Taenia solium and Cysticercosis

How is cysticercosis different from taeniasis?

Cysticercosis is an infection of larval stages in humans and pigs, while taeniasis is an intestinal infection with the adult tapeworm.

How are humans usually exposed to Taenia solium eggs?

Humans are usually exposed to eggs by ingestion of food/water contaminated with feces containing these eggs or proglottids.

What happens to oncospheres after ingestion by humans?

Oncospheres hatch in the intestine, invade the intestinal wall, enter the bloodstream, and migrate to multiple tissues and organs where they mature into cysticerci over 60-70 days.

What can cause neurocysticercosis?

Some cysts of Taenia solium migrate to the central nervous system, causing neurocysticercosis. Signup and view all the answers

How can humans acquire intestinal infections with T.solium?

Humans can acquire intestinal infections after eating undercooked pork containing cysticerci. Signup and view all the answers

How do adult tapeworms attach to the small intestine?

Cysts evaginate and attach to the small intestine by their scolices. Signup and view all the answers

What is the primary location where eggs of Echinococcus granulosus hatch after ingestion by an intermediate host?

Small intestine Signup and view all the answers

What is the function of the protoscolices in the life cycle of Echinococcus granulosus?

They evaginate, attach to the intestinal mucosa, and develop into adult stages Signup and view all the answers

What is the most common clinical manifestation of Echinococcus granulosus infections in humans?

Hepatic and pulmonary signs/symptoms Signup and view all the answers

What can occur if hydatid cysts rupture in humans?

Fever, urticaria, eosinophilia, and potentially anaphylactic shock Signup and view all the answers

What is the role of canids in the life cycle of Echinococcus granulosus?

They act as the definitive host Signup and view all the answers

What is the term for the six-hooked larvae that penetrate the intestinal wall and migrate to various organs?

Oncospheres Signup and view all the answers

What are the preventive measures to avoid Dyphillobothrium latum infection?

Avoid handling and caressing infected dogs, and ingestion of water and vegetables polluted by infected dog feces. Signup and view all the answers

Describe the characteristic feature of the terminal proglottids of Dyphillobothrium latum.

The terminal proglottids are characterized by the presence of an egg-filled uterus with a few short branches in the middle one-third of the segment, usually described by the central rosette. Signup and view all the answers

What are the intermediate hosts for the life cycle of Dyphillobothrium latum?

The first intermediate host is a suitable crustacean, and the second intermediate host is usually a small fish. Signup and view all the answers

What is the infectious stage for the definitive host in the life cycle of Dyphillobothrium latum?

The infectious stage for the definitive host is the plerocercoid larvae (spargana). Signup and view all the answers

What is the characteristic rosette-shaped structure found in Dyphillobothrium latum?

The characteristic rosette-shaped structure found in Dyphillobothrium latum is the uterus centrally filled with eggs. Signup and view all the answers

How long can adult Dyphillobothrium latum worms grow and how many proglottids can they have?

Adult Dyphillobothrium latum worms can grow more than 10 m in length, with more than 3,000 proglottids. Signup and view all the answers

What is the role of arthropods in the life cycle of Hymenolepis nana?

Arthropods serve as intermediate hosts for Hymenolepis nana, allowing the development of cysticercoids which can infect humans or rodents upon ingestion. Signup and view all the answers

How are the eggs of Hymenolepis nana immediately infective to hosts?

The eggs of Hymenolepis nana are immediately infective when passed with the stool as they contain oncospheres (hexacanth larvae) that can penetrate the intestinal villus upon ingestion. Signup and view all the answers

What is the fate of the cysticercoids in the host's intestine?

The cysticercoids, upon rupture of the villus, return to the intestinal lumen, evaginate their scoleces, attach to the intestinal mucosa, and develop into adults that reside in the ileal portion of the small intestine producing gravid proglottids. Signup and view all the answers

What differentiates Hymenolepis nana var. fraterna from Hymenolepis nana?

Hymenolepis nana var. fraterna infects rodents and uses arthropods as intermediate hosts, while Hymenolepis nana infects humans and rodents but uses arthropods as intermediate hosts for its cysticercoid development. Signup and view all the answers

How do the eggs of Hymenolepis nana infect humans or rodents?

Upon ingestion of the eggs either in contaminated food or water, or from hands contaminated with feces, the oncospheres contained in the eggs are released in the host. Signup and view all the answers

How are the eggs of Hymenolepis nana released from the host's body?

Eggs of Hymenolepis nana are passed in the stool when released from proglottids through its genital atrium or when proglottids disintegrate in the small intestine. Signup and view all the answers

What is the role of larger predator species in the life cycle of diphyllobothriids?

Larger predator species serve as paratenic hosts by consuming smaller intermediate hosts, allowing the plerocercoid to migrate to their musculature. Humans acquire the parasite by consuming undercooked fish from these larger predator species. Signup and view all the answers

How do adult diphyllobothriids attach themselves to the intestinal mucosa of the definitive host?

Adult diphyllobothriids attach to the intestinal mucosa using two bilateral groves called bothria located on their scolex. Signup and view all the answers

What are the common symptoms experienced by patients with diphyllobothriasis?

Most infections are asymptomatic, but gastrointestinal symptoms may occur in some patients. Rarely, massive infections can cause intestinal obstruction, and aberrant migration of proglottids can lead to cholecystitis or cholangitis. Signup and view all the answers

What is the primary method of preventing diphyllobothriasis in humans?

Prevention can be achieved by avoiding the consumption of raw or undercooked fish, such as sushimi, and by not tasting fish while cooking. Signup and view all the answers

What is the definitive host specificity among medically important diphyllobothriids?

Definitive host specificity among medically important diphyllobothriids is low. In addition to humans, other carnivorous, fish-eating mammals and a few birds can also serve as definitive hosts. Signup and view all the answers

Describe the life cycle of a Hymenolepis nana, including its size and preferred location in the body.

Adult worms of Hymenolepis nana measure 1-3 cm in length and reside in the small intestine of their definitive host. Immature eggs are discharged from the proglottids and passed in the feces, appearing in the feces 5 to 6 weeks after infection. The intermediate host is typically an insect, such as a beetle or flea. Signup and view all the answers