Experimental infection of laboratory rodents and calves with microfilariae of Onchocerca gibsoni.

Uterine microfilariae of Onchocerca gibsoni migrated to skin of all parts of the body when inoculated into rats and mice. Higher microfilarial densities were obtained in the skin of mice compared with rats. In guinea pigs very few microfilariae migrated to the skin and densities of microfilariae were very low. Densities of skin microfilariae were lower in rats when inoculated intraperitoneally compared with inoculation by 2 subcutaneous routes. In the latter case, higher densities of microfilariae were obtained in areas of skin closer to the injection sites. Persistence of microfilariae in the skin of rats was variable but only low numbers were recovered between 21 and 70 days after infection. Microfilariae also migrated to the skin in calves experimentally infected by subcutaneous injection into the dewlap. Microfilaria were recovered consistently and in high numbers from skin snips along the ventral midline. Small numbers of microfilariae were occasionally found in skin snips from the dorsal midline.