Rapid self-test for the detection of antibodies against Treponema pallidum in blood
Intended Purpose
SYPH-CHECK-1® is a manual qualitative immunochromatographic screening test for the detection of antibodies against Treponema pallidum from a finger prick whole blood sample. It can be used at home by lay users for self-testing for the detection of possible Syphilis infection.
General Points
Syphilis is a veneral disease that progresses through distinct stages of infection: primary, secondary, latent and tertiary.
These stages produce diverse clinical symptoms, typically producing initial sores known as chancres then syphilitic rash followed by long periods of dormancy. Untreated infection eventually leads to cardiovascular problems and neurosyphilis.
Caused by spirochaete Treponema pallidum (TP), the infection is usually acquired by sexual contact, although the disease may be transmitted by transfusion of infected blood. Intrauterine infection also occurs. The organism has proved virtually impossible to culture in artificial media, and diagnosis of the infection usually depends on the detection of antibodies in the blood, which appear soon after initial infection.
Test Procedure
Prepare everything properly before starting the testing procedure. Place the content of the box on a clean, dry and flat surface (e.g. table). Then perform the test as follows:
- Wash your hands thoroughly. Use soap and warm water. Dry your hand with clean towel.
- Prepare the test device and capillary pipette: Take them out from the protective pouch (tear at the notch) and place them in the reach of your hands (you will need them later). Discard the desiccant bag.
- Prepare the lancet. Hold the lancet without touching the trigger button. Unlock the cap twisting it off ¼ turn until you feel it separates from the lancet and then continue twisting it (2-3 rotations). Don’t pull just twist and discard the cap when finished. ①②
- Clean the end of the middle or ring finger with cotton damped with alcohol. Massage the chosen finger towards the tip for 10 to 15 seconds to enhance the blood flow.
- Prick the finger: put the lancet firmly against the side of the previously cleaned finger, and press the release trigger button.③ The lancet will automatically retract into the body of the device. Gently massage the finger to create a nice round blood droplet.④
- Collect the blood with the capillary pipette: Gently touch the blood droplet with the open end of the capillary pipette. It must be filled until the line indicated on the capillary pipette. Do not press the bulb, it fills by itself. Make another blood droplet if the line is not reached. As far as possible, avoid air bubbles. ⑤
- Put the blood collected with the pipette into the sample well of the device, by pressing on the pipette bulb. ⑥
- Wait 30-40 sec for the blood being totally absorbed into the sample well.
- Add the diluent: Unscrew the blue cap of the diluent dropper vial (leave the white cap tightly screwed) and add the diluent as follows: Hold the diluent dropper vial vertically and slowly add exactly 4 drops in the sample well of the device with an interval of 2-3 seconds between each drop. ⑦
- Read the result after 10 minutes. Do not interpret after 15 minutes.
Results Interpretation
The intensity and the colour of the lines do not have any importance for the interpretation of the test results.
Analyze
Result
Summary
Positive result
Negative result
Invalid result
Questions and Answers
How does SYPH-CHECK-1® work?
When present in the body, TP induce the production of specific antibodies by the immune system. These circulating antibodies are able to recognize the spirochaete and to stick on them. The TP antigens coated on the SYPH-CHECK-1* strip specifically detect those antibodies by producing a coloured line under the T mark of the cassette when the level of anti-TP antibodies is greater than 0.1 IU/mL (determined against W.H.O.* reference) indicating the presence of TP spirochaete. A control line capturing the reagent excess appears as a coloured line under the C mark of the cassette.
*World Health Organization
When should the test be performed?
SYPH-CHECK-1® test should be performed in case of appearance of clinical symptoms, the main ones being chancres and specific rash. The test can be performed at any time of the day.
Can the result be incorrect?
The results are accurate as long as the instructions are carefully respected. Nevertheless, the result can be incorrect if SYPH-CHECK-1® test gets wet before test performing or if the quantity of blood added to the sample well is not correct. The pipette provided in the box allows making sure the collected blood volume is correct. Very early stage of the infection could also lead to negative results due to the low concentration of anti TP antibodies in blood.
How to interpret the test if the colour and the intensity of the lines are different?
The colour and intensity of the lines have no importance for result interpretation. The lines should only be homogeneous and complete. The test should be considered as positive regardless the colour intensity of the test lines (T), even weak.
What is the line that appears under the mark C (Control) for?
When this line appears, it only means that the test has been performed well.
If I read the result after 15 minutes, will the result be reliable?
No. The test should be read 10 minutes after adding the diluent. The result is reliable up to 15 minutes.
What do I have to do if the result is positive?
If the result is positive, it means that anti-TP antibodies are present in blood and that you should consult a doctor to show him the test results. Then, the doctor will decide whether additional investigation should be performed.
What do I have to do if the result is negative?
If the result is negative, it means that the test could not detect anti-TP antibodies in blood sample. Meanwhile it is recommended to consult a doctor if symptoms persist.
What is the accuracy of SYPH-CHECK-1®?
The SYPH-CHECK-1® test is accurate and has been used for more than 15 years by professionals in the field. Evaluation reports show an overall agreement of 97% [96.1 – 98.3 %**] with reference methods. Although this test is reliable, false positive or false negative results could be obtained. This is especially true for elderly or drug addicts’ patients or patients with cirrhosis, mononucleosis, autoimmune disease, herpes simplex virus (HSV) infection and cytomegalo-viruses (CMV) and heterophilic antibodies which may show false positive results when using the SYPH-CHECK-1® test.
** CI 95% : 95% Confidence Interval.