Question:medium

The symptoms of malaria do not appear immediately after the entry of sporozoites into the human body when bitten by female Anopheles mosquito. Explain why it happens.

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Pre-formed antibodies (antitoxins) provide immediate protection against specific toxins or venoms, as they neutralize harmful substances before the body has a chance to produce its own immune response.
Updated On: Jan 13, 2026
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Solution and Explanation

Explanation for the delayed onset of malaria symptoms post-sporozoite inoculation:
- The interval before malaria symptoms manifest is attributed to the developmental phase of sporozoites into merozoites.
- Upon a female Anopheles mosquito's bite, sporozoites are introduced into the human circulatory system. These travel to the liver for maturation into schizonts.
- Subsequently, schizonts liberate merozoites into the bloodstream, which then infiltrate erythrocytes.
- Malaria symptoms, characterized by fever and chills, arise when merozoites lyse red blood cells, releasing endotoxins. This parasitic cycle requires days to weeks to develop, explaining the asymptomatic period immediately following a mosquito bite.
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