wla lngTaenia saginata

Scientific classification
Kingdom: Animalia
Phylum: Platyhelminthes
Class: Cestoda
Order: Cyclophyllidea
Family: Taeniidae
Genus: Taenia
Species: T. saginata
Binomial name
Taenia saginata
Goeze, 1782
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 America.

Taenia saginata proglottid stained to show uterine branches. The pore on the side identifies T. saginata as a cyclophyllid cestode.
T. saginata is normally 4 m to 10 m in length, but can become very large, over 12 m long in some situations. The body is whitish in colour, divided into the anterior scolex, followed by a short neck and a highly extended body proper called the strobila. Unlike other tapeworms, the scolex does not have a rostellum or scolex armature. It is composed of four powerful suckers. The strobila is composed a series of ribbon-like segments called proglottids. The segments are made up of mature and gravid proglottids. T. saginata is the largest of genus Taenia, consisting between 1000 to 2000 proglottids, and can also have a lifespan of 25 years in a host's intestine.

The mature proglottid contains the uterus (unbranched), ovary, genital pore, testes, and vitelline gland. It does not have a digestive system, mouth, anus, or digestive tract. It is also an acoelomate, meaning it does not have a body cavity. In the gravid proglottid, the uterus is branched and filled with eggs. The gravid segments detach and are passed in the feces. Each of these segments can act as a worm. 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.
Epidemiology

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.

Symptoms
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.
Diagnosis

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 eye, so can aid with identification. Observation of scolex help distinguish between T. saginata, T. solium and T. asiatica. When the uterus is injected with India ink, its branches become visible. Counting the uterine branches enables some identification (Taenia saginata uteri have 12 or more branches on each side, while other species such as Taenia solium only have five to 10).
Differentiation of the species from other species of Taenia, such as T. solium and T. asiatica, is notoriously difficult because of their close morphological resemblance, and their eggs are more or less identical. Identification often requires histological observation of the uterine branches and PCR detection of ribosomal 5.8S gene. T. saginata’s uterus stems out from its center to form 12 to 20 branches, but in contrast to its closely related Taenia species, the branches are much less in number and comparatively thicker; in addition, the ovaries are bilobed and testes are twice as many.
Treatment
Treatment for cestode infection with the drug praziquantel opens membrane calcium channels, causing paralysis of the worm, thus aiding the body in expelling the parasite through peristalsis. Niclosamide, used to treat many different kinds of infections with trematodes and adult tapeworms, is also quite effective.
Epidemiology
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.
TAENIA SOLIUM
Taenia solium, also called the pork tapeworm, is a cyclophyllid cestode in the family Taeniidae. It infects pigs and humans in Asia, Africa, South America, parts of Southern Europe and pockets of North America. In the larval stage, it causes cysticercosis, which is a major cause of seizures in humans. Like all cyclophyllid cestodes, T. solium has four suckers on its scolex ("head"). T. solium also has two rows of three hooks.
T. solium , commonly known as tapeworm, is a triploblastic aceolomate. It is normally 2 to 3 m in length, but can become very large, over 50 m long in some situations.
T. solium has a very similar life cycle to Taenia saginata. Cysticerci have three morphologically distinct types. The common one is the ordinary "cellulose" cysticercus, which has a fluid-filled bladder 0.5 cm to 1.5 cm in length and an invaginated scolex. The intermediate form has a scolex, while the "racemose" has no evident scolex but is believed to be larger and much more dangerous. They are 20 cm in length and have 60 ml of fluid, and 13% of patients might have all three types in the brain. Humans are usually infected through eating infected pork, fostering adult tapeworms in the intestine, and passing eggs through feces, but autoinfection is also possible. In that case, a cysticercus (a larva sometimes called a "bladder worm") develops in the human, who acts as an intermediate host. This happens if eggs get to the stomach, usually as a result of contaminated hands, but also due to retroperistalsis. Cysticerci often occur in the central nervous system, which can cause major neurological problems, such as hydrocephalus, paraplegy, meningitis, convulsions and even death. The condition of having cysticerci in one's body is called cysticercosis.
Eggs can be diagnosed only to the family level, but if a proglottid's uterus is stained with India ink, the number of visible uterine branches can help identify the species; unlike the Taenia saginata uteri, T. solium uteri have only five to 10 uterine branches on each side.
Infection with T. solium adults is treated with niclosamide, which is one of the most popular drugs for adult tapeworm infections, as well as for fluke infections. As cysticercosis is a major risk, it is important to wash one's hands before eating and to suppress vomiting if a patient may be infected with T. solium. If neurocysticercosis occurs, the drug of choice is either albendazole or praziquantel. These drugs damage the parasites' skin internally, causing it to disintegrate and is then removed by the host's immune system.
Infection may be prevented with proper disposal of human feces around pigs, cooking meat thoroughly and/or freezing the meat at −10°C for 5 days. Most cases occur because infected food handlers contaminate the food.

