**Question:** In an outbreak of cholera in a village of 2,000 population, 20 cases have occurred and 5 died. Case fatality rate is

A. 10%
B. 20%
C. 20%
D. 25%

**Correct Answer:** B. 20%

**Core Concept:** Cholera is a watery diarrheal illness caused by the bacterium Vibrio cholerae.

**Why the Correct Answer is Right:** The case fatality rate (CFR) is a measure of the proportion of deaths among cases of a particular disease or condition. In this scenario, there are 20 cases and 5 deaths. To calculate the case fatality rate, we use the following formula:

CFR = (Number of deaths / Total number of cases) x 100%

Using the given data, we have:

CFR = (5 / 20) x 100% = 25%

So, the correct answer is D. 25%.

**Why Each Wrong Option is Incorrect:**

A. The case fatality rate is 10%, which is lower than the actual value (25%).
B. The case fatality rate is 20%, which is higher than the actual value (25%).
C. The case fatality rate is 20%, which is also higher than the actual value (25%).

**Clinical Pearl:** Understanding case fatality rates is crucial for public health professionals to assess the severity of an outbreak, monitor disease trends, and allocate resources effectively. In this case, the high case fatality rate (25%) indicates a serious outbreak that requires immediate intervention and public health measures to control the spread of the disease and improve patient outcomes.