Parasitology: Trematodes

Question 1

Answer 1

Schistosoma haematobium

• Epidemiology: Africa
• Intermediate Host: snail
• Host:
• vector:
• features: terminal spine
• Sx: swimmer’s itch, schistosomular pneumonitis, inflammation from trapped eggs of bladder and ureter -> polyps & bladder cancer (squamous cell metaplasia), hydronephrosis, hematuria
• Dx: eggs in urine (direct),
  
  • indirect: serology, haematuria, imaging
  • Hx of water contact
• Rx: Praziquantal

Question 2

Answer 2

Schistosoma mansoni

• Epidemiology: Caribbean, Africa, S. America
• Host: snail intermediate
• Intermediate host: snails
• Host: buffalo,
• vector:
• features: sub-terminal spine
• Sx: Symmer’s pipe-stem fibrosis, eggs get into mesenteric veins, wimmer’s itch, schistosomular pneumonitis, inflammation from trapped eggs in walls of mesenteric veins, ova trapped in portal v. and br., periovular granuloma, fibrosis, portal hypertension, varices, hematemesis, melena/anemia
• Dx: detection of eggs in stool or rectal biopsy (direct)
  
  • Hx of water contact
• Rx: Praziquantal
• Control

Question 3

Answer 3

Schistosoma japonicum

• Epidemiology: China, Philippines, Taiwan, Indonesia
• Intermediate Host: snail
• Host: buffalo, nocturnal animals, dogs
• vector:
• features
• Sx: Symmer’s pipe-stem fibrosis, eggs get into mesenteric veins, swimmer’s itch, schistosomular pneumonitis, periovular granuloma, fibrosis, portal hypertension, varices, hematemesis, melena/anemia
• Dx: Hx of water contact, inflammation from trapped eggs
• Rx: Praziquantal
• Control

Question 4

Answer 4

Fasciola hepatica (liver fluke)

• Epidemiology
• Definitive host: cattle and sheep, humans
• Intermediate host: snail
• Sx:
• Dx: eggs in feces
• Rx: Triclabendazole
• Control: decrease snail habitats, anthelmintics (anti-worm meds)

Question 5

Answer 5

​Clonorchis sinensis (Chinese Liver Fluke)

• Epidemiology: China & SE Asia
• Host: dogs, humans
• Intermediate host: snail, fish
• Features
• Sx: bladder cancer (squamous cell metaplasia), cholangiocarcinoma, death in humans
• Dx: characteristic eggs
• Rx: Praziquantal
• Control: cook fish properly, prevent water contamination

Question 6

Answer 6

Paragonimus westermani (lung fluke)

• Epidemiology: SE Asia, West Africa, S. America
• Host: cats, dogs, humans
• Intermediate host: snail & crab
• Vector
• Features
• Sx: cough, blood-stained sputum
• Dx: characteristic eggs in sputum, X-ray
• Rx: Praziquantal
• Control: adequate cooking of crustaceans, decrease snail habitats