The collagenase technique: how to isolate and examine adult Onchocerca volvulus for the evaluation of drug effects
Schulz-Key, H.
Tropical Medicine and Parasitology Official Organ of Deutsche Tropenmedizinische Gesellschaft and of Deutsche Gesellschaft für Technische Zusammenarbeit 39(Suppl): 423-440
1988
ISSN/ISBN: 0177-2392 PMID: 2852394 Document Number: 305713
The collagenase technique developed more than 12 years ago has successfully been applied to isolate living and intact O. volvulus from excised onchocercomata for various biological, morphological, biochemical, immunological and in vitro studies. The experience gained with this technique and its modifications is critically reviewed giving practical active for the selection, preservation and treatment of nodules for different purposes, especially for the evaluation of antifilarial drug effects. The composition of the worm load, the morphology of adult worms found in untreated patients, signs of degeneration and aging of worms are described to show the broad morphological spectrum of the worm population in endemic areas to avoid false conclusions in drug trials. When these parameters are carefully considered, the collagenase technique provides a reliable method for examination of onchocercomata. An immediate answer can be obtained concerning the viability of the parasite. The qualitative and quantitative assessment of reproduction (embryogram) can give other valuable information on any changes in the reproductive dynamics and provide a sensitive indicator of any disturbances in adult worms which may explain the early or late reinvasion of microfilariae into the skin after treatment with microfilaricidal drugs.