Hiroshi Yamasaki

National Institute of Infectious Diseases, Tokyo, Edo, Tōkyō, Japan

Are you Hiroshi Yamasaki?

Claim your profile

Publications (294)1129.96 Total impact

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Human toxocariasis which is caused mainly by the larvae of Toxocara canis and Toxocara cati, is a worldwide zoonotic disease that can be a potentially serious human infection. The enzyme-linked immunosorbent assay (ELISA) using T. canis excretory-secretory (TES) antigens harvested from T. canis larvae is currently the serological test for confirming toxocariasis. An alternative to producing large amounts of Toxocara TES and improved diagnosis for toxocariasis is through the development of highly specific recombinant antigens such as the T. canis second stage larva excretory-secretory 30kDa protein (recTES-30). The aim of this study was to evaluate the sensitivity and specificity of a rapid diagnostic kit (RDT, named as iToxocara kit) in comparison to recTES-30 ELISA in Serendah Orang Asli village in Selangor, Malaysia. A total of 133 subjects were included in the study. The overall prevalence rates by ELISA and RDT were 29.3% and 33.1% respectively, with more positive cases detected in males than females. However, no association was found between toxocariasis and gender or age. The percentage sensitivity, specificity, positive predictive value and negative predictive value of RDT were 85.7%, 90.1%, 80% and 93.2%, respectively. The prevalence for toxocariasis in this population using both ELISA and RDT was 27.1% (36/133) and the K-concordance test suggested good agreement of the two tests with a Cohen's kappa of 0.722, P<0.01. In addition, the followed-up Spearman rank correlation showed a moderately high correlation at R=0.704 and P <0.01. In conclusion, the RDT kit was faster and easier to use than an ELISA and is useful for the laboratory diagnosis of hospitalized cases of toxocariasis. Copyright © 2015. Published by Elsevier B.V.
    Acta tropica 04/2015; 46. DOI:10.1016/j.actatropica.2015.04.011 · 2.52 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Gnathostomiasis caused by Gnathostoma spinigerum, is a hazardous food- borne helminthic zoonosis, and is endemic especially in developing countries in Asia. Definitive diagnosis, relying upon identification of worms from human tissues or body, is rarely accomplished. Consequently, sensitive supporting tools such as serological tests have been used widely. But these methods are time con- suming, need sophisticated equipment and are impractical in some settings. In the present study a dot enzyme-linked immunosorbent assay (dot-ELISA), using C. spin igerum recombinant matrix metalloproteinase protein as the antigen, was developed and assessed using sera of gnathostomiasis and other parasitosis pa- tients as well as healthy controls. The accuracy, sensitivity, specificity, positive and negative predictive values were 97.4%, 100%, 96.1%, 92.9%, and 100%, respectively. The dot-ELISA appears to be a suitable rapid test for diagnostic purpose as well as epidemiological studies.
    The Southeast Asian journal of tropical medicine and public health 09/2014; 45(5):990-6. · 0.55 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A diagnostic kit using an immunochromatographic device was developed to replace the time-consuming immunodiagnostic methods for human sparganosis. The kit was found to be faster and easier to use than an enzyme-linked immunosorbent assay (ELISA) and showed higher sensitivity and specificity. It will be useful for the laboratory diagnosis of hospitalized cases of sparganosis.
    Clinical and vaccine Immunology: CVI 07/2014; 21(9). DOI:10.1128/CVI.00149-14 · 2.37 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Taenia saginata, T. solium, and T. asiatica are causative agents of taeniasis in humans. The difficulty of morphological identification of human taeniids can lead to misdiagnosis or confusion. To overcome this problem, several molecular methods have been developed, but use of these tends to be time-consuming. Here, a rapid and high-throughput pyrosequencing approach was developed for the identification of three human taeniids originating from various countries. Primers targeting the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene of the three Taenia species were designed. Variations in a 26-nucleotide target region were used for identification. The reproducibility and accuracy of the pyrosequencing technology was confirmed by Sanger sequencing. This technique will be a valuable tool to distinguish between sympatric human taeniids that occur in Thailand, Asia and Pacific countries. This method could potentially be used for the molecular identification of the taeniid species that might be associated with suspicious cysts and lesions, or cyst residues in humans or livestock at the slaughterhouse.
