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Mainly ectoparasites of fish Monogenean
mammal flukes Digenean
Most species are dorsoventrally flattened Trematode Characteristics
Usually leaf shaped Trematode Characteristics
Covered by a cytoplasmic tegument Trematode Characteristics
No body cavity Trematode Characteristics
Digestive system either absent or rudimentary (cecae) Trematode
Reproduction: Most species are hermaphroditic Trematode
Larvae can reproduce asexually Trematode
Larvae can reproduce asexually Exception: Schistosomes; Adult  worms reproduce sexually
cattle, sheep Fasciola hepatica
deer Fascioloides magna
dogs and cats Paragonimus kellicotti
dogs, etc Nanophyetus salmincola
is deposited in freshwater via the feces of the definitive host The egg
The operculum opens and a ciliated swims out to penetrate an intermediate host, usually a snail (8), to which it is chemically attracted miracidium
In the snail, cilia are lost, and it develops into a to asexually produce more sporocysts sporocyst
which also asexually produce more rediae Rediae
which emerge, swim, and penetrate a second intermediate host, the final host, or encyst on vegetation Tailed cercariae
They transform into , which are juvenile flukes metacercariae
grow from the metacercariae when they are consumed by the definitive host adults
BILE DUCTS Dicrocoelium
bile ducts Fasciola spp
RUMEN Paramphistomum
LIVER Fascioloides
LUNGS Paragonimus
BLOOD Schistosoma
Large (2-3 cm); Distinct shoulders Fasciola hepatica
Causative agent of Fascioliasis,Liver fluke disease,Liver rot (condemnation) Fasciola hepatica
Infective Stage,Encysted metacercariae on vegetation Fasciola hepatica
Most common and important fluke of ruminants (economic importance Fasciola hepatica
Found in areas where sheep & cattle are raised Human Infections
Humans consume raw (infected) watercress Human Infections
U.S., Europe, the Middle East & Asia Human Infections
Definitive hosts: Most Mammals Fasciola hepatica
PPP ~ 10-12 weeks Fasciola hepatica
(1.5-2 mo.) associated with a massive infection (> 2,000) larval flukes (maritas Ovine Fasciolosis acute
Abdominal pain (disinclination to move Ovine Fasciolosis acute
Complicated by concurrent infections with Clostridium perfringens & C. novyi (Black disease Ovine Fasciolosis acute
Severe hemorrhagic anemia; rupture of blood vessels Ovine Fasciolosis acute
Sudden death Ovine Fasciolosis acute
Occurs 6-10 weeks after ingestion of 500-1,500 metacercariae Ovine Fasciolosis subacute
Cholangitis (inflammation of the bile ducts) Ovine Fasciolosis subacute
Rapid & severe hemorrhagic anemia Ovine Fasciolosis subacute
Death in 1-2 weeks Ovine Fasciolosis subacute
Adult flukes in bile ducts Chronic fasciolosis
Most common form of disease Chronic fasciolosis
Gradual loss in condition, weakness, anemia, hypoproteinemia Chronic fasciolosis
Edematous sub-Q swellings (bottle jaw) Chronic fasciolosis
Liver damage (migrating flukes)Hemorrhage; coagulative necrosis; fibrosis Bovine Fasciolosis Acute Pathology
Mechanical/chemical irritation by adults/ young adults Bile duct inflammation & fibrosis: wall thickening, stenosis (pipe-stem fibrosis in cattle) Bovine Fasciolosis Chronic Pathology
Goat: rare, anemia, ascites & death Bovine Fasciolosis Chronic Pathology
Yearling pinto filly presented to the Texas A & M VTH for chronic weight loss F. hepatica in a Horse
FEC: 140 strongyle-type eggs/gm, Fasciola eggs and occult blood + Severe chronic fibrosing cholangio-hepatitis with numerous F. hepatica trematodes (necropsy) F. hepatica in a Horse
Additional Complications Clostridium novyi & C. perfringens Minor liver trauma from fluke infestation can allow C. novyi to invade, multiply & secrete toxins Sheep may die very fast F. hepatica
Additional Complications Drought Only green plants = metacercariae-infested plants around water Acute infections can rapidly break out F. hepatica
Diagnosis F. hepatica Farm conditions Marsh areas
Diagnosis F. hepatica ID eggs in feces (chronic infections)Sedimentation technique
Infective stage metacercariae Fascioloides magna
Regional importance in sheep/goat rearing Fascioloides magna
Very large (up to 10 cm) No shoulders Fascioloides magna
Economic importance in cattle industry Fascioloides magna
Distribution similar to Fasciola spp Fascioloides magna
Definitive HostsDeer Fascioloides magna
Aberrant Hosts Cattle Sheep Fascioloides magna
Eggs usually are not passed in cattle and sheep Fascioloides magna
Adults encapsulated in liver Fascioloides magna
Similar to chronic fascioliasis in cattleSimilar to acute fascioliasis in goats and sheep Fascioloides magna Clinical Signs
Usually little pathology in deer Fascioloides magna
liver damage; economic loss in cattle Fascioloides magna
Pathology in Sheep & Goats Extensive liver damage; hemorrhage and necrosis of parenchyma Fascioloides magna
Control snails and/or snail habitat (often impractical Treatment and Prevention of Fascioloides
conical shaped trematodes Rumen flukes Paramphistomum cervi
< 1.0 cm long Sheep, cattle, cervids, water buffalo, elephant Paramphistomum cervi
Worldwide distribution Paramphistomum cervi
Life-cycle very similar to Fasciola Paramphistomum cervi
