1. Lab session 4
Helminths
Worms

2. Platyheminthes (flatworm)
Nematodes (roundworms)
2 types platyhelminthes
Trematodes (flukes)
Cestodes (tapeworms)
Flat body, hermaphroditic – both male and female reproductive organs
Both testes and ovaries

3. Complex life cycle
Intermediate host – larvae of the worm (immature worm), asexual reproduction takes place
Definitive host – adult worm (mature worm), sexual reproduction takes place.
Flukes – flat leaf like body
hermaphroditic

4. Clonorchis sinensis Chinese liver fluke

6. Adult worm – bile ducts of humans
Eggs are released in the feces
When it reaches a body of water larva comes out
Ingested by a specific species of snail
Asexual reproduction takes place
Larvae come out of the snail
Penetrates a fish and forms a cyst in the fish
When people eat undercooked, contaminated fish larvae end up in the bile ducts
Develop into adult worms
Cycle continues

7. Diagnosis is based on the presence of eggs in the feces.
Flower vase
Operculum
Lid-like structure

8. Cestodes (tapeworms) Scolex – head Segmented body
Segment – proglottids
Hermaphroditic
Each proglottid has testes and ovaries

11. Taenia saginta (beef tapeworm)
Adult – human intestinal tract
Eggs are released in the feces
Ingested by cattle
Larvae come out in the intestinal tract
Cysts in the muscle
Cyst (sleeping, resting larva)
Undercooked, contaminated meat ingested by humans
Scolex comes out of the cyst
Attaches to the intestinal wall
Makes proglottids

12. All tapeworms make identical eggs
Taenia pisiformis

14. Nematodes (roundworms)
Dioecious
Male and female worms

15. Entirobius vermicularis (pinworm)
Intestinal tract of humans
Female worm comes out of the anus
Releases its eggs
Eggs – clothing, bedding, airborne
Ingested by another host
Eggs reach intestinal tract
Larvae come out
Grows into an adult worm
Intense itching in the perianal area

16. flat
More curved
Larva curled up

17. Ascaris lumbricoides Adult – intestinal tract
Eggs released in the feces
Ingested in contaminated food and water
Larvae come out in the intestinal tract
Grow into adult worms
Eat semidigested food
Blockage (obstruction) of the intestinal tract.

18. Irregular surface

19. Necator americanus Hookworm
Adult – intestinal tract
Eggs – feces
Larvae come out in the soil
When people step on them, they penetrate the skin
Migrate to the intestinal tract
Attach to the intestinal wall
Feed on blood
Grow into adult worms
Anemia
Wearing shoes

21. Trichuris trichura whipworm
Adult – intestine
Eggs – feces
Contaminated food or water
Larvae come out in the intestinal tract
Bloody diarrhea

22. Football shaped
eye

23. Trichinella spiralis Transmitted in contaminated, undercooked
Encysted pork
Larvae come out of the cyst in the intestinal tract
Grow into adult worms
Female releases larvae
From cysts in the muscle
Diaphragm muscle