    PLoS ONE 06/2014; 9(6):e100611. DOI:10.1371/journal.pone.0100611 · 3.23 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Human sparganosis is one of the neglected diseases but important food-borne parasitic zoonoses. The disease is caused by larvae (spargana) of diphyllobothriidean tapeworm. Here, we describe nine cases of human sparganosis, caused by Spirometra erinaceieuropaei in a hospital in Thailand during 2001-2012. Clinical characteristics, treatment, and outcome of cases were revealed. Diagnosis and identification of causative parasite species was made by histopathological investigations followed by a polymerase chain reaction-based molecular method using formalin-fixed paraffin embedded tissues. The DNA samples were extracted from tissues and a partial fragment of cytochrome c oxidase subunit 1 (cox1) gene was amplified for the detection of parasitic DNA. Infection could be prevented by increasing activities on health communication by responsible public health agencies.
    The American journal of tropical medicine and hygiene 05/2014; 91(2). DOI:10.4269/ajtmh.14-0178 · 2.74 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The cause of diphyllobothriosis in 5 persons in Harbin and Shanghai, China, during 2008-2011, initially attributed to the tapeworm Diphyllobothrium latum, was confirmed as D. nihonkaiense by using molecular analysis of expelled proglottids. The use of morphologic characteristics alone to identify this organism was inadequate and led to misidentification of the species.
    Emerging Infectious Diseases 02/2014; 20(2):315-8. DOI:10.3201/eid2002.121889 · 7.33 Impact Factor
  • Source
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A 52-year-old woman presented with lower back pain, progressive symmetrical paraparesis with sensory impairment, and sphincter disturbance. Magnetic resonance imaging (MRI) of the whole spine revealed multiple intradural extramedullary serpiginous-mass lesions in the subarachnoid space continuously from the prepontine to the anterior part of the medulla oblongata levels, C7, T2-T8, and T12 vertebral levels distally until the end of the theca sac and filling-in the right S1 neural foramen. Sparganosis was diagnosed by demonstration of the sparganum in histopathological sections of surgically resected tissues and also by the presence of serum IgG antibodies by ELISA. DNA was extracted from unstained tissue sections, and a partial fragment of mitochondrial cytochrome c oxidase subunit 1 (cox1) gene was amplified using a primer set specific for Spirometra spp. cox1. After sequencing of the PCR-amplicon and alignment of the nucleotide sequence data, the causative agent was identified as the larva of Spirometra erinaceieuropaei.
    The Korean Journal of Parasitology 12/2013; 51(6):739-42. DOI:10.3347/kjp.2013.51.6.739 · 0.97 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Neurognathostomiasis is a severe form of human gnathostomiasis which can lead to disease and death. Diagnosis of neurognathostomiasis is made presumptively by using clinical manifestations. Immunoblotting, which recognizes antigenic components of molecular mass 21 kDa and 24 kDa in larval extracts of Gnathostoma spinigerum (Gs 21/24), has high sensitivity and specificity for diagnosis of neurognathostomiasis. However, only very small amounts of the Gs 21/24 antigens can be prepared from parasites harvested from natural or experimental animals. To overcome this problem, we recently produced a recombinant matrix metalloproteinase (rMMP) protein from G. spinigerum. In this study, we evaluated this rMMP alongside the Gs 21/24 antigens for serodiagnosis of human neurognathostomiasis. We studied sera from 40 patients from Srinagarind Hospital, Khon Kaen University, Thailand, with clinical criteria consistent with those of neurognathostomiasis, and sera from 30 healthy control adults from Thailand. All sera were tested for specific IgG antibodies against both G. spinigerum crude larval extract and rMMP protein using immunoblot analysis. The sensitivity and specificity for both antigenic preparations were all 100%. These results show that G. spinigerum rMMP protein can be used as an alternative diagnostic antigen, in place of larval extract, for serodiagnosis of neurognathostomiasis.
