Y Sako

Shenyang Pharmaceutical University, Shenyang, Liaoning, China

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Publications (18)25.1 Total impact

  • Article: Short report: evidence and potential for transmission of human and swine textitTaenia solium cysticercosis in the Piracuruca region, Piaui, Brazil.
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    ABSTRACT: The study conducted in the Cocal dos Alves municipality, located in the Piracuruca region of Piaui State, Brazil in November of 2003 was based on both a socio-behavioral survey and analysis of serum antibodies and parasitic materials. Pig raising is the main economic activity with 91.4% using extensive farming. On the studied population, 54.3% of people did not apply any sanitary measures to wastewater, 45.7% used septic tanks, and 69.1% consumed water without treatment. The data collected indicated the occurrence and active transmission of the taeniasis-cysticercosis complex in the region. One of seven voluntary persons was positive in antibody-ELISA tests using both native and recombinant antigens. Multiplex PCR and DNA sequencing of cyst samples obtained from a pig revealed the presence of the Afro-American genotype of Taenia solium. This study revealed the occurrence of human and porcine cysticercosis in the Piracuruca region of Piaui State, middle-north of Brazil.
    Am. J. Trop. Med. Hyg. 01/2006; 75(5):933-935.
  • Article: Evaluation of clinical and serological data from Taenia solium cysticercosis patients in eastern Inner Mongolia Autonomous Region, China.
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    ABSTRACT: Neurocysticercosis (NCC) is one of the major causes of neurological disease in China. ELISA and immunoblotting using glycoproteins purified by preparative isoelectric focusing were used to detect human cysticercosis in Tongliao area, Inner Mongolia, China in 1998. Approximately 89% (39 of 44 inpatients and outpatients with suspected NCC at Tongliao City Hospital) were residents of Inner Mongolia. About 53% were male and 77% were of working age (18-59 years), and 32% were farmers. Immunoblotting and ELISA showed a high correlation. Of the 44 patients, 31 positive by cerebral computed tomography (CT) scan were confirmed serologically to have cysticercosis. In the ELISA, patients with no lesions by CT scan had lower OD values, similar to those of normal serum. These findings confirm that both ELISA and immunoblotting assays are sufficiently sensitive to detect asymptomatic or symptomatic cysticercosis patients.
    Transactions of the Royal Society of Tropical Medicine and Hygiene 09/2005; 99(8):625-30. · 2.16 Impact Factor
  • Article: Evaluation of tongue inspection and serology for diagnosis of Taenia solium cysticercosis in swine: usefulness of ELISA using purified glycoproteins and recombinant antigen.
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    ABSTRACT: Evaluation of serology using glycoproteins (GPs) purified by preparative isoelectric focusing (pH 8.8) and recombinant chimeric antigen (RecTs) of Taenia solium was carried out using (1) blood samples on filter papers from pigs infected with different doses of eggs of T. solium in Mexico, (2) serum samples from pigs found infected naturally in Vietnam and Ecuador and (3) serum samples from pigs suspected to be infected with T. solium by tongue inspection in Tanzania. Antibody responses (IgG) were detectable in experimentally infected pigs confirmed harbouring 16 or more cysts at necropsy from 30 days after egg inoculation. One of three pigs naturally infected and harbouring 2.5 cysts/kg muscle and most of pigs harbouring=5.0 cysts/kg were also seropositive by ELISA. Although pigs may be infected with other taeniid species such as Taenia hydatigena, pigs harbouring this parasite were negative in ELISA. Approximately, 76 and 78% of sera from pigs having nodule(s) in the tongue (positive tongue inspection) were serologically positive by both ELISA and immunoblot, respectively. Furthermore, approximately 34 and 18% of sera from pigs having no nodules in the tongue (negative tongue inspection) were also seropositive by ELISA and immunoblot, respectively. ELISA using the two antigens was more sensitive than immunoblot and reliable for differentiation of pigs infected with cysticerci of T. solium from those either uninfected or infected with other taeniid species. Pigs without nodule by tongue inspection should be checked serologically in endemic areas.
    Veterinary Parasitology 03/2003; 111(4):309-22. · 2.58 Impact Factor
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    Article: Cysticercosis/taeniasis: recent advances in serological and molecular diagnoses.
