Paragonimus Westermani, also known as the oriental lung fluke, is a species of parasitic flatworm that infects humans and other mammals. It is most commonly found in Eastern Asia, Africa, and South/Central America. The parasite has a complex life cycle involving freshwater snails and crustaceans as intermediate hosts before infecting the lungs of humans. Common symptoms in humans include coughing, bronchitis, and blood in sputum. Diagnosis involves examining stool, sputum, or biopsy samples under a microscope. Treatment typically involves the drug paraziquantel.

1. Paragonimus Westermani

2. Paragonimus Westermani
Paragonimus waterman is also
known as Japanese lung fluke or
oriental lung fluke .
It is the most common species of
lung fluke that infect humans .
It causes Paragonimiasis .

3. Geographical Distribution
Eastern Asia
Africa
South and Central
America

4. History
 It was discovered by
Cornerad Kerbert in
1878

5. Species of paragonimus
 P. westermani filipinus
 P. westermani ichunencis
 P. westermani japonicus

6. Morphology
 Paragonimus westermani resembles coffee bean in size ,
shape ,and colour .
 Adult worms are 7.5 -12 mm long and 4-6 mm wide .
 Thickness is 3.5 – 5 mm .
 Skin is thickly covered with scale like spines .
 Have oral and ventral suckers .
 Testes are located posteriorly .

8. Morphology
Eggs :
 80- 120 micrometres and 45-70 micrometres wide .
 Yellowish brown with thick shell
cercaria :
 Circadian are often indistinguishable between species .
 Have large posterior sucker and exterior is spine.
Metacercaria :
 They are usually encysted in tissues.
 The exterior is spined and has two suckes .

10. Morphology
Adult :
 Reddish-brown and ovoid .
 7-16 mm in length and 4-8 mm wide .
 Hermaphrodite
 Have oval and ventral suckers .

11. Discovery
 P.westermani was discovered when tow Bengal Tigers died of
paragonimiasis in zoo in Europe in 1878 .
 P.westermani was discovered in lungs of humans by Ringer in 1879
.
 Mansion proposed the snail as an intermediate host .
 From 1916- 1932 Japanese scientists describe whole life cycle in
snail.
 P.westermani was named after Pieter westerman ,a zoo keeper who
noted the trematode in Bengal Tigers in Amsterdam zoo .

12. Hosts
First intermediate host :
Freshwater snail
2nd intermediate host :
Crustaceans ( mostly crabs )
Definitive host :
Humans and other mammals .

13. Life cycle
In snail :
 Unembryonated eggs are passed in the septum if human or feline (cats) .
 Two weeks later , miracidia develop in the egg and hatches .
 Miracidia penetrate its first intermediate host (snail ) .
 With in snail mother sporocyst form and produce many mother rediae .
 Mother rediae produce daughter rediae which shed crawling cercariae
into freshwater .
 Mature cercariae develops within 3-5 months.

14. Life cycle
In Crustaceans :
 The crawling cercariae penetrates freshwater crabs and encryption
in its muscles becoming meta cercaria .
 Metacercaria takes 2 months to develop .
In Humans and other mammals:
 Humans or felines then eat the infected crabs raw .
 Once eaten, the Metacercaria penetrates the gut and excess in
duodenum , penetrate through the intestinal wall into peritoneal
cavity ,then through abdominal wall and diaphragm into lungs .

15. Life cycle
 In lungs they encapsulate themselves and
become adults .
 But when they reach Brain and straited muscles
the eggs lid cannot exit , So , this can be life
threatening.
 Infections may persist for 20 years in Humans .

17. Pathogenicity
 Once in the lungs or other site , the eggs in the tissues
become Pseudotubercles ,and gets into the spinal
cord ,it’s can cause paralysis.
 This condition in Heart can cause death .
 The symptoms are localised in the pulmonary system
which include , bad cough ,bronchitis and blood in
sputum (hemoptysis ) .

18. Diagnosis
Stool or sputum demonstration
Antibody detection
X –Ray of chest cavity
Biopsy (lungs and other organs or
tissues)

19. Prevention
 More hygienic food cooking and preparation .
 Elimination of first intermediate host .
 Hand washing habits etc.

20. Treatment
 Paraziquantel
 Course of corticosteroids ( for cerebral
infection )
 Triclabendazole

21. Thank You for Your Attention 😊