Vitamin B12 deficiency is seen in which tapeworm disease
**Core Concept**
Vitamin B12 deficiency can occur due to impaired absorption from the gastrointestinal tract, which is a common issue in parasitic infections that affect the small intestine. In this context, certain tapeworms can lead to malabsorption of essential nutrients, including vitamin B12.
**Why the Correct Answer is Right**
The correct answer is Diphyllobothriasis, a parasitic infection caused by the tapeworm Diphyllobothrium latum. This tapeworm infects the small intestine and can lead to vitamin B12 deficiency by competing with the host for nutrient absorption. The tapeworm absorbs vitamin B12 from the host's diet, leading to a deficiency in the host. This is a classic example of a nutritional deficiency caused by a parasitic infection.
**Why Each Wrong Option is Incorrect**
* **Option A:** Hymenolepiasis (caused by Hymenolepis nana) is a tapeworm infection that primarily affects the large intestine and does not typically lead to vitamin B12 deficiency.
* **Option B:** Taeniasis (caused by Taenia saginata or Taenia solium) is a tapeworm infection that affects the small intestine, but it is not typically associated with vitamin B12 deficiency.
* **Option C:** Echinococcosis (caused by Echinococcus species) is a parasitic infection that affects the liver and other organs, but it is not typically associated with vitamin B12 deficiency.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that certain parasitic infections can lead to nutritional deficiencies, including vitamin B12 deficiency. A high index of suspicion for parasitic infections should be maintained in patients with unexplained nutritional deficiencies.
**Correct Answer: D. Diphyllobothriasis**