Cysticercosis is caused by the ingestion of the eggs of the tapeworm called Taenia solium. In this disease, the larval form of the tapeworm develops in an intermediate host. Usually, pigs are the intermediate host for T. solium, but sometimes humans can serve as accidental hosts. Cysticercosis only occurs when the tapeworm eggs are ingested (fecal oral route), not when the cysts in undercooked pork is eaten; the latter is associated with taeniasis.

Cysticercosis is caused by the ingestion of the eggs of the tapeworm called Taenia solium. In this disease, the larval form of the tapeworm develops in an intermediate host. Usually, pigs are the intermediate host for T. solium, but sometimes humans can serve as accidental hosts. Cysticercosis only occurs when the tapeworm eggs are ingested (fecal oral route), not when the cysts in undercooked pork is eaten; the latter is associated with taeniasis.

Lifecycle of Taenia solium (pork tapeworm)

The normal lifecycle of Taenia solium involves part development in pigs and another part in humans. The pigs ingest the feces of the individual infected with the tapeworm infection, which contain the tapeworm eggs. The eggs reach the pigs’ intestine, hatch into larvae, penetrate through the intestinal wall and move into the muscle tissue. In the tissue, they develop into larval cysts called cysticerci. When the meat of the pigs (pork) is eaten by a human, the cysticerci are released. Cysticerci attach themselves to the intestinal wall and mature into adult tapeworms that produce eggs. This is called as taeniasis or adult tapeworm infection. The ingested eggs move into the bloodstream, travel until they find their way into the subcutaneous tissues, muscle, brain, or other tissues. After 60 to 90 days, the eggs develop into larval cysts. These cysts stay in the tissue for an indefinite period, without proceeding to the next stage of the life cycle. During this period, the larvae ‘disguise’ and protect themselves from the immune system, while presenting only mild symptoms. This is the stage of cysticercosis. If humans ingest tapeworm eggs through food or water contaminated with human fecal matter, they may also develop cysticercosis. Some humans having taeniasis infect themselves with eggs by accidentally ingesting their own fecal matter through bad hygienic practices. Cysticercosis develops as the eggs mature to larval form in the intestine and go through development similar to that they undergo in pigs.

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