian dogs. Most hunters surveyed used hand washing as a zoonotic disease risk reduction technique.

CONCLUSIONS

Leptospirosis is an emerging disease of growing significance. The infection requires a 'one health' approach to understand its epidemiology. With shifting climatic patterns influencing human-animal-environment interactions, ongoing monitoring of diseases like leptospirosis is critical to helping prevent infection of individuals and disease outbreaks.

Hunting Dogs

Herding and hunting dogs are intense, high-drive dogs that work, and often live, outdoors and in constant or repeated close contact with domestic and wild animals. These dogs are at increased risk for injury and exposure to infectious diseases, toxic substances, and environmental threats. The common practice of feeding or allowing access to raw meat from farm or game animals enhances disease transmission risk. These dogs can be affected by infectious diseases and injurious agents that are rarely encountered in other groups of dogs. In addition, their extreme work ethic may lead to delays in diagnosis.

Herding Dogs

Herding is done predominantly by breeds developed over centuries to millennia specifically for that purpose. Working-level herding breed dogs are intense, high-drive dogs that will work despite severe illness or pain, thereby masking clues that they are ailing or the nature of their problem. The handler should recognize subtle changes that might signal ill health, and veterinarians should take an active role in training handlers on essential skills. Herding dogs typically work entirely outdoors in rural to wilderness environments with continuous exposure to other domestic animals and wildlife and may be affected by trauma, toxin exposure, infectious diseases, and parasitic infections.

Clinical findings in dogs diagnosed with leptospirosis in England

BACKGROUND

Leptospirosis is a zoonotic disease of worldwide importance. This study describes the clinical findings and outcome of dogs diagnosed with leptospirosis in England.

METHODS

Retrospective review of medical records of dogs diagnosed with leptospirosis from a single referral hospital located in Eastern England.

RESULTS

Thirty-eight dogs met the inclusion criteria. Clinical signs included inappetence (76%), vomiting (68%), lethargy (58%), polydipsia and polyuria (18%) and abdominal pain (16%). Disease manifestations included hepatic and renal involvement (47%), hepatic only (37%), renal only (16%); no dogs were found to have respiratory involvement. Clinicopathological findings at presentation included anaemia (42%), thrombocytopenia (43%), increased alanine transaminase activity (ALT) (66%), hyperbilirubinemia (55%), azotaemia (68%), hypoalbuminaemia (49%) and glucosuria (32%). Seven serovars of Leptospira interrogans or Leptospira kirschneri were detected; the most prevalent was Copenhageni (48%). Seventy-one percent survived to discharge. Dogs in the non-surviving group had a higher creatinine at presentation compared to survivors (p = 0.02).

CONCLUSIONS

Copenhageni was the most prevalent serovar in this population. This supports the use of a vaccine including this serovar, in this region. Renal involvement was associated with reduced survival to discharge. A hepatic only form was common in this population, and leptospirosis should be included as a differential diagnosis for dogs suffering with a hepatopathy. No cases had significant pulmonary involvement, but ongoing clinical vigilance for this disease manifestation is essential.

Incidence and demographic risk factors for leptospirosis in dogs in the UK

OBJECTIVES

To estimate the annual incidence risk of leptospirosis diagnosis in practice-attending dogs in the UK during 2016 and identify risk factors for diagnosis.

METHODS

Incidence of leptospirosis diagnosis in dogs during 2016 was estimated from dogs in primary-care practices from the VetCompass Programme (n = 905,543). A case-control study of laboratory cases (n = 362) versus VetCompass controls explored factors (age, sex, neutering, breed, Kennel Club group, urban-rural location, indices of deprivation) associated with leptospirosis diagnosis through multivariable logistic regression.

