Which of the following helminths primarily produces gastrointestinal symptoms, without lung involvement, during the course of its infection?
**Core Concept**
Trichuris trichiura, also known as the whipworm, is a parasitic helminth that primarily inhabits the large intestine of humans, causing gastrointestinal symptoms such as diarrhea, abdominal pain, and weight loss. Unlike other helminths, Trichuris trichiura does not typically involve the lungs during its life cycle.
**Why the Correct Answer is Right**
Trichuris trichiura's life cycle is characterized by the ingestion of embryonated eggs, which hatch in the large intestine, releasing larvae that penetrate the intestinal mucosa. The larvae then mature into adult worms, which attach to the intestinal wall using their whip-like tail. This attachment and feeding behavior lead to inflammation, ulceration, and eventually, gastrointestinal symptoms. In contrast to other helminths, such as Strongyloides stercoralis, which can cause both gastrointestinal and respiratory symptoms due to its migratory behavior, Trichuris trichiura primarily affects the large intestine.
**Why Each Wrong Option is Incorrect**
**Option A:** Dirofilaria immitis is a filarial parasite that primarily affects dogs and cats, causing heartworm disease. It does not typically produce gastrointestinal symptoms in humans.
**Option B:** Strongyloides stercoralis is a nematode parasite that can cause both gastrointestinal and respiratory symptoms due to its migratory behavior through the lungs.
**Option D:** Ascaris lumbricoides, also known as the roundworm, can cause gastrointestinal symptoms such as diarrhea and abdominal pain, but it also frequently involves the lungs during its life cycle, causing respiratory symptoms.
**Clinical Pearl / High-Yield Fact**
Trichuris trichiura infection is often associated with malabsorption and weight loss due to the chronic inflammation and damage to the intestinal mucosa caused by the whipworms.
**Correct Answer:**
✓ Correct Answer: C. Trichuris trichiura