Flukes migrate to the rumen Cause of pathology (duodenal erosions Paramphistomum cervi
Once in the rumen, adults are relatively harmless Paramphistomum cervi
Treatment: Rafoxanide, niclofolan, oxyclozanide Paramphistomum cervi
Lancet fluke < 1.0 cm long Dicrocoelium dendriticum
Sheep, cattle, deer and rabbits Dicrocoelium dendriticum
Worldwide distribution Dicrocoelium dendriticum
Zoonosis (rare) Dicrocoelium dendriticum
Adults in bile ducts Dicrocoelium dendriticum
Eggs passed in feces Dicrocoelium dendriticum
Eggs ingested by land snails Dicrocoelium dendriticum
Cercariae deposited in slime balls Dicrocoelium dendriticum
Up to 50,000 adults (no liver damage Dicrocoelium dendriticum
1 human case in New Jersey Dicrocoelium dendriticum
Diagnosis - eggs Dicrocoelium dendriticum
Treatment – Albendazole, Praziquantel Dicrocoelium dendriticum
Humans,Domestic animals,Cattle,Sheep,Water buffalo,Many others Schistosomes
Infective stage cercariae Schistosomes
Egg-induced inflammation of liver (and other organ tissues Schistosomes
Progressive fibrosis (pipe-stem fibrosis)Cirrhosis Liver dysfunction Liver failureGranulomas in infected tissues due to egg enzymes Schistosomes
Anemia,Edema,Weight loss Schistosomes
ID eggs in feces, nasal mucus (nasal schistosomiasis), rectal scraping Schistosomes
Radiograph & ultrasound of liver and spleen (more often done in humans)Hepatomegaly, Splenomegaly Schistosomes
Flukes in blood vessels at necropsy Schistosomes
Antischistosome vaccines are under development. Schistosomes
Infects dogs, cats, raccoons, bobcats, lynx, horse Heterobilharzia americana
Intermediate host Snail (Lymnea Heterobilharzia americana
Infects the mesenteric veins Heterobilharzia americana
Infective stage Cercariae Heterobilharzia americana
Distributed in SE regions of the US; Causes “swimmer’s itch” (in humans) Heterobilharzia americana
Pathology/Clinical Signs (Very similar to Schistosoma spp) Heterobilharzia americana
Egg-induced inflammation of liver (and other organ tissues) Heterobilharzia americana
Progressive fibrosis (pipe-stem fibrosis)Cirrhosis,Liver dysfunction,Liver failureIntestinal damage,Granulomas in infected tissues due to egg enzymes Heterobilharzia americana
Anemia,Edema,Weight loss Heterobilharzia americana
Diagnosis Clinical signs,Eggs in feces (80 X 50 µm) Heterobilharzia americana
Heterobilharzia americana Prevention Avoid contact with water containing infected snails
in antelopes and cattle S. leiperi and S. margrawiei
in cattle S. mattheei
in humans S. haematobium
worm pairs found in mesenteric, gastric and hepatic veins Many Schistosoma
Hepatomegaly with diffuse multiple pin-point yellowish foci Many Schistosoma
Petechiae, multifocal, diffuse in gastric and duodenal mucosae Many Schistosoma
Nonpathogenic, but vector for bacteria that causes severe disease in dogs in Pacific northwest Nanophyetus salmincola
Minute fluke 0.5 x 0.3mm Nanophyetus salmincola
Infective stagemetacercariae Nanophyetus salmincola
Definitive hosts: Carnivores Nanophyetus salmincola
snail oxytrema Nanophyetus salmincola
no raw fish or salamanders Nanophyetus salmincola
Vectored by the fluke; Only affects dogs Neorickettsia helminthoeca
Lymphadenopathy,Vomiting and diarrheaRapid weight loss,80-90% fatality without treatment Neorickettsia helminthoeca
Pus discharge from eyes; depressionThirst Neorickettsia helminthoeca
Oxytetracycline (broad spectrum antibiotic) Neorickettsia helminthoeca
DIAGNOSE BY:History and clinical signsFind fluke eggs on fecal exams Salmon Poisoning
Praziquantel Nanophyetus salmincola
Lung fluke Paragonimus kellicotti
Infective stage: metacercariae in crayfish Paragonimus kellicotti
Cause of Paragonimiasis (lung fluke disease) Paragonimus kellicotti
Occurs usually in pairs in pulmonary cysts Paragonimus kellicotti
Can infect many species of wild mammals Paragonimus kellicotti
Radiograph of an experimentally infected dog showing “signet ring-like” lesions Paragonimus kellicotti
Similar to respiratory infections Chronic cough,Pulmonary distress, Persistent pneumoniaBlood stained sputum Paragonimus kellicotti
Flotation or Sedimentation: detection of eggs in feces or sputum, Treat with Praziquantel Paragonimus kellicotti
Adults attach to the mucous membrane of the small intestine Alaria
Miracidia develop in eggs laid in the water Alaria
They enter snails (Helisoma Alaria
Cercariae penetrate the skin & enter tissues of a tadpole (leopard frog) Alaria
MESOCERCARIAE = unencysted metacercariae Alaria
In males & non-lactating cats – Penetration of the diaphragm → metacecariae (diplostomulum type) to the lungs→ esophagus→ small intestine Alaria life cycle
In lactating queens -Transmammary transmission (mesocercariae shed in the milk); may also infect future litters Alaria life cycle
Also occurs in lactating mice alaria
throughout the World Alaria spp
Catarrhal enteritis in moderate to heavy infections Alaria
Clinical illness due to wandering mesocercariae Alaria
Zoonotic! (Eating improperly cooked frog legs!) Alaria
A human fatality was documented as a result of pulmonary hemorrhage. Alaria
Identify large, yellow-brown-greenish, operculated eggs in feces Alaria
Anthelmintics Praziquantel,Albendazole Alaria
Created by: alljacks



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