Taenia saginata

The bovine tapeworm (beef tapeworm), Taenia saginata, has been used to reduce body weight in obese individuals, something that it does very efficiently. It can also be very long-lived, and arguably a very effective immunomodulator, but it does not meet the criteria for a therapeutic helminth, which include causing no pathology in the host and posing no risk of infection to others. (See Therapeutic helminths.)

Disadvantages of Taenia saginata

After 166 days, this animal starts to shed proglottid sacks, each of which will contain thousands of eggs that are remarkably resilient. These sacks are motile, so they literally walk out of their host’s anus and down his or her leg, with obvious potential to infect animals and other humans.

The only way to prevent the shedding of proglottid sacks is to eliminate the infection every 5 months, which, depending on the drug used, would be likely to have an adverse effect on any other species of helminth that is being hosted for therapeutic purposes.

There is a risk of a T. saginata host developing deficiency diseases and, potentially, other health problems. When fully grown, this animal will consume up to 30% of its host's calories to feed its considerable size (normally 9 to 15 feet in length, but potentially reaching up to 60 feet). It will also slow peristalsis to increase its uptake of nutrients.

Due to its size, T. saginata may cause intestinal obstruction, especially in someone prone to develop strictures, such as a patient with Crohn’s disease.

Although rare, there is also a risk of intestinal perforation by T. saginata, [1] and a potential for oral expulsion. [2]

Genetic modification of Taenia saginata

Researchers considering possible alternatives to the organisms currently being used in helminthic therapy have suggested that some of the risks presented by T. saginata might be amenable to genetic modification, especially its infectivity, and possibly also its size. If such modification were achieved, this species may then become a more viable option for therapeutic use.