Paragonimiasis (lung fluke disease)

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Paragonimiasis (lung fluke disease)

  1. 1. By :group one
  2. 2. Introduction Paragonimiasis is a food-borne parasitic infection caused by 15 different species of Paragonimus trematodes cause a sub-acute to chronic inflammatory disease of the lung 2
  3. 3.  P. westermani was discovered in the lungs of a human by Ringer in 1879 and eggs in the sputum were recognized independently by Manson and Erwin von Baelz in 1880 3
  4. 4.  Manson proposed the snail as an intermediate host and various Japanese workers detailed the whole life cycle in the snail between 1916 and 1922 The species name P. westermani was named after a zookeeper who noted the trematode in a Bengal tiger in an Amsterdam Zoo. 4
  5. 5. Epidemiology Humans become infected after eating raw freshwater crabs or crayfish that have been encysted with the metacerciaria. Southeast Asia is more predominately more infected because of lifestyles. Raw seafood is popular in these countries. Crab collectors string raw crabs together and bring them miles inland to sell in Taiwan markets. 5
  6. 6.  These raw crabs are then marinated or pickled in vinegar or wine to coagulate the crustacean muscle. This process of cooking does not kill the metacercariae, consequently infecting the host. Smashing rice-eating crabs in rice paddies, splashing juices containing metacercariae, can also transmit the parasite, or using juices strained from fresh crabs to medicinal uses. 6
  7. 7.  This parasite is easily spread because it is able to infect other animals (zoonosis). An assortment of mammals and birds can be infected and act as paratenic hosts. Ingestion of the paratenic host can lead to infection of this parasite. Paragonimus westermani is distributed in southeast Asia and Japan. 7
  8. 8.  Other species of Paragonimus are common in parts of Asia, Africa and South and Central America. P. westermani has been increasingly recognized in the United States during the past 15 years because of the increase of immigrants from endemic areas such as Southeast Asia. Estimated to infects 22 million people worldwide. 8
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  11. 11. Life cycle The eggs are excreted unembryonated in the sputum, or alternately they are swallowed and passed with stool In the external environment, the eggs become embryonated , and miracidia hatch and seek the first intermediate host, a snail, and penetrate its soft tissues 11
  12. 12.  Miracidia go through several developmental stages inside the snail sporocysts , rediae , with the latter giving rise to many cercariae , which emerge from the snail. The cercariae invade the second intermediate host, a crustacean such as a crab or crayfish, where they encyst and become metacercariae. 12
  13. 13.  This is the infective stage for the mammalian host Human infection with P. westermani occurs by eating inadequately cooked or pickled crab or crayfish that harbor metacercariae of the parasite 13
  14. 14.  The metacercariae excyst in the duodenum penetrate through the intestinal wall into the peritoneal cavity, then through the abdominal wall and diaphragm into the lungs, where they become encapsulated and develop into adults (7.5 to 12 mm by 4 to 6 mm). 14
  15. 15.  The worms can also reach other organs and tissues, such as the brain and striated muscles, respectively. However, when this takes place completion of the life cycles is not achieved, because the eggs laid cannot exit these sites. Time from infection to oviposition is 65 to 90 days. 15
  16. 16.  Infections may persist for 20 years in humans. Animals such as pigs, dogs, and a variety of feline species can also harbor P. westermani. 16
  17. 17. Life cycle 17
  18. 18. Adult worm 18
  19. 19. Transmission Time from infection to oviposition (laying eggs) is 65 to 90 days. Infections may persist for 20 years in humans.  Humans are infected by eating undercooked freshwater crabs and crayfish infected with the metacercariae. 19
  20. 20. pathology The immature flukes burrow out of the human intestine into the peritoneum, where they mature and tunnel their way into the lungs. Here they cause inflammation, haemorrhage, and necrosis of the lung parenchyma. Adult flukes (stout, bean-shaped, ~1 cm long) live in cavities in proximity to airways. 20
  21. 21. Clinical features Days-weeks after eating infected food, migration of the flukes within the peritoneal and pleural cavities causes signs of inflammatory and allergic responses fever rashes urticaria abdominal and chest pain or discomfort. 21
  22. 22.  Ova are expelled either in expectorated sputum or in the faeces after being swallowed. Flukes that miss the lungs produce extrapulmonary symptoms (due to cysts, granulomas, and abscesses) in muscles, abdominal viscera, brain, genitalia. 22
  23. 23. o The classic feature of chronic pulmonary disease is persistent cough with production of a thick brownish- red sputum (due to the presence of ova and flukes). Some times hemoptysis Physical examination of the chest often reveals little and the patients appear quite well. 23
