## **Core Concept**
The question tests understanding of the infectious potential of tuberculosis (TB), specifically the capacity of a sputum-positive TB patient to spread the disease. TB is caused by *Mycobacterium tuberculosis*, which primarily affects the lungs but can spread to other parts of the body. Sputum-positive patients are those whose sputum contains detectable amounts of TB bacteria, making them infectious.

## **Why the Correct Answer is Right**
A single sputum-positive TB patient can infect up to 10-15 people per year if not treated. This estimate varies depending on factors such as the patient's infectiousness, the presence of cough, and the effectiveness of local public health measures to contain the spread of TB. The infectiousness of TB is largely dependent on the bacterial load in the sputum, with higher loads indicating greater infectious potential.

## **Why Each Wrong Option is Incorrect**
- **Option A:** 1-5 people. This underestimates the potential infectiousness of a sputum-positive TB patient.
- **Option B:** 5-10 people. While closer, this still underestimates the upper range of potential infections.
- **Option D:** 20 people. This overestimates the commonly cited range for the number of people a single sputum-positive TB patient can infect per year.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that prompt identification and treatment of TB, especially sputum-positive cases, are critical to preventing the spread of the disease. Public health strategies, including directly observed treatment, short-course (DOTS), are essential in controlling TB epidemics.

## **Correct Answer:** . 10-15 people.