Microbiology-Liver Flukes and Schistosomiasis Flashcards
2 major categories of trematodes that cause hepatobiliary disease?
1) Liver flukes: opisthorchiidae and fasciolidae 2) Blood flukes: schistosoma
Medically significant liver flukes from the opisthorchiidae (3)
Clonorchis sinensis (Chinese liver fluke), opisthorchis viverrini (SE Asian liver fluke), opisthorchis felineus (Cat liver fluke)
What is the life cycle of the liver flukes (clonorchis sinensis, opisthorchis viverrini and opisthorchis felineus)?
1) Trematodes live in bile duct, secrete embryonated eggs in feces 2) Snail eats eggs in fresh water 3) Eggs grows to cercariae and encyst in fresh water fish 4) Human eats raw carp (cyprinidae) and infectious metacercariae 5) Excyst in duodenum 6) Juvenile fluke ascends bile duct and becomes an adult, egg secreting fluke.
How do liver flukes cause disease?
They sit in the bile duct, grazing on the epithelium. This causes chronic inflammation for months and even years within the biliary tract. Ultimately you get fibrosis, distortion and distention in the bile duct.
What liver flukes most commonly causes acute disease?
Opisthorchis felineus and fasciola
A 44 year old woman presents with abdominal pain, fatigue, dyspepsia and hepatomegaly. Labs reveal eosinophilia and elevated IgE levels. Cholangiography is shown below. What are the most serious complications this patient is at risk for?
Note the filling defects on cholangiography indicating liver fluke infection. Chronic disease can induce bile duct proliferation, predisposing the person to ascending cholangitis or cholangiocarcinoma.
What liver flukes are recognized carcinogens?
Opisthorchis viverrini and Clonorchis sinesis
A 44 year old woman presents with abdominal pain, fatigue, dyspepsia and hepatomegaly. Labs reveal eosinophilia and elevated IgE levels. Cholangiography is shown below. How do you confirm your diagnosis?
Parasite eggs in feces (note operculum at the head that acts as an escape hatch)
A 44 year old woman presents with abdominal pain, fatigue, dyspepsia and hepatomegaly. Labs reveal eosinophilia and elevated IgE levels. Cholangiography is shown below. Stool sample reveals small eggs. How do you treat this patient?
Praziquantel or albendazole
How do fasciola hepatica and fasciola gigantica differ from the Clonorchis and Opisthorchis liver flukes?
They are twice as big
Where do you typically find fasciola hepatica and fasciola gigantica?
Fasciola hepatica is found throughout the world. Fasciola hepatica is found is Subsaharan Africa and SE Asia.
How do you get infected by fasciola?
1) Flukes live in bile ducts of grazing animals and secrete unembryonated eggs in feces 2) Eggs hatch in fresh water and infects snails 3) Cercariae are released from the snail back into the water 4) Cercariae encysts on water plants 5) People eat water plants 6) Metacercariae excysts in duodenum and punches its way out of the gut 7) Penetrates through liver and lands in bile duct
A 37 year old Chinese immigrant presents complaining of abdominal pain, malaise, fever and weight loss for the past 3 months. Labs reveal eosinophilia. She has a history of eating lots of seaweed. Liver biopsy is shown below. What will her condition progress to if she remains untreated?
Fasciola has an invasive stage, which she is experiencing now. Once it lands in the biliary tree, it will cause obstructive symptoms like intermittent abdominal pain, ascending cholangitis, jaundice and stones.
Why is it easier to diagnose fasciola compared to clonorchis or opisthorcis? How could you make a false diagnosis?
The eggs are some of the largest ones you can find. You can also diagnose by antibody detection. You could make a false diagnosis in someone who at the liver of an animal that had fasciola.
A 37 year old Chinese immigrant presents complaining of abdominal pain, malaise, fever and weight loss for the past 3 months. Labs reveal eosinophilia. She has a history of eating lots of seaweed. Liver biopsy is shown below. How do you treat her?
Fasciola cannot be treated with praziquantel. It is treated with triclabendazole, bithionol or nitazoxanide.
What is the life cycle of schistosomes?
There is no metacercaria state, they emerge as cercaria from snails. Cercaria infect humans by detecting human skin molecules and direct skin penetration by release of digestive enzymes. The tail is left behind and the head finds a blood vessel and migrates to the portal and enteric veins where they grow into adult flukes.
What does the pairing of male and female schistosomes look like?
Hot dog or a taco, the male being the bun or the taco shell
How do the schistosomes cause disease?
The worms sit in blood vessels for years without doing any direct damage. Their eggs impact into small vessels in the bowel and induce a surrounding granuloma formation. The granuloma allows it to traverse the GI mucosa and release into the lumen where they can leave in feces. However, sometimes the eggs can go backwards into the liver and induce the same inflammatory damage and fibrosis (shown below).
What causes this? Why is this really scary?
Calcified pipe stem fibrosis from schistosome eggs implanting in the liver. This type of severe fibrosis can cause portosystemic shunts that allow eggs to implant in lungs and other areas of the body.
How do you diagnose schistosomiasis?
Parasite eggs (schistosoma mansoni eggs are large w/a prominent lateral spine, schistosoma japonicum is round with an inconspicuous lateral spine) in feces and serology
