Public health priority: Sporadic cases: Routine. Action should be carried out as part of routine duties. Case investigation should commence within 1 working day, and data entry should be completed within 2 working days. Outbreak: High. Act as soon as possible, generally within one working day. Data entry should be commenced within 1 working day.
Case management: Cases should receive appropriate antibiotics. Identify likely source.
Management of co-exposed persons: Whilst person-to-person transmission is very rare, there may be individuals who have been exposed to a common source (co-exposed). Identify co-exposed individuals (e.g. those at the same workplace) and advise them of the signs and symptoms of leptospirosis to aid early diagnosis and treatment. In response to leptospirosis linked to workplace/occupational settings, [SafeWork NSW] and [NSW Department of Primary Industries] should be involved (if relevant).
There are various Leptospira serovars which are maintained in a range of animal reservoir species. Human infections are usually acquired from the maintenance host species for each serovar.
Common serovars detected in NSW since leptospirosis became notifiable in January 1991 include:
For further information on Leptospira serovars found in Australia, or other countries, refer to the Queensland Health Forensic and Scientific Services
Leptospirosis Reference Laboratory.
Leptospirosis is transmitted by direct contact with the urine or tissues of infected animals. It can also be transmitted to humans who are in contact with water, soil or environments contaminated with infected urine, or who ingest contaminated water. The bacteria enter through cuts in the skin or through mucous membranes (such as the eyes, nose or mouth); bacteria can also be inhaled in dust (aerosols).
Human-to-human transmission occurs only very rarely. Blood is potentially infectious in the first week of the disease and urine is infectious from the end of the first week and can remain infectious for months.
Often there is a history of contact with animals or exposure to environments contaminated by the tissues or secretions of potentially infected animals. Many animals can carry Leptospira spp. and may be completely asymptomatic. Animal species commonly associated with leptospirosis include cattle, pigs, sheep, dogs, rodents and marsupials.
Outbreaks are usually related to exposure to water sources (e.g. flood water runoff), or environments contaminated with the tissues or secretions (e.g. urine) of infected animals.
The typical incubation period is 5 to 14 days (range 2 to 30 days).
Person-to-person spread very rarely occurs.
The usual clinical presentation is fever, chills, headache, severe myalgia (particularly of the calves, thighs and lumbar region) and conjunctival suffusion. Severity varies with the infecting serovar.
About 5-15% of cases progress to severe disease, which can include:
The case fatality rate increases with increasing age and comorbidities.
Leptospirosis is most commonly diagnosed in people with frequent exposure to outdoor environments including flooded areas, those doing farm work, or having direct or indirect contact with livestock and rodents. At-risk groups for leptospirosis include males and young adults, primarily linked to occupation. Occupations that are at particular risk include farmers, and meatworkers. Leptospirosis also occurs among those who have recreational exposure to freshwater (such as swimming, camping or rafting), and those with a history of travel, particularly to tropical regions. Leptospirosis risk is also increased after periods of high rainfall and flooding and in areas with poor sanitation. Leptospirosis clusters have been associated with domestic and workplace rodent infestations.
Leptospirosis is endemic in temperate and tropical regions and is considered an important re-emerging disease due to changing risks groups, increasing magnitude and frequency of outbreaks and the emergence of new predominant serovars. In Australia, outbreaks are rare and usually related to flooding, although a large outbreak in 2018 was linked to berry picking1. Sporadic cases typically have recreational or occupational exposures, frequently farming, abattoir or veterinary work. Globally, leptospirosis has increased in incidence over recent years, with increasing frequency and severity of outbreaks attributable to climatic, sociodemographic and environmental factors – these include climate change, flooding, population growth and rapid urbanisation (often associated with unsanitary conditions, such as inadequate waste disposal), and agricultural intensification2.
Within 1 working day of a confirmed or probable case begin follow up investigation. Within 2 working days of notification, enter cases onto the NSW Notifiable Conditions Information Management System (NCIMS).
In an outbreak setting, data should be entered within 1 working day following notification.
Public health units work collaboratively with healthcare providers and patients to investigate leptospirosis case notifications, provide information and education about leptospirosis prevention, and to identify further cases with similar exposures (see Section 10 for details).
In the context of responding to a leptospirosis outbreak or cases occurring in workplace settings, the following jurisdictional government agencies should be included for information sharing and joint investigation (see Section 11 for details):
probable cases should be notified.
