Leptospirosis

Leptospirosis is a bacterial zoonosis caused by pathogenic spirochaetes of the genus *Leptospira* ^[1]. The disease is described as prevalent worldwide and as one of the most important zoonotic bacterial diseases ^[2][1]. The provided sources also note revisions in leptospiral taxonomy and improvements in typing methods, diagnostics, and vaccines, indicating that the organism and its detection are active areas of update ^[3].

Clinical infection may be asymptomatic, or it may produce symptomatic disease ranging from mild illness to severe disease ^[1]. Severe leptospirosis is described as being characterized by icterus and/or multi-organ dysfunction and may be fatal ^[1]. One source additionally notes hemoptysis in a reported case, with rapid progression to acute respiratory failure and ARDS in the setting of fever, jaundice, and acute liver and kidney failure ^[4]. The pathogenesis of severe disease is said to be poorly understood but associated with dysregulated immune responses, including a cytokine storm with immunoparesis ^[1].

Leptospirosis is prevalent across all continents and is considered a worldwide zoonotic bacterial disease ^[1]. It is reported to commonly affect resource-poor populations and to cause significant morbidity and mortality ^[2]. The available material estimates approximately one million cases globally each year with about 60,000 deaths ^[1]. In dogs, it is also described as prevalent in urban and rural settings, including small-breed dogs, puppies as young as 11 weeks, geriatric dogs, and inadequately vaccinated animals ^[3].

The provided sources describe leptospirosis as a zoonotic infection linked to animal exposure, but they do not give a complete route summary in the available text ^[3][1]. One case report specifically mentions injury while hunting and slaughtering pigs after heavy rainfall as the exposure context, supporting animal-contact and environment-associated exposure as relevant surveillance clues ^[4]. Source-backed detail on persistence in water or soil, specific shedding patterns, or the relative importance of particular reservoirs is not yet available in the supplied material ^[4].

The provided sources identify resource-poor populations as commonly affected ^[2]. They also note prevalence in dogs that are small-breed urban animals, puppies, geriatric dogs, rural dogs, and dogs that have been inadequately vaccinated ^[3]. In the human case material, relevant exposure history included hunting and slaughtering pigs after heavy rainfall, but broader human risk-group definitions are not fully specified in the supplied text ^[4].

Prevention in the provided sources centers on exposure control through behavioural modifications and personal protective measures ^[1]. Human vaccines are limited in availability, with very few countries having licensed a vaccine and the available vaccines described as protecting only against rodent-associated serogroups ^[1]. The same source states that prophylactic antibiotic efficacy has not been confirmed in clinical trials ^[1]. For animal health, the veterinary consensus notes widespread use of vaccines and highlights that inadequately vaccinated dogs remain affected ^[3].

In surveillance terms, leptospirosis should be read as a globally distributed zoonosis with substantial under-recognized burden and potentially severe outcomes ^[2][1]. Case finding is strengthened by attention to febrile illness with jaundice, organ dysfunction, hemoptysis, or rapid respiratory deterioration after animal or environmental exposure, as illustrated by the cited case report ^[4]. The sources also indicate that updated taxonomy, typing methods, diagnostics, and vaccines may affect interpretation of recent trends and comparisons across settings ^[3].

1. 1 Rajapakse S et al. Leptospirosis. Nat Rev Dis Primers. 2025 May 2. PMID: 40316520. doi: 10.1038/s41572-025-00614-5. PubMed: https://pubmed.ncbi.nlm.nih.gov/40316520/
2. 2 Rajapakse S et al. Leptospirosis: clinical aspects. Clin Med (Lond). 2022 Jan. PMID: 35078790. doi: 10.7861/clinmed.2021-0784. PubMed: https://pubmed.ncbi.nlm.nih.gov/35078790/
3. 3 Sykes JE et al. Updated ACVIM consensus statement on leptospirosis in dogs. J Vet Intern Med. 2023 Nov-Dec. PMID: 37861061. doi: 10.1111/jvim.16903. PubMed: https://pubmed.ncbi.nlm.nih.gov/37861061/
4. 4 一位47歲男性以咳血為表現之鉤端螺旋體病病例報告. 台灣專科護理師學刊. 2024. doi: 10.53106/2410325x2024121102008. DOI: https://doi.org/10.53106/2410325x2024121102008
5. 5 Leptospirosis. Human Diseases from Wildlife. 2014. doi: 10.1201/b17428-15. DOI: https://doi.org/10.1201/b17428-15
6. 6 Leptospirosis. Retina Atlas. 2019. doi: 10.1007/978-981-13-8546-9_20. DOI: https://doi.org/10.1007/978-981-13-8546-9_20

ICD-10

A27

ICD-11

1B95

Total cases

366K

Total deaths

61

Peak month

2024-05

Coverage

9 reporting countries · 2000-01-01 → 2026-06-20