Leptospirosis diagnostic serology service

The leptospirosis diagnostic serology service is located within the Department of Microbiology at Monash University, Melbourne and performs testing for human leptospirosis for Victoria, Australia. It is accredited for testing by the National Association of Testing Authorities and by the Royal College of Pathologists of Australasia.

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Information about our service

Our service

We perform the Microscopic Agglutination Test (MAT). This test detects antibodies specific for the leptospira bacteria and is the World Health Organisation (WHO) gold standard test to diagnose leptospirosis. WHO also recommends MAT confirmation of all sera that has tested positive for leptospiral DNA using polymerase chain reaction (PCR). Using the MAT test we can determine the infecting serovar and the level of leptospiral antibodies present in the sera. Currently we test for antibodies against the following serovars: Arborea, Australis, Canicola, Copenhageni, Grippotyphosa, Hardjo, Pomona, Tarassovi and Zanoni. These serovars have been carefully chosen based on epidemiological data of leptospirosis disease in the Australasian area.

Other tests for leptospirosis

Other tests for leptospirosis include an IgM ELISA, PCR or direct culture. The IgM test detects early production of antibodies (IgM) and therefore can become positive earlier than the MAT, but suffers from both false positive and false negative problems. It also gives no indication of the infecting serovar and therefore cannot provide potentially important epidemiological information. Reliance on ELISA alone is not recommended. PCR tests to detect leptospiral DNA are also available. However, like all diagnostic PCRs, a negative result does not necessarily mean that the patient has not been infected as PCR can fail to generate a product for a variety of reasons. Additionally, the PCR test cannot give information on infecting serovar or the current status of infection. Direct culture of leptospires from urine or serum takes time and is very difficult, with an extremely low success rate. It is therefore not a recommended practice for diagnosis of disease in individual patients.

Sample information

A blood sample for leptospirosis serology should be taken as soon as the patient presents to a clinic/hospital with a febrile illness and leptospirosis is considered a possible cause. A second specimen should be taken 5-7 days later if the clinical picture & history indicate significant possibility of leptospira infection. Further tests may be conducted with sera taken at similar intervals if necessary.

Specimen collection and transport

Test name Leptospirosis Serology
Laboratory and delivery details Leptospirosis Serology (Boyce Laboratory)
via Medicine Store
G55, 23 Innovation Walk (Building 77)
Monash University, Clayton Campus
Specimen type/volumeSerum at least 0.2 ml
Container and storagePlain tube at room temperature
DetailsTests for antibody to Leptospira serovars

Interpretation of results

We provide three interpretations with our reports

1. “No antibodies detected against this panel of leptospiral serovars. Antibodies in leptospirosis may take up to 14 days, or longer, to appear. A second specimen is suggested in 10-14 days if a clinical/epidemiological suspicion of leptospirosis persists.”

This interpretation is provided when the titres for each of the serovars tested is < 50. There may be no infection or no detectable levels of antibodies because the patient is in the early stages of infection. Antibodies appear 7-10 days into the infection but sometimes antibodies do not appear until 3-4 weeks after infection, or very rarely, even longer.

2. “This low titre may represent either residual antibody from a past infection or early antibody in a current infection. A repeat specimen is suggested if diagnosis is not established.”

This interpretation is provided when the titre for antibodies against a particular serovar is greater than 50 but the titre is not considered high. This low antibody level may indicate the patient is in the early stages of infection. Alternatively, low antibody levels may indicate a previous infection. This is because over time, antibody levels gradually drop following infection but low levels may persist for up to 10 years post-infection.

3. “Probable recent infection”.

This interpretation is provided when the titre for antibodies against a serovar is high or higher than the previous titre in serum from the same patient. If two samples are provided (10-14 days apart) and the infection is current, a second specimen may be positive (when the first was negative) or show a rise in titre compared with the titre of the first sample. A rising titre of 4-fold or greater is diagnostic of a recent infection. A single high titre can also indicate a recent infection but antibodies can often remain high (titre ≥ 400) for many months following an infection.

Overview

Your doctor has decided based on your symptoms, together with your work, recent activity or travel history, that you may have (or have recently had) a disease called leptospirosis. Leptospira bacteria can live harmlessly inside many animals including most farm animals (e.g. cattle, pigs, sheep, horses), domestic animals (e.g. dogs), and vermin (e.g. rats and other rodents). However, if transmitted to humans, these bacteria cause a very serious disease called leptospirosis. Symptoms begin 2-4 weeks after infection and include fever, chills, muscle pain and headaches. These symptoms are common to many diseases and it is important to identify the cause so that the patient can be given the correct treatment and care. This means that often, many blood tests are ordered testing for a range of diseases, including a test for leptospirosis.

Who can catch leptospirosis?

Leptospira bacteria can be transmitted to humans by direct contact with urine or other fluids of infected animals. It is for this reason that farmers and abattoir workers are at a higher risk of contracting leptospirosis than the general population. Leptospirosis can also infect people who drink/ingest or have contact with water or soil contaminated with leptospires. This might occur during work or recreational activities involving flood water, wet paddocks, dams, reservoirs or lakes, located here or anywhere in the world that you might have travelled recently. Leptospires grow best in these watery environments during warm weather. For this reason, there is more leptospirosis disease in wet, tropical areas and in the southern parts of Australia during warm, wet weather e.g. during spring and autumn. If you would like to know more about this disease, visit the website: http://www.cdc.gov/leptospirosis/

Treatment

Your doctor would have prescribed specific antibiotics to treat this disease; this treatment may have started before our test result to ensure that your infection was promptly treated. Left untreated, leptospirosis infection can cause the failure of major organs (kidney, liver), meningitis, and even death.

Our service

The Leptospirosis diagnostic serology service is located within the Department of Microbiology at Monash University in Melbourne and performs testing for human leptospirosis in Victoria, Australia. It is accredited for testing by the National Association of Testing Authorities and by the Royal College of Pathologists of Australasia.

We perform the Microscopic Agglutination Test (MAT) to test for the presence of specific antibodies in the blood that indicate that the body has been in contact with the leptospira bacteria. These antibodies are only made by the body once an infection with leptospires has started. Sometimes, the first blood test is negative because the blood was taken very early in the infection and the body had not yet made these antibodies. If your doctor still suspects you have this disease after the first test comes back negative, he/she will order a second test 10-14 days after the first.

Why have I received a bill for the leptospirosis test?

Most people who have received a bill for this service had visited their local doctor when they were unwell, who then referred them to a pathology service for tests, or they were a private patient in a hospital. Unfortunately, the cost for our laboratory to perform this important test is significantly more than the government currently offers as a Medicare rebate. It is for this reason that we are unable to bulk bill Medicare. However, like other medical bills, a Medicare rebate is usually available for you to claim part of the cost after paying for our service. Our payment options are outlined below.

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Payment options

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Contact us

Telephone: +61 3 9902 9193
Fax: +61 3 9902 9224
Email: med-lepto@monash.edu

Mailing address:  
Leptospirosis Laboratory
Department of Microbiology,
19 Innovation Walk,
Wellington Road,
Clayton, Victoria,
3800