You can get infected by eating raw,improperly cooked fish or freshly salted fish-Heterophyes heterophyes Parasite

Heterophyes Parasite has a oval shape,tick and light brown colour.Is formed of body and tail,2 dark eyes spots,is a oral sucker and has 7 pairs of penetration glands.

The adult worms live in the samll intestine of man,dog,cat and other fish eating animals.Eggs are discharged with faeces.
The eggs does not hatch in water but is ingested by snail that lives in brackish water.Whitin the snail and develops into other generation that leave the sanil to the water.This penetrate the skin of fishes (like Bolthy and Boury fishes of Egypt).In the muscle of fish the parasite reach the infective stage.So,the cycle needs 2 intermediate hosts.

The definitive host is infected by eating raw fish,improperly cooked (for exemple grilled) or freshly salted fish (less then 10 days).
In the small intestine,the cyst wallis dissolved and start the infective stage.Eggs appear in faeces 2-3 weeks after infection.

Symptomatology:
-Mild inflammation and superficial necrosis of the mucous at the site of attachment.
As symptoms: colicky pain,diarrhoea with mucus and blood.
-Eggs emboli: eggs may find their way into circulation where they are carried to ectopic sites (for exemple heart and can lea to myocarditis and heart failure).

Eggs can be detected in faeces by laboratory test.

Infection by heterophyes parasite can be controled by periodic examination of water (avoiding defecation in water),by mass treatment and proper cooking of fish.

READ MORE:
Parasites that can infect humans who eat raw fish