Trematodes Flashcards
Describe the general morphology of trematodes
- Flat, leaf shaped w/ 2 muscular suckers (one for taking in nutrition and the other for attachment)
- most are hermaphroditic
- most have operculum on egg
- all require mollusk as 1st intermediate host
What makes the schistosomes different from the rest of the flukes
- they have cylindric bodies, have separate sexes, and don’t have an operculum
What are the 8 clinically relevant trematodes
- F. buski
- F. hepatica
- C. sinensis
- P westermani
- S masoni
- S japonicum
- S haematobium
- Cercarial dermatitis
Describe F. buski in terms of common name, distribution, what causes it, symptoms, how to dx, and prevention
Common name: Giant intestinal fluke
Distribution: SE Asia and India
Cause: ingestion of aquatic vegetables like water chestnuts contaminated w/ larva
Symptoms: correlates w/ worm burden. Severe cases feel like duodenal ulcer, profuse stools w/ malabsorption syndrome similar to giardiasis
DX: stool w/ large golden egg w/ operculum
Prevention: sanitation, education, eliminate snail intermediate
Describe F. hepatica in terms of common name, distribution, what causes it, symptoms, how to dx, and prevention
Common name: Sheep liver fluke
Distribution: worldwide, especially in sheep raising area
Cause: consumption of contaminated watercress in areas where sheep/herbivores are present
Symptoms: hepatitis, hepatomegaly, RUQ pain, biliary obstruction, liver rot
DX: eggs in bile, look like F buski, this is a problem b/c the treatment is different than F buski
Prevention: sanitation, education, eliminate snail intermediate, avoid watercress in areas frequented by sheep/herbivores
Describe C. sinensis in terms of common name, distribution, what causes it, symptoms, how to dx, and prevention
Common name: Chinese liver fluke
Distribution: Asia or Asian refugees
Cause: eating raw, pickled, or cold smoked freshwater fish contaminated w/ metacercaria
Symptoms: asymptomatic to biliary obstruction, jaundice, hepatomegaly, can cause adenocarcinoma of bile ducts
DX: stool w/ distinctive eggs, ELISA
Prevention : avoid eating uncooked freshwater fis, sanitation
Describe P. westermani in terms of common name, distribution, what causes it, symptoms, how to dx, and prevention
Common name: Lung fluke
Distribution: Asia, Africa, Latin America
Cause: consumption of contaminated undercooked crabs/crayfish
Symptoms: Fever chills, cough d/t inflammation->rust colored sputum from destruction of lung tissue, dyspnea, lung fibrosis. Other symptoms if worms migrate
DX: sputum, feces, or pleural effusions have golden operculated eggs
Prevention: education, sanitation
How do schistosomes evade host defenses
they coat themselves with substances that the host recognizes as self., this accounts for chronic infections
What portions of schistosomes elicits inflammation and tissue destruction
eggs elicit inflammatory rxn and larvae produce enzymes that aid in tissue destruction for migration
Why are schistosomes considered a disease of economic development
b/c land irrigation projects result in greater dispersion of infected snails
Describe S. masoni in terms of distribution, what causes it, symptoms, where it like to reside in the body, how to dx, treatment and prevention
Distribution: endemic in Africa, Saudi Arabia, and Madagascar
Cause: cercariae are free swimming and penetrate the skin
Symptoms: itch/rash-> cough-> hepatitis (as it goes from skin to lungs to liver
-chronic dx= hepatosplenomegaly, fibrous occurs at each site of infection, portal vein gets clay pipestem fibrosis. katayama syndrome
Where it like to reside in the body: mesenteric vein
DX: egg w/ large sharp lateral spine
Treatment: antihistamines and corticosteroids for katayama syndrome
Prevention : Education, sanitation, killing snails
Describe S. japnicum in terms of common name , distribution, what causes it, symptoms, where it like to reside in the body, how to dx, and prevention
Common name: oriental blood fluke
Distribution: China, Philippines, Indonesia
Cause: cercariae are free swimming and penetrate the skin
Symptoms: Katayama more common because eggs are smaller, more common, and enter more tissues including the brain
Where it like to reside in the body: mesenteric vein
DX: small golden eggs w/ tiny spikes
Prevention: Education, sanitation
Describe S. Haematobium in terms of distribution, what causes it, symptoms, where it like to reside in the body, how to dx, and prevention
Distribution: Africa and Asia
Cause: cercariae are free swimming and penetrate the skin
Symptoms: itch/rash-> cough-> hepatitis and hematuria/dysuria. May lead to SCC of bladder
Where it like to reside in the body: veins of the bladder and urinary system
DX: egg w/ large sharp terminal spine in bladder or urine
Prevention :Education, sanitation
What causes swimmers itch
non human schistosomes cercariae penetrate the skin but cannot develop into flukes
What Rx are used to treat trematodes
Praziquantel, mebendazole, triclabendazole
