INTENDED USE
The Leptospira IgG/IgM Rapid Test Cassette is a lateral flow immunoassay designed for the qualitative detection of IgG and IgM antibodies to Leptospira interrogans in human whole blood, serum, or plasma. This test serves as an aid in diagnosing infection caused by Leptospira interrogans.
SUMMARY
Leptospirosis can range from mild, flu-like symptoms to severe liver and kidney dysfunction. The bacteria are shed in the urine of infected animals, posing a risk to humans, especially veterinarians, abattoir workers, farmers, and individuals exposed to contaminated water sources. The bacteria enter through skin abrasions, mucosal surfaces, or the eyes. Symptoms typically appear after an incubation period of 10–12 days, though this can vary from 3 to 30 days. Antibodies are usually detectable between days 6 and 10 of illness and peak at 3 to 4 weeks. The Leptospira IgG/IgM Rapid Test is a simple, qualitative, visual test that can detect these antibodies within 15 minutes.
PRINCIPLE OF THE TEST
The Leptospira IgG/IgM Rapid Test Cassette is a membrane-based immunoassay for detecting IgG and IgM antibodies to Leptospira interrogans. The test contains:
- A conjugate pad with Leptospira recombinant antigens bound to colloidal gold.
- A nitrocellulose membrane with a control line (C) and two test lines for IgG and IgM detection.
When the sample is applied to the cassette, it migrates by capillary action. If IgM antibodies are present, they bind to the conjugates and form a colored IgM line. Similarly, if IgG antibodies are present, a colored IgG line forms. A control line confirms that the test was conducted correctly. Absence of both test lines indicates a negative result.
WARNINGS AND PRECAUTIONS
- For in vitro diagnostic use only.
- For use by healthcare professionals.
- Do not use the test after its expiration date.
- Read all instructions carefully before use.
- Keep the test cassette in the sealed pouch until ready for use.
- Handle all specimens as potentially infectious.
- Dispose of used test materials according to federal, state, and local regulations.
COMPOSITION
Each test cassette includes:
- A membrane strip with mouse anti-human IgM and IgG antibodies for detection.
- A control line with goat anti-Leptospira antibodies.
- A conjugate pad with colloidal gold bound to Leptospira recombinant antigens.
STORAGE AND STABILITY
- Store the test kit at 4-30°C (40-86°F) in its sealed pouch. The kit is stable until the expiration date printed on the packaging.
- Once opened, use the test within one hour.
- Avoid storing the test in excessively hot or humid conditions.
SPECIMEN COLLECTION
- The test can be performed on whole blood, serum, or plasma.
- Collect specimens following standard clinical procedures.
- Serum or plasma should be separated from blood as soon as possible to avoid hemolysis.
- Store specimens at 2-8°C if testing is delayed (up to 7 days). For longer storage, freeze at -20°C. Do not freeze whole blood.
- Thaw frozen specimens slowly and mix well before testing. Avoid using hemolyzed, lipemic, or turbid samples.
TEST PROCEDURE
- Allow the test device and specimens to reach room temperature (15-30°C or 59-86°F).
- Remove the test cassette from the sealed pouch and place it on a flat surface.
- Using the dropper, add 1 drop of the specimen (~35 µL) to the specimen well, followed by 2 drops of buffer (~70 µL). Start the timer.
- Wait 15 minutes for the result. Do not interpret results after 20 minutes.
RESULT INTERPRETATION
- Positive: The control line and at least one test line (IgG or IgM) appear. IgM indicates a recent infection; IgG suggests a previous or ongoing infection. If both lines appear, it indicates both types of antibodies.
- Negative: Only the control line appears, indicating no detectable antibodies.
- Invalid: If the control line does not appear, the test is invalid. Review the procedure and repeat with a new cassette.
QUALITY CONTROL
Each test includes a procedural control. A colored line in the control region ensures the proper volume of specimen and correct test procedures. It is recommended that positive and negative controls be used to confirm proper test performance.
LIMITATIONS
The Leptospira IgG/IgM Rapid Test is a qualitative test. The intensity of the test lines does not reflect the concentration of antibodies.
- The results should be used as an aid to diagnosis. Physicians should interpret them alongside the patient’s medical history and other diagnostic methods.
- A negative result indicates that antibodies are either absent or at undetectable levels.
PERFORMANCE CHARACTERISTICS
In clinical studies comparing the Leptospira IgG/IgM Rapid Test to commercially available tests, the following results were obtained:
- IgG sensitivity: 98.89%
- IgG specificity: 98.82%
- IgM sensitivity: 97.52%
- IgM specificity: 99.40%
- Overall accuracy: 99.03%
No cross-reactivity was observed with other infectious agents, such as HIV, HAV, HCV, HBsAg, or endogenous substances like hemoglobin and bilirubin.
BIBLIOGRAPHY
- Bharti AR, et al. Leptospirosis: a zoonotic disease of global importance. Lancet Infect Dis. 2003; 3(12): 757-71.
- Stimson AM. Note on an organism found in yellow-fever tissue. Public Health Reports 1907; 22: 541.
Above information are For professional in vitro diagnostic use only