Beef Tapeworm, Taenia saginata or Taeniarhynchus saginata

The beef tapeworm (Taenia saginata or Taeniarhynchus saginata) is a species of tapeworm that is classified within the Platyhelminthes phylum. It can affect both cattle and humans, and causes the disease taeniasis in humans. It can be found in many areas that have a beef market including Africa, the Philippines, Latin America, and Eastern Europe, although it is not abundant in this area. It does occur in the United States, but it is not common due to high sanitation standards.

The beef tapeworm can reach an average body length between thirteen and thirty-two feet, although some individuals can grow to be thirty-nine feet in length. Its white body is dived into a head, or scolex, a neck, and a long body known as a strobila. The scolex of this species differs from that of other tapeworms in that it lacks a scolex armature and a rostellum, instead holding four strong suckers. The body is comprised of segments that resemble ribbons, which are actually mature and pregnant proglottids. This species is the largest within its genus, holding between one thousand and two thousand proglottids. Mature beef tapeworms have both male and female sexual organs, including testes, an ovary, a genital pore, and a vitelline gland. This species does not have a mouth, anus, digestive tract, or digestive system. It can live to be twenty-five years of age within a host.

Despite the beef tapeworm’s common name and its prevalence in cattle, its definitive or main hosts are actually humans. Adult worms residing in the small intestine of a human will lay eggs in the proglottids, making them pregnant sections, which are then released in feces. The proglottid segments can act as worms if ingested, but if they are not consumed, they will dry up, releasing the eggs within. These eggs can only develop within cattle, the worm’s intermediate host. Once the eggs are in the stomach of an intermediate host, the digestive enzymes will break down the eggs, allowing the development of oncospheres, or zygotes. The zygotes penetrate through the mucous lining of the digestive tract and travel through the blood stream where they develop into small larvae. The larval stage beef tapeworm will develop into cysts within the blood stream that are sometimes known as Cysticercus bovis. It is thought that the cysts develop with the muscle tissue and have been found in the liver and the lungs of the intermediate host. In humans, a beef tapeworm infection begins when undercooked meat is consumed. Once the stomach acids break down the cysticercus containing a larval tapeworm, the worm will move into the intestine to develop. The worm will reach maturity after about two months, reaching an average size of about sixteen feet.

Most hosts of a beef tapeworm do not show signs of infection, but if the infection is bad, hosts may experience abdominal pain, headaches, dizziness, weight loss, diarrhea, nausea, constipation, and chronic indigestion. In humans, the tapeworm may create a blockage in the intestine or cause an allergic reaction when it releases antigens.

The most common method of diagnosing a beef tapeworm is stool examinations. Although it is relatively simple to locate the eggs of this species within feces, it is difficult to distinguish them from other species within its family. In order to distinguish the tapeworm from other worms, experts can examine the feces for proglottids or scolex. Sometimes the proglottid segments can be found on the thighs of an infected human host, which helps in the diagnosis procedure. Because the beef tapeworm is so similar in appearance to other tapeworms, histological examinations are typically conducted to confirm an infection. These tests include examining the uterine branches of the worm and PCR tests.

Most beef tapeworm infections can be treated using medicines including praziquantel, which paralyzes the worm and allows the host to flush it out of the intestines, or Niclosamide, which is often used to treat worm infections of the Trematoda class. In order to prevent an infection in humans, it is important to thoroughly cook beef products. Salting or freezing the beef products will also kill the infective larvae within the meat, but other measures, like sanitary disposal of human waste, should be taken.

Image Caption: This is an adult Taenia saginata tapeworm. Credit: Wikipedia