SCHISTO Flashcards
Which of the following species of Schistosoma is responsible for urogenital disease?
A) Schistosoma mansoni
B) Schistosoma japonicum
C) Schistosoma haematobium
D) Schistosoma mekongi
Answer: C) Schistosoma haematobium
Rationale: Among the six species that cause human schistosomiasis, Schistosoma haematobium is the only one responsible for urogenital disease, while the others cause intestinal schistosomiasis.
How does Schistosoma infection occur?
A) Ingestion of contaminated food
B) Mosquito bite transmission
C) Direct penetration of intact skin by cercariae
D) Airborne inhalation of spores
Answer: C) Direct penetration of intact skin by cercariae
Rationale: Schistosomes infect humans when cercariae, the larval stage released from infected snails, penetrate the skin upon contact with contaminated freshwater.
What is the major pathological consequence of schistosome egg deposition in the liver?
A) Hepatocellular carcinoma
B) Periportal fibrosis (Symmers clay pipestem fibrosis)
C) Cirrhosis
D) Biliary obstruction
Answer: B) Periportal fibrosis (Symmers clay pipestem fibrosis)
Rationale: Schistosome eggs trapped in the liver trigger granulomatous inflammation, leading to periportal fibrosis, also known as Symmers clay pipestem fibrosis. This can result in portal hypertension and severe complications.
What is the primary diagnostic method for confirming schistosomiasis?
A) Serology for schistosome antibodies
B) Detection of eggs in stool or urine
C) Liver biopsy
D) Polymerase chain reaction (PCR) for schistosomal DNA
Answer: B) Detection of eggs in stool or urine
Rationale: The gold standard for diagnosing schistosomiasis is detecting schistosome eggs in feces (for S. mansoni, S. japonicum) or urine (for S. haematobium). Serological and molecular tests may be useful but are not the primary methods.
What is the most characteristic symptom of acute schistosomiasis (Katayama fever)?
A) Painless terminal hematuria
B) Jaundice
C) Serum sickness–like symptoms with fever and myalgia
D) Profound weight loss
Answer: C) Serum sickness–like symptoms with fever and myalgia
Rationale: Acute schistosomiasis (Katayama fever) presents as a hypersensitivity reaction to migrating larvae and eggs, leading to fever, myalgia, malaise, and other systemic symptoms.
What is a common complication of chronic Schistosoma haematobium infection?
A) Squamous cell carcinoma of the bladder
B) Hepatosplenomegaly
C) Intestinal obstruction
D) Cerebral aneurysm
Answer: A) Squamous cell carcinoma of the bladder
Rationale: Chronic S. haematobium infection is strongly associated with squamous cell carcinoma of the bladder, classified as a group 1 carcinogen by the IARC.
Which of the following is the drug of choice for treating schistosomiasis?
A) Ivermectin
B) Albendazole
C) Praziquantel
D) Metronidazole
Answer: C) Praziquantel
Rationale: Praziquantel is the recommended treatment for all forms of schistosomiasis, as it effectively kills adult worms and leads to resolution of many disease manifestations.
In hepatosplenic schistosomiasis, which of the following is the most severe complication?
A) Hematemesis
B) Hepatic steatosis
C) Pancreatitis
D) Autoimmune hepatitis
Answer: A) Hematemesis
Rationale: In hepatosplenic schistosomiasis, periportal fibrosis can lead to portal hypertension, which increases the risk of variceal bleeding and hematemesis, a life-threatening complication.
Which Schistosoma species is primarily associated with granulomatous brain lesions and seizures?
A) Schistosoma mekongi
B) Schistosoma intercalatum
C) Schistosoma japonicum
D) Schistosoma haematobium
Answer: C) Schistosoma japonicum
Rationale: S. japonicum has a tendency to cause granulomatous lesions in the brain, leading to seizures, encephalopathy, and other neurological symptoms.
What is the prepatent period for most Schistosoma species?
A) 1–2 weeks
B) 3–4 weeks
C) 5–7 weeks (up to 12 weeks for S. haematobium)
D) 6 months
Answer: C) 5–7 weeks (up to 12 weeks for S. haematobium)
Rationale: The prepatent period, which is the time from cercarial penetration to sexual maturation and egg production, is typically 5–7 weeks, except for S. haematobium, which may take up to 12 weeks
Which Schistosoma species has eggs that are ~140 µm long with a terminal spine?
A) Schistosoma mansoni
B) Schistosoma haematobium
C) Schistosoma japonicum
D) Schistosoma mekongi
Answer: B) Schistosoma haematobium
Rationale: S. haematobium eggs are around 140 µm long and have a terminal spine, distinguishing them from S. mansoni (lateral spine) and S. japonicum (rounder, smaller with a small lateral spine or knob).
Which Schistosoma species has the largest eggs with a lateral spine?
A) Schistosoma japonicum
B) Schistosoma haematobium
C) Schistosoma mansoni
D) Schistosoma intercalatum
Answer: C) Schistosoma mansoni
Rationale: S. mansoni eggs are approximately 150 µm long and have a distinct lateral spine, making them the largest among the common species.
What is the average lifespan of an adult schistosome in the human body?
A) 1–2 years
B) 3–5 years
C) 10–15 years
D) 25–30 years
Answer: B) 3–5 years
Rationale: The typical lifespan of an adult schistosome is 3–5 years, though in some cases, they can survive for up to 30 years.
