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Microbiology

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Helminth

Question
26 out of 100
 

Fish is one of host for following except?



A Paragonimus westermani

B Clonorchis sinensis

C Opisthorchis viverrini

D Diphyllobothrium latum

Ans. A Paragonimus westermani

a. Paragonimus has a complex life-cycle that involves two intermediate hosts and humans who are definitive hosts.

b. Eggs first develop in water after being expelled by coughing (unembryonated) or being passed in human feces. In the external environment, the eggs become embryonated.

c. In the next stage, the parasite miracidia hatch and invades the first intermediate host such as a species of freshwater snail.

d. Miracidia penetrate its soft tissues of the snail and mature into cercariae in 3 to 5 months.

e. Cercariae next invade the second intermediate host such as crabs or crayfish which eat infected snails and encyst to develop into metacercariae within 2 months.

f. Infection of humans or other mammals (definitive hosts) occurs via consumption of raw or undercooked crustaceans by eating inadequately cooked or pickled crab or crayfish that harbor metacercariae of P.westermani.

g. 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.

h. The worms can also reach other organs and tissues, such as the brain and striated muscles, respectively.

Helminth Flashcard List

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