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    ABSTRACT: Serodiagnosis by immunoblot, using recombinant chimeric T. solium antigen and native glycoprotein antigens, has been applied for neurocysticercosis cases. Specific antibodies against both antigens were detected in serum samples from NCC patients involving multiple cysts in the brain, whereas it was not always easy to detect specific antibodies in NCC cases with a solitary cyst or calcified lesion(s). On the other hand, the diagnosis for human taeniasis or worm carriers has been routinely performed by stool examination. In this study, multiplex PCR has been established to differentiate taeniasis using Taenia mitochondrial DNA in fecal samples from worm carriers. Furthermore, the molecular identification of human taeniid cestodes by base excision sequence scanning thymine-base analysis has also been introduced. This method provides four thymine-base peak profiles unique for Asian and American/African genotypes of T. solium, T. saginata and T. asiatica. By comparing thymine base peak profiles, it is possible to differentiate human taeniid cestodes without DNA sequencing. The approaches are powerful tools for the routine diagnosis of taeniasis and the molecular identification of taeniid cestodes.
    The Southeast Asian journal of tropical medicine and public health 02/2003; 34 Suppl 2:98-102. · 0.60 Impact Factor
  • Article: Dogs as alternative intermediate hosts of Taenia solium in Papua (Irian Jaya), Indonesia confirmed by highly specific ELISA and immunoblot using native and recombinant antigens and mitochondrial DNA analysis.
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    ABSTRACT: Serology (ELISA and immunoblot) using native glycoproteins, affinity purified glycoproteins, and a recombinant antigen is known to be highly specific to Taenia solium cysticercosis in humans and pigs. These techniques were applied for dogs in the highly endemic area of cysticercosis in Papua (Irian Jaya), Indonesia. Analysis of dog sera by both ELISA and immunoblot revealed 7 of 64 dogs were highly positive. Examination of two sero-positive dogs revealed cysticerci of T. solium in the brain and heart of these dogs. Mitochondrial DNA analysis confirmed that they were the same as T. solium previously confirmed from pigs and biopsies from local people from Irian Jaya. It is suggested that the life cycle of T. solium may be completed not only between humans and pigs but also between humans and dogs.
    Journal of Helminthology 01/2003; 76(4):311-4. · 1.38 Impact Factor
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    Article: A phylogenetic hypothesis for the distribution of two genotypes of the pig tapeworm Taenia solium worldwide.
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    ABSTRACT: Genetic polymorphism was determined among 13 isolates of Taenia solium from various regions using PCR-amplified sequences of 2 mitochondrial genes: cytochrome c oxidase subunit 1 and cytochrome b. The 2 phylogenies obtained were similar to each other regardless of the genes examined. The isolates from Asia (China, Thailand, Irian Jaya and India) formed a single cluster, whereas the isolates from Latin America (Mexico, Peru, Ecuador, Bolivia and Brazil) combined with those from Africa (Tanzania, Mozambique and Cameroon) to form an additional cluster. These results and historical data of swine domestication, distribution of pigs and colonization suggest that T. solium was introduced recently into Latin America and Africa from different regions of Europe during the colonial age, which started 500 years ago, and that the tapeworm of another origin independently spread in Asian countries.
    Parasitology 07/2002; 124(Pt 6):657-62. · 2.96 Impact Factor
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    Article: Recent advances in basic and applied science for the control of taeniasis/cysticercosis in Asia.