  24. 24.  Aberrant migration of the flukes may produce signs of a cerebral SOL (epilepsy, raised ICP, psychiatric syndromes, meningeal irritation) or spinal SOL, necrosis of abdominal viscera, transitory subcutaneous swellings. Extrapulmonary disease may occur in the absence of pulmonary signs, but this is uncommon. 24
  25. 25.  Ectopic lesions from can involve any organ including abdominal viscera, the heart, and the mediastinum. Paragonimus flukes may also invade the liver, spleen, intestinal wall, peritoneum, and abdominal lymph nodes 25
  26. 26. In the skin P. skrjabini often produces skin nodules, subcutaneous abscesses a type of creeping eruption known as "trematode larva migrans." 26
  27. 27. In the CNS The most clinically recognizable ectopic lesions arise from cerebral paragonimiasis, which, in highly endemic countries, more commonly affects children. Many patients with central nervous system disease also have pulmonary infections. CNS involvement occurs in up to 25% of hospitalized patients 27
  28. 28.  These children present with eosinophilic meningoencephalitis, seizures or signs of space-occupying lesions. 28
  29. 29. Diagnosis: presence of ova or adult flukes in the sputum, faeces, or effusion but these are not present until 2 to 3 months after infection. serology. X-ray the chest cavity and look for worms. easily misdiagnosed, because pulmonary infections look like tuberculosis, pneumonia, or spirochaetosis 29
  30. 30. Microscopy Sputum examined microscopically may reveal Paragonimus eggs released by the flukes in the lungs. Keep in mind that the acid-fast stain that is used for TB testing of sputum destroys eggs. 30
  31. 31.  The eggs may also be found by multiple stool exams on different days as a result of coughed-up eggs that are swallowed. The microscopic eggs are yellowish brown, 80-120 µm long by 45-70 µm wide, thick-shelled, and with an obvious operculum. 31
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  34. 34. Serology and blood tests Serologic tests can be especially useful for early infections (prior to maturation of flukes) or for ectopic infections where eggs are not passed in stool. Paragonimus-specific antibody test by micro-ELISA Peripheral eosinophilia is common and can be intense, especially during the early larval migration stages. 34
  35. 35. lung biopsy can also be used to diagnose this parasite. 35
  36. 36. Lung biopsy 36
  37. 37. X-ray the chestMany patients have a spectrum of abnormalities on chest radiographs: lobar infiltrates coin lesions cavities calcified nodules, hilar enlargement, pleural thickening and effusions. 37
  38. 38. Scattered areas ofpatchy pneumoniawith "cotton wool"opacities and ringshadows 38
  39. 39. There are typicalfluffy, cotton wooldensities in the rightlung base and leftsuprahilar areaproduced by themigrating larvaewhich havepenetrated thediaphragm andpleura in the firststage 39
  40. 40. Lateral chestradiograph of a 38-year-old Koreanman withparagonimiasisshows a wormmigration tractidentified by themeandering linearopacity (arrow)abutting the majorpleural fissure 40
  41. 41. Ring-shaped opacities of contiguous cavities giving the characteristic appearance of a bunch of grapes are highly suggestive of pulmonary paragonimiasis. 41
  42. 42. CT and MRI of the brain Central nervous system disease may provide similar "grapebunch“ findings, characteristically seen in the temporal and occipital lobes on computed tomography of the brain 42
  43. 43. Contrast-enhancedCT scan shows aconglomerate ofring-shaped lesionsin the right parietallobe withsurrounding edema. 43
  44. 44. MRI of cerebralparagonimiasis in itsearly active stage in a 24-year-old Korean woman.Contrast-enhanced TI-weighted images showmultiple conglomerate,ring-enhancing lesionswith massivesurrounding edema inthe right frontal lobe.Note the mass effectdistorting anddisplacing the frontalhorn and body of theright lateral ventricl 44
  45. 45. Management:Praziquantel is the drug of choice: adult or pediatric dosage, 25 mg/kg given orally 3 times per day for 2 consecutive days.Alternatives:Triclabendazole (not available in the U.S.), adult or pediatric dosage, 10 mg/kg orally once or twice; or Bithionol: adult or pediatric dosage, 30-50 mg/kg on alternate days for 10-15 doses. 45
  46. 46.  For cerebral disease, Treat cautiously a short course of corticosteroids may be given. dexamethasone 4 mg IV q6 h as cover neurological deterioration, in some cases producing seizures and coma. Beware of raised ICP due to dying parasites. 46
  47. 47. Prevention improve health education to decrease consumption of undercooked crustaceans mass treatment of persons in endemic areas. Never eat raw freshwater crabs or crayfish. Cook crabs and crayfish for to at least 145°F (~63°C). Travelers should be advised to avoid traditional meals containing undercooked freshwater crustaceans. 47
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