QCM : Cestode Infections: Pathology and Prevention — 12 questions

Explication

Plerocercoid larvae infect humans when ingested in uncooked fish, attach to the small intestine, and mature into adult worms, as stated in the source excerpt. Review: Diphyllobothriasis epidemiology, morphology, and life cycle. Course evidence: "Man and other animals are infected by eating uncooked fish that contains plerocercoid larvae (15 x 2 mm) which attach to the small intestinal wall and mature into adult worms in 3 to 5 weeks."

Explication

The source explicitly states that diagnosis is by microscopic stool examination for ova and parasites and complete blood count showing possible low hemoglobin and hematocrit levels, making these the correct diagnostic methods for diphyllobothriasis. Review: Clinical manifestations and diagnosis of diphyllobothriasis. Course evidence: "Diagnosis is by microscopic stool examination for ova and parasites and complete blood count showing possible low hemoglobin and hematocrit levels."

Explication

The source states that adult tapeworms mature in 3 to 4 months and may live up to 25 years in the small intestine, making 'Up to 25 years' the correct answer. Review: Taenia solium and T. saginata life cycle and human infection. Course evidence: "Adult tapeworms mature in 3 to 4 months and may live up to 25 years, releasing gravid proglottids with eggs in feces."

Explication

Human cysticercosis is caused by the development of T. solium oncospheres into cysticerci in tissues, as stated explicitly in the source. The other options describe incorrect or unrelated mechanisms. Review: Pathology, clinical features, and complications of taeniasis and cysticercosis. Course evidence: "Human cysticercosis results from T. solium oncospheres developing into cysticerci in tissues, especially brain, muscle, and subcutaneous tissue."

Explication

The source states that eggs hatch in the ileum, larvae penetrate villi, mature into cysticercoid larvae, and adults attach to villus mucosa, showing larvae invade tissue while adults attach to mucosal surface. Review: Hymenolepis nana infection, life cycle, clinical symptoms, diagnosis, and treatment. Course evidence: "Humans acquire Hymenolepis nana infection mainly through ingestion of infective eggs via fecal-oral exposure. Eggs hatch in the ileum, larvae penetrate villi, mature into cysticercoid larvae, and adults attach to villus mucosa. Most infections are…"

Explication

The definitive host becomes infected by ingesting the cyst-containing organs of the infected intermediate host, which completes the parasite's life cycle as stated in the source. Review: Echinococcus granulosus life cycle and epidemiology of cystic echinococcosis. Course evidence: "Definitive hosts become infected by ingesting cyst-containing organs of intermediate hosts, completing the cycle."

Explication

The source states that cyst contents may trigger anaphylactic reactions if ruptured, indicating their role in provoking severe allergic responses upon rupture. Producing protoscolices and daughter cysts is a function of the cyst itself, not specifically the contents upon rupture. Intracranial pressure and systemic symptoms are consequences of cyst location or presence, not directly the function of the cyst contents when ruptured. Review: Hydatid cyst development, pathology, and host interactions. Course evidence: "Cyst contents may trigger anaphylactic reactions if ruptured."

Explication

According to the source, E. multilocularis's definitive hosts are mainly foxes with secondary hosts, and no intermediate hosts are specified here, while E. vogeli's definitive hosts are bush dogs and dogs, and its intermediate hosts are rodents. This distinguishes their host relationships clearly. Review: Differences in life cycles and hosts of Echinococcus multilocularis, E. vogeli, and E. oligarthrus. Course evidence: "- E. multilocularis's definitive hosts are mainly foxes, with secondary hosts like dogs, cats, coyotes, and wolves. - E. vogeli's definitive hosts are bush dogs and dogs; its intermediate hosts are rodents, with larval development forming multiple vesicles.…"

Explication

The source states that the primary infection of alveolar echinococcosis is in the liver (60%), usually the right lobe, making it the most common site. The lungs and brain are affected less frequently by hematogenous spread, and the spleen is not mentioned as a primary site. Review: Clinical manifestations and organ involvement in cystic and alveolar echinococcosis. Course evidence: "The primary infection of alveolar echinococcosis is in the liver (60%), usually the right lobe, but direct extension to contiguous organs, as well as hematogenous metastases to the lungs (20%) and brain (<2%) is not uncommon."

Explication

Diagnostics in cystic echinococcosis is defined as a process based on clinical suspicion, imaging techniques, and serological tests to identify cysts and complications, making option 0 the correct function. Review: Diagnosis and clinical signs of cystic echinococcosis including secondary infection. Course evidence: "Diagnostics : A process based on clinical suspicion, imaging techniques such as ultrasound, CT, or MRI, and serological tests detecting Echinococcus antibodies to identify cysts and complications."

Explication

The source states that surgery is the primary treatment for hepatic hydatid cysts, with cystectomy and pericystectomy offering good cure rates. Chemotherapy is used when surgery is contraindicated, and surgery is not described as a last resort or only for symptom reduction. Review: Treatment options for hydatid cysts including surgery, chemotherapy, and PAIR technique. Course evidence: "Surgery is the primary treatment for hepatic hydatid cysts, with cystectomy and pericystectomy offering good cure rates."

Explication

The source states that preventing cestode infections requires good personal hygiene and proper disposal of sewage to interrupt transmission, highlighting their role in breaking the parasite's transmission cycle rather than directly killing larvae or enhancing immunity. Review: Prevention and control measures for cestode infections. Course evidence: "- Preventing cestode infections requires good personal hygiene and proper disposal of sewage to interrupt transmission. - Proper cooking or freezing of fish and meat kills infective larvae and prevents human infection. - Handwashing after handling pets…"