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    ABSTRACT: Detection of seven specific bands by immunoblot (IB) using glycoproteins (GPs) purified by lentil-lectin affinity chromatography has been the gold-standard for neurocysticercosis (NCC) serodiagnosis since 1989. However, due to the presence of contaminants, it was impossible to apply the GPs to ELISA. Our group at Asahikawa Medical College (AMC) succeeded in purifying the GPs by preparative isoelectric focusing; these higher quality GPs were suitable for ELISA. Based on the results of both IB and ELISA testing, developed at AMC for a field survey in Irian Jaya, it became evident that that area had pandemic NCC. We found many NCC patients, pigs full of cysts, and one dog infected with two cysts: these findings were based on serology. Recently, we conducted another survey to detect of the worm carriers of T. solium. Three of the 38 local people were positive by copro-antigen specific to Taenia species; these three patients expelled segments of Taenia spp and these were confirmed as those of T. solium by mitochondrial DNA analysis. When viable eggs of any taeniid species could be obtained, they can be developed into metacestodes in NOD-scid mice; it then becomes possible to analyze morphological dynamics, metacestode antigenicity, the efficacy of new metacestocidal drugs, and mitochondrial DNA. Mitochondrial DNA analysis of the specimens obtained in Irian Jaya was compared with that of other isolates worldwide. T. solium is now divided into two genotypes: the Asian type, and the Africa-American type. Some aspects of the pathological differences between the Asian and Africa-American types and the antigenic components of these two types are discussed.
    The Southeast Asian journal of tropical medicine and public health 02/2002; 33 Suppl 3:79-82. · 0.60 Impact Factor
  • Article: Comparison of the antigenicity of protoscoleces and microvesicles of Echinococcus multilocularis prepared from rats.
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    ABSTRACT: Rats are known to be relatively resistant to infection with Echinococcus multilocularis. However, when rats are inoculated with the parasite tissues, E. multilocularis proliferates slowly at first but after 6 months the cysts increase in size considerably and contain large numbers of protoscoleces. As rats survive for 18 months or longer, approximately 100 ml of packed protoscoleces can be produced from each rat. A comparison of the antigenicity of the protoscoleces and microvesicles by immunoblot methods showed that both Em18 and Em16 are shared components between both protoscoleces and microvesicles, although the latter have some additional antigenic components. In antigens prepared from protoscoleces, the banding patterns around Em18 were much simpler than those from microvesicles. Therefore, for serodiagnosis of E. multilocularis, antigens should be carefully prepared from protoscoleces rather than microvesicles from the rat.
    Journal of Helminthology 01/2002; 75(4):355-8. · 1.38 Impact Factor
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    Article: Recent advances in serodiagnosis for cysticercosis.
    Y Sako, A Ito
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    ABSTRACT: Neurocysticercosis (NCC) caused by infection with the larval stage of Taenia solium is an important cause of neurological disease worldwide. Up to the present, many studies on characterizing species-specific antigens of T. solium have been done and several high quality antigens for serodiagnosis are available. Hence the research on serodiagnosis has been shifted to the next phase, stable production of diagnostic antigens using molecular techniques. In order to establish an enzyme-linked immunosorbent assay (ELISA) using recombinant proteins, we carried out molecular cloning and identified four diagnostic antigen candidates (Ag1, Ag1V1, Ag2, and Ag2V1). Recombinant proteins, except Ag2V1, were successfully expressed using an Escherichia coli expression system. Immunoblot analysis using NCC patient sera detected recombinant proteins. But as reactivity to rAg1 was too weak, Ag1 was not suitable for the immunodiagnosis antigen. Therefore Ag1V1 and Ag2 were chosen for ELISA antigens and Ag1V1/Ag2 chimeric protein was expressed. Of 49 serum samples from NCC patients confirmed to be seropositive by immunoblot analysis, 44 (89.7%) were positive by ELISA. Serum samples from patients with other parasitic infections did not recognized Ag1V1/Ag2 chimeric protein. Ag1V1/Ag2 chimeric protein obtained in this study is of value for differential immunodiagnosis.
    The Southeast Asian journal of tropical medicine and public health 02/2001; 32 Suppl 2:98-104. · 0.60 Impact Factor
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    Article: Differential serodiagnosis of cystic and alveolar echinococcosis using native and recombinant antigens in Japan.
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    ABSTRACT: Our group at Asahikawa Medical College has established differential serodiagnosis for zoonotic larval cestodiases such as alveolar echinococcosis (AE), cystic echinococcosis (CE) and neurocysticercosis (NCC) using purified specific antigens. In this brief review, we introduce (a) four imported CE cases in Japan, easily identified serologically, (b) most recent advances in serology for differentiation of AE and monitoring of prognosis of AE in Japan. It includes application of affinity purified Em18 and prototype of a recombinant Em18 antigen. Serology using affinity purified Em18 antigens is showing much higher sensitivity for detection of AE cases which are usually undetectable by the ongoing serology for AE authorized in Hokkaido, Japan. As serology for AE, CE or NCC is still not popular in the majority of Asian countries, we expect that this review paper stimulates researchers who are interested in serology or serodiagnosis for these larval cestodiases including AE, CE and NCC.
