Trematodes: flukes = flatworms Flashcards Preview

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Platynosomum concinnum (syn. P. fastosom)
- adult characteristics
- egg characteristics

- adults are hermaphroditic
- eggs are operculated (the top that pops off). they are very dense and heavy such that a fecal float is not sufficient, can only do a sedimentation)


Platyosomum concinuum
Life Cycle
prepatent period

1. adults in bile ducts of cats make operculated eggs that leave host via feces
2. eggs containing a miracidium are ingested by 1st IH - terrestrial snail
3. miracidium hatches and undergoes asexual reproduction to become a cercariae
4. paratenic host - ingested by pill pug
2nd IH - lizard or gecko ingests the snail containing the cercariae
5. cercaiae encyst and become metacercariae in bile duct of lizard
6. the lizard is ingested by a cat and metacercariae excyst and migrate to the bile ducts/liver and mature
prepatent period = 8 - 12 weeks


Platynosomum concinnum
clinical signs

- normally no severe disease, if chronic will see biliary hyperplasia and liver failure, may see temporary inappetence

- if large numbers will see "lizard poisoning" - weight loss, emaciation, diarrhea, vomiting, jaundice, death


Platyosomum concinnum

diagnosis: sedimentation - rare to see if bile ducts occluded and necropsy

treatment: none approved though use praziquantel, epsiprantel, fenbendazole and albendazole have been used


Paragonimus kellicotti
- common name
- main infection location and species
- geographic distribution
- any IH and paratenic hosts

= the lung fluke
- found in the lungs of dogs and cats as an incidental host, the primary DH are minks and muskrats
- found in the eastern US
- 2 IH: 1 = aquatic snail, 2 = crayfish or crab


Paragonimus kellicoti
- adult characteristics
- egg characteristics

adults - covered in spines
eggs - much larger than lizard flukes (Playtnosomum concinnum)


Paragonimus kellicotti
life cycle
pre-patent period

1. adults found in pairs within cysts in the lungs produce eggs which are coughed up and swallowed and passed thru feces of dogs and cats.
2. eggs must reach the water where they enter their 1st IH - the aquatic snail within which they undergo asexual reproduction and become cercariae and emerge from the snail.
3. cercariae penetrate their 2nd IH - a crustacean (crayfish) and encyst as metacercariae in heart, liver, muscles.
4. the 2nd IH is ingested by the DH. the metacercariae penetrate the intestine and migrate to the lung where they mature (takes between 1 - 2 weeks)
pre-patent period = 3 - 36 days


Paragonimus kellicotti
infective stage

cercariae within their 1st IH the aquatic snail and 2nd IH the crayfish


Platynosomum concinnum
infective stage

cercaiae within their 1st IH - the terrestrial snail and 2nd IH the lizard or toad


Paragonimus kellicotti
clinical signs and pathogenicity

- juvenille migration causes peritonitis and pleural hemorrhage
- adults cause chronic bronchitis, coughing, chronic eosinophilic granulomatous pneumonia

- zoonotic! acquired by eating undercooked crustaceans. dont typically cause clinical signs but if they do:
1st: fever, abdominal pain, diarrhea, pleural effusions.
2nd: bronchopneumonia, coughing
- rarely will undergo aberrant migration to the brain cause neuro signs and ultimately death. this only happens in humans.


Paragonimus kellicotti

diagnosis: sedimentation (very large, heavy eggs), tracheal wash, radiography

treatment: none approved but have used praziquantel, fenbendazole and albendazole


Nanophetus salmincola
- common name
- location and species found
- geographic distribution
- IH and any paratenic hosts

= salmon poisoning fluke
- found in the small intestine of any mammal that eats fish ie dogs, cats, coyotes, foxes, bears, humans, etc.
- found mostly in Pacific Northwest
- 2 IH: 1. aquatic snail 2. fish (trout and salmon)


interesting fact on nanophyetus salmincola

fecal floatation samples sent out from Fl often come back as this fluke which is only found in the Pacific Northwest. it usually ends up being spirometrum or something but think... this fluke is only found on the west coast and cannot be found on floatations, they are found in sedimentations!


Nanophyetus salmincola
adult and egg characteristics

adults: super small
eggs: yellow-brown, operculated


Nanophyetus samincola
life cycle
prepatent period

1. adults in intestine produce eggs which pass thru the DH feces
2. eggs hatch in water to produce a miracidium. the miracidium penetrates the aquatic snail.
3. cercariae emerge from snail and penetrate 2nd IH: fish. they encyst as metacercariae in various tissues.
4. 2nd IH: fish are ingested by the DH from which the metacercariae mature in SI.


