In an outbreak of cholera in a village of 2000 population, 20 cases have occurred and 5 cases died, case fatality rate is?

Appeared in: Hariyana-CHO-2021

Explanation

The Case Fatality Rate (CFR) measures the proportion of deaths among confirmed cases of a disease.
The formula for CFR is: (Number of deaths from a disease / Total number of cases of that disease) × 100.
Given the data, there were 5 deaths among 20 cases of cholera.
Plugging the values into the formula: (5 deaths / 20 cases) × 100 = 25%.
This rate indicates the severity or 'killing power' of the disease in this specific outbreak.

Option A: A result of 1% is obtained by calculating (20 cases / 2000 population) × 100. This formula represents the attack rate, which is the proportion of the population that got the disease, not the proportion of cases that resulted in death.
Option C: A result of 5% would imply 1 death for every 20 cases, as (1/20) × 100 = 5%. However, the data clearly states there were 5 deaths, not 1.
Option D: A result of 0.25% is obtained by calculating (5 deaths / 2000 population) × 100. This formula represents the crude mortality rate from cholera for the entire village population, not the case fatality rate.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Calculation of Case Fatality Rate (CFR) in an outbreak scenario as background academic context rather than a clinical decision trigger.
Understanding CFR is crucial for nurses and public health professionals to assess the severity of an outbreak and the effectiveness of treatments. A high CFR may trigger more aggressive public health interventions.
CFR helps in communicating the risk of a disease to the public and policymakers, guiding resource allocation for prevention and control measures.
What if the question asked for the survival rate among cases? The survival rate is 100% - CFR. In this scenario, it would be 100% - 25% = 75%. This means 15 out of the 20 people who got sick survived.

How to Approach the Question

First, carefully read the question to identify the specific epidemiological measure being asked for, which is the 'case fatality rate'.
Recall the correct formula for Case Fatality Rate: (Number of deaths from a disease / Total number of cases of that disease) × 100.
Identify the numerator (number of deaths = 5) and the denominator (total number of cases = 20) from the information provided in the question.
Note that the total population (2000) is extraneous information for this specific calculation and should be ignored to avoid calculating the wrong rate (like mortality or attack rate).
Perform the calculation: (5 / 20) × 100 = 25%.
Compare the result with the given options and select the matching one.

Concept Tested & Keywords

Concept Tested: Calculation of Case Fatality Rate (CFR) in an outbreak scenario.
Stem keywords: outbreak, cholera, population, cases, died, case fatality rate
Lead-in keywords: is?
Negative lead-in flag: false

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E6 NursingResearch Suresh Sharma 5e Part 2 p. 198-200

E6 Parks TextBook of Preventive & Social Medicine part 1 — Subpart A (pp 26-201 of 604) p. 51-53

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