Trematodes, Acanthocephalans, & Annelids

Flukes

Dorsoventrally flattened, leaf-shaped, unsegmented, endoparasites with complex, indirect cycles via snails, absorbing nutrients from hosts through their integument 

Fasciola hepatica

“Liver Fluke”

Transmission: ingestion

Host: mud snail → ruminants, rabbits, horses

Signs: liver rot

Most economically important fluke

Paramphistomum & Cotylophoron

“Rumen Flukes”

Transmission: ingestion

Only juveniles are pathogenic

Dicrocoelium dendriticum

“Lancet Fluke”

Host: land snail → wood ant → ruminants

Where: bile duct of ruminants

Nanophyetus salmincola

“Salmon Poisoning Fluke of Dogs”

Transmission: ingestion of raw salmon or trout

Carries Neorickettsia helminthoeca, causing Salmon Poisoning Dz

Paragonimus spp.

“Lung Fluke of Dogs & Cats”

Host: water snail → crawfish → dogs & cats

Signs: subclincical, bronchitis, pneumonia, death

Migrate to lungs & form cysts, eggs coughed up & swallowed. 

Alaria sp.

“Intestinal Fluke of Dogs & Cats”

Host: water snail → tadpole → frog, snake, mouse → dog or cat

Signs: migrate though lungs, coughed, swallowed, develop in SI

Platynosum sp.

“Lizard Poisoning Fluke of Cats”

Host: land snail → pill bugs, sow bugs, toads, gecko, skinks → cats

Signs: D, V, icterus, death from obstruction of bile duct or liver failure

Heterobilharzia americanum

“Blood Fluke” “Canine Schistome”

Host: freshwater snail → raccoon, dogs

Signs: wt loss, D, V, melena, severe GI/liver dz, death

Cercaria penetrates skin, causes swimmer’s itch in humans

Acanthocephala, Thorny-Headed Worms

Resemble roundworms, absorb nutrients through body surface, mainly target aquatic birds & wildlife

Macracanthorhynchus hirudinaceus

“Thorny-Headed Worm of Swine”

Host: beetles → swine

Signs: perforation, peritonitis, death

Onicola canis

“Thorny-Headed Worm of Dogs”

Host: armadillo → dogs

Same signs as swine species

Annelida, Leeches

Segmented worms

Hirudo medicinalis

“Medicinal Leech”

Voracious blood feeders that can cause anemia 7 death form blood loss