RESULTS

Annual incidence risk of leptospirosis in the VetCompass population was 0.8 cases per 100,000 dogs (0.0008%, 95% CI 9.1 × 10^-8 -5.2 × 10^-5 ). Adult dogs, especially 1- < 5 years olds (odds ratio [OR] = 0.38, 95% CI 0.27-0.54), and dogs attending urban clinics (OR = 0.26, 95% CI 0.19-0.35) had reduced odds of leptospirosis versus dogs < 1 year old and rural dogs, respectively. Dogs attending clinics in less deprived areas had increased odds of diagnosis (OR = 3.63, 95% CI 2.28-5.78) compared to crossbreds, Cocker Spaniels (OR = 4.25, 95% CI 2.65-6.84), Collies (OR = 3.53, 95% CI 2.22-5.62) and Lurchers (OR = 3.49, 95% CI 1.50-8.11) had increased odds of diagnosis.

DISCUSSION

Leptospirosis is rarely diagnosed in clinical practice, suggesting that many true cases may be missed. Demographic risk factors identified here may inform the index of suspicion and encourage increased use of confirmatory diagnostic testing.

Evaluation of changes in the epidemiology of leptospirosis in dogs after introduction of a quadrivalent antileptospiral vaccine in a highly endemic area

Background

Since 2003, a marked increase in leptospirosis serogroup Australis has been observed in dogs in Switzerland. In 2013, a new quadrivalent antileptospiral vaccine (L4) was introduced, adding serogroups Australis and Grippotyphosa to Canicola and Icterohaemorrhagiae of the previous bivalent vaccines (L2).

Objective

To examine whether introduction of L4 was associated with decreased incidence of leptospirosis and decreased odds for dogs with acute kidney injury (AKI) to be diagnosed with leptospirosis.

Animals

Four hundred and sixty‐nine dogs with AKI presented to a referral hospital, including 269 dogs with leptospirosis and 200 controls with other causes.

Methods

Descriptive section: disease incidence was evaluated for 3 consecutive periods: before (PRE, 2011‐2012), transition (TRANS, 2013‐2014), and after introduction of L4 (POST, 2015‐2017). Analytical section: variables associated with a diagnosis of leptospirosis were investigated in a case‐control study using multivariable logistic regression, and focusing on vaccination.

Results

The number of dogs diagnosed with leptospirosis (AKI‐L) decreased from 56.5 (PRE) to 15.7 (POST) cases/year while controls increased from 16.5 to 38.0 cases/year. Control dogs (AKI‐nL) showed a decrease in L2 vaccination (100% to 26%) and an increase in L4 vaccination (0% to 70%). The odds ratio for vaccinated dogs to be diagnosed with leptospirosis was 0.11 (95% confidence interval [CI], 0.06‐0.22; P < .001) for L4 and 2.08 (0.58‐7.42; P = .26) for L2.

Conclusions and Clinical Importance

The introduction of L4 was associated with a marked decrease in dogs with leptospirosis and AKI in Switzerland. Use of the L4 vaccine was associated with significantly decreased odds of disease.

Leptospira infection and shedding in dogs in Thailand

BACKGROUND

Leptospirosis is a widespread zoonosis and has been recognized as a re-emerging infectious disease in humans and dogs, but prevalence of Leptospira shedding in dogs in Thailand is unknown. The aim of this study was to determine urinary shedding of Leptospira in dogs in Thailand, to evaluate antibody prevalence by microscopic agglutination test (MAT) and enzyme-linked immunosorbent assay (ELISA), and to assess risk factors for Leptospira infection. In Northern, Northeastern, and Central Thailand, 273 stray (n = 119) or client-owned (n = 154) dogs from rural (n = 139) or urban (n = 134) areas were randomly included. Dogs that had received antibiotics within 4 weeks prior to sampling were excluded. No dog had received vaccination against Leptospira. Urine was evaluated by real-time polymerase chain reaction (PCR) specific for lipL32 gene of pathogenic Leptospira. Additionally, urine was cultured for 6 months in Ellinghausen-McCullough-Johnson-Harris (EMJH) medium. Antibodies were measured by ELISA and MAT against 24 serovars belonging to 15 serogroups and 1 undesignated serogroup. Risk factor analysis was performed with backwards stepwise selection based on Wald.

