Which of the following is true with Giardia lamblia-
**Core Concept**
Giardia lamblia is a protozoan parasite that causes giardiasis, a gastrointestinal infection characterized by diarrhea, weight loss, and malabsorption. The parasite infects the small intestine and adheres to the intestinal mucosa, leading to inflammation and damage.
**Why the Correct Answer is Right**
Giardia lamblia adheres to the intestinal mucosa through a unique mechanism involving the use of a ventral disc, which is a flat, adhesive structure on the surface of the parasite. This disc allows Giardia to attach to the intestinal mucosa and evade the host's immune system. Additionally, Giardia has a complex life cycle that involves two stages: the trophozoite stage, which is the active, feeding form of the parasite, and the cyst stage, which is the dormant, infectious form.
**Why Each Wrong Option is Incorrect**
**Option A:** Giardia lamblia is not typically associated with respiratory symptoms. While giardiasis can cause systemic symptoms such as fever and malaise, it primarily affects the gastrointestinal tract.
**Option B:** Giardia lamblia does not require an intermediate host to complete its life cycle. It can infect humans directly through contaminated water or food.
**Option C:** Giardia lamblia is not typically transmitted through vectors such as mosquitoes or ticks. It is primarily spread through the fecal-oral route, where contaminated water or food is consumed.
**Clinical Pearl / High-Yield Fact**
A key clinical feature of giardiasis is the presence of bulky, foul-smelling stools that may contain mucus and blood. Patients may also experience abdominal cramps, bloating, and weight loss.
**Correct Answer:** C