DIPHYLLOBOTHRIUM PACIFICUM PDF

Related Pages Causal Agents Several members of the cestode tapeworm family Diphyllobothriidae are known to infect humans. These pseudophyllidean cestodes have a scolex bearing bothria grooves , instead of suckers as in the cyclophyllidean cestodes the group including nearly all human-infecting species. All species associated with human diphyllobothriid infections have marine or aquatic life cycles and transmission occurs via ingestion of undercooked fish. Recent research incorporating morphologic and molecular data has led to the re-classification and re-naming of most of the human-infecting diphyllobothriids. However, it is possible that many historical cases were falsely attributed to this species. Sporadic case reports exist involving several other diphyllobothriid species, although some of the species identifications in these reports are of questionable validity.

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Resources Causal Agents Several members of the cestode tapeworm family Diphyllobothriidae are known to infect humans. These pseudophyllidean cestodes have a scolex bearing bothria grooves , instead of suckers as in the cyclophyllidean cestodes the group including nearly all human-infecting species. All species associated with human diphyllobothriid infections have marine or aquatic life cycles and transmission occurs via ingestion of undercooked fish.

Recent research incorporating morphologic and molecular data has led to the re-classification and re-naming of most of the human-infecting diphyllobothriids.

However, it is possible that many historical cases were falsely attributed to this species. Sporadic case reports exist involving several other diphyllobothriid species, although some of the species identifications in these reports are of questionable validity. Life Cycle Eggs are passed unembryonated in feces. Under appropriate conditions, the eggs mature approximately 18 to 20 days and yield oncospheres which develop into a coracidia. After ingestion by a suitable crustacean first intermediate host the coracidia develop into procercoid larvae.

Procercoid larvae are released from the crustacean upon predation by the second intermediate host usually a small fish and migrate into the deeper tissues where they develop into a plerocercoid larvae spargana , which is the infectious stage for the definitive host. Because humans do not generally eat these small fish species raw, the second intermediate host probably does not represent an important source of human infection. However, these small second intermediate hosts can be eaten by larger predator species that then serve as paratenic hosts.

In this case, the plerocercoid migrates to the musculature of the larger predator fish; humans and other definitive host species acquire the parasite via consumption of undercooked paratenic host fish.

In the definitive host, the plerocercoid develops into adult tapeworms in the small intestine. Adult diphyllobothriids attach to the intestinal mucosa by means of two bilateral groves bothria of their scolex.

The adults can reach more than 10 m in length, with more than 3, proglottids. Immature eggs are discharged from the proglottids up to 1,, eggs per day per worm and are passed in the feces. Eggs appear in the feces 5 to 6 weeks after infection. Hosts Intermediate and paratenic hosts include a wide diversity of freshwater and marine fishes, commonly perch and pike for Dibothriocephalus latus and salmon for D.

Definitive host specificity among the medically important diphyllobothriids is low. In addition to humans, other carnivorous, fish-eating mammals and a few birds can also serve as definitive hosts. Non-human definitive hosts for D.

Pinnipeds are the natural definitive host for Adenocephalus pacificus and it has also been found in dogs and jackals. Among the cetacean-associated species, Diphyllobothrium stemmacephalum is found mostly in dolphins and porpoises, and D.

Geographic Distribution Dibothriocephalus latus has a relatively wide distribution, but is most common in circumpolar regions; it is also known to occur very rarely in South America, perhaps through importation and aquaculture. While found in hosts across the Pacific Ocean, a large majority of Adenocephalus pacificus cases occur on the Pacific coast of South America and one case has occurred in South Australia.

Diphyllobothrium stemmacephalum and D. Note that the global trade and consumption of wild-caught fish leads to human cases occurring regularly outside of naturally endemic regions. Clinical Presentation Diphyllobothriasis can be a long-lasting infection, up to 25 years. Most infections are asymptomatic but gastrointestinal symptoms may occur in some patients. Aberrant migration of proglottids can cause cholecystitis or cholangitis. Rarely, massive infections may cause intestinal obstruction.

There is an operculum at one end that can be inconspicuous, and at the opposite abopercular end is a small knob that can be barely discernible. The eggs are passed in the stool unembryonated.

Although eggs of Adenocephalus pacificus are generally smaller than those of Dibothriocephalus spp. Figure A: Eggs of diphyllobothriids in an iodine-stained wet mount. Figure B: Note the knob at the abopercular end. Figure C: Eggs of diphyllobothriids within a proglottid. Figure D: Eggs of diphyllobothriids within a proglottid.

Figure E: Diphyllobothriid egg in an unstained wet mount. Figure F: Diphyllobothriid eggs in an unstained wet mount of stool.

Note the opercula are open. Figure G: Diphyllobothriid egg in an unstained wet mount. Figure H: Diphyllobothriid egg in an unstained wet mount of stool, with an open operculum. Figure I: Diphyllobothriid egg in an unstained wet mount. Figure J: Diphyllobothriid egg in an unstained wet mount. Diphyllobothriid tapeworm adults Mature diphyllobothriids are large tapeworms reaching 2—15 meters in length, with occasional larger specimens.

