Trematodes Flashcards by Julia Harrington

Life cycle of all trematodes?

Miracidium comes out of egg
Travels to snail - 1st intermediate host
Forms sporocyst inside snail
1st and 2nd gen redia form
Redia -> larvae known as cercariae
Cercariae (L3) -> metacercariae (encysted) on plant
Ingested by humans or penetrate skin

Cercariae only in schistosomiasis - need to penetrate skin

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Multiple liver cysts

Fasciola
Chlonorchis sinensis Opistorchis viverrini /felineus
Toxacara
Echinococcus
Entamoeba

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What is the difference in pathology between fasciola and chlonorchis/opistorchis?

Fasciola invades directly through bowel to liver

Chlonorchis/opistorchis travels through ampulla of water - less symptoms but does cause biliary obstruction

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Why may you not see eggs in the faeces with fasciola?

In acute fasciola, immature flukes travel from bowel to liver, and do not produce eggs

Only chronic phase, adults live in biliary tract

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Which other tests are helpful in ∆ of fasciola if the stool microscopy is negative?

Eosinophila
Serology - ELISA - Fas2 (vomit from parasite)

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Rx of fasciola?

2 doses of Triclabendazole

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How can you monitor Rx for fasciola?

Eosinophils
Stool samples - pass eggs in stool - live in biliary tract after acute infection where they are in liver

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What are the symptoms of chronic fasciola infection?

Cholangitis, biliary obstruction - live in biliary tract

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Acute symptoms and signs of fasciola?

weight loss, abdominal pain, fever, diarrhoea

hepatomegaly, jaundice, splenomegaly

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Where does fasciola travel to?

Liver
Then lung, peritoneum, abdomen

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What do you do if a patient fails initial Rx to fasciola?

Repeat triclabendazole Rx, same dose

There is some resistance to Rx being seen!

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Intermediate/definitive host in fasciola hepatica?

Intermediate -
1st - snail
2nd - human

Definitive -
Sheep
Cattle

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What alternative drug can you use for managing fasciola?

Nitazoxanide

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How do fasciola affect the liver?

parenchimal destruction
Abscess formation

Later:
Obstruction and dilation of bile ducts, fibrosis, abscess and granuloma, cholangitis

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What is this, why and what is distinct about it?

Fasciola hepatica

Partially opened operculum
LARGE!

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What is the difference between a cercariae and metacercariae?

Metacercaricae encapsulated in a cyst
(Schisto does not have because doesn’t go through GI tract - I think)

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What is the larval stage of trematodes known as?

Cercariae

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What is specific about anatomy of trematodes?

Haemaphrodite - can produce eggs

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What structure is this?

Cercariae

Look for any surface to form a cyst or can just form a cyst in water

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How many months until you see eggs in stool following infection with fasciola?

3-4 months

(ELISA 2-3 weeks)

Adult only forms once larval stage have migrated to liver -> bile duct

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When do you see eosinophilia in fasciola infection?

acute phase

Often normal in chronic phase

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What will happen if you ingest the fasciola eggs?

Nothing!
Need to Ingest the metacircariae

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6 yr old boy presenting with haemoptysis and new onset seizures, has a nodular appearance on CT head and nodular lesions on CT chest. ∆?

Paragonimus westermani (classical)

In Latin America - P.mexicana

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How does paragonimus present?

Chronic cough, SOB, haemoptysis.
Can have CNS lesions
May get a skin nodule

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How do you ∆ paragonimus?

Ova in sputum, stool, CSF, pleural fluid

How do you Rx paragonimus?

Praziquantel

Best test in the acute phase for F.Hepatica?

ELISA

Trematode most commonly found in Korea/China/Thailand/ Vietnam?

Chlonorchis sinensis and Opistorchis viverrini / felineus

Intermediate host for Chlonorchis sinensis and Opistorchis viverrini / felineus?

Fish

Which of the trematodes produce biliary obstruction and inflammation?

F.Heptica/Gigantica Chlonorchis sinensis and Opistorchis viverrini / felineus

∆ of Chlonorchis sinensis and Opistorchis viverrini / felineus

Eggs in Stool OR ELISA

Rx of Chlonorchis sinensis and Opistorchis viverrini / felineus

Praziquantel

What is the species also known as the Great Intestinal Fluke in China?

Fasciolopsis buski

∆ and Rx of Fasciolopsis buski?

Eggs in stool Praziquantel

Which species has a crab as its intermediate host?

Paragonimus westermani/mexicanus

What is the classic clinical presentation of Paragonimus westermani/mexicanus?

Lung symptoms - haemoptysis, cough, SOB (penetrate diaphragm) Also * Rash and urticaria * Marked eosinophilia * Abdominal symptoms

How do you ∆ paragonimiasis?

Eggs in sputum Eggs in stool CXR - soap bubble appearance of granulation

Rx of paragonimiasis?

Praziquantel

What are the 3 species of schistosoma?

Schistosoma mansoni Schistosoma japonicum Schistosoma haematobium

Different patterns of disease of the schistosoma species?

