Question:medium
Which of the following is the carrying agent (vector) for the disease with the given characteristic on polarized microscopy?
Which of the following is the carrying agent (vector) for the disease with the given characteristic on polarized microscopy?
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The Maltese-cross tetrad inside RBCs means babesiosis - which arthropod transmits it?
Updated On: Jun 23, 2026
- Anopheles
- Ixodes scapularis ticks
- Louse
- Rat flea
Show Solution
The Correct Option is B
Solution and Explanation
Step 1: Decode the slide. Four pear-shaped parasites inside a single red cell, arranged with their tips touching to form a cross (the Maltese cross tetrad), are diagnostic of Babesia, an intraerythrocytic protozoan.
Step 2: Link disease to vector. Babesiosis is spread by the hard tick Ixodes scapularis, the deer tick that also carries Borrelia burgdorferi (Lyme). Therefore the carrying agent is the Ixodes tick.
Step 3: Distinguish from malaria. Because ring forms can mimic Plasmodium falciparum, remember two clues: only Babesia forms the Maltese cross, and Babesia lacks the haemozoin pigment that malaria deposits. These separate the two on a blood film.
Step 4: Reject other vectors. Anopheles mosquitoes carry malaria, body lice carry epidemic typhus and relapsing fever, and the rat flea carries plague. Only the Ixodes tick transmits Babesia.\[\boxed{\text{Ixodes scapularis ticks}}\]
Step 2: Link disease to vector. Babesiosis is spread by the hard tick Ixodes scapularis, the deer tick that also carries Borrelia burgdorferi (Lyme). Therefore the carrying agent is the Ixodes tick.
Step 3: Distinguish from malaria. Because ring forms can mimic Plasmodium falciparum, remember two clues: only Babesia forms the Maltese cross, and Babesia lacks the haemozoin pigment that malaria deposits. These separate the two on a blood film.
Step 4: Reject other vectors. Anopheles mosquitoes carry malaria, body lice carry epidemic typhus and relapsing fever, and the rat flea carries plague. Only the Ixodes tick transmits Babesia.\[\boxed{\text{Ixodes scapularis ticks}}\]
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