A 40 year old patient is presented with unilateral palpebral edema and ipsilateral lymphadenopathy. He later develops megaesophagus and megacolon as complications. Which of the following vector is responsible for this parasitic infection?

Correct Answer: C

Rationale: The correct answer is C: Rhodnius prolixus. This parasite is responsible for causing Chagas disease. The initial symptoms of unilateral palpebral edema and ipsilateral lymphadenopathy are characteristic of the acute phase of Chagas disease. The development of megaesophagus and megacolon are complications seen in the chronic phase. Rhodnius prolixus is a vector for Trypanosoma cruzi, the parasite that causes Chagas disease. Glossina morsitans is the vector for African trypanosomiasis (sleeping sickness), Ixodes scapularis is the vector for Lyme disease, and Simulium damnosum is the vector for onchocerciasis (river blindness), making them incorrect choices for this particular parasitic infection.

Correct Answer: B

Rationale: The correct answer is B: Vitamin B12 deficiency. As a strict vegetarian who does not consume any meat, fish, or milk products, Mr XY is at risk for Vitamin B12 deficiency. Vitamin B12 is primarily found in animal products and is essential for red blood cell production. Anemia can result from Vitamin B12 deficiency, leading to symptoms such as fatigue and weakness. Iron deficiency (A) is also common in vegetarians, but in this case, the focus is on Vitamin B12 due to the exclusion of all animal products. Defects in erythropoietin production (C) are not related to Mr XY's dietary choices. Calcium-deficiency (D) is not directly related to anemia in this scenario.

Correct Answer: B

Rationale: Rationale: 1. Bone marrow increases erythropoiesis in response to iron therapy. 2. Reticulocytes are immature red blood cells derived from erythroblasts, indicating active erythropoiesis. 3. Myelocytes are precursors of granulocytes, not involved in erythropoiesis. 4. Ring sideroblasts are abnormal erythroblasts with iron granules, not indicative of active erythropoiesis. 5. Target cells are red blood cells with central "target-like" appearance due to excess membrane, not directly related to erythropoiesis.

Correct Answer: D

Rationale: Step-by-step rationale for why choice D (Infectious mononucleosis) is correct: 1. Infectious mononucleosis is caused by the Epstein-Barr virus. 2. Dohle bodies are seen in the peripheral blood of patients with infectious mononucleosis. 3. These bodies represent aggregates of rough endoplasmic reticulum in neutrophils. 4. The appearance of Dohle bodies is attributed to the viral infection in infectious mononucleosis. Summary: A: Chronic myeloid leukemia - Dohle bodies are not typically seen in this condition. B: Leukemoid reaction - Dohle bodies are not specific to a leukemoid reaction. C: Chediak-Higashi syndrome - This syndrome is characterized by giant granules in neutrophils, not Dohle bodies.

Correct Answer: C

Rationale: The correct answer is C: Temporary collecting of water in jungles. Anopheles balabacensis is a forest-dwelling mosquito species commonly found in jungle environments. They prefer to breed in temporary water collections such as rainwater puddles, small ponds, or stream edges within the jungle. Breeding in urban areas, drains, or rock pools would not be typical for this species based on its natural habitat preference. Therefore, the most suitable breeding site for this vector in Sabah would be temporary water collections in jungles.