Search

In 2017, highly fatal canine leptospirosis emerged in Sydney, Australia. Based on results of microscopic agglutination testing (MAT), serovar Copenhageni appeared to be the most common causative serovar. Prior to this, no clinical cases had been reported since 1976. In a serosurvey of healthy dogs in Australian shelters in 2004, 2.4% of 431 New South Wales dogs had serological evidence of exposure to Copenhageni, the most prevalent serovar. The aim of this study was to estimate the current prevalence of Leptospira exposure and associated serovars in healthy Sydney dogs, previously unvaccinated against Leptospira. Serum samples from 411 healthy dogs in leptospirosis hotspots and neighbouring suburbs were collected before vaccination. MAT for 23 serovars was performed at the WHO Leptospirosis Reference Laboratory in Queensland, Australia. The overall seroprevalence was 4.1% (17/411) with low titres (1/50–1/200) detected. Eleven dogs were from known leptospirosis hotspots. Eight dogs were known to hunt rodents. One dog had been in contact with a leptospirosis positive dog 1 year prior. Serovar Topaz was the most prevalent serovar (n = 5) followed by serovars Australis (n = 4), Copenhageni (n = 4), Djasiman (n = 2), Cynopteri (n = 1), Javanica (n = 1), Medanensis (n = 1), and Pomona (n = 1). In conclusion, serological evidence of exposure of dogs in Sydney to Leptospira is low, but apparently has increased since 2004. Positive titres to serovars not previously reported to cause disease in dogs could be due to low virulence of those serovars or cross‐reactivity with other serovars. [ABSTRACT FROM AUTHOR]

An outbreak of canine leptospirosis commenced in Sydney, Australia in 2017. The aim of this retrospective study was to determine if clusters of leptospirosis occurred during this outbreak, and if these were associated with host factors, to assist investigation of the drivers of emerging leptospirosis at this location. Within the City of Sydney local government area, 13 cases were reported during the outbreak. Administrative data on the canine population were collected and mapped. Clusters of leptospirosis cases were detected using a retrospective space-time analysis and a discrete Poisson probability statistical model. Sydney dog population registration [55.6%, 95% confidence interval (CI) 51.8-58.1%] was lower than the Australian national average (80%). The distribution of dog types, based on the United Kennel Club standards, was significantly (p < .0001) different to that of the national profile: there was a distinct preference in Sydney for companion dogs. The age distribution of dogs in Sydney did not reflect a typical right-skewed curve; instead, a relatively uniform distribution was observed between the age group of 1 to 8 years. A primary disease cluster (radius 1.1 km) in the eastern area of the Sydney City Council was identified (4 cases observed between 24 May and 9 August 2019 vs. 0.10 cases expected), p = .0450. When adjusted for the age, breed type and sex distribution of the population, similar clusters were identified; in the case of age-adjustment, the spatiotemporal cluster identified was larger and of longer duration (seven cases observed between 28 June and 11 November 2019 versus 0.34 cases expected), p = .0025. The presence of clusters of canine leptospirosis in the City of Sydney during this outbreak, which persisted after adjustment for demographics (age, sex, breed type), suggest that environmental factors - rather than host or pathogen factors - might be responsible for the emergence of leptospirosis. Environmental factors that potentially might be linked to this outbreak of canine leptospirosis and the clusters observed require investigation., (© 2021 The Authors. Transboundary and Emerging Diseases published by Wiley-VCH GmbH.)