**Question:** Which of the following Px is true for Typhoid carriers?

A. They have a fever
B. They exhibit gastrointestinal symptoms
C. They are resistant to Typhoid infection
D. They develop complications like pericarditis

**Core Concept:**
Typhoid carriers are individuals who carry the Salmonella Typhi bacteria in their gut without exhibiting clinical symptoms of Typhoid fever. They can serve as a reservoir for the bacteria, potentially transmitting it to others through fecal-oral route.

**Why the Correct Answer is Right:**
The correct answer is **C. They are resistant to Typhoid infection**. Typhoid carriers develop a state of immunity due to the presence of Salmonella Typhi antigens and antibodies in their system, which protects them from developing clinical Typhoid fever.

**Why Each Wrong Option is Incorrect:**

A. Fever is a characteristic symptom of Typhoid fever, not Typhoid carriers. Typhoid carriers do not have fever as they are not infected.
B. Gastrointestinal symptoms are specific to Typhoid fever patients, not carriers. Typhoid carriers display no gastrointestinal symptoms.
D. Typhoid carriers do not develop complications like pericarditis, which is a severe complication of acute Typhoid fever.

**Clinical Pearl:**
Understanding the role of Typhoid carriers is crucial for public health control measures. Mass vaccination campaigns and improving sanitation can help reduce the prevalence of Typhoid carriers, thereby decreasing the transmission of the disease.