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Paragonimus westermani (Japanese lung fluke or oriental lung fluke) is the most common species of lung fluke that infects humans, causing paragonimiasis. [2] Human infections are most common in eastern Asia and in South America. Paragonimiasis may present as a sub-acute to chronic inflammatory disease of the lung. It was discovered by Dutch ...
Paragonimiasis is a food-borne parasitic disease caused by several species of lung flukes belonging to genus Paragonimus. [4] Infection is acquired by eating crustaceans such as crabs and crayfishes which host the infective forms called metacercariae, or by eating raw or undercooked meat of mammals harboring the metacercariae from crustaceans.
The lung fluke encysts within the tissue of crustaceans until the crustacean is consumed by humans or other animals. Once the fluke has been ingested, enzymes within the digestive tract of the consumer break down the parasitic cysts. The immature parasite continues to mature within the lungs of its new host, feeding on its intestine, and lay eggs.
Paragonimiasis is caused by the body's natural immune response to the worms and eggs that are present and also migrating from the intestines to the lungs. [citation needed] As a rule, the parasites begin to cause symptoms about three weeks after ingesting live metacercariae. After about eight weeks, they begin to produce eggs in the lungs.
As the larvae travel towards the respiratory system, they mature, and by the time they reach the lungs, they are full adults. [10] Once they reach the lungs the females lay eggs and once they hatch the new larvae travel up the windpipe to be swallowed and then expelled, repeating the cycle. [ 8 ]
Metagonimus yokogawai has adult flukes that parasitize the small intestine and causes inflammation. [5] This species was discovered by Fujiro Katsurada with egg samples from Japan and Taiwan [6] With this discovery, he was able to make a new genus of trematodes that this new parasite would fall under [6] The size of these eggs are about 29 μm. [7]
Fasciola gigantica causes outbreaks in tropical areas of South Asia, Southeast Asia, and Africa.The geographical distribution of F. gigantica overlaps with F. hepatica in many African and Asian countries and sometimes in the same country, although in such cases, the ecological requirement of the flukes and their snail hosts are distinct.
The sexually mature monoecious adult self-fertilises in the mammalian rumen, and retains the eggs inside its uterus. [5] Eggs are then released in the host intestine and are expelled along with faeces. Eggs are deposited in water and hatch at optimal temperature of 27 °C (81 °F) in 12–17 days to become ciliated miracidia. The non-feeding ...