Question
A 30 year old patient presents with muscle weakness, headache, appetite and weight loss, fatigue, diarrhea and passing a worm in stool. On lab investigations, Vitamin B12 deficiency is present in him. Which of the parasites may cause deficiency of vitamin B12
| A. |
T. Solium |
| B. |
Diphyllobothrium latum |
| C. |
Echinococcus granulosus |
| D. |
Hymenolepis nana |
|
Correct Answer » B Explanation |
 |
Detailed Explanation:
Clinical Reasoning for the Correct Answer:
– Diphyllobothrium latum (the fish tapeworm) infects humans via ingestion of undercooked freshwater fish.
– It attaches to the small intestine and absorbs Vitamin B12, leading to deficiency.
– Vitamin B12 deficiency produces neuropsychiatric and hematologic symptoms (e.g., weakness, fatigue, paresthesia, glossitis, megaloblastic anemia).
– Case clues: chronic symptoms, worm in stool, confirmed B12 deficiency → classic for Diphyllobothrium latum.
Why Option A (Taenia solium) is Incorrect:
– Taenia solium (pork tapeworm) causes taeniasis in intestines or cysticercosis in tissues.
– It does not consume significant Vitamin B12 or cause deficiency.
– Symptoms are mainly due to gastrointestinal disturbance or neurological when cysticerci invade the CNS.
– Classic associations: neurocysticercosis, seizures in endemic regions (not B12 deficiency).
Why Option C (Echinococcus granulosus) is Incorrect:
– Echinococcus granulosus causes hydatid disease (cystic echinococcosis).
– Manifests as slowly growing cysts in the liver, lung, or other organs.
– No link to Vitamin B12 absorption or deficiency; does not reside in gut or cause worms to pass in stool.
Why Option D (Hymenolepis nana) is Incorrect:
– Hymenolepis nana (dwarf tapeworm) mainly causes mild gastrointestinal symptoms or is asymptomatic.
– No evidence for B12 malabsorption or significant deficiency.
– Common in children; may cause anal pruritus or diarrhea but not B12 deficiency.