Population of a village on 1st June 2007 is 16,500. Since 1st January 2007, 22 new cases of TB were detected. Total registered cases were 220. What is the incidence of TB
**Question:** Population of a village on 1st June 2007 is 16,500. Since 1st January 2007, 22 new cases of TB were detected. Total registered cases were 220. What is the incidence of TB?
**Core Concept:** Incidence is defined as the number of new cases of a disease occurring in a defined population during a specified period. In this context, we are calculating the incidence of Tuberculosis (TB) in the village population.
**Why the Correct Answer is Right:**
1. **Incidence (I):** To calculate the incidence, we need to find the number of new cases of TB that occurred in the village population from January 1, 2007, to June 30, 2007. In our case, we have 22 new cases detected during this period.
2. **Total Population (P):** The total number of people living in the village on June 30, 2007, is given as 16,500.
3. **Total Registered Cases (R):** We know there were 220 registered TB cases on June 30, 2007.
**Why Each Wrong Option is Incorrect:**
A. This option is incorrect because it only considers the total registered cases without considering the new cases that occurred during the specified period, which is essential to calculate the incidence accurately.
B. This option is incorrect because it only considers the new cases without considering the total registered cases, which affects the incidence calculation.
C. This option is incorrect because it uses a different time frame for incidence calculation, which is irrelevant to the question's focus on the period from January 1, 2007, to June 30, 2007.
D. This option is incorrect because it uses the total registered cases without considering the new cases that occurred during the specified period, which affects the incidence calculation.
**Clinical Pearls and High-Yield Facts:**
- Tuberculosis is a common infectious disease caused by Mycobacterium tuberculosis, affecting the lungs (pulmonary TB) or other parts of the body (extrapulmonary TB).
- Incidence is calculated as: Incidence (I) = (New cases during specified period) / (Total population during specified period)
**Correct Answer Explanation:**
The correct answer is derived by using the formula:
Incidence (I) = (New cases during specified period) / (Total population during specified period)
In this case, the new cases occurred from January 1, 2007, to June 30, 2007, which is the specified period (2 months). The total population is the number of people living in the village on June 30, 2007 (16,500).
**Incidence (I):**
Incidence (I) = (22) / (16,500) = 0.0136 per day (approximately)
**Why the Incidence