Controlled studies on the effect of nodulectomy on the concentration of microfilariae in the skin of patients exposed o continuing transmission of Onchocerca volvulus in the rain-forest zone of Western Nigeria.

Two sets of controlled experiments were conducted, using 13 adult onchocerciasis patients from a village in the hyperendemic rain-forest zone of Western Nigeria, to determine the effect of the excision of one or two onchocercal nodules on the concentration of microfilariae in the skin. The results show that, in patients with established infections who are exposed to continuing reinfection, nodulectomy per se does not reduce the microfilarial density, overall or in the same anatomical region from which the nodule is excised, to any significant degree. It is therefore concluded that the indirect assessment of the activity of test drugs against the adult Onchocerca volvulus by serial estimation of microfilarial concentrations over a period of about 24 months is unlikely to be compromised by limited selective nodulectomy.