Nanopheytus salmincola: infective stage

the metacercariae


Nanopheytus salmincola
clinical signs and pathogenicity

- usually asymptomatic but can develop enteritis

- the rickettsial agent, Neorickettsia helminthoeca, that comes with it causes problems known as "salmon poisoning" which causes fever, anorexia, vomiting, diarrhea and death in 1 - 2 weeks.
- most common signs are hemorrhagic enteritis and significant LN enlargement.


Nanopheytus salmincola

diagnosis: sedimentation
treatment: praziquantel, fenbendazole. tetracyclines are most effective for Neorickettsia helminthoeca



tubular flukes that are not hermaphroditic so they have both sexes. they are digenetic hosts (use snails as intermediate hosts)


digenetic hosts

flukes that use snails as IH including trematodes and shistosomes


Heterobilharzia americana
- common name
- location found and in what species
- geographic distribution
- IH and paratenic hosts if any

"canine blood fluke"
- found in the mesenteric and hepatic veins of dogs, bobcats and racoons
- found along the gulf coast, LA bayous and Mississippi delta
- IH: aquatic snail (Lymnaea cubensis)


Heterobilharzia americana
adult and egg characteristics

the adult male has a slit along the body called a diphoric canal that the female stays in.
- they look like pieces of thread and are easy to miss.

eggs are kind of circular


Heterobilharzia americana
prepatent period

1. adults in mesenteric v. produce eggs which make their way to the intestine and are passed via feces.
2. eggs must reach water where they hatch and release a miracidium which penetrates their 1st IH: aquatic snail.
3. once in snail develop to cercariae.
4. cercariae leave the snail and penetrate the skin of the DH where they migrate to the lungs, liver and mesenteric v. where they mature to adults. they reproduce in the liver.

prepatent period: 60 days


Heterobilharzia americana infective stage



Heterobilharzia americana
clinical signs and pathogenicity

- often asymptomatic but can cause significant liver and bowel wall pathology leading to diarrhea, vomiting, weight loss, lethargy, anorexia, excessive thirst, hypercalcemia
- often see anemia

- cercariae can cause skin irritation

- egg migration can cause granulamotous inflammation. they can somehow migrate everywhere

- ZOONOTIC: "swimmer's itch" aka cercarial dermatitis


Heterobilharzia americana

diagnosis: sedimentation
treatment: praziquantel, fenbendazole


Alaria spp.
- common name
- found where and what species
- geographic distribution
- IH and paratenic hosts if any

- no common name
- found in the SI of dogs, cats and other mammals
- none mentioned
- 2 IH: 1. aquatic snail 2. tadpole


interesting fact about alaria spp.

it can travel to the mammary gland of the adult cat allowing for transmammary transmission


Alaria spp.
adult and egg characteristics

adults: spoon-shaped with appendages at anterior end
eggs: are SUUUUPER large


Alaria spp.
prepatent period

1. adults in intestine produce eggs which are passed thru feces
2. eggs hatch in water to release a miracidium. the miracidium penetrates the aquatic snail where it turns into a cercariae.
3. cercariae emerge from snail and penetrate the 2nd IH: tadpole where it develops into a mesocercariae.
4. the 2nd IH can be ingested by either a paratenic host (mouse, snake, frog) or ingested by the DH
5. once ingested by the DH the mesocercariae develop into metacercariae where they penetrate the body cavity and migrate to lungs or carried up trachea and swallowed into the SI where they will mature into adults.
- if the DH is a lactating cat, the mesocercariae can migrate to mammary gland and infect kittens


infective stage of alaria spp.?



clinical signs and pathogenicity of alaria spp.

clinical signs: usually none but migration to lungs can cause pulmonary hemorrhage


diagnosis and treatment of alaria spp.

diagnosis: sedimentation
treatment: none approved, but praziquantel, epsiprantel and fenbendazole have been used.


Platynosomum concinnum (syn. P. Fastosum)
- common name
- what it mainly infects (species and location)
- geographic distribution
- any intermediate or paratenic hosts

the lizard poisoning fluke
- infect the bile ducts of cats
- found mostly in Fl
- 2 intermediate hosts: terrestrial snails, anolis spp. lizards (and toads)
- 1 paratenic host - pill bugs (isopods)