HELMINTH

Phylum Platyhelminthes

• Also known as flat worms

• Are hemaphroditic

• No body cavities

• Uses flame cells for excretion.

Classes under the Phylum Platyhelminthes

Tubellaria (Planarians)

Trematoda (Flukes)

Cestoda (Tapeworms)

Class Tubellaria

Also known as planarians, they are non-parasitic helminths, resides in fresh water

Class Trematoda

• Also known as Flukes, they are parasitic, monozoic or have unsegmented body.

• Long & Narrow bodies (e.g. Schistosoma)

• Thickly fleshed (e.g. stomach flukes)

• Leaf-like (e.g. fasciola)

• They have NO alimentary tract and rely on their tegument (outer covering that absorbs nutrients) uses pincoytosis and diffusion.

Class Cestoda

Are known as tapeworms are parasitic, and polyzoic or have segmented body.

Subclass Monogenea, Subclass Digenea

The classification of Class Trematoda based on LC (Flukes) are:

Subclass Monogenea

• Subclass of Class Trematoda that uses ONE HOST for reproduction

• Mostly parasitize fishes, amphibians and reptiles.

• LC is DIRECT no Intermediate Host

Subclass Digenea

• Subcalss of Class Trematoda that needs MORE THAN ONE host for reproduction.

• An Endoparasite of Dom & Wild Animals.

• Exhibits Sexual reproduction in FH (In vertebrates)

• Exhibits Asexual rep in IH (In mollusks)

• more commonly seen in veterinary medicine

• Are Hermaphroditic endoparasites.

• Have indirect LC, involving sexual and asexual generations involving diff hosts.

LC of Subclass Digenea

Egg —> Miracidium —> Sporocyst —>
Redia —> Cercaria —>Metacercaria —>Marita —> Adult (EMSRCMMA)

Marita

young fluke

Microcercous, Cercariaecum, Trichocercous

Classification of Flukes based on their tail

Microcercous

(Paragonimus spp.) Has small stumpy tail

Cercariaecum

No tail

Trichocercous

Spiny tail

Monostome, Aphistome, Distome, Holostome, Echinosrtome, Schistomes

Classification of Flukes based on anatomical structure:

Monostome

• E.g Cyclocoelum spp.

• WITH Oral sucker

• NO Ventral sucker

Amphistome

• E.g. Zygocotyle spp.

• With Oral Sucker

• Acetabulum found at the posterior end.

Distome

• E.g. is Alloglossidium spp.

• WITH oral and ventral sucker located away from posterior end.

Holostome

• e.g Cyathocotyle spp.

• Type of distome that has the body split into distinct anterior and posterior portions.

Echinostome

• Echinostoma spp.

• WITH Spines surrounding oral sucker / head collars are present.

Schistosome

• E.g Schistosoma spp.

• Has strong oral sucker and acetabulum near the anterior end.

Lymnaea truncatula, Lymnaea viridis

IH of Fasciola hepatica

Ruminants

FH of F. hepatica

17 weeks

Life cycle of F. hepatica usually last until ____

3 hrs

Miracidium of F. hepatica must find a snail host within how many hrs?

Aquatic environment

Sporocyst of F. hepatica needs what type of env. to become a Redia?

6 weeks

F. hepatica miracidium usually takes how many weeks to become a Metacercaria?

600

One miracidium of F. hepatica can produce how many metacercaria?

Liver parenchyma

Predilection site of f. hepatica metacercaria / young flukes are found here and they will stay for about 6-8 weeks.

Bile ducts (occasionally gall bladder)

When F. hepatica becomes an adult, it will then go to which body organ?

10-12 weeks

Prepatent period of F. hepatica

Liver rot

Fasciola may cause this to sheeps, alpaca and llamas. It may become a subclinical infection in cattle.

Acute fascioliasis

• Occurs when >2000 fasciola metacercaria are ingested in short period.

• CS: Distended and painful abdomen, anemia, sudden death after 2-6 weeks of infection.

• Can be accompanied by infection w/ Clostridium novyi w/ css Black diseas. Proliferate on the lesions young fluke create on the liver parenchyma.

Subacute fascioliasis

• Occurs when 500-1500 fasciola metacercaria are ingested over a longer period. CS: Hemorrhage in the liver, anemia, death 7-10 wks post infection.

Chronic fascioliasis

• Occurs when 200-500 fasciola metacercaria are ingested over a longer period.