A confirmed case requires laboratory definitive evidence.
A probable case requires laboratory suggestive evidence.
1. Isolation of pathogenic Leptospira species in culture
2. A fourfold or greater rise in Leptospira agglutination titre between acute and convalescent phase sera obtained at least two weeks apart and preferably conducted at the same laboratory
3. A single Leptospira micro agglutination titre (MAT) greater than or equal to 400 supported by a positive enzyme-linked immunosorbent assay (EIA) IgM result.
Detection of pathogenic Leptospira species by nucleic acid testing.
The most recent Australian national notifiable diseases
case definition for leptospirosis can be found at the Department of Health website.
Appropriate specimen testing for suspected leptospirosis cases is outlined below:
Note that culture is the ‘gold standard’ for detection during the leptospiraemic phase and has greater sensitivity than PCR due to the six week culture period used.
*Specimen type is as clinically indicated
The Leptospirosis Reference Laboratory (QHFSS) is located in Brisbane, Queensland.
As at April 2022, the following tests are available from private pathology service providers in NSW:
Public health unit staff carry out case investigation in collaboration with the case's treating doctor and the case.
PHU staff should ensure that action has been taken to:
Clinicians should commence empiric treatment if leptospirosis is clinically suspected. Do not wait for laboratory results. Refer to latest edition of the
Therapeutic Guidelines: Antibiotic.
A history of possible exposures should be sought using the leptospirosis questionnaire. Attempt to identify the source of infection, such as exposure to urine or tissues of infected animals or contaminated drinking or recreational water.
It is important to determine:
The case or relevant care-giver should be informed about the nature of the infection and the mode of transmission. To avoid future infection, cases should be advised to avoid urine or tissues of infected animals and avoid swimming or wading in potentially contaminated water or walking barefoot in mud or moist soil that may have been contaminated with animal urine.
If direct or indirect contact with urine or infected animal tissues is anticipated, skin abrasions should be covered with an occlusive dressing and gloves and other protective clothing should be worn. (refer to the
Isolation and restriction
Exclusion of infected persons is not required. Leptospirosis is rarely transmissible from person to person. Use standard precautions in a clinical environment.
Active case finding
See Section 11 for active case finding in special situations.
If the case has occupational risk factors such as working with animals/animal products, fruit picking, or in an environment where rodents may be active, discuss with SafeWork NSW and NSW Department of Primary Industries, as appropriate.
In occupational settings and outbreaks, active case finding among identified co-exposed persons should be considered (Section 11). The aim of identifying co-exposed persons is to alert them to the possibility that they could develop disease due to a common source exposure.
A co-exposed person is defined as anyone who may have experienced the same occupational, animal, or environmental exposures as the case, or who may have been exposed to contaminated items associated with the case (e.g. clothing/boots). Person-to-person transmission is extremely unlikely. Co-exposed persons may include people at the workplace (including those without direct contact with animals or animal products) and home.
Post-exposure antibiotic prophylaxis may be considered in an outbreak situation, particularly if the cause of illness is still under investigation, or the purported transmission pathway cannot be interrupted. The decision to initiate post-exposure antibiotic prophylaxis should be discussed with Enterics and Zoonoses Branch.
Leptospirosis information (Appendix 1) should be provided to co-exposed persons with advice to seek medical attention should they develop symptoms.
It is not necessary to isolate or restrict workers from attending an occupational setting. It is however imperative that all workers are informed about the risks of exposure and they are encouraged to take appropriate personal protective measures to reduce their risk (e.g. wearing waterproof boots if in contact with potentially contaminated soil/mud, covering any scratches with waterproof dressings, wearing impermeable gloves, washing hands prior to eating).
In addition to the generic case and co-exposed person follow-up requirements described above, further actions are required in the following instances:
Leptospirosis case investigation may identify a plausible link with a workplace (such as an abattoir or dairy farm). Two cases or more within a three-month period in an at-risk workplace is considered a workplace outbreak.
Responses to cases occurring in workplace settings (including outbreaks) need to be carried out in collaboration between the Public Health Unit, SafeWork NSW, and the NSW Department of Primary Industries (if relevant).
Immediate responses include working with the employer and management to:
The role of SafeWork NSW is to investigate and identify unsafe working conditions, and to monitor and enforce compliance. This may involve a site visit and discussions with the employer. SafeWork NSW may, in consultation with NSW Health and NSW Department of Primary Industries, provide information and advice to the employer.