MIP 260 Exam 3 Spring 2026

Trematodes (Flukes)

-Have indirect life cycles

-almost always have a snail as 1st intermediate host

-leaf like body

-have a digestive system

Metacercariae

fluke infective stage

Cestodes (Tapeworms)

-no digestive system -> absorb nutrients through tegument

-Body = scolex and strobila (proglottids)

-Hermaphroditic

-segmented body

Trematode life cycle

-Egg (miracidium; ciliated larva)

-Enters snail

-Develops: sporocyst -> rediae -> cercariae

-Cercariae leave snail

-Become metcercariae (infective stage)

-Host ingests -> adult develops

--(Asexual reproduction in snail)

Schistosoma spp. (Blood fluke)

-Dioecious

-Live in blood vessels

Schistosomiasis

-Eggs -> granulomas -> fibrosis

-Clinical signs: hematuria, liver damage, cancer risk

Schistosoma transmission

Cercariae penetrates skin directly

Fasciola (liver fluke)

-Infects liver & bile ducts

-Infected via vegetation

Fasciola can cause

-Liver destruction -> fibrosis

-Hemorrhage + Anemia

Fasciola Diagnosis

Operculated eggs in stool

Dicrocoelium Dendriticum life cycle

1. Snail -> slime balls containing cercariae

2. Ant eats slime ball

3. Parasite enters ant brain

4. Ant climbs grass

5. Ant gets eaten by grazing animal

(Parasite Manipulates host behavior)

Clinorchis Sinensis Transmission

Raw/undercooked freshwater fish

Clinorchis Sinensis is located where in the body (infection)

bile ducts

Clinorchis pathology

-inflammation -> fibrosis

-Can lead to bile duct cancer

Clinorchis symptoms

-Abdominal pain

-Jaundice

-Hepatomegaly (enlarged liver)

Heterophyes Heterophyes

-Small intestine parasite

-From fish

Nanophyetus salmincola

-Fish transmission

-Intestinal

-Dogs usually host or infected

Paramphistomum cervi

-Rumen parasite (live stock)

-Highly pathogenic

-No strong treatment

Scolex

attachment

Neck

growth

Proglottids

-reproductive segments

-immature -> mature -> gravid

Diphyllobothrium latum (Broad Fish Tapeworm)

-longest human tapeworm

-Scolex has bothrium (grooves)

Bothrium

grooves that help in attachment (on scolex)

Diphyllobothrium life cycle

1. Egg -> water

2. Copepod (1st intermediate host)

3. Fish (2nd intermediate host)

4. Human eats fish

Diphyllobothrium infective stage

Plerocercoid in fish

Diphyllobothrium symptoms

mild but can cause vitamin deficiency anemia, and even intestinal blockages

Taenia Solium (Pork Tapeworm)

-from undercooked pork (cysticerci)

-Scolex has hooks and suckers

T. solium transmission

eggs are ingested NOT cysts

T. solium pathology

Larvae spread to brain, eyes, muscle; and can cause Neurocysticercosis (seizures, death)

T. solium; ingesting pork vs eggs

pork gives an intestinal worm, eggs can produce larvae in tissue (very dangerous)

Cestode infective stage

Larval cyst

Fish transmission

Clinorchis, Diphyllobothrium

Plant transmission

Fasciola

Skin penetration

Schistosoma spp. infects humans by -

Pork transmission

Taenia Solium

Egg ingestion transmission

Cysticercosis