No alimentary canal (direct absorption of nutrients through the skin) Anterior scolex (head end) with attachment structures which go into digestive systems Food uptake via tegument and scolex

Hermaphrodites: produce vast number of eggs Do not reproduce in intermediate host (vs. trematodes) NB main exception echinococcus (hydatid cyst disease)

Passive (trophic) - always through food

T. saginata - "beef tapeworm" T. solium - "pork tapeworm" T. asiatica - "asian tapeworm"

Scolex with four suckers 4-10 m long (max. 25 m) & take up most of the intestine 1000-2000 proglottids (sections) Each mature proglottid contains ~100,000 eggs - ~6 proglottids detach & pass in faeces/day

- Worldwide distribution ~60 mil. cases p. a. - Common in Africa; parts of Eastern Europe, Southeast Asia, Central and South America - Infection of humans by eating raw (steak tartare) or undercooked ("rare") beef

- Can live 25 years in small intestine - Caused by human faecal material going near to animals that act as intermediate host

- Can have more than one tapeworm at one time - Variable, often asymptomatic - Heavy infestations: Loss of appetite, weight loss, abdominal pain, diarrhea, constipation, chronic indigestion, dizziness - Most seriously = intestinal blockage; e.g. proglottids lodged in appendix, or bile/pancreatic ducts

- Caused by excessive absorption of nutrients by parasite - so much of nutrients in small intestine absorbed by tapeworm, not get into system at all - Problems caused by physical presence of tapeworm (not immunological factor) and its ability to absorb

- Examine faecal samples for eggs, only useful to identify family (Taeniidae). Difficult to differentiate between Taenia spp. - Eggs detected in faeces 2-3 months after infection - Examine stained proglottids to count uterine branches - help differentiate between Saginata (12+ branches per side) and other species (5-10 branches) - Comparison of ribosomal 5.8S gene - distinctivve restriction patterns - Molecular approach better - can see patterns in restrictive enzymes and see which enzyme present

- Praziquantel recommended drug, niclosamide - Intestinal blockage may require surgery - Cook beef until no longer pink inside (infective stage (cysticerci) dies at 56°C) - Freeze beef at -5°C - Good sanitation and meat inspection programmes - check presence of cysticerci in meat

- 2-7 m in length - Scolex with four suckers + two rows of hooks (= teeth) - ~1000 proglottids - Each mature proglottid = 50,000 eggs

- Worldwide ~4 million cases p.a. - Developing countries in Asia, Africa, South America - Infection by eating raw or undercooked pork (eg. BBQ pork sausages) - Less of an impact than beef tapeworm

- Exact same life cycle as T. saginata with different parasite and intermediate host - AUTOINFECTION - eggs can get stuck in human tissue and reinfect the individual and cause tissue cyst => more tissue damage - Cysticercosis (cysts within tissue) can occur in other zoonotic Taenia species, always occurs in genus Echinococcus

Adult worms: - Variable, similar to T. Saginata - Rare: perforates intestinal wall --> peritonitis