A patient presents with diarrhea and GI disturbance, analysis of stool on wet mount shows motile protozoa without RBCs and pus cells. The diagnosis is –
**Core Concept**
The patient's symptoms of diarrhea and gastrointestinal disturbance, along with the presence of motile protozoa on a wet mount stool analysis, suggest an infection caused by a protozoan parasite. This is a common cause of gastrointestinal illness, often associated with contaminated food or water.
**Why the Correct Answer is Right**
The presence of motile protozoa on a wet mount stool analysis is diagnostic for Giardiasis, caused by the protozoan parasite *Giardia lamblia*. Giardiasis is characterized by malabsorption, weight loss, and chronic diarrhea. The parasite attaches to the intestinal mucosa and interferes with nutrient absorption, leading to the patient's symptoms. The absence of RBCs and pus cells in the stool rules out bacterial or amoebic infections.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not match the description of the patient's symptoms and the presence of motile protozoa on the stool analysis. A bacterial infection would typically present with fever, abdominal pain, and the presence of pus cells in the stool.
* **Option B:** This option is incorrect because it refers to a viral infection, which would not typically present with motile protozoa on a stool analysis. Viral gastroenteritis is often associated with norovirus or rotavirus.
* **Option C:** This option is incorrect because it refers to an amoebic infection, which would typically present with dysentery (diarrhea with blood and pus) and would not be diagnosed by the presence of motile protozoa on a wet mount.
**Clinical Pearl / High-Yield Fact**
In cases of suspected giardiasis, the patient should be asked about recent travel history, exposure to contaminated water, and consumption of undercooked food. Additionally, a stool test for *Giardia lamblia* should be performed, and treatment with metronidazole or albendazole should be initiated promptly.
**Correct Answer:** C.