Life cycle
This infection is caused by ingestion of eggs shed in the feces of a human tapeworm carrier. Pigs and humans become infected by ingesting eggs or gravid proglottids. Humans are infected either by ingestion of food contaminated with feces containing eggs, or by autoinfection. In the latter case, a human infected with adult T. solium can ingest eggs produced by that tapeworm, either through fecal contamination or, possibly, from proglottids carried into the stomach by reverse peristalsis. Once eggs are ingested, oncospheres hatch in the intestine, invade the intestinal wall, and migrate to striated muscles, as well as the brain, liver, and other tissues, where they develop into cysticerci. In humans, cysts can cause serious sequelae if they localize in the brain, resulting in neurocysticercosis. The parasite life cycle is completed, resulting in human tapeworm infection, when humans ingest undercooked pork containing cysticerci. Cysts evaginate and attach to the small intestine by their scolices. Adult tapeworms develop, (up to 2 to 7 m in length and produce less than 1000 proglottids, each with approximately 50,000 eggs) and reside in the small intestine for years.
Pathogenesis

Ingestion of T. solium eggs or proglottid rupture within the host intestine can cause larvae to migrate into host tissue and cause cysticercosis. This is the most frequent and severe disease caused by T. solium. In symptomatic cases, a wide spectrum of symptoms may be expressed, including headaches, dizziness and occasional seizures. In more severe cases, dementia or hypertension can occur due to perturbation of the normal circulation of cerebrospinal fluid. (Any increase in intracranial pressure will result in a corresponding increase in arterial blood pressure, as the body seeks to maintain circulation to the brain.) The severity of cysticercosis depends on location, size and number of parasite larvae in tissues, as well as the host immune response. Other symptoms include sensory deficits, involuntary movements, and brain system dysfunction. In children, ocular location of cysts is more common than cystation in other locations of the body. Heavy infection with T. solium can lead to neurocysticercosis, which can lead to epilepsy, seizures, lesions in the brain, blindness, tumor-like growths, and low eosinophil levels.
Diagnosis
Taenia solium adult
Diagnosis requires biopsy of the infected tissue and examination of feces. T. solium eggs and proglottids found in feces diagnoses taeniasis and not cysticercosis. Cysticercosis is diagnosed primarily on confirming the presence of hooks on the scolex of T. solium. Radiological tests, such as X-ray, CT scans which demonstrate "ring-enhancing brain lesions", and MRIs, can also be used to detect diseases. X-rays are used to identify calcified larvae in the subcutaneous and muscle tissues, and CT scans and MRIs are used to find lesions in the brain.

Treatment
Praziquantel (PZQ) is the drug of choice for the treatment of T. solium infection. Some consider niclosamide to be the drug of choice for all types of tapeworms. For cysticercosis,treatment with albendazole combined with steroids reduces the inflammation. Surgical intervention may be necessary to treat central nervous system lesions. Albendazole appears to be more effective and a safe drug for neurocysticercosis.
Epidemiology
Stained T. solium proglottid
T. solium is found worldwide, but is more common in cosmopolitan areas. Because pigs are intermediate hosts of the parasite, completion of the life cycle occurs in regions where humans live in close contact with pigs and eat undercooked pork. Cysticercosis is often seen in areas where poor hygiene allows for contamination of food, soil or water supplies. Prevalence rates in the United States have shown immigrants from Mexico, Central and South America and Southeast Asia account for most of the domestic cases of cysticercosis. Taeniasis and cysticercosis are very rare in predominantly Muslim countries, as Islam forbids the consumption of pork. Human cysticercosis is acquired by ingesting T. solium eggs shed in the feces of a human tapeworm carrier via gravid proglottids, so can occur in populations that neither eat pork nor share environments with pigs, although the completion of the life cycle can occur only where humans live in close contact with pigs and eat pork.
In 1990 and 1991, four unrelated members of an Orthodox Jewish community in New York City developed recurrent seizures and brain lesions, which were found to have been caused by T. solium. In keeping with their religion, none of the patients ate pork; additionally, none had any history of recent foreign travel. Several immediate family members of these four patients with seizures were found to have cysticercus antibodies. The families of the four patients had all employed housekeepers from Latin American countries, and one of the housekeepers tested positive for cysticercus antibodies, leading to the conclusion that the housekeepers were the most likely source of the infections.

TAENIA SAGINATA

TAENIA SOLIUM