Taenia is a genus of tapeworm that includes some important parasites of livestock. Not all members of the Genus Taenia have an armed scolex (hooks located in the "head" region), for example, Taenia saginata has an unarmed scolex, while Taenia solium has an armed scolex.3
Proglottids have central ovary, with a vitellarium (yolk gland) posterior to it. As in all cyclophyllid cestodes, there is genital pore on the side of the proglottid. Eggs are released when proglottid deteriorates, and so a uterine pore is unnecessary.
Important species include:
- Taenia saginata, which is also known as the "beef tapeworm," though it also infects humans, and can only reproduce while in the human gut.
- Taenia solium, which is known as the "pork tapeworm." Like Taenia saginata humans serve as its primary host, and it can only reproduce by the dispersal of proglottids while in the gut. These reinfect pigs when human faeces is improperly disposed of. This infection is most common in parts of Africa.
- Taenia pisiformis, which is common in wild dogs and in rabbits, who serve as intermediate hosts.
- Taenia crassiceps
- Taenia gonyamai, parasite of antelope (larval-) and lions (adult forms).
- Taenia taeniaeformis, which uses rodents as intermediate hosts and then inhabits cats as the definitive host.
The life cycle begins with either the eggs or the gravid proglottids being passed in the feces, which can last for days to months in the environment (1). Then, cattle or pigs ingest the contaminated vegetation with eggs or proglottids (2). The oncospheres hatch in the small intestine of the cattle or pig(3) and invade the intestinal wall to travel to the striated muscles to develop into cysticerci. Humans can become infected when eating raw beef or pork meat (4). In the human, the cysticercus develop into adults in two months in the intestines. Using their scolex, they attach to the small intestine(5) where they reside(6). Taenia saginata are about 1,000-2,000 proglottids long with each gravid proglottid containing 100,000 eggs, while Taenia solium contain about 1,000 proglottids with each gravid proglottid containing 50,000 eggs.2
Treatment with Praziquantel (PZQ) has been approved by the FDA and is quite effective.2
- ^ (German)Sachs, R (1969). "Untersuchungen zur Artbestimmung und Differenzierung der Muskelfinnen ostafrikanischer Wildtiere". ZARRAYropenmedizin und Parasitologie 20 (1): 39–50.
3. Roberts, L.S. and Janovy, John Jr. Foundations of Parasitology 7th Edition. McGraw-Hill. 2005.