Most common presenting symptom of threadworm infection amongst the following is –
**Core Concept**
Threadworm infection, caused by the pinworm (Enterobius vermicularis), is a common intestinal helminthic infection affecting humans worldwide. The pathogenesis of threadworm infection involves the migration of eggs through the intestinal mucosa and the subsequent release of eggs on the perianal skin.
**Why the Correct Answer is Right**
The most common presenting symptom of threadworm infection is perianal itching or pruritus ani. This occurs due to the allergic reaction to the eggs laid by the female threadworms on the perianal skin. The eggs cause an intense itching sensation, which can lead to sleep disturbances and anxiety in affected individuals. The itching is usually worse at night and can be relieved by scratching, which can further lead to skin irritation and potential bacterial superinfection.
**Why Each Wrong Option is Incorrect**
**Option A:** Abdominal pain is not a common presenting symptom of threadworm infection, although it can occur in some cases. The infection primarily affects the intestinal mucosa but does not usually cause significant pain.
**Option B:** Diarrhea is not a typical symptom of threadworm infection. While some patients may experience mild gastrointestinal disturbances, diarrhea is more commonly associated with other intestinal pathogens.
**Option C:** Weight loss is not a common presenting symptom of threadworm infection. The infection does not typically lead to significant malabsorption or weight loss.
**Clinical Pearl / High-Yield Fact**
Threadworm infection can be diagnosed by applying cellophane tape to the perianal area in the morning and examining it under a microscope for the presence of eggs. This method is a simple and effective way to confirm the diagnosis.
**Correct Answer:** C.