Article

Update on the Human Broad Tapeworm (Genus Diphyllobothrium), Including Clinical Relevance

Institute of Parasitology, Biology Centre of the Academy of Sciences of the Czech Republic, Ceské Budejovice, Czech Republic.
Clinical microbiology reviews (Impact Factor: 17.41). 02/2009; 22(1):146-60, Table of Contents. DOI: 10.1128/CMR.00033-08
Source: PubMed

ABSTRACT

Tapeworms (Cestoda) continue to be an important cause of morbidity in humans worldwide. Diphyllobothriosis, a human disease caused by tapeworms of the genus Diphyllobothrium, is the most important fish-borne zoonosis caused by a cestode parasite. Up to 20 million humans are estimated to be infected worldwide. Besides humans, definitive hosts of Diphyllobothrium include piscivorous birds and mammals, which represent a significant zoonotic reservoir. The second intermediate hosts include both freshwater and marine fish, especially anadromous species such as salmonids. The zoonosis occurs most commonly in countries where the consumption of raw or marinated fish is a frequent practice. Due to the increasing popularity of dishes utilizing uncooked fish, numerous cases of human infections have appeared recently, even in the most developed countries. As many as 14 valid species of Diphyllobothrium can cause human diphyllobothriosis, with D. latum and D. nihonkaiense being the most important pathogens. In this paper, all taxa from humans reported are reviewed, with brief information on their life history and their current distribution. Data on diagnostics, epidemiology, clinical relevance, and control of the disease are also summarized. The importance of reliable identification of human-infecting species with molecular tools (sequences of mitochondrial genes) as well as the necessity of epidemiological studies aimed at determining the sources of infections are pointed out.

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    • "Pseudophyllidean cestodes of the genus Diphyllobothrium are intestinal parasites infecting fish-eating birds and mammals as definitive hosts (including humans), and using copepod crustaceans and freshwater, anadromous, or catadromous fish as first and second intermediate hosts, respectively (Dick et al. 2001; Scholz et al. 2009). Human diphyllobothriasis represents an important fish-borne zoonosis since the second half of the 19th century (Arizono et al. 2009b; Scholz et al. 2009). We applied molecular techniques to identify and report D. dendriticum and D. nihonkaiense in North American bears. "
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    ABSTRACT: Between May 2011 and June 2013, we collected the carcasses and gastrointestinal tracts of 40 American black bears (Ursus americanus Pallas, 1780) and 13 grizzly bears (Ursus arctos L., 1758) from populations of Alberta and British Columbia, Canada. Specimens were examined for helminths, which were identified to the species level by applying an integrated morphological and molecular approach. Our goal was to investigate parasite biodiversity and infection parameters in the sampled grizzly and black bears. We found seven parasite taxa:. The statistical significance of infection prevalence, intensity, and abundance for each helminth species was assessed relative to host species, gender, age class, sampling season, and location. This is the first unequivocal report of the potentially zoonotic tapeworms D. dendriticum and D. nihonkaiense in North American bears. Furthermore, we provide insight into the biology and ecology of the nematodes B. transfuga, D. ursi, and species of Uncinaria Frölich, 1789, and enrich the information available on the recently described tapeworm T. arctos.
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    • "Prior to this study, no data on vitellogenesis, which is one of the key steps in the formation of female gametes in invertebrates (flatworms) with polylecithal eggs (Neoophora ) [5] [6], were available. Just recently, Yoneva et al. [7] studied the vitellogenesis of the broad fish tapeworm, Diphyllobothrium latum (Linnaeus, 1758), the most frequent causative agent of human diphyllobothriosis [8]. Among the basal bothriate eucestodes, vitellogenesis was studied in several species of the Caryophyllidea, but with most data limited to the parasites of cyprinids in the Palearctic Region (e.g. "
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    ABSTRACT: The recently erected cestode order Diphyllobothriidea is unique among all tapeworm orders in that its species infect all major groups of tetrapods, including man. In the present paper, the vitellogenesis of representatives of all three currently recognized families of this order was evaluated, based on ultrastructural (transmission electron microscopy) and cytochemical (detection of glycogen) observations. Vitelline follicles of all taxa studied, i.e. Cephalochlamys namaquensis from clawed frogs (Xenopus), Duthiersia expansa from monitors (Varanus) and Schistocephalus solidus that matures in fish-eating birds, contain vitelline cells at various stages of development and interstitial cells. Developing vitellocytes are characterized by the presence of mitochondria, granular endoplasmic reticulum and Golgi complexes involved in the synthesis of shell globules and formation of shell globule clusters. Mature vitellocytes contain lipids and glycogen in different proportions. The most significant differences among the three diphyllobothriidean families were found in the presence or absence of lamellar bodies. Variations of vitelline clusters morphology and types of lipid droplets are described and discussed in relation to the presumed evolutionary history of diphyllobothriideans, which belong to the most basal cestode groups.
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    • "Prior to this study, no data on vitellogenesis, which is one of the key steps in the formation of female gametes in invertebrates (flatworms) with polylecithal eggs (Neoophora ) [5] [6], were available. Just recently, Yoneva et al. [7] studied the vitellogenesis of the broad fish tapeworm, Diphyllobothrium latum (Linnaeus, 1758), the most frequent causative agent of human diphyllobothriosis [8]. Among the basal bothriate eucestodes, vitellogenesis was studied in several species of the Caryophyllidea, but with most data limited to the parasites of cyprinids in the Palearctic Region (e.g. "
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    ABSTRACT: The recently erected cestode order Diphyllobothriidea is unique among all tapeworm orders in that its species infect all major groups of tetrapods including man. In the present paper, vitellogenesis of representatives of all three currently recognized families of this order was evaluated, based on the ultrastructural (transmission electron microscopy) and cytochemical (detection of glycogen) observations. Vitelline follicles of all taxa studied, i.e. Cephalochlamys namaquensis from clawed frogs (Xenopus), Duthiersia expansa from monitors (Varanus) and Schistocephalus solidus that matures in fish-eating birds, contain vitelline cells at various stages of development and intestitial cells. Developing vitellocytes are characterized by the presence of mitochondria, granular endoplasmic reticulum and Golgi complexes involved in the synthesis of shell globules and formation of shell globule clusters. Mature vitellocytes contain lipids and glycogen in different proportions. The most significant differences among the three diphyllobothriidean families were found in the presence or absence of lamellar bodies. Variations of vitelline clusters morphology and types of lipid droplets are described and discussed in relation to the presumed evolutionary history of diphyllobothriideans, which belong among the most basal cestode groups.
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