RESULTS

Twelve of 273 (4.4%; 95% confidence interval (CI): 2.0-6.8%) urine samples were PCR-positive. In 1/273 dogs (0.4%; 95% CI: 0.01-1.1%) Leptospira could be cultured from urine. MAT detected antibodies in 33/273 dogs (12.1%; 95% CI: 8.2-16.0%) against 19 different serovars (Anhoa, Australis, Ballum, Bataviae, Bratislava, Broomi, Canicola, Copenhageni, Coxi, Grippotyphosa, Haemolytica, Icterohaemorrhagiae, Khorat, Paidjan, Patoc, Pyrogenes, Rachmati, Saxkoebing, Sejroe). In 111/252 dogs (44.0%; 95% CI: 37.9-50.2%) immunoglobulin M (IgM) and/or immunoglobulin G (IgG) antibodies were found by ELISA. Female dogs had a significantly higher risk for Leptospira infection (p = 0.023).

CONCLUSIONS

Leptospira shedding occurs in randomly sampled dogs in Thailand, with infection rates comparable to those of Europe and the USA. Therefore, the potential zoonotic risk should not be underestimated and use of Leptospira vaccines are recommended.

SEROEPIDEMIOLOGIC SURVEY OF CANINE LEPTOSPIROSIS IN NORTHERN TAIWAN DURING 2008–2015

Leptospirosis is an important infectious zoonosis that may cause life-threatening illness in both humans and animals. This study aimed to identify the serovars of Leptospira using the microscopic agglutination test (MAT) and the effect of season on serum-positive cases detected in National Taiwan University Veterinary Hospital from August 2008 to September 2015. This study also compared the characteristics of serum-positive and serum-negative cases. Among 159 suspected cases, 78 serum-positive (MAT titer [Formula: see text]) and 81 serum-negative cases were identified. In serum-positive cases, the most common pathogenic serovars were Canicola (18.2%), Icterohaemorrhagiae (23.6%), and Shermani (20.0%). Significantly more serum-positive cases were identified in fall (September to November) than other seasons ([Formula: see text]). Dogs aged 1–5 years (odds ratio [Formula: see text] 1.7) were more likely to be identified as being serum-positive cases of canine leptospirosis than serum-negative cases. However, no significant difference was observed regarding breed, gender, and regional distribution. The serum concentrations of liver enzymes, total bilirubin, blood urea nitrogen, and creatinine were elevated in both serum-positive and serum-negative cases, with no significance. White blood cell (WBC) counts of serum-positive cases were statistically higher than those of serum-negative cases ([Formula: see text]). In conclusion, more precaution must be taken with dogs aged 1–5 years because of their higher risk of leptospirosis; additionally, significantly elevated WBC count may be a suitable indicator in suspected cases of canine leptospirosis.

Re-evaluating the LD50 requirements in the codified potency testing of veterinary vaccines containing Leptospira (L.) serogroup Icterohaemorrhagiae and L. serogroup Canicola in the United States

Approximately one-third of the reportable USDA Category D and E laboratory animals in the United States are expended on the potency testing of leptospiral vaccines by the codified hamster vaccination-challenge assay. Valid tests require ≥80% of challenge controls to succumb to disease and an LD50 between 10 and 10,000. This work evaluates the risk associated with the removal of LD50 limits; thereby, eliminating back-titration hamsters from in vivo potency assays for Leptospira (L.) serogroups Canicola and Icterohaemorrhagiae. The impact was assessed through 1) retrospective analysis of industry and CVB serial release data from July 2011-April 2015 and 2) evaluation through vaccination-challenge assays. For the initial vaccination-challenge assays (n = 3/serogroup), one group received potent bacterin (PB) and six groups received subpotent bacterins (SB1-SB6). PB and SB1 were challenged with a single dilution of Leptospira between 10 and 10,000 LD50. SB2-SB6 received serial dilutions of more concentrated challenge. Based on the retrospective analysis and in vivo assays, 80% of the challenge controls succumbing to disease reasonably ensured the minimal LD50 was administered. Subpotent vaccines were not at increased risk for being deemed potent when challenged with >10,000 LD50, but potent vaccines were at risk of being deemed subpotent when challenged with >10,000 LD50.

