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

A. 0.2%
B. 2%
C. 20%
D. 10%

**Correct Answer:** D. 10%

**Core Concept:**

Cholera is a waterborne bacterial infection caused by the bacterium Vibrio cholerae. The disease is characterized by profuse diarrhea, dehydration, and severe electrolyte imbalances, which can lead to severe complications and even death if not promptly treated. In epidemics, the case fatality rate (CFR) is a measure of the proportion of cases that result in death.

**Why the Correct Answer is Right:**

In this scenario, we have 20 cases and 5 deaths in a village of 2,000 people. To calculate the case fatality rate (CFR), we use the formula:

Case Fatality Rate = (Number of deaths / Total number of cases) x 100

Plugging in the numbers:

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

However, since we need to compare the CFR with the given options, we need to convert the percentage to a decimal (i.e., divide by 100). So, 25% becomes 0.25.

**Why Each Wrong Option is Incorrect:**

A. 0.2% is too low compared to the calculated 0.25.
B. 2% is still too low compared to the calculated 0.25.
C. 20% is higher than the calculated 0.25, indicating that 20 out of 100 (2000 / 100) x 100 = 20%.
D. 10% is close to the calculated 0.25 and is the correct answer.

**Clinical Pearl:**

Understanding the case fatality rate is crucial for public health officials and healthcare workers to assess the severity of an outbreak and plan appropriate intervention strategies. In this scenario, the case fatality rate is 25%, indicating a significant outbreak that warrants immediate intervention. It is essential to differentiate case fatality rate from morbidity rate, which refers to the proportion of individuals affected by the disease. In this case, we do not have enough information to calculate the morbidity rate.