    The Southeast Asian journal of tropical medicine and public health 02/2001; 32 Suppl 2:111-5. · 0.60 Impact Factor
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    Article: NOD-scid mouse as an experimental animal model for cysticercosis.
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    ABSTRACT: The major three species of human taeniid cestodes, Taenia solium, T. saginata and T. saginata asiatica (= T. asiatica) which require humans as the definitive host are still not rare in developing countries. Among these, T. solium is the most serious with medical and economic importance. Neurocysticercosis (NCC) in humans is now recognized as the major cause of neurologic disease in the world. As these human taeniid cestodes obligatory require domestic animals such as swine, cattle and swine as the major intermediate host animals respectively, it is not easy to analyze the basic research in these domestic animals. In this brief review, we introduce experimental animal model for these three species in order to obtain fully developed metacestode stage in severe combined immunodeficiency (scid) mice. Non-obese diabetic scid (NOD-scid) mice are expected to be a satisfactory animal model and to have advantages for analysis by several view points of developmental biology with gene expression throughout development, antigenic homology of cyst fluid of these three species, evaluation of drug efficacy or metacestocidal drug designs, confirmation of unknown taeniid gravid segments for identification based on the morphology and DNA analysis of metacestodes. The animal model is not only available for human Taenia spp but can also be applied to other taeniid cestodes of economic importance or in veterinary parasitology.
    The Southeast Asian journal of tropical medicine and public health 02/2001; 32 Suppl 2:85-9. · 0.60 Impact Factor
  • Article: Mitochondrial genetic code in cestodes.
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    ABSTRACT: The flatworm mitochondrial genetic code, which has been used for all species of the Platyhelminthes, is mainly characterized by AUA codon for isoleucine, AAA codon for asparagine and UAA codon for tyrosine. In eight species of cestodes (Echinococcus multilocularis, Echinococcus granlosus, Taenia solium Taenia saginata, Taenia hydatigena, Taenia crassiceps, Hymenolepis nama and Mesocestoides corti), the cytochrome c oxidase subunit I (COI) genes were partially sequenced to verify this genetic code. Comparison of the COI-encoding nucleotide sequences with those of human, sea urchin, fruit fly, nematode and yeast indicated that the assignments of AUA and AAA codons are adequate for cestodes. In addition, the nucleotide sequences of ATPase subunit 6 (ATP6) gene and its flanking region were compared to examine initiation and stop codons. In the related species of T. solium and T. saginata, the deduced amino acid sequences of ATP6 were homogeneous; however, the conversion of initiation codon AUG into GUG was observed in T. saginata. We also found the similar conversion in T. crassiceps. The C-terminal sequences of putative ATP6 proteins were highly conserved among the eight species and the stop codon UAG was altered to UAA in all Taenia species. The features of the gene-junctional region between NADH dehydrogenase subunit 4 (ND4) and glutamine tRNA (tRNAGln) genes also supported that UAA serves as a stop codon. Based on these results, we propose that the flatworm mitochondrial code should be modified for cestodes, particularly, in an initiating methionine codon (GUG) and a terminating codon (UAA).
    Molecular and Biochemical Parasitology 01/2001; 111(2):415-24. · 2.55 Impact Factor
  • Article: Molecular characterization and diagnostic value of Taenia solium low-molecular-weight antigen genes.
