wla lngTaenia saginata
Species: T. saginata
Taenia saginata, also known as Taeniarhynchus saginata or the beef tapeworm, is a parasite of both cattle and humans, causing taeniasis in humans. Taenia saginata occurs where cattle are raised by infected humans maintaining poor hygiene, human feces are 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, Southeast Asia, and Latin ...view middle of the document...
When they dry up, the proglottid ruptures, and the eggs are released. The egg can only infect cattle, the intermediate host. Inside the cow's duodenum, the oncosphere hatches with the help of the gastric and intestinal secretions, and migrates through the blood to the muscle. There it develops into infective cysticercoid cysticerci.
The life cycle of Taenia saginata
The life cycle is indirect and complicated, and is completed in humans as the definitive host and cattle as the intermediate host. The adult worm inhabits the small intestine of humans. Fertilized eggs are released through the faeces along with the gravid proglottid which gets detached from the strobila. Cattle ingest the infective embryo while grazing. The digestive enzymes will break the thick shell of the egg and allow formation of the zygotes called "oncospheres". These zygotes then penetrate the mucous layer of the digestive tract and enter the circulation of the host. This is where the young larval stages form a pea-sized, fluid filled cyst, also known as “Cysticercus bovis” and these cysts seem to form in the muscular fibers and are sometimes seen in specific organs like the lungs and liver. Humans acquire the infective larvae from eating undercooked meat i.e.,measley beef. The digestive enzymes break down the cysticercus and the larval cyst is released and the inverted scolex is able to come out and attach to the host’s intestine. Adult tapeworm take about 2 months to develop, and within three months it can reach 5 m long.
The disease is relatively common in Africa, some parts of Eastern Europe, the Philippines, and Latin America. Humans become infected when they eat undercooked beef. Prevention is easy; cook beef until it is no longer pink inside and 56°C in the center, because this kills the cysticerci. Also, beef frozen at -5°C is considered to be safe to consume.
This parasite is found anywhere where beef is eaten, even in countries such as the United States, with strict federal sanitation policies. In the US, the incidence of infection is low, but 25% of infected cattle are still sold.
Tapeworms are usually asymptomatic. However heavy infection often results in weight loss, dizziness, abdominal pain, diarrhea, headaches, nausea, constipation, or chronic indigestion, and loss of appetite. There can be intestinal obstruction in humans and this can be alleviated by surgery. The tapeworm can also expel antigens that can cause an allergic reaction in the individual.
The basic diagnosis is done from a stool sample. Feces are examined to find parasite eggs. 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 it as Taenia saginata. Proglottids sometimes trickle down the thighs of infected humans and are visible with unaided...