A simple technique to assess the total number of Onchocerca volvulus microfilariae in skin snips

A technique for the assessment of the total number of microfilariae in skin snips from onchocerciasis patients is described. For the digestion of the skin tissue the biopsies are incubated at room temperature for 24 hours in medium 199, containing 3 mg/ml collagenase and antibiotics. This process leaves the microfilariae unharmed. A comparative study of the emergence of the microfilariae in different media showed that only 20% of the total number were released after 30 minutes in distilled water. After 24 hours incubation in isotonic saline 80% were found.