Laboratory evaluation of a new technique for counting microfilariae in blood.

The technique involves taking a measured volume of blood (20-40 mm3) from a finger or ear prick on to a conventional 3 X 1 in microscope slide and lysing it with water. Microfilariae could either be counted immediately, whilst still alive, or the smear dried, fixed and stained. A comparison between counts of microfilariae in freshly prepared slides and stained slides showed that few microfilariae were lost in the staining process.