1. The Pork Tapeworm Taenia solium

2. Appearance and General Information
The pork tapeworm is a flatworm, belonging to the phylum Platyhelminthes. It is one of the most potentially dangerous adult tapeworms to humans. 3
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Its body is white and ribbon like. 5
It is about 6 mm wide, 4 and usually 2 to 3 metres long, but some specimens can reach over 9 metres. 3

3. Parts of the Tapeworm Taenia solium has 3 main body parts:
The head (scolex)
A neck
An elongated body (the strobilia)

4. The Scolex The Strobilia
Tapeworm Scolex
The scolex of the tapeworm is spheroid and about 1 mm in diameter. It has 4 suckers surrounding the rostellum (mouthparts), for attachment. 5
The Strobilia
The strobilia is divided into 800 – 900 segments, called proglottids. Growth occurs from the neck, so the oldest segments, known as gravid proglottids, are at the posterior end of the tapeworm. 5

5. The Life Cycle of Taenia solium

6. Life Cycle in Humans
Humans are the primary hosts, so they are infected with the adult stage of the tapeworm. Infection occurs when a person eats ‘measly’ pork infected with the tapeworm larvae. The larvae, called cysticerci, are small oval capsules, containing an inverted scolex. When stimulated by stomach enzymes, the scolex pops out and anchors to the wall of the small intestine, and the strobilia begins to grow. 5 It takes between 5 and 12 weeks for the tapeworm to mature. 3 Adult tapeworms may live for up to 25 years. 4
A cysticercus

7. Reproduction
The pork tapeworm is a hermaphrodite, which means it can self-fertilise. 5 Each proglottid contains male and female organs which fertilise each other. A gravid proglottid may contain up to 50,000 eggs. 5
The eggs pass out in the faeces, either individually or in the proglottids. They can survive in the environment for up to 2 months. 5
A Taenia solium egg

8. Life Cycle in Pigs
Pigs are the intermediate, or secondary hosts. They become infected when they ingest eggs in human faeces or infected vegetation. Once inside, the tapeworm eggs hatch into motile larvae (oncospheres) and attach to the intestinal wall. 5 The larvae penetrate the intestine and travel through blood and lymphatic vessels to various organs in the body, particularly to the muscles, brain tissue and the liver. 5
Measly Pork
In these areas they form cysts, called cysticerci, around 1 to 2 cm in diameter. This takes around 70 days, however the cysts continue to grow for up to a year. 5 The cysticerci then remain dormant unless the infected pork is eaten by humans.

9. Humans as Intermediate Hosts
Humans can accidentally become the secondary hosts, either by autoinfection, where tapeworm eggs hatch inside the intestine, or by eating food contaminated with tapeworm eggs. 5 If this happens, cysts will form inside the person. The cysticerci can form in nearly any tissue or organ, but are usually found in subcutaneous connective tissue, the eye, the brain, or in the heart, liver or lungs. 3
Cysts in the Brain

10. Problems Caused by Cysts
When a cysticercus dies, it can cause a severe inflammatory response, which may be fatal to the host, particularly if it is in the brain. 3 Dead cysts are slowly calcified, which is particularly devastating for ocular cysts. 3 In rare cases, a cyst may become prolific, and develop branching extensions. This can cause tumor-like growths. 4

11. Symptoms
Taeniasis (infection by the adult tapeworm) Taeniasis does not usually show any symptoms; however in severe cases intestinal irritation, anaemia and indigestion can result. 5 Cysticercosis (infection by the larval stage) Cysticercosis is much more severe than taeniasis. Cysts in the brain (neurocysticercosis) may cause epilepsy, severe headaches, blindness and even death. 6 In the eye, cysts can cause irreparable damage to the retina. 3 When in the muscle, skin or liver, there are few effects, however in some cases subcutaneous nodules may develop. 3 Symptoms may take several years to appear. 5

12. Facts and Statistics
Neurocysticercosis is the most frequent preventable cause of epilepsy worldwide (World Health Organisation 2015)
Neurocysticercosis causes up to 50,000 death per year (Encyclopedia of Life n.d.)
Up to 20 million people worldwide are infected with pork tapeworm cysticerci (Encyclopedia of Life n.d.)
Taeniasis affects up to 50 million people worldwide (Standford University 2004)

13. Where It Is Found
Taenia solium is found worldwide, wherever pork is eaten. Human infection mostly occurs in areas where people eat undercooked pork and live in close contact with pigs, i.e. areas like West Africa, South East Asia, India, Mexico and Latin America. 5
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14. Map Showing Countries at Risk of Cysticercosis

15. How Humans Encounter It
People become infected by the tapeworm when they consume ‘measly pork’ - undercooked pork that contains cysts. Infection by cysticerci can occur either by autoinfection, where tapeworm eggs hatch inside the intestine, or by consumption of food or water contaminated with tapeworm eggs. 5

16. Prevention
Prevention in Pork Pigs should be kept away from human faeces. Untreated human sewage should not be used as fertiliser for crops. Prevention in Humans High standards of personal hygiene are very important to prevent tapeworm eggs being ingested by humans. Tapeworm cysts in pork can be killed by either cooking the meat thoroughly, or by freezing at -10°C for 5 days. 1

17. Treatment
Praziquantel is the most effective drug used to treat taeniasis, however Niclosamide can also be used. 5 As the death of cysts causes an inflammatory response, treatment of cysticercosis varies, and may include: long term courses with Albendazole and/or Praziquantel, in addition to supporting therapy with corticosteroids and/or epilepsy preventing drugs. Surgery is often successful in removing cysts. 6 There is no standard treatment for neurocysticercosis; treatment is tailored to the individual’s situation. 6

18. Bibliography
1. Centers for Disease Control and Prevention 2014, Parasites - Cysticercosis, viewed 31 August 2015, 2. Medline Plus 2015, Tapeworm - beef or pork, viewed 31 August 2015, 3. Schmidt, G & Roberts, L 1989, Foundations of Parasitology (4th ed), Times Mirror/Mosby College Publishing, St Louis. 4. Stanford University n.d., Taenia Solium, viewed 1 September 2015, 5. Wikipedia 2015, Taenia solium, viewed 26 August 2015, 6. World Health Organisation 2015, Taeniasis/Cysticercosis, viewed 27 August 2015, 7. Encyclopedia of Life n.d., Taenia solium, viewed 8 September 2015,