Towards the international collaboration for detection, surveillance and control of taeniasis/ cysticercosis and echinococcosis in Asia and the Pacific.

Both cysticercosis and echinococcosis are potentially among the most serious helminth zoonoses threatening human health worldwide. However, due to the lack of reliable tools for confirmation or identification of patients or infected animals, epidemiological data are expected to be underestimated. Conversely, sometimes, such data are over estimated due to the lack of specificity. The most important issue for doing field surveys is that they use evidence based science. In this communication, advanced immunological and molecular tools for detection of individuals infected with either metacestodes or adult tapeworms are briefly overviewed, and the applications of such tools for epidemiological surveys in Indonesia, China and other countries are introduced. As immunological tools are based on antigen-antibody responses, there may exist some cross-reactions. Therefore, immunodiagnostic tools are expected to be useful for primary screening, and should be combined with confirmation of direct parasitological evidence (morphology or DNA), and imaging techniques for cysts. As a risk factor for human cysticercosis is the presence of tapeworm carriers, detection of taeniasis cases and differentiation of the three human Taenia species (Taenia solium, T. saginata and T. asiatica) in Asia and the Pacific requires consideration. Similarly, in northwest China, Echinococcus granulosus and E. multilocularis are coendemic and differentiation of these species is required in humans and definitive hosts. It is stressed that combination of several tools for identification of the parasite and for confirmation of diseases is important for obtaining highly reliable data before consideration of control of these zoonoses. Recent projects coordinated by Asahikawa Medical College have concentrated on immunological and molecular diagnostic techniques transferable to colleagues from endemic regions of Asia and the Pacific, and on organization of two international symposia to establish a platform for further collaboration in the future.

Taeniasis and cysticercosis in Asia and the Pacific: present state of knowledge and perspectives.

Several topics on taeniasis and cysticercosis in Asia and the Pacific are overviewed. In Asia and the Pacific, three human taeniid species have been recognized: Taenia solium, Taenia saginata and Taenia asiatica. The first topic is on evolution of T. solium. Mitochondrial DNA polymorphisms of T. solium worldwide are discussed with emphasis of two specific genotypes: American-African and Asian. The second topic is recent major advances in sero- and molecular-diagnosis of T. solium cysticercosis in humans, pigs and dogs. The third is the present situation of T. solium taeniasis/cysticercosis in Papua (Irian Jaya), Indonesia. The forth is the present situation of T. solium cysticercosis and T. saginata taeniasis in Bali, Indonesia. The fifth is the present situation of T. asiatica taeniasis in Asia and the Pacific and in North Sumatra, Indonesia. The sixth is on the debate of the exact definition of T. asiatica. Because T. asiatica can not be differentiated from T. saginata morphologically, it is time to re-evaluate T. saginata in Asia and the Pacific. New and broad-based surveys across this region are necessary from epidemiological and public health perspectives, based on evidence.

Fundamental study of expression-library immunization against Taenia taeniaeformis in rats.

Expression-library immunization has been proposed as an effective means to screen a large number of genes of the pathogen as candidate protective molecules. In this study, we examined the efficacy of expression-library immunization using a T. taeniaeformis rat model system. Total RNAs were isolated from the last 15 segments of adult T. taeniaeformis and poly A RNA was purified. cDNA library was produced using SuperScript Plasmid System, which contains a mammalian expression vector, pCMV*SPORT6. From about 3,500 clones examined, more than 800 clones were found to contain DNA fragments. About 200 clones were sequenced and the homology search was carried out. The blast search revealed that 29% of the expression genes were mitochondrial genes (rRNA; 17%, protein; 12%). Nuclear rRNA genes (10%), nuclear protein (9%) and genes from Escherichia coli were also detected. Forty-two percent of sequences did not show a significant similarity to any genes deposited in the public database. Rats were immunized with expression-library and injected orally with 1,000 T. taeniaeformis eggs. However the protective effect of expression-library vaccine was not confirmed.