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    ABSTRACT: Neurocysticercosis (NCC) caused by infection with the larvae of Taenia solium is an important cause of neurological disease worldwide. In order to establish an enzyme-linked immunosorbent assay (ELISA) for this infection using recombinant proteins, we carried out molecular cloning and identified four candidates as diagnostic antigens (designated Ag1, Ag1V1, Ag2, and Ag2V1). Except for Ag2V1, these clones could encode a 7-kDa polypeptide, and Ag2V1 could encode a 10-kDa polypeptide. All of the clones were very similar. Except for Ag2V1, recombinant proteins were successfully expressed using an Escherichia coli expression system. Immunoblot analysis of NCC patient sera detected recombinant proteins, but because reactivity to recombinant Ag1 was too weak, Ag1 was not suitable as an immunodiagnostic antigen. So, Ag1V1 and Ag2 were chosen as ELISA antigens, and the Ag1V1/Ag2 chimeric protein was expressed. Of 49 serum samples from NCC patients confirmed to be seropositive by immunoblot analysis, 44 (89.7%) were positive by ELISA. No assays of serum samples from patients with other parasitic infections recognized the Ag1V1/Ag2 chimeric protein. The Ag1V1/Ag2 chimeric protein obtained in this study had a high value for differential immunodiagnosis.
    Journal of Clinical Microbiology 01/2001; 38(12):4439-44. · 4.15 Impact Factor
  • Article: Neurocysticercosis and echinococcosis in Asia: recent advances in the establishment of highly reliable differential serodiagnosis for international collaboration.
    A Ito, M Nakao, Y Sako, K Nakava
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    ABSTRACT: Neurocysticercosis (NCC) and echinococcosis, caused by the larval stage of taeniid cestodes, are recognized as major parasitic zoonoses threatening human life worldwide. Cystic echinococcosis (CE), caused by Echinococcus granulosus, has well been known to be more widely distributing in Europe and Asia (Eurasia) than alveolar echinococcosis (AE) caused by E. multilocularis. However, it has recently been found that AE is more widely distributing or spreading in Eurasia. Furthermore, NCC caused by Taenia solium is also spreading in Eurasia. Due to the lack of reliable methodology for diagnosing these zoonotic cestodiases worldwide, prevalence rates of these diseases are extremely underestimated. Our group has been working for the establishment of differential serodiagnosis and molecular diagnosis of AE. CE and NCC as international collaboration projects sponsored by the Ministry of Education, Japan from 1994 until 2000 at least. In this paper, we introduce (1) the most recent original work on the establishment of differential serodiagnoses of NCC, AE and CE, (2) international collaboration work on epidemiology of these diseases in several countries, and discuss (3) what we can and should do for the control of such global parasitic diseases. It is stressed that international collaboration or cooperation work on the control of parasitic diseases is only successful based on the original scientific contribution of high standard.
    The Southeast Asian journal of tropical medicine and public health 02/2000; 31 Suppl 1:16-20. · 0.60 Impact Factor
  • Article: Taenia solium infection in Irian Jaya (west Papua), Indonesia: a pilot serological survey of human and porcine cysticercosis in Jayawijaya district.
    Transactions of the Royal Society of Tropical Medicine and Hygiene 95(4):388-90. · 2.16 Impact Factor
  • Article: Resurgence of cases of epileptic seizures and burns associated with cysticercosis in Assologaima, Jayawijaya, Irian Jaya, Indonesia, 1991-95.
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    ABSTRACT: Historically, neurocysticercosis (NCC) caused by the larval stage, cysticercus or cysticerci, of the pork tapeworm Taenia solium was recognized in Paniai District, western Irian Jaya Province, Indonesia, in the early 1970s. In the 1990s, we observed a rapid increase in the number of cases of epileptic seizures and burns in Assologaima Sub-District, Jayawijaya District, eastern Irian Jaya. There were totals of 1120 new cases of burns and 293 new cases of epileptic seizures during 1991-95 in Assologaima where the number of inhabitants was 15,939. Histopathological examination of resected cysts from patients and a pig revealed that they were cysticerci of T. solium. DNA analysis of these cysts revealed that the nucleotide sequences of 391 base-pair fragments of the mitochondrial cytochrome c oxidase subunit 1 gene were exactly the same in those from patients and the pig. Although 3 of 391 base-pair fragments might differ from that of T. solium reported previously, there were no differences in the amino-acid sequences. Approximately 67% and 65% of persons with epileptic seizures and with subcutaneous nodules, respectively, showed antibody responses highly specific to cysticercosis. Therefore, most cases of epileptic seizures and burns were considered to be associated with cysticercosis in Irian Jaya.
