Life Cycle
The life cycle involves humans as a definite host and pigs as an intermediate host. Pigs ingest contaminated food or water that contains eggs or proglottids from human feces. The eggs (ova) develop into cysticerci in pig muscles. Humans become infected when they ingest raw or undercooked pork that contain viable cysticerci. Upon reaching the small intestine, the scolex attaches to the intestinal wall and a proglottid chain grows. T. solium releases three to six proglottids/day, bearing 30,000 to 70,000 eggs per proglottid into the intestine. Nearly 250,000 ova are passed daily into the human feces and to the environment, and the cycle continues. Infections with cysticercus occur after humans consume the ova from exogenous sources or through self-infection via the fecal-oral route. Humans, in this case, are intermediate hosts. Ova are digested in the stomach and release oncospheres which penetrate the intestinal wall and reach the bloodstream. These oncospheres develop into cysticerci in any organ but are common in brain, subcutaneous tissue, or eyes.
Read more about this topic: Cysticercosis
Famous quotes containing the words life and/or cycle:
“In Vietnam, some of us lost control of our lives. I want my life back. I almost feel like I’ve been missing in action for twenty-two years.”
—Wanda Sparks, U.S. nurse. As quoted in the New York Times Magazine, p. 72 (November 7, 1993)
“Oh, life is a glorious cycle of song,
A medley of extemporanea;
And love is a thing that can never go wrong;
And I am Marie of Roumania.”
—Dorothy Parker (1893–1967)