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.

Neurocysticercosis: clinical manifestation, neuroimaging, serology and molecular confirmation of histopathologic specimens.

Diagnosis of neurocysticercosis (NCC) is usually based on neuroimaging and/or immunological analysis of cerebrospinal fluid (CSF) and/or serum samples for detection of specific antibodies against T. solium antigens. Additional confirmative diagnosis may be possible by morphological and molecular confirmation of resected histopathologic specimens. The majority of NCC cases do not always show typical neuroimaging figures with invaginated scolex. So, serology using highly specific antigens of T. solium, either semi-purified native or recombinant antigens, is essential for confirming NCC cases. There is some debate about the usefulness of CSF and serum for immunodiagnosis. When NCC cases with a solitary cyst or with calcified lesions are examined, serology is not always sensitive to differentiating such cases. Malignant brain tumor is most commonly suspected in Japan and is often treated surgically as an urgent task, if the clinicians have no experience of NCC cases. Only histopathological specimens are expected to show direct evidence of T. solium cysticercosis. Morphology is not always sufficient for identification of the Taenia species, even if the majority of cysticerci in the human brain are expected to be T. solium. Crucial confirmation is based on molecular identification. In this review, these four issues are briefly summarized.

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.

Molecular identification of Taenia solium cysticercus genotype in the histopathological specimens.

PCR-based molecular diagnosis was done for identification of causative agents found in paraffin-embedded specimens that were resected from two suspected neurocysticercosis patients. DNA samples were extracted from tissues or sections and cytochrome c oxidase subunit 1 gene and cytochrome b gene were amplified for the detection of taeniid DNA. Two different genes were successfully amplified in both specimens, but the sizes of amplified products seemed to depend on the quality of DNA. Based on the nucleotide sequences of the PCR-amplified genes, the causative agents from two cases were identified as T. solium Asian genotype. When infection with T. solium is not confirmed by histopathological examination, molecular diagnosis will be more useful for definitive diagnosis.

Cysticercosis: IgG-ELISA evaluations of peak1 antigen and <30 kDa antigen of delipidized extract of Taenia solium metacestodes.

The antigenicity of ether-delipidized Taenia solium metacestode extract (DLPAg) was investigated by IgG-ELISA. The antigen showed higher antigenicity than that of non-delipidized antigen (NDLPAg). Then the DLPAg was subjected to Sephacryl S-200 gel chromatography and a partially purified antigen (DLPP1Ag) was identified as the promised antigen by IgG-ELISA using 25 sera from cysticercosis cases, 177 cases of 24 heterologous infections, and healthy controls. Sensitivity was 52% and specificity was 91.8% at the cut-off value (X + 7SD), 0.399. Cross-reactivity occurred with 17 cases of eight diseases: cystic echinococcosis (7/11), taeniasis (1/16), gnathostomiasis (2/8), strongyloidiasis (1/12), angiostrongyliasis (1/12), paragonimiasis heterotremus (2/15), opisthorchiasis (1/9) and fascioliasis (2/7). When DLPP1Ag was fractionated through Ultra free centrifugal tube (retained 30 kDa) and Amicon (PM10), MWCOP1Ag (<30-10> kDa) was obtained; the antigen showed better results than DLPP1Ag with 88% sensitivity and 95.6% specificity at the cut-off value (X + 4SD), 0.264. Nine cases of six diseases cross-reacted with this antigen: cystic echinococcosis (2/11), gnathostomiasis (2/8), trichinellosis (2/12), toxocariasis (1/5), schistosomiasis (1/6), and fascioliasis (1/7). MWCOP1Ag gave higher sensitivity than that of DLPP1Ag but some cross-reactivity occurred.

Echinococcosis and cysticercosis in Asia: evaluation of the modern technology for epidemiological study.

The recent emergence of zoonotic parasitic diseases of public health importance represents a growing global concern. Among zoonotic helminthic diseases, both echinococcosis and cysticercosis are the most serious diseases threatening human life. Neurocysticercosis (NCC) caused by ingestion of eggs of the pork tapeworm, Taenia solium, is spreading worldwide and not rare even in Muslim or Jewish communities. Alveolar echinococcosis (AE) caused by the proliferation of metacestodes of the fox tapeworm, Echinococcus multilocularis, is the most potentially lethal parasitic infection of the non-tropical northern hemisphere, whereas cystic echinococcosis (CE) caused by the proliferation of metacestodes of the dog tapeworm, E. granulosus, has rather a cosmopolitan distribution. As the life cycles of T. solium, E. multilocularis and E. granulosus are completed through predator-prey interactions, including humans, it is crucial to interrupt the cycle for control of these zoonotic cestodiases. Both NCC and CE are expected to be eradicable, since the principal life cycles of T. solium and E. granulosus are maintained between humans and pigs and between dogs and herbivorous domestic animals, respectively. In contrast, AE is perhaps not eradicable, since the life cycle of E. multilocularis is maintained between wild foxes and rodents. Modern technologies, including imaging, immunology and molecular biology, have been applied for epidemiological surveys. In the present review, we introduce such technologies applied in Japan, China and Indonesia, and point out the problems that need to be solved for control of these three zoonotic cestodiases.