Taenia serialis

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Taenia serialis
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Platyhelminthes
Class: Cestoda
Order: Cyclophyllidea
Family: Taeniidae
Genus: Taenia
Species:
T. serialis
Binomial name
Taenia serialis
(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. [1] [2] In definitive hosts, T. serialis is acquired by eating tissues from a variety of intermediate hosts. [1] [3] 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. [1] [4]

Contents

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. [4]

The infection with the metacestode larval form (coenurus) of T. serialis is called Coenurosis. [3] [4] 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. [1] The symptoms are variable, and depend on the location and number of larvae. [3] [4] Epsiprantel, praziquantel, fenbendazole and surgical removal [4] [5] are used to combat coenuri infection but discretion should be used when treating this evoloving cestode of medical importance. [1]

Morphology

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. Taenia serialis is morphologically very similar to Taenia multiceps; however, they infect different areas of the body. T. serialis infects the subcutaneous tissue and T. multiceps will commonly infect the eyes and brain. [6]

Life Cycle

The eggs are expelled in feces of the dog and ingested by the intermediate rabbit host. In the rabbit or other accidental intermediate host the eggs hatch within the intestines then invade the intestinal wall and move into the bloodstream. The larva circulates in the blood to the central nervous system, muscles, or soft tissue where they can form a coenurus metacestode, which is the intermediate stage of the parasite. A coenurus is a fluid-filled cyst with one or more scoleces surrounded by a fibrous capsule. These normally form after 3 months and are a 10 cm wide lesion. [7] These painless nodules present in the skin or subcutaneous tissue are a sign of infection and are used to diagnose a host with the parasite. [6] 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. This life cycle is also very similar to T. pisiformis a canine and rabbit infecting parasite; however, T. pisiformis infected the body cavity of the rabbit and T. serialis infects muscle and subcutaneous tissue.

Treatment

Treating the lesions can be done with surgery or medicine. Oral praziquantel can be used to kill coenuri; however, the dead parasite will cause a large inflammatory response in the host. The inflammation can be managed with the use of corticosteroids. In many cases surgical removal of the coenurus is a safer option with leakage of fluid from the cyst during surgery being unlikely to cause a new cyst and surgical excision is often curative. [8]

Geographic distribution

Taenia serialis has been found in a number of locations including North America, South America, Europe and Africa. [3] [4]

Related Research Articles

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<i>Taenia solium</i> Species of Cestoda

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Spirometra is a genus of pseudophyllid cestodes that reproduce in canines and felines, but can also cause pathology in humans if infected. As an adult, this tapeworm lives in the small intestine of its definitive host and produces eggs that pass with the animal's feces. When the eggs reach water, the eggs hatch into coracidia which are eaten by copepods. The copepods are eaten by a second intermediate host to continue the life cycle. Humans can become infected if they accidentally eat frog legs or fish with the plerocercoid stage encysted in the muscle. In humans, an infection of Spirometra is termed sparganosis.

<i>Taenia</i> (tapeworm) Genus of flatworms

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<i>Echinococcus granulosus</i> Species of flatworm

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<i>Echinococcus multilocularis</i> Species of flatworm

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<i>Dipylidium caninum</i> Species of flatworm

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<i>Hymenolepis nana</i> Species of flatworm

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<i>Taenia crassiceps</i> Species of Cestoda

Taenia crassiceps is a tapeworm in the family Taeniidae. It is a parasitic organism whose adult form infects the intestine of carnivores, like canids. It is related to Taenia solium, the pork tapeworm, and to Taenia saginata, the beef tapeworm. It is commonly found in the Northern Hemisphere, especially throughout Canada and the northern United States.

<i>Taenia pisiformis</i> Species of flatworm

Taenia pisiformis, commonly called the rabbit tapeworm, is an endoparasitic tapeworm which causes infection in lagomorphs, rodents, and carnivores. Adult T. pisiformis typically occur within the small intestines of the definitive hosts, the carnivores. Lagomorphs, the intermediate hosts, are infected by fecal contamination of grasses and other food sources by the definitive hosts. The larval stage is often referred to as Cysticercus pisiformis and is found on the livers and peritoneal cavities of the intermediate hosts. T. pisiformis can be found worldwide.

Eucestoda Subclass of tapeworms

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Spirometra erinaceieuropaei is a parasitic tapeworm that infects domestic animals and humans. The medical term for this infection in humans and other animals is sparganosis. Morphologically, these worms are similar to other worms in the genus Spirometra. They have a long body consisting of three sections: the scolex, the neck, and the strobilia. They have a complex life cycle that consists of three hosts, and can live in varying environments and bodily tissues. Humans can contract this parasite in three main ways. Historically, humans are considered a paratenic host; however, the first case of an adult S. erinaceieuropaei infection in humans was reported in 2017. Spirometra tapeworms exist worldwide and infection is common in animals, but S. erinaceieuropaei infections are rare in humans. Treatment for infection typically includes surgical removal and anti-worm medication.

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Diphyllobothriasis is the infection caused by tapeworms of the genus Diphyllobothrium.

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<i>Taenia taeniaeformis</i> Species of flatworm

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Coenurosis in humans

Coenurosis is a parasitic infection that results when humans ingest the eggs of dog tapeworm species Taenia multiceps, T. serialis, T. brauni, or T. glomerata.

Coenurosis

Coenurosis, also known as caenurosis, coenuriasis, gid or sturdy, is a parasitic infection that develops in the intermediate hosts of some tapeworm species. It is caused by the coenurus, the larval stage of these tapeworms. The disease occurs mainly in sheep and other ungulates, but it can also occur in humans by accidental ingestion of tapeworm eggs.

<i>Taenia hydatigena</i> Species of flatworm

Taenia hydatigena is one of the adult forms of the canine and feline tapeworm. This infection has a worldwide geographic distribution. Humans with taeniasis can infect other humans or animal intermediate hosts by eggs and gravid proglottids passed in the feces.

References

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  2. Taenia serialis. The American Heritage Medical Dictionary. 2007. Houghton Mifflin Company 6 Dec. 2011 http://medical-dictionary.thefreedictionary.com/Taenia+serialis
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  4. 1 2 3 4 5 6 Coenurosis Fact Sheet. Parasites and Health. Centers for Disease Control. December 2011. http://dpd.cdc.gov/dpdx/html/Coenurosis.htm
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  7. Veterinary Ophthalomology http://onlinelibrary.wiley.com/doi/10.1046/j.1463-5224.2002.00230.x/full
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