Which stage of malarial parasite is responsible for relapse?

Options

A. Merozoite
B. Sporozoite
C. Gametocyte
D. hypnozoite

Answer

### Step-by-Step Solution:

1. **Understanding the Malarial Parasite Lifecycle**: The lifecycle of the malarial parasite involves several stages, including sporozoite, merozoite, gametocyte, and hypnozoite. Each stage has a specific role in the infection process.

2. **Identifying the Initial Stage**: When a female Anopheles mosquito bites a human, the first form of the parasite that enters the human body is the **sporozoite**. This stage is responsible for the initial infection.

3. **Transformation into Merozoite**: The sporozoites then mature into **merozoites**. Merozoites invade red blood cells (RBCs) and are responsible for the clinical symptoms of malaria.

4. **Dormant Phase**: After some time, the sporozoites can enter a dormant phase known as **hypnozoite**. This stage does not actively cause disease but can remain in the liver for an extended period.

5. **Reactivation and Relapse**: The hypnozoites can reactivate and undergo a process called **schizogony**, which leads to the production of new merozoites. This reactivation results in a relapse of the malaria infection.

6. **Conclusion**: Therefore, the stage of the malarial parasite responsible for relapse is the **hypnozoite**.

### Final Answer:
The stage of the malarial parasite responsible for relapse is **hypnozoite**.

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