phenylephrine-hydrochloride and Onchocerciasis

Various factors governing resistance to the microfilariae (mf) of Onchocerca lienalis in mice have been examined to provide baseline data for use of this model in immunological studies. The survival of mf during a primary infection followed a similar course in the skin from most anatomical regions of the body. Mice were highly resistant to secondary infections, manifested by parasite densities over the body that were reduced by 83-100% compared with controls. Recoveries of mf from the ears, used in later experiments, were a representative measure of parasite survival in other skin sites. The resistance to challenge induced by a primary infection was not dependent on the route of administration (intravenous, intraperitoneal, subcutaneous and intramuscular) of the latter and was apparently systemic. Primary infections of various durations that were chemically-abbreviated conferred maximum protection when of 15 days or longer (95-97%) and substantial resistance when of only 7 days (84%). Similar levels of protection were demonstrated in mice that were sensitized with single or multiply-divided mf doses, or challenged in a similar manner. Primary infections containing as few as 20 mf induced almost the same degree of protection (80%) as 50 to 10,000 mf (88-97%). Apparently, resistance to re-exposure with O. lienalis mf is mediated by a highly effective mechanism(s) in CBA mice.

Topics: Animals; Ear; Female; Immunity, Active; Mice; Mice, Inbred CBA; Nose; Onchocerca; Onchocerciasis; Skin

In southern Germany many of the red deer are infected with 4 filariid species. The microfilariae of 3 subcutaneous and one intradermal filariae are described. Skin snips were taken according to a regular pattern from the hides of several killed deer. The emerging microfilariae were identified and counted, and the characteristic distribution of each species in the skin was plotted. The adult worms of O. tarsicola are located on the abductor tendons of the tibiotarsal or radiocarpal joints. Some microfilariae are found in the tissues near the adults, but they concentrate at a considerable distance away, in the skin which covers the outer parts of the ears and the nose. The adult worms of O. tubingensis are found in subcutaneous nodules on the caudal part of the back. The microfilariae are distributed on the ventral part of the body with maximum densities in the region of the sternum and with lower densities on the inner sides of the hindlegs. O. flexuosa is also found in nodules on the back and flanks of the deer, while the microfilariae are distributed on the posterior part of the body with maximum densities on the inner sides of the hindlegs. C. wenki lives intradermally on the dorsal part of the trunk. The microfilariae are found in the skin near the adults. The infection rates of 94 red deer investigated during 1907-1974 were high: O. tarsicola 82%, O. tubingensis 23%, O. flexuosa 96%, C. wenki 85%. The prepatent period of all species is no longer than 6 months.

Topics: Age Factors; Animals; Back; Carpus, Animal; Deer; Ear; Female; Filariasis; Filarioidea; Germany, West; Hindlimb; Male; Nose; Onchocerca; Onchocerciasis; Skin; Sternum; Time Factors