Beef tapeworm

Taxobox
name = "Taenia saginata"
regnum = Animalia

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image_width = 250px
phylum = Platyhelminthes
classis = Cestoda
ordo = Cyclophyllidea
familia = Taeniidae
genus = Taenia
species = "T. saginata"
binomial = "Taenia saginata"
binomial_authority = Goeze, 1782

"Taenia saginata", also known as "Taeniarhynchus saginata" or the Beef tapeworm, is a parasite of both cattle and humans, but which can only reproduce asexually in humans. "Taenia saginata" occurs where cattle are raised by infected humans maintaining poor hygine, human feces is improperly disposed of, meat inspection programs are poor, and where meat is eaten without proper cooking. The disease is relatively common in Africa, some parts of Eastern Europe, the Philippines, Mexico, and Latin America.Lange Microbiology, Chapter 46. Medical Parasitology.]

"Taenia saginata" are normally 3m to 5m in length, but it can become very large, over 20m in some situations. It does not have a rostellum or scolex armature. The scolex is composed of 4 powerful suckers. The segments are made up of mature and gravid proglottid. The mature proglottid contains the uterus (unbranched), ovary, genital pore, testes, and vitelline gland. In the gravid proglottid the uterus is branched that are filled with eggs. It is the gravid segments that detaches and are passed in the feces. Each of these segments can act like a worm. When they dry up it ruptures and the eggs are released. The egg can only infect cattle, the intermediate host. Inside the cow's duodenum the oncosphere hatch with the help of the gastric and intestinal secretions and migrates through the blood to the muscle. There it develops into infective cysticerci.Schmidt, GD, et al. (2005). Foundations of Parasitology. New York, New York. McGraw-Hill Companies, Inc.]

Humans become infected when they eat beef that is not cooked fully. Prevention is easy. Cook beef until it is no longer pink inside because cysticerci die at 56 degrees Celsius. Also, if beef is frozen at -5 degrees Celsius it is considered to be safe to consume.

This parasite is found anywhere where beef is eaten, even in countries like the United States where there are strict federal sanitation polices. In the U.S. the incidence of becoming infected is low however, one-fourth of infected cattle are still sold.

Symptoms are usually asymptomatic, as impossible as that may sound. Some symptoms include dizziness, abdominal pain, diarrhea, headaches, nausea, and loss of appetite. There can be intestinal obstruction in humans and this alleviated by surgery. The tapeworm can also expel antigens that can cause an allergic reaction in the individual.

Diagnosis: The eggs look like other eggs from the family Taeniidae, so it is only possible to identify the eggs to the family, not to the species, level. Since it is difficult to diagnose using eggs alone, looking at the scolex or the gravid proglottids can help identify if it is "Taenia saginata". Proglottids sometimes trickle down the thighs of infected humans and are visible with unaided eye and aid with identification. When the uterus is injected with India ink, its branches become visible. Counting the uterine branches enables some identification ("Taenia saginata" uteri have twelve or more branches on each side, while other species like "Taenia solium" only have five to ten).

Treatment for cestode infection can be done with the drug praziquantel. Praziquantel opens membrane calcium channels causing paralysis of the worm, aiding the body in expelling the parasite through peristalsis. Niclosamide, used to treat many different kinds of infections with trematodes and adult tapeworms, is quite effective.

References