Review of taeniasis in Asia.

Although Asian Taenia is closely related to T. saginata, it is a genetically distinct entity and can be distinguished from the classical T. saginata. Man is the only definite host of this parasite. The domestic pig and wild boar in Taiwan as well as domestic pig in Korea have been determined to be the natural intermediate hosts. Moreover, the pig has been demonstrated to be the most favorable experimental intermediate host. The cysticerci are situated mainly in the liver. They are smaller than T. saginata cysticerci and have a shorter developmental period of four weeks. The scolex of Asian Taenia cysticercus is often armed with two rows of hooklets. The adult worm of Asian Taenia is shorter and has less number of segments than the classical T. saginata. Recently, results of polymerase chain reaction studies indicate that the Asian Taenia is much more closely related to T. saginata than other taeniid species. Therefore, it is appropriate to designate Asian Taenia as a new subspecies of Taenia saginata asiatica. People in the Asian-Pacific region acquired the infection by eating raw or undercooked meat and/or viscera of pigs. Human experimental infections have succeeded in confirming the life cycle of Asian Taenia and the transmission pathway of the infection. In addition, multiple infection occurs very often and the infection has a family pattern. "Discharge of proglottids" is the most important clinical manifestation which is also useful in the diagnosis. Praziquantel is the drug of choice. The infection of Asian Taenia can be prevented by avoiding to eat raw or undercooked meat and viscera of pigs in the endemic regions.