Ankylostomiasis caused by hookworms, two nematodes in humans, Anccylostoma duodenalis and Necator americanus. The infected human release in the feces the eggs to the ground, the egg grows to lavae and matures, this larvae is the infectious stage to humans and have the hability to penetrate human skin and access bloodstream. In bloodstream they migrate through lungs and then to the small intestine where they evolve to adults, reproduce and release eggs. The adult also suck blood from the small intestine wall causing the disease.
Strongyloidiasis caused by a nematode called Strongyloides stercoralis. They have a similar biological cycle to the hookworms but they release larvae in feces and the adult lives in tunnels in the mucosa of the small intestine. There´s also posibility of autoinfection from larvae released in the small intestine. The disease may be asymptomatic at first but in immunocompromised individuals strongyloidiasis can cause a hyperinfective syndrome which is severe, inmunosupressive drugs are associated with this.
Trichuriasis caused by Trichuris trichiura or human whipworm: The human gets infected through accidental ingestion of eggs found in the earth and can contamine water and food. The egg evolves, first in the small as larvae and then in the large intestine to adult where they reproduce and release the eggs through feces.
Trichinosis, caused by a nematode Trichinella spiralis. Human gets infected by eating pig flesh containing larvae in muslce tissue. In the intestine, larvae evolve to adult which live in the mucosa and release larvae.
Fascioliasis caused by Fasciola hepatica, a trematode. The human gets infected by ingesting vegetables that grow in water where the larvae stick on these vegetables. The larvae ultimately reach the liver and grows to adult causing symptoms.
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