Epidemiological studies on onchocerciasis by means of a new field technique.

A new membrane filter concentration technique for the detection and quantification of Onchocerca volvulus microfilariae in skin snips was compared for sensitivity and efficiency with a widely used "standard" technique. A field study was carried out in five villages in an onchocerciasis focus north-east of the town of Sokodé, Mô river valley, Togo. Use of the new technique resulted in a substantial rise in the observed prevalence and density of microfilariae.