The Beef Tapeworm and the Human Host
Esoteric Facts About Taenia saginata, Large Cestode of Humans
Mar 24, 2009
Until 1782, when J. Goeze described the species, scientists believed that Taenia saginata, the beef tapeworm, was the same as T. solium, the pork tapeworm. Through the 19th and 20th centuries, the worm was referred to by at least ten different names in scientific literature including, perhaps appropriately, Taenia confusa.
Why Do People Get Beef Tapeworm?
More than two hundred years after its discovery, we know that T. saginata is the most common Taenia sp. tapeworm of humans. We understand its life cycle and why it’s successful:
- Like many animals, cows deliberately eat feces, including human feces, which promotes infection in cows.
- Worm segments routinely migrate out of the human intestine on their own. In 1857, Küchenmeister wrote: “The passage of the segments without faeces is a constant annoyance… The [segments] … in the trowsers, or under the petticoats, being disagreeable, from their clammy coldness, disturb the patients greatly; and women especially are afraid lest the proglottids should fall unperceived upon the ground when they are walking or standing (p. 137).” It’s easy to see that infected cattle herders can unwittingly deposit many tapeworm segments where their herds graze and have likely done so for millennia.
- Taenia saginata has lots of segments to spread around - between one thousand and two thousand per adult worm.
- Humans have spread Taenia saginata around the world - with cows. Believed domesticated in the present-day Middle East, India, and Africa, cattle now live on every continent except Antarctica.
The History of Beef Tapeworm Diagnosis and Treatment
Diagnosis and treatment of beef tapeworm have come a long way:
- Early scientists believed that tapeworms came from spontaneous generation - that they just appeared in the intestine.
- Before scientists knew the life cycle of the beef tapeworm, they thought that the cysts in beef were a different parasite, which they named Cysticercus bovis.
- Later, scientists thought that cysts in beef were T. saginata worms that had gotten lost in the wrong host.
- Ancient and cultural remedies for T. saginata infection included eating the dried, powdered proglottids of T. solium, drinking a tea made from pomegranate rind, root, or root bark, and various other herbal preparations, most of which were meant to make the patient expel intestinal worms. (Don’t try these remedies: some of them are dangerous.)
Strange Facts from Beef Tapeworm Research
Sometimes scientific research takes unexpected turns:
- Parasitologist M. Wong needed T. saginata eggs in the 1970’s for her research. Because the worm must have a human host, Wong infected herself deliberately and hosted two worms, which she named Horace the Second A and B.
- Study of fossilized human feces from 3200 – 2500 BC reveals Taenia sp. eggs from Africa, the Middle East, China, Europe, and Canada. The oldest are from France, while Canadian finds date from 17th century Newfoundland.
- The oldest known Taenia infection was diagnosed in an Egyptian mummy from 5200 years ago.
Despite its long success, if humans on Earth achieved global standards of sanitation like those in the West today, beef tapeworm would be exterminated.
Sources
Animal and Vegetable Parasites of the Human Body. Küchenmeister, Frederich. Trans. Edwin Lankester. London: Sydenham Society, 1857.
Foundations of Parasitology 6th Ed. Roberts, Larry S. and John Janovy Jr. Boston: McGraw Hill, 2000.
“Human Intestinal Parasites in the Past: New Findings and a Review.” Gonçalves, Marcelo Luiz Carvalho, Adauto Araújo, and Luiz Fernando Ferreira. Mem Inst Oswaldo Cruz, 98(Suppl.1): 103-118, 2003.
Parasites and Parasitic Infections in Early Medicine and Science. Hoeppli, R. Singapore: University of Malaya Press, 1959.
“The Infectious Nature of Parasitology.” Mayberry, Lillian. Journal of Parasitology, 82(6): 855-864, 1996.
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