    The Korean Journal of Parasitology 12/2013; 51(6):751-4. DOI:10.3347/kjp.2013.51.6.751 · 0.97 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Onchocerpa lupi was first isolated from a wolf in Russia. Since then, canine ocular onchocercosis has been increasingly reported, particularly in Europe and the United States. It is thought that blackflies and midges are the vectors of transmission, and it is possible that these vectors could transmit the parasite to humans. The first human case of O. lupi in Turkey was reported in 2011. In this report we present the third human case of O. lupi infection in Turkey. Our patient was a 28-year-old male who displayed a painless, immobile mass under the conjunctiva. The mass measured 10 × 12 mm in size. Pathological examination of the surgically excised tissue was suggestive of infection by a filarial nematode. Subsequently, the parasite was identified as O. lupi through molecular analysis. All of the previously reported cases of O. lupi in both humans and dogs were more symptomatic than in our patient, Onchocerca infection should not be ruled out during the differential diagnosis of the subconjunctival and orbital cystic mass in instances where there is little to no inflammation. It is important to consider biopsy and carry out molecular analysis to identify the parasite.
    Acta Parasitologica 09/2013; 58(3):384-8. DOI:10.2478/s11686-013-0152-8 · 0.97 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This study aimed to investigate intestinal helminth infection in stray dogs in Osaka Prefecture, by surveying coprological samples from dogs captured from 2006-2011. Of 212 fecal samples collected, overall prevalence of infection was 39.2%. The most common species was Toxocara canis (25.0%), followed by Trichuris vulpis (8.0%), Spirometra erinaceieuropaei (3.3%), Taeniidae (2.4%), Ancylostoma caninum (1.9%) and Toxascaris leonina (0.5%). In the molecular analysis, all of the taeniid eggs were negative for Echinococcus multilocularis and were identified as other taeniid species (e.g., Taenia pisiformis). Our results suggest that stray dogs remain important infection reservoirs of zoonotic parasites in Osaka Prefecture. Therefore, control of stray dogs is crucial for reducing the risk of public health problems due to parasitic infections.
    Journal of Veterinary Medical Science 06/2013; 75(10). DOI:10.1292/jvms.12-0499 · 0.88 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Matrix metalloproteinase (MMPs) is the extracellular zinc-dependent endopeptidase and is secreted for degrading extracellular matrix molecules of host tissues. A cDNA encoding MMP-like protein of Gnathostoma spinigerum larvae was amplified by reverse transcription-polymerase chain reaction, and was cloned into a prokaryotic expression vector, and expressed in Escherichia coli. Total immunoglobulin G class (total IgG) antibody responses to the recombinant MMP-like protein were analyzed by immunoblot diagnosis of human gnathostomiasis. Serum samples from proven and clinically suspected cases of gnathostomiasis, other parasitic diseases patients, and from healthy volunteers were tested. The immunoblotting gave high sensitivity (100%) and specificity (94.7%). Positive and negative predictive values were 85.4% and 100%, respectively. Recombinant MMP-like protein can be used as a diagnostic antigen and potentially replace native parasite antigens to develop a gnathostomiasis diagnostic kit.
    The American journal of tropical medicine and hygiene 05/2013; 89. DOI:10.4269/ajtmh.12-0617 · 2.74 Impact Factor
  • Source
    Hiroshi Yamasaki
    [Show abstract] [Hide abstract]
    ABSTRACT: This mini-review describes recent epidemiological trends in cysticercosis and taeniasis in Japan. Some of the topics discussed herein were presented at the first symposium on "Current perspectives of researches", that was held in Osong in Chungbuk Province, South Korea, in October 2011 and organized by Prof. K. S. Eom, Chungbuk National University School of Medicine. To better understand the trends in the occurrence of cysticercosis and taeniasis in Japan, clinical cases reported in 2005 have been updated. In addition, the current status of infections successively occurring in Japan since 2010 is also discussed.
