Mark the incorrect statement w.r.t. infection of Entamoeba histolytica

Options

A. It is a protozoan parasite of human
B. It is characterised by constipation and abdominal pain
C. It is a parasite in small intestine of man
D. Houseflies act as mechanical carriers and serve to transmit the parasite from faeces of infected person to food and food products

Explanation

To solve the question of identifying the incorrect statement regarding the infection of Entamoeba histolytica, we will analyze the provided information step by step.

### Step-by-Step Solution:

1. **Identify the Disease**:
- Entamoeba histolytica causes a disease known as Amoebiasis. This is the first point to note.

2. **Nature of the Organism**:
- Entamoeba histolytica is classified as a protozoan parasite. This is an important characteristic of the organism.

3. **Location in the Human Body**:
- The parasite primarily resides in the large intestine of humans. This is a crucial detail as it helps in understanding the symptoms and transmission.

4. **Symptoms of Infection**:
- Common symptoms include abdominal pain, loose motions (diarrhea), and sometimes constipation. It is important to note that the symptoms can vary and may include diarrhea with constipation.

5. **Mode of Transmission**:
- The infection spreads through contaminated food and water, often due to poor sanitation and the improper disposal of feces. Houseflies can act as mechanical carriers, transmitting the parasite from feces to food.

6. **Evaluate the Statements**:
- Now, we will evaluate the statements provided in the options:
- **Option 1**: "It is a protozoan parasite of humans." - This is correct.
- **Option 2**: "It is characterized by constipation and abdominal pain." - This is misleading; while abdominal pain is a symptom, constipation is not a primary characteristic of the infection.
- **Option 3**: "Parasite in small intestine of man." - This is incorrect because the parasite resides in the large intestine, not the small intestine.
- **Option 4**: "Houseflies act as a mechanical carrier and serve to transmit the parasite from feces of infected person to food." - This is correct.

7. **Conclusion**:
- The incorrect statement is **Option 3**: "Parasite in small intestine of man." This is the statement that does not accurately reflect the infection of Entamoeba histolytica.

### Final Answer:
The incorrect statement regarding the infection of Entamoeba histolytica is **Option 3**: "Parasite in small intestine of man."

---