Malaria is caused by a protozoan which invades human red blood cells.1Malaria is one of the world’s most prevalent diseases. According to the WHO, the worldwide prevalence of the disease is estimated to be 300-500 million cases and over 1 million deaths each year. Most of the victims are infants, young children. Over half of the world’s population lives in malarious areas. Microscopic analysis of appropriately stained thick and thin blood smears has been the standard diagnostic technique for identifying malaria infections for more than a century.2The technique is capable of accurate and reliable diagnosis when performed by skilled microscopists using defined protocols. The skill of the microscopist and use of proven and defined procedures, frequently present the greatest obstacles to fully achieving the potential accuracy of microscopic diagnosis. Although there is a logistical burden associated with performing a time-intensive, labor-intensive, and equipment-intensive procedure such as diagnostic microscopy, it is the training required to establish and sustain competent performance of microscopy that poses the greatest difficulty in employing this diagnostic technology.
The Malaria P.f./P.v. Rapid Test Device (Whole Blood) is a rapid test to qualitatively detect the presence of the P. falciparum- specific HRP-II antigens and/or Pan-malarial Lactate Dehydrogenase antigens found in P. falciparum (P.f), and P. vivax (P.v.). The test utilizes colloid gold conjugate to selectively detect P.f-specific and P. vivax (P.v.)-specific antigensin whole blood.
The Malaria P.f./P.v. Rapid Test Device (Whole Blood) is a qualitative, membrane based immunoassay for the detection of P.f and P.vantigens in whole blood. The membrane is precoated with anti-HRP-II antibodies and anti-pLDH antibodies. During testing, the whole blood specimen reacts with the dye conjugate, which has been pre-coated on the test strip. The mixture then migrates upward on the membrane by capillary action, reacts with anti-Histidine-Rich Protein II (HRP-II) antibodies on the membrane on P.f Test Line region and with anti-pLDH antibodies on the membrane on P.v. Line region. If the specimen contains HRP-II or Plasmodium-specific P.vivaLDH or both, a colored line will appear in P.f line region or P.v. line region or two colored lines will appear in P.f line region and P.v. line region. The absence of the colored lines in P.f line region or P.v. line region indicates that the specimen does not contain HRP II and/or Plasmodium-specific P.vivaLDH. To serve as a procedure control, a colored line will always appear in the control line region indicating that proper volume of specimen has been added and membrane wicking has occurred.
The test device contains anti-HRP-II of Plasmodium falciparum antibodies conjugated gold and anti-Plasmodium falcioarum P.vivax LDH antibodies conjugated gold an anti-HRP-II antibodies and anti-pLDH antibodies coated on the membrane.
• Test devices • Disposable specimen droppers
• Buffer • Package insert
Materials Required But Not Supplied
• Pipette and disposable tips(optional) • Specimen collection containers
• Lances(for fingerstick whole blood only) • Timer
Specimen Collection And Preparation
• The Malaria P.f./ P.v. Rapid Test Device (Whole Blood) can be performed using whole blood.
• Both Fingerstick Whole Blood and Venipuncture Whole Blood can be used.
• To collect Fingerstick Whole Blood specimens:
• Wash the patient’s hand with soap and warm water or clean with an alcohol swab. Allow to dry.
• Massage the hand without touching the puncture site by rubbing down the hand towards the fingertip of the middle or ring finger.
• Puncture the skin with a sterile lancet. Wipe away the first sign of blood.
• Gently rub the hand from wrist to palm to finger to form a rounded drop of blood over the puncture site.
• Testing should be performed immediately after specimen collection. Do not leave the specimens at room temperature for prolonged periods. Whole blood collected by venipuncture should be stored at 2-8°C if the test is to be run within 2 days of collection. For long term storage, specimens should be kept below -20°C. Whole blood collected by fingerstick should be tested immediately.
• Bring specimens to room temperature prior to testing. Frozen specimens must be completely thawed and mixed well prior to testing. Specimens should not be frozen and thawed repeatedly for more than three times.
• If specimens are to be shipped, they should be packed in compliance with federal regulations covering the transportation of etiologic agents.
