Leptospirosis

Notification requirement for leptospirosis

Leptospirosis is a ‘routine’ notifiable condition and must be notified by pathology services in writing within 5 days of diagnosis. Medical practitioners are not required to notify cases of leptospirosis.

This is a Victorian statutory requirement.

Primary school and children’s services centre exclusion for leptospirosis

Exclusion is not applicable.

Infectious agent of leptospirosis

Leptospires are members of the order Spirochaetes. Pathogenic leptospires belong to the species Leptospira interrogans, which is subdivided into serovars. In Australia, the most common serovar is L. interrogans serovar hardjo. Serovar arborea has also been notable in Victoria in recent years.

Identification of leptospirosis

Clinical features

This group of zoonotic bacterial diseases may present with a variety of manifestations. Common clinical features include fever (which may be biphasic), headache, chills, a rash, myalgia and inflamed conjunctivae. In endemic areas, many infections are either asymptomatic or too mild to be diagnosed.

More severe manifestations occur rarely, and include meningitis, haemolytic anaemia, haemorrhage into skin and mucous membranes, hepatorenal failure, jaundice, mental confusion, respiratory distress and haemoptysis.

The acute illness may lasts from a few days to 3 weeks or more, with full recovery often taking several months.

Diagnosis

Leptospires may be isolated from the blood (days 0–7) and cerebrospinal fluid (days 4–10) during the acute illness, and from the urine after day 10.

The diagnosis is more commonly confirmed serologically by the demonstration of a fourfold or greater rise in Leptospira antibody in paired sera taken in the acute phase and at least 2 weeks later. A single Leptospira microagglutination titre of 400 or greater with a positive IgM result is also sufficient for confirmation.

Incubation period of Leptospira

The incubation period is typically 10–12 days, with a range of 4–19 days.

Public health significance and occurrence of leptospirosis

Leptospirosis occurs worldwide in developed and developing countries, in both rural and urban settings. The disease is an occupational hazard for farmers, sewer workers, miners, dairy workers, abattoir workers and fish workers. It is a recreational hazard to bathers, campers and some sportspeople in infected areas.

Farmers, farm workers and meat industry workers in Victoria are the occupational groups most commonly affected by leptospirosis.

Reservoir of Leptospira

Serovars vary with the wild and domestic animal affected. Animal hosts in Victoria include rats, cows and pigs. Asymptomatic kidney infections in carrier animals can lead to prolonged and sometime lifelong excretion of leptospires in the urine.

Mode of transmission of Leptospira

Leptospira is transmitted primarily through contact of skin with water, moist soil or vegetation contaminated with the urine of infected animals. The infection may also be transmitted through direct contact with urine or tissues of infected animals, or by inhalation of aerosols of contaminated fluids, such as may occur in abattoirs. Ingestion of foods contaminated with urine of infected rats is an occasional route of infection.

Period of communicability of leptospirosis

Direct transmission from person to person is rare. Leptospires may be excreted in the urine for a month, but urinary excretion in humans and animals for up to 11 months has been reported.

Susceptibility and resistance to leptospirosis

Immunity to the specific serovar follows infection, but may not protect against infection with a different serovar.

Control measures for leptospirosis

Preventive measures

There is no human vaccine available.

General preventive measures include:

• education for the public on modes of transmission, such as advice to avoid swimming or wading in potentially contaminated waters, and to use appropriate personal protection when work requires potential exposure
• protecting workers in hazardous occupations with boots and gloves
• covering abrasions and sores on skin with waterproof dressings
• rodent control around human habitations
• prompt treatment and isolation of infected domestic animals.

The Department of Environment, Land, Water & Planning can be consulted for advice on herd immunisation.

Control of case

The usual antibiotic treatment is doxycycline, benzylpenicillin or ceftriaxone. Mild cases and cases where fever has resolved may not require antibiotics. Consult the current version of Therapeutic guidelines: antibiotic or seek specialist infectious diseases advice.

Although person-to-person transmission is rare, cases should be nursed with blood and body fluid precautions. Any articles soiled with urine should be disinfected. The patient should be advised that they may continue to excrete leptospires in the urine for a month or more after the acute infection.

Control of contacts

Not applicable.

Control of environment

The exposure history of each case should be investigated to identify and control possible sources of infection, such as exposure to infected animals and potentially contaminated bodies of water. Environmental control measures may include environmental clean-ups and draining of, or restricting access to, potentially contaminated water bodies.

The Department of Environment, Land, Water & Planning investigates suspected animal industry sources, such as dairies and piggeries, and may recommend animal vaccination or other disease control measures.

Outbreak measures for leptospirosis

See ‘Control measures for leptospirosis’.