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 vector is responsible for transmitting Trypanosoma cruzi, causing Chagas disease. The initial symptoms of unilateral palpebral edema and lymphadenopathy are characteristic of Chagas disease. The complications of megaesophagus and megacolon are also common manifestations of chronic Chagas disease. Glossina morsitans (A) transmits African trypanosomiasis (sleeping sickness), Ixodes scapularis (B) transmits Lyme disease, and Simulium damnosum (D) transmits onchocerciasis (river blindness), so they are not associated with the symptoms described.

Correct Answer: B

Rationale: Correct Answer: B (Vitamin B12 deficiency) Rationale: 1. Mr. XY is a strict vegetarian, avoiding meat, fish, and milk products. 2. Vitamin B12 is mainly found in animal products, crucial for red blood cell production. 3. Vegetarians at risk of B12 deficiency due to limited dietary sources. 4. Anemia can result from B12 deficiency, leading to decreased red blood cell production. Summary: A: Iron deficiency - Possible but less likely since vegetarian diets can still provide iron. C: Defects in erythropoietin production - Unrelated to diet, more related to kidney function. D: Calcium-deficiency - Not directly related to anemia; more associated with bone health.

Correct Answer: B

Rationale: The correct answer is B: Reticulocytes. Reticulocytes are immature red blood cells released by the bone marrow into the bloodstream in response to increased erythropoietic activity. They indicate ongoing erythropoiesis as they mature into fully functional red blood cells. Myelocytes (A) are immature granulocytic precursors, not involved in erythropoiesis. Ring sideroblasts (C) are seen in conditions like sideroblastic anemia and indicate abnormal iron metabolism. Target cells (D) are red blood cells with a central bull's eye appearance and are associated with conditions like liver disease and thalassemias, not specifically erythropoiesis.

Correct Answer: D

Rationale: The correct answer is D: Infectious mononucleosis. Dohle bodies are seen in infectious mononucleosis due to the accumulation of rough endoplasmic reticulum in neutrophils. This is a result of the viral infection causing stress on the neutrophils. In chronic myeloid leukemia (A), leukemoid reaction (B), and Chediak-Higashi syndrome (C), Dohle bodies are not typically observed. In chronic myeloid leukemia, the characteristic finding is the Philadelphia chromosome. Leukemoid reaction is a reactive increase in white blood cells due to infection or inflammation. Chediak-Higashi syndrome is a rare autosomal recessive disorder characterized by defective phagolysosome formation.

Correct Answer: C

Rationale: The correct answer is C because Anopheles balabacensis, the main vector transmitting malaria in Sabah, breeds in temporary water collections in jungles. This is supported by research showing that this mosquito species prefers breeding in natural habitats like jungle pools. Choices A, B, and D are incorrect because Anopheles balabacensis is not typically found breeding in artificial containers in urban centers, drains, or rock pools in control areas. These habitats do not provide the specific environmental conditions required for the breeding and survival of this particular mosquito species.