Onchocerca volvulus: transplantation of adult worms into chimpanzees.

Adult Onchocerca volvulus were transplanted into chimpanzees with or without complete or partial digestion of associated nodule tissue. Survival of adults worms was limited, but low level microfilarial densities remained detectable in skin over partially digested nodule transplants for 12 months. Human nodule tissue transplanted with adult worms showed enhanced survival as compared to subcutaneous tissue transplanted without worms. It is postulated that this reflects the action of an immunosuppressive factor utilized by the parasite to permit its own survival.