Manual of basic techniques for a health laboratory - libdoc.who.int

4. Parasitology 189The above materials and reagents are available commercially as a test kit. The quantitiessupplied are sufficient to carry out 250 tests. Before carrying out the test,prepare your materials and reconstitute the amount of reagents required for theday’s work. Read and follow carefully the instructions provided in the kit.MethodCollection of samples1. Using a blood lancet, make a small puncture wound in the first, second or thirdfinger of the patient. Collect the blood into a heparinized microhaematocrit tube(Fig. 4.153) until it is three-quarters full.2. Immediately rotate the tube gently so that the blood runs from one end of thetube to the other (Fig. 4.154). Repeat the movement twice. This ensures that theblood and the heparin are mixed together, and prevents the sample from clottingin the tube.Fig. 4.153 Collecting a blood sample using amicrohaematocrit tubeFig. 4.154 Rotating the tube to mix the sample3. Place the microhaematocrit tube in the special holder (suppliedwith the kit; Fig. 4.155). Keep the holder covered asmuch as possible to avoid dust and to prevent the bloodsample from drying in the tube.Microhaematocrit tube holders have 10 numbered slits.Make sure that you place the first tube in the first slit, etc.Once the holder is full, pass it to the person performing thetest.Performing the test1. Prepare two test cards. Place one drop of the reconstitutedantigen in wells 1 and 2 of the first card and in all the wellsof the second card. Hold the vial vertically to have constantcalibrated drops (Fig. 4.156).2. Using the first card, check the quality of the reagent. Place one drop of thereconstituted positive control in well 1 and one drop of the reconstituted negativecontrol in well 2 (Fig. 4.157).Note: It is only necessary to do this once at the beginning of each day in a fieldsurvey.Fig. 4.155 A microhaematocrit tube holder