Lecture 31 & 32: Trematodes

What two trematodes are contracted by ingestion of metacercaria encysted on vegetation?

fasciola hepatica (liver fluke), paramphistomum sp.

What two trematodes are contracted by ingestion of metacercaria encysted in fish, crawdad, crabs, etc.?

nanophytes salmincola, paragonimus kellicotti

What two trematodes are contracted by ingestion of metacercaria encysted in insects/invertebrates?

dicrocoelium dendriticum, platynosum fastosum

What treamatode is contracted by skin penetration by swimming cercariae?

heterobilharzia americana (canine blood fluke)

What is the adult worm morphology of liver and lung flukes?

• dorsoventrally flattened

• bilaterally symmetrical

• monoecious and hermaphroditic

What does the lifecycle of liver and lung flukes involve?

2 intermediated hosts that are mostly aquatic

What must the first intermediate host of liver and lung flukes always be?

snail

True or false: trematodes are parasitic in all systems of vertebrate DHs.

true

Liver/lung fluke

What stage of trematode life cycle is transferred from the first IH to the second?

cercariae

What stage of trematode life cycle is transferred to the DH?

metacercariae

Who is the DH of paragonimus kellicoti?

dogs, cats, people

What is the common name of paragonimus kellicoti?

lung fluke

How is paragonimus kellicoti contracted?

ingestion of uncooked or poorly cooked crayfish

What are the clinical signs of a paragonimus kellicoti infection?

dyspnea, hemoptysis (bloody septum), pneumothorax

How are paragonimus kellicoti infections diagnosed?

fecal exam

What trematode species is this?

paragonimus kellicoti

Where do the adult paragonimus kellicoti worms live and reproduce?

lungs

What is the disease in a paragonimus kellicoti infection associated with?

inflammatory response to excretory/secretory (cysteine proteases) products of adult worms

What trematode is commonly called the canine blood fluke?

hetrobilharzia americana

What species is hetrobilharzia Americana typically associated with?

raccoons

Where two paired adult hetrobilharzia Americana worms live?

mesenteric vessels → granulomatous transport through the tissues to GI

How many IH hosts does hetrobilharzia Americana have?

one

How is hetrobilharzia americana transferred?

infection by skin penetration

What is the causative agent of zoonotic “swimmer’s itch”?

hetrobilharzia americana

What are clinical signs of hetrobilharzia Americana infections?

weight loss, dysrexia, elevated liver enzymes, vomiting, diarrhea, polyuria, polydipsia

Describe the life cycle of hetrobilharzia Americana?

1. Eggs in host feces

2. In water, miracidium hatches from egg

3. Miracidium infects IH snail

4. Cercariae released into water by snail

5. Cercariae penetrate skin of DH

6. Paired adult worms live in blood vessels

Hetrobilharzia americana

What trematode species is commonly called salmon poisoning fluke?

nanophyetus salmicola

nanophyetus salmicola

Who are the DHs of nanophyetus salmicola?

dogs, cats, fish eating mammals

Who are the IHs of nanophyetus salmicola?

snail, salmonid fish

How are nanophyetus salmicola flukes acquired?

by ingestion of metacercaria in kidneys, muscles, and fins of raw salmonid fish

Nanophyetus salmicola are vectors for __________.

salmon poisoning by Neorickettsia helminthoeca

What are the clinical signs of salmon poisoning?

hemorrhagic enteritis, lymphadenopathy, clinically indistinguishable from canine parvovirus

What trematode species is commonly called liver poisoning fluke?

platynosomum fastosum

Who is the DH of platynosomum fastosum and where does it reside?

felines, bile ducts

Who are the IHs of platynosomum fastosum?

pulmonate snail, pill bugs, lizards may by paratenic host

How are platynosomum fastosum infections acquired?

ingestion of metacercaria → migrate up bile ducts

What are the clinical signs of platynosomum fastosum infections?

vomiting, diarrhea, icterus

platynosomum fastosum

What trematode species is commonly called raccoon pancreatic fluke?

eurytrema procyonis

How are the DHs of eurytrema procyonis?

felines, red and grey fox, raccoons

Who are the IHs of eurytrema procyonis?

terrestrial snail, arthropods

How are eurytrema procyonis infections contracted and where do they end up?

ingestion of metacercaria → pancreatic ducts with periductal fibrosis

What are the clinical signs of eurytrema procyonis?

weight loss, vomiting, pancreatitis

Eurytrema procyonis

Who are the IHs and DHs of alaria sp.?

IH:

• Snail (1)

• Tadpole (2)

• Snake (alt 2)

DH:

• cat

• dog

The ____ stage of alaria sp. is capable of being passed from host to host and via lactogenic transmission.

larval

What are the adverse effects of alaria sp. associated with?

aberrant migration of mesocercaria

What trematode species is commonly called the liver fluke?

fasiciola hepatica

Who are the DHs of fasciola hepatica?

cattle, sheep, and goats

How are fasciola hepatica infections acquired?

ingestion of metacercaria encysted on vegetation

What are the clinical signs of a fasciola hepatica infection?

liver disease, anemia, hypoproteinemia, bottle jaw, loss of condition

Fasciola hepatica

What is the distribution of fascioliasis based on?

• presence/absence of infected hosts

• presence of suitable snail IH

• suitable soil substrate promotes moisture retention (snail habitat)

• slope, drainage, water runoff

• natural and artificial ponds for watering herd

What are the two therapeutic options for treating fascioliasis?

clorsulon and albendazole

How does clorsulon treat fascioliasis?

• binds to serum proteins and ingested by the fluke

• inhibits enzymes important in glycolytic energy process

• not able to extract energy from glucose, disruption of cellular energy production

How does albendazole treat fascioliasis?

binds to beta-tubulin, interferes with development and energy uptake

Why are herd level outbreaks of fascioliasis often associated with drought conditions?

shrinking water line exposes green vegetation

What trematode species is commonly called deer liver fluke?

fascioloides magna

What trematode species is commonly called the rumen fluke?

paramphistomum sp.

Where are adult paramphistomum sp. formed?

stomach (abomasum)

What stage of paramphistomum sp. are pathogenic and where are they found?

immature stages in duodenum and ileum

What are the clinical signs of parmphistomum sp. infections?

necrosis, hemorrhagic inflammatory disease, hypoproteinaemia, diarrhea, dehydration

paramphistomum sp.

True or false: established flukecidal drugs are the preferred tx of paramphistomum sp.

false

What trematode species is commonly called lancet liver fluke?

dicroelium dendriticum

Who are the DHs of dicrocoelium dendriticum?

cattle, sheep, goats, pig, wild ungulates, rodents, rabbits

Who are the IHs of dicrocoelkum dendriticum?

terrestrial snail, ants

What is the dicrocoelium dendriticum life cycle through the snail?

miracida hatch from egg when ingested by snail, asexual replication in snail, emerge in slime ball

What is the dicrocoelium dendriticum life cycle through the ant?

ingested by ant, infect brain, remain attached to vegetation