Humans are the only known definitive hosts for the T. Human infection begins with the ingestion of infected raw or undercooked pork. The T. There it will mature and increase its number of proglottids.
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Taenia solium can also cause cysticercosis. Life Cycle Taeniasis is the infection of humans with the adult tapeworm of Taenia saginata, T. Humans are the only definitive hosts for these three species. Eggs or gravid proglottids are passed with feces ; the eggs can survive for days to months in the environment. Cattle T. A cysticercus can survive for several years in the animal. Humans become infected by ingesting raw or undercooked infected meat. In the human intestine, the cysticercus develops over 2 months into an adult tapeworm, which can survive for years.
The adult tapeworms attach to the small intestine by their scolex and reside in the small intestine. Length of adult worms is usually 5 m or less for T. The adults produce proglottids which mature, become gravid, detach from the tapeworm, and migrate to the anus or are passed in the stool approximately 6 per day.
The eggs contained in the gravid proglottids are released after the proglottids are passed with the feces. Geographic Distribution Taenia saginata and T. Taenia solium is more prevalent in poorer communities where humans live in close contact with pigs and eat undercooked pork. Clinical Presentation Taenia saginata taeniasis produces only mild abdominal symptoms. The most striking feature consists of the passage active and passive of proglottids.
Occasionally, appendicitis or cholangitis can result from migrating proglottids. Taenia solium taeniasis is less frequently symptomatic than Taenia saginata taeniasis. The main symptom is often the passage passive of proglottids.
The most important feature of Taenia solium taeniasis is the risk of development of cysticercosis. Taenia spp. The eggs of Taenia spp. The eggs measure micrometers in diameter and are radially-striated. The internal oncosphere contains six refractile hooks. Figure A: Taenia sp. Figure E: Unstained Taenia sp. Four hooks can easily be seen in this image. Figure B: Taenia sp. Figure C: Iodine-stained wet mount of a Taenia sp. Figure D: Iodine-stained wet mount of a Taenia sp.
The scolex of T. There are usually 13 hooks of each size. Figure A: Scolex of T. Note the four large suckers and rostellum containing two rows of hooks. Figure B: Scolex of T. Figure C: Scolex of T. Note the four large suckers and lack of rostellum and rostellar hooks. Gravid proglottids are longer than wide and the two species, T. Proglottids of T. Figure A: Mature proglottid of T. Figure E: Proglottid of T. Figure B: Mature proglottid of T. Figure C: Mature proglottid of T.
Note the number of primary uterine branches Figure D: Mature proglottid of T. Note the number of primary uterine branches Cross-sections of Taenia spp. Figure A: Cross-section of a proglottid of Taenia sp. Note the thick outer tegument and the loose parenchyma filling the body. Calcareous corpuscles red arrows , characteristic of the cestodes, can be seen in the parenchyma. Figure E: Close-up of a cross-section of a Taenia sp. Image courtesy of the Michael E. DeBakey V. Medical Center in Houston, TX.
Figure B: Cross-section of a proglottid of Taenia sp. Eggs blue arrows can also be seen. Figure F: Close-up of a cross-section of a Taenia sp. Image courtesy of Ameripath. Figure C: Higher magnification of the image in Figure B, showing a close-up of the eggs. Note the characteristic striations, typical for the taeniids.
Not visible in these images are the hooks commonly seen in cestode eggs. Adults can reach a length of meters, but the scolex is only millimeters in diameter. Figure A: Taenia saginata adult worm. The adult in this image is approximately 4 meters in length. Figure B: Taenia saginata adult worm. Laboratory Diagnosis Microscopy Microscopic identification of eggs and proglottids in feces is diagnostic for taeniasis, but is not possible during the first 3 months following infection, prior to development of adult tapeworms.
Repeated examination and concentration techniques will increase the likelihood of detecting light infections. Nevertheless, identification of Taenia is not possible if solely based on microscopic examination of eggs, because all Taenia species produce eggs that are morphologically identical. Eggs of Taenia spp. Microscopic identification of gravid proglottids or, more rarely, examination of the scolex allows species determination.
Separation of T. Taenia saginata has primary lateral uterine branches, while T. Visualization of the branches can be improved by clearing the specimen in lactophenol followed by India ink injection into the lateral genital pore.
Gently sandwich the proglottids between two glass microscope slides, with the genital pore exposed along the edge of the two slides. Using a small gauge 25 or 27 g tuberculin syringe, slowly inject India ink into the genital pore. Allow the ink to flow down the uterine stem and into the primary uterine branches.
Count the number of primary uterine branches to determine the species for T. Antibody detection May prove useful especially in the early invasive stages, when the eggs and proglottids are not yet apparent in the stools. For an overview including prevention, control, and treatment visit www. Page last reviewed: December 18,
Taenia Solium (Pork Tapeworm) Infection and Cysticercosis
Taeniasis is an intestinal infestation of adult tapeworms. It is acquired by humans through the ingestion of tapeworm larval cysts cysticerci in raw or undercooked pork. One tapeworm carrier can excrete tens of thousands of eggs per day and has therefore a special importance in the epidemiology of the parasite. Cysticercosis develops when humans or pigs ingest the excreted tapeworm eggs. This happens most likely as a result of poor hygiene, through contaminated food or water and when pigs have access to human faeces.
Taenia solium can also cause cysticercosis. Life Cycle Taeniasis is the infection of humans with the adult tapeworm of Taenia saginata, T. Humans are the only definitive hosts for these three species. Eggs or gravid proglottids are passed with feces ; the eggs can survive for days to months in the environment. Cattle T. A cysticercus can survive for several years in the animal.