    Transactions of the Royal Society of Tropical Medicine and Hygiene 94(1):46-50. · 2.16 Impact Factor
  • Article: Evaluation of tongue inspection and serology for diagnosis of Taenia solium cysticercosis in swine: usefulness of ELISA using purified glycoproteins and recombinant antigen
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    ABSTRACT: Evaluation of serology using glycoproteins (GPs) purified by preparative isoelectric focusing (pH 8.8) and recombinant chimeric antigen (RecTs) of Taenia solium was carried out using (1) blood samples on filter papers from pigs infected with different doses of eggs of T. solium in Mexico, (2) serum samples from pigs found infected naturally in Vietnam and Ecuador and (3) serum samples from pigs suspected to be infected with T. solium by tongue inspection in Tanzania. Antibody responses (IgG) were detectable in experimentally infected pigs confirmed harbouring 16 or more cysts at necropsy from 30 days after egg inoculation. One of three pigs naturally infected and harbouring 2.5 cysts/kg muscle and most of pigs harbouring=5.0 cysts/kg were also seropositive by ELISA. Although pigs may be infected with other taeniid species such as Taenia hydatigena, pigs harbouring this parasite were negative in ELISA. Approximately, 76 and 78% of sera from pigs having nodule(s) in the tongue (positive tongue inspection) were serologically positive by both ELISA and immunoblot, respectively. Furthermore, approximately 34 and 18% of sera from pigs having no nodules in the tongue (negative tongue inspection) were also seropositive by ELISA and immunoblot, respectively. ELISA using the two antigens was more sensitive than immunoblot and reliable for differentiation of pigs infected with cysticerci of T. solium from those either uninfected or infected with other taeniid species. Pigs without nodule by tongue inspection should be checked serologically in endemic areas.
    Veterinary Parasitology.
  • Article: Multiple genotypes of Taenia solium - ramifications for diagnosis, treatment and control
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    ABSTRACT: Mitochondrial DNA sequences of Taenia solium have fully been analyzed. Analysis of the full length of cytochrome c oxidase subunit 1 (1620 bp) and cytochrome b (1068 bp) genes of T. solium, isolated from Asia (China, Thailand, Indonesia and India), from Latin America (Mexico, Ecuador, Bolivia, Peru and Brazil) and from Africa (Tanzania, Mozambique and Cameroon), has revealed that the two phylogenies obtained were similar to each other regardless of the genes examined. The isolates from Asia formed a single cluster, whereas those from Latin America combined with those from Africa to form an additional cluster. It was estimated that these two genotypes emerged approximately 4-8 x 10(5) years ago. These results together with recent study of the ancient of human taeniid cestodes emerged several MYA in Africa, historical data on swine domestication, distribution of pigs and colonization patterns suggest that T. solium was introduced recently into Latin America and Africa from different regions of Europe during the colonial age, which started 500 years ago, and that T. solium of another origin independently spread in Asian countries, perhaps from China. Why did not T. solium of European origin invade or spread into Asia during the colonial age? Analysis of T. solium distribution must include other Taenia species, especially T. saginata and T. asiatica, which can not be differentiated from each other morphologically. BESS T-base analysis for differentiation of all human Taenia species including the two genotypes of T. solium, and T. saginata and T. asiatica has also been characterized. BESS T-base analysis differentiates African isolates from Latin American isolates as well but more samples should be analyzed for obtaining conclusive evidence for the latter. Serological analysis of cyst fluid of T. solium cysticerci obtained in China and Indonesia and from Mozambique and Ecuador indicates geographical differences in their banding patterns. These differences are discussed in the light of possible differences in pathology of T. solium worldwide. As it has been speculated that the ancient T. solium emerged several million years ago in Africa, it is necessary to analyze more isolates from Africa. Such working hypothesis may be evaluated combined with symptomatology and serology when we get additional DNA data from such areas, since there are some varieties of manifestation of neurocysticercosis with or without subcutaneous cysticercosis and of antigens of cyst fluid of T. solium from Asia and from Africa and/or America. Transfer of techniques of molecular identification and sero- and immuno-diagnoses between researchers and technicians from endemic countries using their own materials should be promoted with the aim of better international cooperation for the control of cysticercosis.