The scolex always has two bothria grooves. The general size and shape of the scolex may be subject to intraspecific variability, though some species-level differences have been described historically.

Proglottids are broader than long, with a single genital pore that opens in the middle of the ventral surface; fully mature specimens may be comprised of a 2,—5, proglottids. The ovaries are characteristically rosette-shaped. Figure A: Section of an adult Dibothriocephalus latus containing many proglottids. The scolex was not present in this specimen. Figure B: Close-up of a few of the proglottids from the specimen in Figure A, showing the rosette-shaped uterus at the center of each proglottid.

Figure C: Another example of a portion of a diphyllobothriid tapeworm passed spontaneously by a human patient. Figure D: Closer view of the specimen in Figure C, showing broad proglottids with craspedote overhanging margins. Figure E: Carmine-stained proglottids of D.

Figure F: Close up the section shown in Figure D, showing the genital pore arrow opening on the ventral surface of the proglottid. Figure G: The elongate scolex and neck region of D.

Image taken at x magnification. Figure B: Diphyllobothriid eggs from the same specimen in Figure A. Laboratory Diagnosis Microscopic identification of eggs in the stool is the basis of family level diagnosis; genus level identification based on eggs is difficult due to overlap in morphological features. Eggs are usually numerous and can be demonstrated without concentration techniques. Identification of proglottids passed in the stool is also of diagnostic value.

Also, treatment may distort morphologic features of expelled cestodes tissues. Molecular identification is generally only used in research capacities at present. More on: Morphologic comparison with other intestinal parasites. Laboratory Safety Standard precautions for the processing of stool samples apply. Unlike taeniid tapeworm eggs e. Taenia, Echinococcus, Hymenolepis , diphyllobothriid eggs are not directly infectious to humans. Suggested Reading Ikuno, H. Epidemiology of Diphyllobothrium nihonkaiense Diphyllobothriasis, Japan, — Emerging Infectious Diseases, 24 8 , p.

Waeschenbach, A. The catholic taste of broad tapeworms—multiple routes to human infection. International Journal for Parasitology, 47 13 , pp. Scholz, T. Fish-borne, zoonotic cestodes Diphyllobothrium and relatives in cold climates: a never-ending story of neglected and re -emergent parasites. Food and Waterborne Parasitology, 4, pp. Kuchta, R. Pacific broad tapeworm Adenocephalus pacificus as a causative agent of globally reemerging diphyllobothriosis.

Emerging infectious diseases, 21 10 , p. DPDx is an educational resource designed for health professionals and laboratory scientists. For an overview including prevention, control, and treatment visit www. Page last reviewed: May 14,

FERDINANDO CARULLI SICILIANA PDF

Широкий лентец (Dibothriocephalus latus или Diphyllobothrium latum)

Resources Causal Agents Several members of the cestode tapeworm family Diphyllobothriidae are known to infect humans. These pseudophyllidean cestodes have a scolex bearing bothria grooves , instead of suckers as in the cyclophyllidean cestodes the group including nearly all human-infecting species. All species associated with human diphyllobothriid infections have marine or aquatic life cycles and transmission occurs via ingestion of undercooked fish. Recent research incorporating morphologic and molecular data has led to the re-classification and re-naming of most of the human-infecting diphyllobothriids. However, it is possible that many historical cases were falsely attributed to this species.

ENGL Z9 PDF

Diphyllobothriasis

History[ edit ] Diphyllobothrium latum scolex The fish tapeworm has a long documented history of infecting people who regularly consume fish and especially those whose customs include the consumption of raw or undercooked fish. In the s, most of the known cases of diphyllobothriasis came from Europe 5 million cases , and Asia 4 million cases with fewer cases coming from North America and South America, and no reliable data on cases from Africa or Australia. Evidence of Diphyllobothrium spp. Due to the changing dietary habits in many parts of the world, autochthonous, or locally acquired, cases of diphyllobothriasis have recently been documented in previously non-endemic areas, such as Brazil. Morphology[ edit ] The adult worm is composed of three fairly distinct morphological segments: the scolex head , the neck, and the lower body. Each side of the scolex has a slit-like groove, which is a bothrium for attachment to the intestine.

HEIDEGGER ORIGINEA OPEREI DE ARTA PDF

Представленная в разделе информация о лекарственных препаратах, методах диагностики и лечения предназначена для медицинских работников и не является инструкцией по применению. Часть взрослой особи Dibothriocephalus проглоттидов. Сколекс в образце отсутствовал. Dibothriocephalus latus, синоним Diphyllobothrium latum; англ. Возбудитель дифиллоботриоза синоним: диботриоцефалёз человека и животных. Название гельминта связано с формой члеников, составляющих его тело стробилу , ширина которых намного больше длины. Широкий лентец отличается своей длиной, в организме хозяина она может достигать 10 и более метров.

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