• CS: Unthriftiness, anemia, pipe stem liver, hepatic fibrosis, submandibular edema, reduced milk prod. - Most common form in the country

Fecalysis (Sedimentation technique), ELISA Tests

Diagnosis for Fascioliasis

Triclabendazole, clorsulon, albendazole, netobimin

TOC for fascioliasis

Fasciola gigantica

Is larger than F. hepatica and is more common in the PH with 3% in Cattle, 35% in Carabaos s (than F. hepatica 1% in Cattle, 7% in Carabaos)

Lymnaea auricularia rubiginosa, Lymnaea viridis/ philipenensis

Fasciola gigantica IH

Fasciola jacksoni

Spp of Fasciola that occurs in the Bile ducts of elephants

Fasciola nianze

Spp of Fasciola that occurs in the Hippopotamus in Africa

Fascioloides magna

• Is under the Genus Fascioloides, lacks anterior Projecting Cone

• Share similar LC with Fasciola may reach 17 months before completion

• Requires colder habitat

• Except PPP is 30 weeks

• Low Pathogenicity And RARELY Css Death In Cattle.

• Problems Usually Are Confined To Liver Condemnation

• GOATS & SHEEP Severely Affected; However, Deaths Have Been Reported Due To The Migration Of These Flukes To Other Organs.

• Histologically, Infected Liver May Show Black, Tortuous Tracts Due To The Migration Of The Flukes.

• Css. BLACK PORPHYRIN PIGMENTS show up on liver

Liver, Bile ducts

Main predilection site of Fascioloides magna

Giant Liver Fluke, Large American liver fluke, Deer fluke

Fascioloides magna is also known as _________

white-tailed deer, elk, caribou

Reservoir hosts of Fascioloides magna in the North american countries

red deer, fallow deer

Reservoir hosts of Fascioloides magna in the European countries

Fossaria, Lymnaea, Stagnicola

Intermediate host of Fascioloides magna

Oxyclozanide

TOC for Fascioloides magna effective for white-tailed deer.

Triclabendazole

TOC for Fascioloides magna effective for red deer

Rafoxanide

TOC for Fascioloides magna effective in cattle.

Albendazole

TOC for Fascioloides magna effective for sheep

Fasciolopsis buski

• Still under genus Fascioloides whose reservoir host are pigs and final hosts are man and dogs

• Mainly seen in small intestine of man.

• They infect final hosts through ingestion of Metacercariae that encyst on aquatic plants. PPP: 9-13 weeks

Planorbis, Segmentina, Hippeutis

IH of Fasciolopsis buski

Family Paramphistomatidae

• Also known as Rumen flukes

• Conical (pear-shaped), thicker and fleshier than their relatives.

Paramphistomes / Amphistomes

Are mainly parasites of the Ruminant Forestomach

Giganticotyle

Part of the Family Paramphistomatidae found on the liver and duodenum instead.

Paramphistomum

• Also known as Rumen Flukes

• Parasitize the rumen. - Resemble maggots.

• WELL-DEVELOPED ventral sucker is located at the posterior extremity.

• PPP: 7-10 WEEKS

• DOC: Oxyclozanide

4 weeks

• How long does it take for Miracidium of Parahistome need to become a cercaria?

Paramphistomum cervi

• Spp of Paramphistomum/ Rumen fluke that parasitize the rumen of cattle, sheep, goat and deer.

• IH: Planorbis & Bulinus snails

Gigantocotyle explanatum

• Spp of Paramphistomum/ Rumen fluke found in liver, bile ducts, gallbladder & duodenum of cattle and buffalo.

• IH: Galba snails

Paramphistomum daubnei

• Spp of Paramphistomum/ Rumen fluke found in Rumen of Cattle and goat.

• IH: Omphiscola snails

Cotylophoron cotylophorum

• Spp of Paramphistomum/ Rumen fluke found in Rumen and reticulum of sheep, goat & cattle.

• IH: Bulinus snails

Family Gastrodiscidae

• Parasitize the Large intestines of larger animals (horses, cattle, and pig)

• Also known as Intestinal fluke

• Have SHORT CONICAL ANTERIOR end and a large posterior discoid body.

• LC is COMPLETE

• Reported to cause colic, lethargy, and diarrhea in severe/ heavily infected cases.

• are mostly nonpathogenic

Gastrodiscus aegyptiacus

• Found in the intestines of horses, donkeys, & pigs.

• IH: Bulinus and Cleopatra snails.

Gastrodiscus secundus

• Found in the large intestine of elephants and horses;

• IH: Planorbis snails

Gastrodiscus hominis

• Found in the cecum and colon of humans and pigs.

• IH: Helicorbis snails.

Homalogaster paloniae

• Found in the large intestine of cattle and buffalo.

• IH: Hippeutis and Polypylis snails.

Family Gastrothylacidae

• Also knowns as Pouched Amphistomes

• Characterized by their EXTREMELY LARGE VENTRAL POUCH that covers the ventral surface of the fluke.

• Mainly parasitize ruminants with the generas.

• IH: FRESHWATER SNAILS

• FH: CATTLE and BUFFALO

Gastrothylax cuminifer

• Spp of Pouched Amphistomes occurs in the rumen and reticulum of ruminants.