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.

Meta-Analyses of Factors Associated with Leptospirosis in Domestic Dogs

Factors related with leptospirosis in domestic dogs have been reported worldwide. The aims of this study were to identify factors associated with this disease described in different observational studies and to combine the coinciding factors in at least four studies using meta-analyses, to obtain a pooled odds ratio (OR) as measure of infection risk. A literature search was performed in electronic databases, electronic databases of specific journals and search engines to find studies published in English, Spanish and Portuguese available from January 1960 to January 2015. Two hundred and eighteen factors were identified in 31 publications including cross-sectional and case-control studies. Finally, independent meta-analyses were performed with six different variables, which included between 4 and 8 articles. The pooled OR indicated that the variables 'mixed-breed dogs', 'flooding occurrence in the habitat of the dog' and 'working dogs' were risk factors for leptospirosis, while 'being a dog less than 1 year old' was a protective factor; however, all these associations were not statistically significant. Otherwise, the variables 'male dog' and 'urban dog' were statistically significant risk factors for infection. This study highlights the need for more formal studies on the epidemiology of canine leptospirosis. Nevertheless, the study revealed that some risk factors for infection coincided in different observational studies. These factors could be considered to raise suspicion about the disease, especially when there is a history of exposure to the bacteria.

Increasing incidence of canine leptospirosis in Switzerland

A marked increase in canine leptospirosis was observed in Switzerland over 10 years with a peak incidence of 28.1 diagnosed cases/100,000 dogs/year in the most affected canton. With 95% affected dogs living at altitudes <800 m, the disease presented a seasonal pattern associated with temperature (r² 0.73) and rainfall (r² 0.39), >90% cases being diagnosed between May and October. The increasing yearly incidence however was only weakly correlated with climatic data including number of summer (r² 0.25) or rainy days (r² 0.38). Serovars Australis and Bratislava showed the highest seropositivity rates with 70.5% and 69.1%, respectively. Main clinical manifestations included renal (99.6%), pulmonary (76.7%), hepatic (26.0%), and hemorrhagic syndromes (18.2%), leading to a high mortality rate (43.3%). Similar to the human disease, liver involvement had the strongest association with negative outcome (OR 16.3). Based on these data, canine leptospirosis presents similar features and severity as the human infection for which it therefore can be considered a model. Its re-emergence in a temperate country with very high incidence rates in canines should thus be viewed as a warning and emphasize the need for increased awareness in other species.

Emerging and Re-Emerging Zoonoses of Dogs and Cats

Simple Summary

Dogs and cats have been sharing our environment for a long time and as pets they bring major psychological well-being to our modern urbanized society. However, they still can be a source of human infection by various pathogens, including viruses, bacteria, parasites, and fungi.

Abstract

Since the middle of the 20th century, pets are more frequently considered as “family members” within households. However, cats and dogs still can be a source of human infection by various zoonotic pathogens. Among emerging or re-emerging zoonoses, viral diseases, such as rabies (mainly from dog pet trade or travel abroad), but also feline cowpox and newly recognized noroviruses or rotaviruses or influenza viruses can sicken our pets and be transmitted to humans. Bacterial zoonoses include bacteria transmitted by bites or scratches, such as pasteurellosis or cat scratch disease, leading to severe clinical manifestations in people because of their age or immune status and also because of our closeness, not to say intimacy, with our pets. Cutaneous contamination with methicillin-resistant Staphylococcus aureus, Leptospira spp., and/or aerosolization of bacteria causing tuberculosis or kennel cough are also emerging/re-emerging pathogens that can be transmitted by our pets, as well as gastro-intestinal pathogens such as Salmonella or Campylobacter. Parasitic and fungal pathogens, such as echinococcosis, leishmaniasis, onchocercosis, or sporotrichosis, are also re-emerging or emerging pet related zoonoses. Common sense and good personal and pet hygiene are the key elements to prevent such a risk of zoonotic infection.