    The Korean Journal of Parasitology 02/2013; 51(1):19-29. DOI:10.3347/kjp.2013.51.1.19 · 0.97 Impact Factor
  • 12/2012; 22(6). DOI:10.1684/ejd.2012.1876
  • [Show abstract] [Hide abstract]
    ABSTRACT: Feline cases of lung fluke infection were recently reported in the upper basin of the Oi River in Shizuoka Prefecture. The causative species of these cases were not identified, although a field survey conducted about 40 years ago in this area demonstrated the prevalence of Paragonimus miyazakii metacercariae in intermediate host crabs. To clarify the current status of lung fluke metacercarial infection in host crabs, we collected the Japanese freshwater crab or Sawagani, Geothelphusa dehaani, at 14 sampling sites in the Kawane area, which is located in the upper basin of the Oi River. Sawagani harboring Paragonimus metacercariae were collected at all sampling sites in this study with a total prevalence of 42% (281 of 677 crabs examined) and a range of 16 to 92%. The number of metacercariae per infected crab ranged from 1 to 19 with a mean of 2.2. Based on the morphological features of the metacercariae and adult worms recovered from rats that were experimentally infected with the metacercariae, the lung flukes examined were identified as P. miyazakii Kamo, Nishida, Hatsushika and Tomimura, 1961; ITS2 sequence data corroborate this conclusion. P. miyazakii is still widely prevalent in this area, implying that the recently reported feline paragonimiasis cases were likely caused by P. miyazakii infection.
    Journal of Veterinary Medical Science 10/2012; 75(3). DOI:10.1292/jvms.12-0325 · 0.88 Impact Factor
  • Hiroshi Yamasaki · Maki Muto · Minoru Yamada · Naoki Arizono · Robert L Rausch
    [Show abstract] [Hide abstract]
    ABSTRACT: Abstract The bear tapeworm Diphyllobothrium ursi is described based upon the morphology of adult tapeworms recovered from the brown bear (Ursus arctos middendorffi) and larval plerocercoids found in sockeye salmon (Oncorhynchus nerka) from Kodiak Island in Alaska in 1952. However, in 1987, D. ursi was synonymized with Diphyllobothrium dendriticum, and the taxonomic relationship between both species has not subsequently been revised. In this study, mitochondrial cytochrome c oxidase subunit 1 gene (cox1) sequences of holotype and paratype D. ursi specimens that had been preserved in a formalin-acetic acid-alcohol solution since the time the species was initially described approximately 60 yr ago were analyzed. Molecular and phylogenetic analysis of the cox1 sequences revealed that D. ursi is more closely related to D. dendriticum than it is to D. nihonkaiense and D. latum. In addition to molecular evidence, differences in the life cycle and ecology of the larval plerocercoids between D. ursi and D. dendriticum also suggest that D. ursi is a distinct species, separate from D. dendriticum and D. nihonkaiense, and also possibly from D. latum.
    Journal of Parasitology 06/2012; 98(6). DOI:10.1645/GE-3063.1 · 1.26 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We report two pediatric cases (6- and 8-year-old Japanese boys) of Diphyllobothrium nihonkaiense infection occurring in July and August 2010. Both patients were asymptomatic, but presented to our hospital after passing tapeworm segments in their stool. A single dose of praziquantel was administered to each patient, and both patients expelled segments. The tapeworms were identified as D. nihonkaiense by mitochondrial cytochrome c oxidase subunit 1 gene analysis. The patients have shown no recurrence after medical treatment. Two cases of D. nihonkaiense infection were encountered during a short time in the summer. Including our cases, reports of paediatric cases of diphyllobothriasis nihonkaiense were increased recently in Japan. It suggests an increase in incidence of diphllobothriasis, even in children.
    Pediatrics International 12/2011; 54(1):163-5. DOI:10.1111/j.1442-200X.2011.03529.x · 0.73 Impact Factor
  • Nihon Naika Gakkai Zasshi 11/2011; 100(11):3336-8. DOI:10.2169/naika.100.3336
  • Hiroshi Yamasaki · Hiroshi Ohmae · Toshiaki Kuramochi
    [Show abstract] [Hide abstract]
    ABSTRACT: Although the diplogonadic human tapeworm, Diplogonoporus grandis, has long been considered to be a synonym of the whale tapeworm, Diplogonoporus balaenopterae, the identity of the both species at the complete mitochondrial genomes and nuclear DNA levels has been not sufficiently undertaken to date. In the present study, to clarify the taxonomic relationships between D. balaenopterae and D. grandis at the molecular level, the complete mitochondrial genomes of both species were sequenced and compared. In addition, the genetic variation in the mitochondrial cytochrome c oxidase subunit 1 gene (cox1) and the nuclear internal transcribed spacer-1 (ITS-1) region of the ribosomal RNA gene were examined. The complete mitochondrial genomes of D. balaenopterae and D. grandis consisted of 13,724 bp and 13,725 bp, respectively. These mitochondrial genomes contained 12 protein-coding, 22 transfer RNA and 2 ribosomal RNA genes and two longer non-coding regions. Except for Hymenolepis diminuta, the genomic organization in both species was essentially identical to that in other cestode genomes examined to date. However, differences were observed between Diplogonoporus and Diphyllobothrium species in abbreviated stop codons, sequences and the number of repeat units in the 2nd non-coding regions. The genetic differences observed in the mitochondrial genomes, cox1 and ITS-1 regions of both species were considered typical of intraspecific variation. In conclusion, D. balaenopterae is a taxonomically valid species and D. grandis is a junior synonym of D. balaenopterae based on the zoological nomenclature. Further, molecular-phylogenetic analysis confirmed that D. balaenopterae is more closely related to Diphyllobothrium stemmacephalum, the type-species of the genus Diphyllobothrium, and the taxonomical validity of the genera Diplogonoporus and Diphyllobothrium was also discussed.
