Filariasis IgG/IgM Infectious Disease Testing Blood Specimen Cassette With Buffer

Filariasis IgG/IgM Infectious Disease Blood Tests, 4mm cassette, with buffer

Intended Use:

The Filariasis IgG/IgM Rapid Test is a lateral flow immunoassay for the simultaneous detection and differentiation of IgG and IgM anti-lymphatic filarial parasites (W. Bancrofti and B. Malayi) in human serum, plasma or whole blood. This test is intended to be used as a screening test and as an aid in the diagnosis of infection with lymphatic filarial parasites. Any reactive specimen with the Filariasis IgG/IgM Rapid Test must be confirmed with alternative testing method(s).

Summary:

The lymphatic filariasis known as Elephantiasis, mainly caused by W. bancrofti and B. malayi, affects about 120 million people over 80 countries1,2. The disease is transmitted to humans by the bites of infected mosquitoes within which the microflariae sucked from an infected human subject develops into third-stage larvae. Generally, repeated and prolonged exposure to infected larvae is required for establishment of human infection.

The definitive parasitologic diagnosis is the demonstration of microflariae in blood samples3. However, this gold standard test is restricted by the requirement for nocturnal blood collection and lack of adequate sensitivity. Detection of circulating antigens is commercially available. Its usefulness is limited for W. bancrofti4. In addition, microfilaremia and antigenemia develop from months to years after exposure.

Antibody detection provides an early means to detect filarial parasite infection. Presence of IgM to the parasite antigens suggest current infection, whereas, IgG corresponds to late stage of infection or past infection5. Furthermore, identification of conserved antigens allows ‘pan-filaria’ test to be applicable. Utilization of recombinant proteins eliminates cross-reaction with individuals having other parasitic diseases6. The Filariasis IgG/IgM Rapid Test uses conserved recombinant antigens to simultaneously detect IgG and IgM to the W. bancrofti and B. malayi parasites without the restriction on specimen collection.

Test Principle:

The Filariasis IgG/IgM Rapid Test is a lateral flow chromatographic immunoassay. The test cassette consists of: 1) a burgundy colored conjugate pad containing recombinant W. bancrofti and B. malayi common antigens conjugated with colloid gold (Filariasis conjugates) and rabbit IgG-gold conjugates, 2) a nitrocellulose membrane strip containing two test bands (T1 and T2 bands) and a control band (C band). The T1 band is pre-coated with monoclonal anti-human IgM for the detection of IgM anti- W. bancrofti and B. malayi, T2 band is pre-coated with reagents for the detection of IgG anti-W. bancrofti and B. malayi, and the C band is pre-coated with goat anti rabbit IgG.

When an adequate volume of test specimen is dispensed into the sample well of the cassette, the specimen migrates by capillary action across the cassette. W. bancrofti or B. malayi IgM antibodies if present in the specimen will bind to the Filariasis conjugates. The immunocomplex is then captured on the membrane by the pre-coated anti-human IgM antibody, forming a burgundy colored T2 band, indicating a W. bancrofti or B. malayi IgM positive test result.

W. bancrofti or B. malayi IgG antibodies if present in the specimen will bind to the Filariasis conjugates. The immunocomplex is then captured by the pre-coated reagents on the membrane, forming a burgundy colored T1 band, indicating a W. bancrofti or B. malayi IgG positive test result.

Absence of any test bands (T1 and T2) suggests a negative result. The test contains an internal control (C band) which should exhibit a burgundy colored band of the immunocomplex of goat anti rabbit IgG/rabbit IgG-gold conjugate regardless of the color development on any of the test bands. Otherwise, the test result is invalid and the specimen must be retested with another device.

ASSAY PROCEDURE

Step 1: Bring the specimen and test components to room temperature if refrigerated or frozen. Mix the specimen well prior to assay once thawed.

Step 2: When ready to test, open the pouch at the notch and remove device. Place the test device on a clean, flat surface.

Step 3: Be sure to label the device with specimen’s ID number.

Step 4: For whole blood test

Apply 1 drop of whole blood into the sample well.

Then add 2 drops of Sample Diluent immediately.

For serum or plasma test

Fill the pipette dropper with the specimen.

Holding the dropper vertically, dispense 1 drop of specimen into

the sample well making sure that there are no air bubbles.

Then add 2 drops of Sample Diluent immediately.

Step 5: Set up timer.

Step 6: Results can be read in 15 minutes. Positive results can be visible in as short as 1 minute.

INTERPRETATION OF RESULTS

POSITIVE:* Two lines appear. One colored line should be in the control line region (C) and another apparent colored line should be in the test line region (T).

NEGATIVE: One colored line appears in the control line region (C). No line appears in the test line region (T).

INVALID: Control line fails to appear. Insufficient specimen volume or incorrect procedural techniques are the most likely reasons for control line failure. Review the procedure and repeat the test with a new test. If the problem persists, discontinue using the test kit immediately and contact your local distributor.

PERFORMANCE

1.Clinical Performance For IgM Test

24 samples from patients with acute lymphatic filariasis and 200 samples collected from a

non-filariasis region were tested by the Filariasis IgG/IgM Rapid Test.Comparison for all subjects is showed in the following table:

Relative Sensitivity: 95.8%; Relative Specificity: 100%; Overall agreement: 99.6%

2. Clinical Performance For IgG Test

26 samples from patients with chronic lymphatic filariasis and 200 samples collected from a non-filariasis region were tested by the Filariasis IgG/IgM Rapid Test. Comparison for all subjects is showed in the following table:

Relative Sensitivity: 92.3%; Relative Specificity: 100%; Overall agreement: 99.1%