Leptospirosis
Queensland Health Guidelines for Public Health Units
Revision History
| Version | Date | Changes |
|---|---|---|
| 1.0 | December 2010 | Full revision of guideline. |
| 1.1 | January 2011 | Change to laboratory suggestive evidence and reporting of probable cases. |
| 2.0 | September 2014 | Full revision of guideline (published January 2015) |
| 2.1 | August 2017 | Change to notification process |
Infectious Agent
Leptospirosis is caused by infection with Leptospira species which are helical Gram-negative aerobic bacteria. There are at least 18 species, eight of which are classified as ‘pathogenic’. Each species is further subdivided into serovars.
Notification Criteria
Laboratory definitive evidence
Isolation of pathogenic Leptospira species
OR
A fourfold or greater rise in Leptospira micro agglutination titre (MAT) between acute and convalescent phase sera obtained at least two weeks apart and preferably conducted at the same laboratory
OR
A single Leptospira micro agglutination titre (MAT) greater than or equal to 400 supported by a positive enzyme-linked immunosorbent assay IgM result.
Laboratory suggestive evidence (not in national case definition)
Detection of Leptospira by nucleic acid testing
Community outbreak criteria
Two or more epidemiologically linked confirmed cases with a suspected local source of exposure.
Notification Procedure
Pathology Laboratories
To notify on confirmation of diagnosis by usual means.
Lab Aspects
Appropriate specimen collection for suspected leptospirosis cases should be informed by the timeline below, with summary as follows:
- Under 7 days: serum for PCR and blood for culture
- 7–10 days: blood for culture and serum for EIA IgM and MAT
- Over 10 days: serum for EIA IgM and MAT
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.
Source: WHO/FAO/OIE Collaborating Centre for Reference and Research on Leptospirosis. National leptospirosis surveillance report no 18. Queensland Health Forensic and Scientific Services: Coopers Plains, 2009.
Reporting to NOCS
Report both confirmed and probable cases. Only confirmed cases will be reported to NNDSS.
Confirmed case
A confirmed case requires laboratory definitive evidence only.
Probable case
A probable case requires laboratory suggestive evidence only.
Objectives of surveillance
To monitor the epidemiology of leptospirosis in Queensland and inform public health initiatives.
Forward a copy of the completed leptospirosis Case Report Form to the Communicable Diseases Branch.
Email to CDIS-NOCS-Support@health.qld.gov.au
Public Health Significance and Occurrence
Leptospirosis occurs worldwide (except the polar regions), but is most common in tropical and subtropical areas, and is common in Queensland.
Leptospirosis is predominantly a disease of males, linked to occupation. Common occupations include agriculture, such as in the banana industry, meatworkers and dairy farmers. The disease is also a recreational hazard for bathers, campers and sportspeople with exposure to contaminated waters. Outbreaks occur among those exposed to river, stream, canal and lake water contaminated by the urine and tissues of infected domestic and wild animals. There have been several cases in white water rafters in Queensland. Leptospirosis appears to be increasing as an urban hazard, especially after heavy rains when floods occur. Clusters have been associated with domestic and workplace infestations of rodents.
Notifications of leptospirosis in Queensland: 2009-2013
| Year | Number of notifications | Notification rate (per 100,000 population)* |
2009 | 102 | 2.3 |
2010 | 84 | 1.9 |
2011 | 181 | 4.0 |
2012 | 82 | 1.8 |
2013 | 73 | 1.6 |
* Notification rates were calculated based on Estimated Resident Populations for respective years except for 2013 for which the 2012 Estimated Resident Population was used.
Clinical Features
Leptospirosis is a zoonotic bacterial disease with varying manifestations. It is usually self-limiting and often clinically unapparent. Clinical illness lasts from a few days to three weeks or longer. Generally, there are two phases in the illness: the leptospiraemic or febrile stage lasting 5–7 days, followed by the convalescent or immune phase which generally lasts 4–30 days. Recovery in untreated cases can take several months. The early phase of the illness is characterised by fever with sudden onset, headache, chills, and severe myalgia (calves and thighs). The pathognomonic finding of leptospirosis, conjunctival suffusion, occurs in about 30% of cases. Other symptoms may include: nausea, vomiting, abdominal pain, diarrhoea, cough, photophobia, and rash.
Five to 15% of cases progress to severe late-phase manifestations. These include:
- prolonged fever
- jaundice
- renal failure
- bleeding
- respiratory insufficiency with or without haemoptysis
- hypotension
- myocarditis, meningitis
- mental confusion
- depression.
Deaths are predominantly due to renal failure, cardiopulmonary failure or widespread haemorrhage. Cases are often under-recognised or misdiagnosed as dengue, malaria and influenza. Serological evidence of leptospiral infection occurs in 10% of cases of aseptic meningitis.
