Early Development of Larval \u3ci\u3eTaenia polyacantha\u3c/i\u3e in Experimental Intermediate Hosts

The early larval development and migration route of Taenia polyacantha were examined using oral inoculation of oncospheres into red-backed voles and Mongolian gerbils. The larvae were recovered in the wall of the small intestine and in the mesenteric lymph nodes by 5 days postinfection (PI) and from the peritoneal cavity after 6 days PI. These results suggest that the larval cestodes developed initially in the wall of the small intestine and the mesenteric lymph nodes, and later migrated to the peritoneal cavity. Although the development of the parasite was quite similar in the 2 host species, pathological changes were different. In Mongolian gerbils, these changes were slight, but in red-backed voles, they were marked and fatal. In addition to oral inoculation, hatched oncospheres were injected intraperitoneally and subcutaneously into red-backed voles, Mongolian gerbils, and AKRlJ mice. Larval development took place at the injection sites in gerbils and mice, but was delayed and abnormal. Some of the parasites in the injection site showed abnormal numerous budding. High pathogenicity was shown after subcutaneous and intraperitoneal injection as well as after oral inoculation