    Parasitology International 11/2011; 61(2):260-6. DOI:10.1016/j.parint.2011.10.007 · 2.11 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: PCR-based molecular diagnosis was made for the identification of causative agents of the clinically suspected pulmonary proliferative sparganosis case found in Thailand using formalin-fixed paraffin-embedded (FFPE) biopsy specimens. As a reference, FFPE biopsy specimen from a typical cutaneous sparganosis case was examined together. DNA samples were extracted from tissues and two partial fragments of cytochrome c oxidase subunit 1 (cox1) gene were amplified for the detection of Spirometra DNA. Two cox1 fragments were amplified successfully for both specimens. After alignment of nucleotide sequences of the PCR-amplicons, the causative agents of both cases were identified as Spirometra erinaceieuropaei.
    Parasitology International 07/2011; 60(4):460-4. DOI:10.1016/j.parint.2011.07.018 · 2.11 Impact Factor

Publication Stats

9k Citations
1,129.96 Total Impact Points


  • 2009–2015
    • National Institute of Infectious Diseases, Tokyo
      Edo, Tōkyō, Japan
  • 2013–2014
    • Khon Kaen University
      • Faculty of Medicine
      Kawn Ken, Khon Kaen, Thailand
  • 2001–2008
    • Kwansei Gakuin University
      • School of Science and Technology
      Nishinomiya, Hyōgo, Japan
  • 2007
    • Health Sciences University of Mongolia
      Улаанбаатар, Ulaanbaatar, Mongolia
  • 2006
    • Universidade Federal de Tocantins
      • Escola de Medicina Veterinária e Zootecnia (EMVZ)
      Palmas, Tocantins, Brazil
  • 1983–2006
    • International Agency for Research on Cancer
      Lyons, Rhône-Alpes, France
  • 2005
    • Federal University of Pernambuco
      • Department of Biochemistry
      Recife, Estado de Pernambuco, Brazil
  • 2004–2005
    • Asahikawa Medical University
      • Department of Parasitology
      Asakhigava, Hokkaidō, Japan
  • 2003–2004
    • National Institute of Health and Nutrition
      Edo, Tōkyō, Japan
  • 1996–2003
    • Juntendo University
      • • Department of Molecular and Cellular Parasitology
      • • Department of Medicine
      Edo, Tōkyō, Japan
    • The University of Western Ontario
      • Department of Anatomy and Cell Biology
      London, Ontario, Canada
    • National Cancer Center, Japan
      Edo, Tōkyō, Japan
  • 2002
    • Stanford University
      • Department of Mechanical Engineering
      Palo Alto, California, United States
  • 1996–1997
    • Cancer Research Center of Lyon
      Lyons, Rhône-Alpes, France
  • 1993
    • Tabor Adelaide
      Unley, South Australia, Australia
  • 1990
    • Centre International de Recherche sur l'Environnement
      Nogent, Île-de-France, France
  • 1989
    • University of Texas MD Anderson Cancer Center
      • Science Park - Research Division
      Houston, TX, United States
  • 1988
    • Nagoya City University
      • Medical School
      Nagoya, Aichi, Japan
  • 1985
    • German Cancer Research Center
      Heidelburg, Baden-Württemberg, Germany