SOP 5: Modified Knott’s Test

The method is used for the detection of microfilariae in the blood. The method is moremore sensitive than a direct smear with fresh blood as it concentratesconcentrates the microfilariae.


  • 2% formalin
  • 1% methylene blue


  1. Mix 1 ml blood with9 ml of 2% formalin in a conical centrifuge tube
  2. Invert the tube gently 4 times to mix the solution
  3. Centrifuge at 500 g500 g for 5 min
  4. Discard supernatant
  5. Stain sediment for 1-2 min with 1-2 drops of 1% methylene blue
  6. Add a drop of the sample on a glass slide and cover with a coverslip
  7. Examine the slide under a light microscope at low power (10x) for microfilariaee

Safety Precautions

  • Wear lab coat and disposable gloves

Clean up procedures

  • Dispose of all slides and cover slips in a sharps container