Infective stage of Trypanosoma gambiense is

Options

A. Metacyclic
B. Crithidial
C. Leptomonas
D. Leishmania.

Answer

To determine the infective stage of Trypanosoma gambiense, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Organism**:
- Trypanosoma gambiense is a protozoan parasite that causes African sleeping sickness. It is transmitted to humans through the bite of the tsetse fly (Glossina species).

2. **Identify the Transmission Vector**:
- The tsetse fly is the vector responsible for transmitting Trypanosoma gambiense. It plays a crucial role in the life cycle of the parasite.

3. **Recognize the Infective Stage**:
- The infective stage of Trypanosoma gambiense is known as the metacyclic form. This form develops in the tsetse fly and is the stage that can infect humans.

4. **Locate the Metacyclic Form**:
- The metacyclic trypomastigotes are found in the salivary glands of the tsetse fly. When the fly bites a human, it injects this form into the bloodstream.

5. **Review the Options**:
- The question provides four options: metacyclic, crithidial, leptomonas, and leishmania.
- Among these, only the metacyclic form is associated with Trypanosoma gambiense.

6. **Conclude the Answer**:
- Therefore, the correct answer to the question regarding the infective stage of Trypanosoma gambiense is **metacyclic**.

### Final Answer:
The infective stage of Trypanosoma gambiense is **metacyclic**.

---