An Evaluation of the Skin Scarification Technic for the Recovery of Microfilariae of Onchocerca volvulus

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  • Liberian Institute of the American Foundation for Tropical Medicine, Inc., Harbel, Liberia
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Skin-scarification smears were made from adult subjects infected with Onchocerca volvulus to compare the distributions of microfilariae in the skin at various anatomical regions and the variations in numbers occurring in multiple smears taken simultaneously, as well as on different days, from the same anatomical region.

The lower extremities and the hips showed the highest microfilarial-recovery rates and, for diagnostic purposes in Liberia, it is recommended that a minimum of four smears be made, one from each hip and calf.

Wide variations were seen in numbers of microfilariae recovered in smears taken simultaneously and on successive days from the same anatomical region. These variations are considered to be due mainly to limitations of the technic, which should not be used for quantitative studies. The skin-scarification technic, however, can provide a rough measure of microfilarial distribution and numbers in infected subjects.