Exoerythrocytic cycle is absent in

Options

A. P.vivax
B. P. falciparum
C. P. malariae
D. P. ovale

Answer

To solve the question "Exoerythrocytic cycle is absent in," we need to understand the context of the exoerythrocytic cycle in relation to malaria and the Plasmodium species. Here’s a step-by-step breakdown of the solution:

### Step 1: Define the Exoerythrocytic Cycle
The exoerythrocytic cycle refers to a stage in the life cycle of the malaria parasite (Plasmodium) that occurs outside of red blood cells (RBCs). This stage primarily takes place in the liver cells after the parasite has entered the human body.

**Hint:** Remember that the exoerythrocytic cycle occurs in the liver and is not associated with symptoms.

### Step 2: Identify the Life Cycle of Plasmodium
In the life cycle of Plasmodium, the parasite begins as sporozoites, which are injected into humans through the bite of an infected mosquito. These sporozoites travel to the liver, where they undergo the exoerythrocytic cycle, transforming into merozoites.

**Hint:** Focus on the transformation of sporozoites to merozoites and where this occurs.

### Step 3: Understand the Role of Merozoites
Merozoites are the infective stage of the malaria parasite that invade red blood cells, leading to the symptoms of malaria. The presence of the exoerythrocytic cycle allows for a period of dormancy and recovery in some species of Plasmodium.

**Hint:** Merozoites are crucial for causing malaria symptoms, while the exoerythrocytic cycle is not.

### Step 4: Identify the Plasmodium Species
Among the various species of Plasmodium, Plasmodium vivax and Plasmodium ovale have an exoerythrocytic cycle, which allows for a dormant phase in the liver. However, Plasmodium falciparum does not have this cycle, leading to continuous symptoms and high mortality rates.

**Hint:** Compare the characteristics of different Plasmodium species regarding the exoerythrocytic cycle.

### Step 5: Conclusion
Based on the information gathered, the exoerythrocytic cycle is absent in **Plasmodium falciparum**. This absence is significant because it results in a higher risk of severe malaria and repeated episodes of fever, known as malarial relapse.

**Final Answer:** Exoerythrocytic cycle is absent in **Plasmodium falciparum**.

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