Comparison of the blood film, Millipore filter and Nuclepore filter techniques for the detection of microfilaremia in a field survey in the Philippines.

The blood film, Millipore filter and Nuclepore filter techniques were applied in a filariasis field survey at a village in the Philippines. venous blood from each person was examined by the three techniques to compare their efficacy of microfilariae detection. Overall positive rate was 16.1% by the combined techniques. Microfilaria positive rate was highest in Nuclepore filter method (15.6%) followed by Millipore technique (13.6%) and blood film (11.5%), but their difference was not significant statistically. The ratio of the total microfilaria counts by the three techniques was 1:29.8:30.3, which seems to reflect the ratio of the blood volumes used. There was no significant difference between the microfilaria counts by the three techniques adjusted to the same volume of 30 microliter and examined by F-test. It is considered that the blood film is still of practical value in field surveys.