(Gervais, 1847) Baillet, 1863
Taenia serialis, also known as a canid tapeworm, is found within canines such as foxes and dogs. Adult T. serialis are parasites of carnivores, particularly dogs, with herbivorous lagomorph mammals such as rabbits and hares, serving as intermediate hosts. In definitive hosts, T. serialis is acquired by eating tissues from a variety of intermediate hosts. Accidental infection of humans though, can occur when eggs are ingested from food or water contaminated with dog feces and the human then becomes the T. serialis intermediate host.
Hatching of the T. serialis usually occurs only if the eggs have been exposed to gastric secretions proceeded by intestinal secretions. The oncospheres hatch in the intestine, invade the intestinal wall, and are carried in the blood throughout the tissues. Within the tissues, the larvae (also called metacestodes) develop into cysticerci or coenuri, which are larvae that group within cysts.
The infection with the metacestode larval form (coenurus) of T. serialis is called Coenurosis. When humans ingest these eggs from definitive host remains, the eggs develop into coenuri. This coenuri can occur in humans within their muscles, brain, eye, or subcutaneous connective tissue though humans are neither the definitive of intermediate hosts of the T. serialis. The symptoms are variable, and depend on the location and number of larvae. Epsiprantel, praziquantel, fenbendazole and surgical removal are used to combat coenuri infection but discretion should be used when treating this evoloving cestode of medical importance.
The eggs of T. serialis are spherical and are 32 to 38 μm in diameter. The larvae form bladders called Coenurus metacestode that can grow to be as large as 10 cm in the intermediate hosts. The larvae are white and can mature to 40mm while the adult can reach lengths of up to 5 meters.
The eggs are expelled in feces of the dog and ingested by the intermediate rabbit host. In the rabbit the eggs hatch within the intestines. The larva circulate in blood to travel to the central nervous system, muscles, or soft tissue. After about 3 months, the larva form a 10 cm wide lesion called a Coenurus metacestode. Once the Coenurus metacestode has been consumed by the fox or dog, it completes its metamorphosis into an adult tapeworm. In the canid, the worm attaches to the intestine and feeds of the food that the host ingests. There the worm matures and can become as long as 5 meters. The adult cestode produces eggs which are spread into the environment by the feces of the definitive host.
- Roberts, L. and G. Schmidt. 2009. Foundations of Parasitology, 8th ed. The McGraw Hill Companies, Inc., New York, New York, p. 351-352.
- Taenia serialis. The American Heritage Medical Dictionary. 2007. Houghton Mifflin Company 6 Dec. 2011 http://medical-dictionary.thefreedictionary.com/Taenia+serialis
- Spickler, A. R. Taenia Infections. “2005 (May 1, 2005).” At http://www.cfsph.iastate.edu/DiseaseInfo/factsheets.php
- Coenurosis Fact Sheet. Parasites and Health. Centers for Disease Control. December 2011. http://dpd.cdc.gov/dpdx/html/Coenurosis.htm
- Johnstone, C. Parasites and Parasitic Diseases of Domestic Animals. Philadelphia, Pennsylvania: University of Pennsylvania Web. 2000. (http://cal.vet.upenn.edu/projects/dxendopar/parasitepages/cestodes/t_serialis.html) (6 December 2011).