week 3

• What is the disease caused by lung flukes?


  Paragonimiasis
• What should students be able to do by the end of the lectures on lung and liver flukes?


  Detail and compare the lifecycles of lung and liver flukes, and understand the diseases they cause.
• What are the main objectives of the lectures on Paragonimiasis?


  • Detail the lifecycles of Paragonimus westermani and liver flukes.
  • Compare and contrast the lifecycles of these flukes.
  • Understand the diseases caused by liver and lung flukes, including pathology, diagnosis, and treatment.
• What class do lung flukes belong to?

  Trematoda
• What is the family name of Paragonimus spp.?

  Troglotrematidae
• How many species of Paragonimus are recorded in humans?


  Seven species
• Name one species of lung fluke.

  Paragonimus westermani
• What is the shape and size of Paragonimus westermani?


  Egg-shaped, 12 mm long and 6 mm wide.
• What is the general lifecycle of trematodes?


  1. Egg
  2. Miracidium
  3. 1st intermediate host (e.g., snail)
  4. Cercaria
  5. 2nd intermediate host (e.g., crustacean)
  6. Metacercaria
  7. Adult in definitive host
• What is the role of the first intermediate host in the trematode lifecycle?


  It is where the miracidium develops into sporocysts.
• What is the primary habitat of Paragonimus spp. in humans?


  Lungs
• What are the two intermediate hosts for Paragonimus westermani?


  1st intermediate host: Semisulcospira spp.; 2nd intermediate host: crabs and crayfish.
• How does transmission to humans occur for Paragonimus westermani?


  Through the consumption of raw or undercooked crustaceans.
• What is the size of Paragonimus westermani eggs?


  110 µm x 60 µm
• What is the significance of the operculum in Paragonimus westermani eggs?


  It is prominent and aids in the hatching process.
• What is the role of miracidia in the lifecycle of Paragonimus westermani?


  They penetrate the snail host to develop further.
• What is the function of the redia stage in the lifecycle?


  Rediae possess a mouth, pharynx, and gut, and are more active than sporocysts.
• What is the appearance of Paragonimus metacercaria?


  Round or elliptical, about 0.5 mm in diameter.
• What happens after excystment of Paragonimus metacercaria?


  Juveniles penetrate the intestine and embed themselves in the abdominal wall.
• Where do adult Paragonimus flukes form pairs in humans?


  In the lungs, within cysts.
• What is the typical pathology of pulmonary paragonimiasis during the acute phase?


  Few or no symptoms, possibly diarrhea, abdominal pain, or fever.
• What are the chronic symptoms of pulmonary paragonimiasis?


  Breathing difficulties, chronic cough, and sputum containing blood.
• What is the most common ectopic infection caused by Paragonimus spp.?


  Cerebral paragonimiasis
• What complications can arise from cerebral paragonimiasis?


  Hemorrhagic events and paralysis.
• What is the drug of choice for treating paragonimiasis?


  Praziquantel
• What are the prevention strategies for paragonimiasis?


  • Avoid eating raw or undercooked crustaceans.
  • Avoid contaminating foods with unboiled crab juice.
  • Destruction of snails that carry larval stages.
  • Sewage treatment.
• What is the significance of cysteine proteases in Paragonimus research?


  They are abundant immunoreactive proteins that may be useful for developing diagnostic tests and novel drug targets.
• What is the preferred second intermediate host for Paragonimus kellicotti in the USA?


  Crayfish (Oronectes spp.)
• How can pulmonary paragonimiasis be misdiagnosed?


  It may be mistaken for tuberculosis, lung cancer, and other respiratory illnesses.
• What diagnostic methods are used for paragonimiasis?


  • Demonstration of eggs in stool or sputum.
  • Biopsy (fine needle aspiration of pulmonary nodules).
  • Serological tests (Intradermal, ELISA, Immunoblotting).
  • Molecular techniques (DNA probes and PCR).
  • Radiological methods (Chest x-rays; MRI).