Fischoederius elongatus

• Spp of Gastrothylacidae/ pouched amphistomes occurs in the rumen, and duodenum of ruminants and rarely humans.

Carmyerius spatosius

• Spp of Gastrothylacidae/ pouched amphistomes in the RUMEN of ruminants

Family Echinostomatidae

• Characterized as Flukes with Head collars

• Are more elongated than their other relatives and their oral suckers are surrounded by HEAD COLLARS.

• The number of spines on their head collars can be used to differentiate spp.

• Have TWO IH:

• a.) Primary IH: Snails

• b.) Secondary IH: Fish or Frogs

• Eggs —> Miracidium —> Snail host

• PPP: 1-2 WEEKS

Kidneys of tadpoles

Cecaria of Echinostomatidae emerge from snail host and may infect or encyst on ______

Light infection

_______________ of these echinostomatidae flukes generally cause no significant effect on hosts

Heavy infection

_______________ of these echinostomatidae flukes leads to inflammation, enteritis, anemia, colic, diarrhea, and emaciation.

DOC: ORFA Oxyclosamide, Rafoxamide, Fenbendazole, Albendazole

Echinostoma, Echinoparyphium, Hypoderaeum

Spp of Echinostomatidae that mainly parasitize birds

Echinoschasmus, Isthmiophora, Euparyphium

Spp of Echinostomatidae mainly parasitize fish-eating mammals.

Echinostoma revolutum

• # of Head collars: 37 spines, some grouped as “corner spines”

• Spp of Flukes with head collars that occurs in CECA, CLOACA and RECTUM Waterfowls, Pigeons occasionally humans.

• 2nd IH: Tadpoles

Echinostoma paraulum

• #of Head collars: 37 Spines w/ “double row” pattern.

• Occurs in the Small intestines of Ducks, Pigeons and Humans:

• Secondary IH: Fish

Echinoparyphium recurvatum

• #of Head collars: 45 spines with corner spines.

• Occurs in the Small intestines of Avian spp & humans

• IH: Snails, fish, shellfish and tadpoles

Echinostoma ilocanum

• No Head collars

• Occurs in the small intestine of man, dog, cat and rat.

• Infection in man is usually through ingestion of raw infected snails.

Gyraulus convexiusculus

• 1st IH snail of Echinostoma ilocanum

Pila luzonica

• 2nd IH snail of Echinostoma ilocanum

Hypoderaeum conoideum

• Head collars: 50 small spines

• Occurs in the Small intestines of Avian spp.

• IH: Snails, fish, shellfish and tadpoles

Euparyphium melis

• Head collars: 27 spines

• Occurs in the Small intestines of Carnivorous mammals such as Cat, fox, mink, badger, otter and hedgehogs.

• 2nd IH: Tadpoles

Echinochasmus perfoliatus

• Head collar: 24 spines in a “single row.”

• Occurs in the Small intestines of Dog, cat, fox, and pig.

Family Philophthalmidae

• Also known as Eye flukes

• ONLY have a SINGLE spp under this family that is of veterinary importance.

Philophthalmus gralli

• Known as “ORIENTAL AVIAN EYE FLUKE”

• parasite of the conjunctival sac of chickens, ostriches, and wild birds.

• PATHOGENIC EFFECTS Causes Conjunctivitis, keratitis, watery discharge, and mild edema.

• TX: Repeated use of Levamisole

contact with water

• What triggers the hatching of embryonated eggs of Philopthalmus gralli?

Melanoides tuberculate

• Philopthalmus gralli miracidium will become a single redia after penetrating what spp snail host?

Snail’s heart

• Predilection site of P. gralli redia, that they will penetrate to release new rediae

Sporocyst stage

What stage does the Philopthalmus skips?

95 days

New redia of philopthalmus will migrate into the digestive glands and after ____ days will produce cercariae

Herbage, Crop

Where do Philophthalmus spp. encyst? When ingested?

Esophagus, Nasal passages, lacrimal gland

Encysted metacercaria of philopthalmus will migrate within an hour to which parts of the avian spp?

• Characterized by their ABSENCE OF ORAL SUCKERS.

• Parasites of Aquatic Birds in the; body cavity, air sacs or nasal cavities.

• They are slightly flattened, lack an oral sucker and usually a ventral sucker

Typhlocoelum, Hyptiasmus

Two important genera of Family Cyclocoelidae

Redia

Which stage in the LC does the Cyclocoelidae fluke enters the host?

sporocyst

Familly cycloelidae lacks this stage in LC?

TRUE

TRUE OR FALSE

• Cercariae of Family Cyclocoelidae will NOT LEAVE THE SNAIL HOST. They will encyst while w/in the host.