Reconstitution And Storage
The kit can be stored at room temperature or refrigerated (2-30°C). The test device is stable through the expiration date printed on the sealed pouch. The test device must remain in the sealed pouch until use. ##DO NOT FREEZE.## Do not use beyond the expiration date.
##Allow the test device, specimen, buffer, and/or controls to equilibrate to room temperature (15-30°C) prior to testing. ##
1. Remove the test device from the foil pouch and use it as soon as possible. Best results will be obtained if the assay is performed within one hour.
2. Place the test device on a clean and level surface. Transfer the specimen by a pipette or a dropper:
• To use a ##Pipette:## Transfer 5 μL of whole blood to specimen well of the test device, and then add 3 drops of buffer (approximately 180ul), and start the timer.
• To use a ##Disposable Specimen Dropper:## Hold the dropper vertically; draw the specimen up to the Fill Line (approximately 5ul). Transfer the specimen to the specimen well, then add 3 drops of buffer (approximately 180ul) and start the timer.
• Wait for the colored line(s) to appear. The result should ## be read at 10 minutes.## Do not interpret the result after ##20 minutes.##
Interpretation of Results
##POSITIVE:## *Two or Three distinct colored lines appear.##
##P. falciparumor mixed malaria infection：## one line appears in the control region, one line appears in P.v. line region and one line appears in P.f line region.
##P. falciparuminfection:## one line appears in the control region, and one line appears in P.f line region.
##Non-falciparum Plasmodium speciesinfection：## one line appears in the control region and one line appears in Pan line region.
##*NOTE:## The color intensity of P.f or P.v. test lines may vary depending on the
concentration of antigens,viz., HRP-II or P.vivaxLDH present in the specimen.
##NEGATIVE: Only one colored line appears in the control region.##
##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 device. If the problem persists, discontinue using the test kit immediately and contact your local distributor.
Internal procedural controls are included in the test. A colored line appearing in the control region (C) is an internal procedural control. It confirms sufficient specimen volume and correct procedural technique. Control standards are not supplied with this kit; however, it is recommended that positive and negative controls be tested as a good laboratory practice to confirm the test procedure and to verify proper test performance.
The Malaria P.f./ P.v. Rapid Test Device (Whole Blood) has been compared with traditional thick or thin blood films microscopic analysis. The correlation between the two systems is 99.0%.
The Malaria P.f./ P.v. Rapid Test Device (Whole Blood) has been tested with microscopy on clinical samples. The results show that the sensitivity of the Malaria P.f./ P.v. Rapid Test Device (Whole Blood) is >98% when compared to results obtained with microscopy.
The Malaria P.f./ P.v. Rapid Test Device (Whole Blood) uses antibodies that are highly specific to Malaria P.f.-specific and P.vivaxLDH antigens in whole blood. The results show that the specificity of the Malaria P.f./ P.v. Rapid Test Device (Whole Blood) is over 99.9%, when compared to results obtained with microscopy.
Comment: Blood Samples infected by Plasmodium falciparum (n=80).Plasmodium vivax (n=50) were included, as well as 451 malaria negative samples to be confirmed with microscopy.
Relative Sensitivity for P.f.-specific antigens:80/80> 99.9% (96.4%～100.0%)*
Relative Sensitivity for P.v. antigens:49/50=98.0% (89.6%～100.0%)*
Relative Specificity:451/451>99.9% (99.3%～100.0%)*
Accuracy:(49+80+451)/(50+80+451)=580/581=99.8% (99.0%～100.0%)* * 95% Confidence Interval.
## Minimum Detection Level##
The run precision has been determined by using 15 replicates of four specimens: a negative, a P.f. positive, a P.v. positive and an P.f./P.v. dual positive. The specimens were correctly identified >99% of the time.
Between run precision has been determined by 15 independent assays on the same four specimens: a negative, a P.f. positive, a P.v. positive and an P.f./P.v. dual positive. Three different lots of the Malaria P.f./P.v. Rapid Test Device (Whole Blood) have been tested using these specimens. The specimens were correctly identified >99% of the time.