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Lab session 4 Helminths Worms.

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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

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