Reservoir
Pathogenic leptospires are maintained in the renal tubules of wild and domestic animals; serovars generally vary with the animal affected, e.g. rats (icterohaemorrhagiae), pigs (pomona), cattle (hardjo) and dogs (canicola). Rodents and domestic mammals such as cattle, pigs and dogs serve as the major reservoir hosts, but Leptospira have been isolated from virtually all mammalian species. Infected animals may excrete leptospires intermittently or regularly for months or years, or for their lifetime.
Mode of Transmission
Transmission can be via:
- Contact of the skin (especially if abraded) or mucous membranes with moist soil, vegetation (sugar cane and banana farm workers have been implicated) or water that has been contaminated with the urine of infected animals
- Direct contact with urine or tissues of infected animals including rodents
- Ingestion of food or water that has been contaminated with urine of infected animals
- Inhalation of droplet aerosols of contaminated fluids
- Contact with contaminated water during outdoor activities such as swimming, wading and white-water rafting in rivers, and lakes and dams.
Incubation Period
Usually 5&endash;14 days, with a range of 2&endash;30 days.
Period of Communicability
Direct person to person transmission is rare. Leptospires may be excreted in the urine, usually for one month, although prolonged excretion has been observed in humans and in animals for months, even years, after acute illness.
Susceptibility and Resistance
Forward a copy of the completed Leptospirosis Case Report Form to the Communicable Diseases Branch.
Management
Cases
Investigation
Follow up is at the discretion of the public health unit, but would generally be limited to severe cases, cases identified in uncommon or low risk occupations, apparent case clusters, and identification of an emerging serovars.
See Laboratory Aspects section above for advice on specimen collection and timing.
The principles of investigation are:
- Confirm the diagnosis. When notified on the basis of single agglutination titre, contact the treating medical practitioner for clinical information and attempt to obtain a second sample for further serological testing. When notified on the basis of a positive enzyme-linked immunosorbent assay IgM result, await MAT testing result.
- Identify likely source of infection. For confirmed cases, in consultation with the treating medical practitioner, attempt to identify the source of infection such as exposure to urine or tissues of infected animals or contaminated water.
- Refer for further investigation if appropriate. If occupational exposure suspected, obtain patient consent and then notify Workplace Health and Safety Queensland.
Forward a copy of the completed Leptospirosis Case Report Form to the Communicable Diseases Branch.
Restriction
Nil; use standard precautions in the clinical setting.
Counselling
The case should be advised of the nature of the infection and its mode of transmission.
Treatment
Antibiotics should be given as early in the course of the illness as possible.
Contacts
Contact Tracing
At the discretion of the PHU as above.
Definition
Any person who may have experienced the same exposure as the case.
Investigation
Advise contacts to seek medical advice and testing if symptoms occur.
Prophylaxis
Nil
Counselling
Contacts should be advised of the nature of the infection and its mode of transmission, and to seek medical advice early if symptoms develop.
Community outbreaks
Search for a common source of exposure. Consider both potential community and occupational exposures. Mitigate identified sources.
Preventive Measures
- Promote public awareness of possible transmission risk when undertaking recreational water based activities including wading, swimming and white water rafting.
- Provide staff working in hazardous occupations with appropriate protective equipment to prevent contamination.
- Ensure cuts and skin abrasions are covered by water tight dressings and encourage frequent hand washing when handling animals.
- Undertake rodent control measures in urban and rural areas.
- Segregate infected domestic animals.
Summary
Prepare a summary report of the investigation for the Communicable Diseases Branch, Queensland Health on request.
References
Heymann D (Ed). 2008. Control of Communicable Diseases Manual, 19th ed. American Public Health Association: Washington.
Department of Health case definitions:
European Centre For Disease Prevention and Control:
http://www.ecdc.europa.eu/en/healthtopics/leptospirosis/pages/index.aspx
World Health Organisation, Western Pacific region:
http://www.wpro.who.int/mediacentre/factsheets/fs_13082012_leptospirosis/en/
Queensland Health. WHO/FAO/OIE Collaborating Centre for Reference and Research on Leptospirosis, Australia and Western Pacific Region [webpage]. Last reviewed 2009. Available at: https://www.health.qld.gov.au/healthsupport/businesses/forensic-and-scientific-services/testing-analysis/diseases/leptospirosis Accessed 6/4/10.
Victoriano AFB, Smythe LD, Gloriani-Barzaga N et al. 2009. Leptospirosis in the Asia Pacific region. BMC Infectious Diseases. 9:147 www.biomedcentral.com/1471-2334/9/147 Accessed 06/04/10.