Schistosoma mansoni - periportal fibrosis Schistosoma japonicum - periportal fibrosis and CNS Schistosoma haematobium

Intermediate host for schistosoma?

Freshwater snail

Difference of schistosoma to other trematodes in transmission?

Cercariae perforate skin directly as opposed to GI tract

What is the name of the stage of the life cycle when schistosomiasis species penetrate the skin?

Schistosomulae (from cercariae) Do not have metacercariae (encysted)

Where do the schistoma adults migrate to?

Schistosoma mansoni and Schistosoma japonicum - venuous plexus of bowels - portal veins Schistosoma haematobium - venous plexus of bladder

Diagnostic test for schistosomiasis?

Eggs in stool or eggs in urine depending on species

What is classic symptom for schistosomiasis?

Swimmers itch as the L3 larvae pass through skin, maculopapular rash as site Go to lungs - eosinophilic pneumonitis - katayama fever

Which of the schistosoma species is in South America?

Mansoni

What is katayama fever and when does it occur?

Acute schistosomiasis (Katayama fever): fever (not always), prostration, hepatosplenomegaly, lymphadenopathy, eosinophilia. 4-8 weeks after exposure Reaction to egg-laying

Symptoms of chronic schistosomiasis?

Chronic schistosomiasis (S.mansoni, S. japonicum) - Early: abdominal pain, colonic polyps - Late: portal fibrosis, portal hypertension, hepatosplenomegaly, variceal bleeding. Chronic schistosomiasis (S. hematobium) - Early: hematuria, dysuria, bladder polyposis - Late (rare in Europe,N.Am.): hydroureter, hydronephrosis, UTI, female reproductive tract, ca of bladder

Which species causes neuroschistosomiasis?

Japonicum (4%) Very rarely haematobium, spinal cord

How else can you test for schistosomiasis apart from direct exam of stool or urine? Who is this useful for?

ELISA Expats with light infection (not see eggs)

Name the species?

Mansoni

What is a differential for swimmers itch?

Avian schistosomiasis - duck schistome, itchy cannot complete life cycle. Found in USA/Canada and SA.

Rx of schistosomiais?

Praziquantel 4-6 weeks post infection (adulticidal)

How else can you manage schistosomiasis acutely?

artemisinin - most effective against the schistosomula - can take it earlier than praziquantel.

How do you Rx acute katayama fever?

Praziquantel and prednisolone Plus praziquantel 4-6 weeks after predicted infection

What is the species?

S.Haematobium

Name the species?

S.Japonicum or S.Mekongi

How do you differentiate a live vs dead schistosoma egg on microscopy?

Flame cell inside the embryo

What type of organism is schistosomiasis?

Trematode

What is the infective stage of schistosomiasis? How?

Cercariae - Penetrate skin. Larval stage L3

How does schistosoma cause disease?

Migration through skin, through venous system to portal system, liver, bladder (depending on species)

What is the intermediate host for schistosomiasis?

Fresh water snails

How do you treat schistosomiasis?

Praziquantel 4-6 weeks after exposure

Name the species

Schistosomiasis mansoni - lateral spine

What is acute katayama fever? How do you treat it?

Acute toxaemic schistosomiasis. fever (not always), prostration, hepatosplenomegaly, lymphadenopathy, eosinophilia. Prednisolone + praziquantel plus repeat prazi 4-6 weeks later

What are the intermediate and definitive hosts for Fasciola hepatica/fasiola gigantica?

Intermediate: Lymnea snail Definitive: Sheep or cattle

What are the symptoms of Fasciola hepatica/fasiola gigantica?

*Liver parenchimal destruction and dilatation of bile ducts * Abscess formation in liver * Adults flukes - release protests - can cause dilation of bile ducts, fibrosis, abscess and granuloma (particularly around egg) - abdo pain, fever, weight loss, diarrhoea

How do you diagnose fasciola hepatica?

ELISA Rapid sedimentation technique of stool

Management of F.hepatica?

Triclabendazole

Name the species

Chlonorchis sinensis

How do you treat the haemaphroditic trematodes?

praziquantel (except F.hepatica)

What is the giant intestinal fluke?

Fasciolopsis buski

What are the first/second hosts for fasciolopsis buski?

1. Snails -> microcircariae travel to plants (ingested by humans)

How does paragonimus westermani present and why?

From gut - Penetrate diaphragm - lung symptoms

How is paragonimus transmitted?

1st host snail. Cercariae travel to 2nd host - crustacean or crab

What is the liver fluke, lung fluke, blood fluke and intestinal fluke?

Liver = fasciola hepatica/gigantica, Chlonorchis sinensis and Opistorchis viverrini / felineus Lung = paragonimus westermani/mexicana Blood = schistosoma spp

Anatomical features of a trematode (not schistosomiasis)?

2 ventral suckers no digestive tract Haemaphrodites

What first intermediate host is common to all trematodes?

Snail

Infective stage of all trematodes?

Metacercariae (Cercariae in schistosomiasis)

What is this and why?