 This allows for the microfilariae that would have been in the tissue to migrate to the liquid phase of the specimen.Additionally, to differentiate the skin-dwelling filariae "M. streptocerca" and "Onchocerca volvulus", a nested polymerase chain reaction (PCR) assay was developed using small amounts of parasite material present in skin biopsies.Prevention can be partially achieved through limiting contact with vectors through the use of DEET and other repellents, but due to the predominantly relatively mild symptoms and the infection being generally asymptomatic, little has formally been done to control the disease.