Lab session 4 Helminths Worms

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

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

Clonorchis sinensis Chinese liver fluke

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

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

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

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

All tapeworms make identical eggs Taenia pisiformis

Nematodes (roundworms) Dioecious Male and female worms

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

flat More curved Larva curled up

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.

Irregular surface

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

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

Football shaped eye

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