Combination of techniques for concentration and identification of microfilariae from peripheral blood.

Human blood containing a known number of Dirofilaria immitis or Brugia malayi microfilariae was incubated with Giemsa-stain or methylene blue solution and then subjected to density gradient centrifugation in Percoll-solution at a density of 1.090 g/ml. This resulted in complete separation of microfilariae from cellular components. Subsequently the microfilaria-containing layer was altered through a polycarbonate membrane. The stained parasites are then easily recognized and identified on the completely transparent membrane. The average recovery was 80%. This technique proved useful as a preparatory method and as a diagnostic tool for the detection of microfilariae in patients with low microfilaraemia.