A useful index to measure the lethality of an acute infectious diseases is-
**Core Concept**
The lethality of an acute infectious disease can be quantitatively assessed using a specific statistical index that correlates the number of deaths with the total number of cases. This index is crucial for evaluating the severity and impact of a disease outbreak.
**Why the Correct Answer is Right**
The correct index is the Case Fatality Rate (CFR), which is defined as the proportion of individuals who die from a particular disease among the total number of people diagnosed with the disease. CFR is a widely used indicator of disease severity and is calculated by dividing the number of deaths due to a specific disease by the total number of reported cases, often expressed as a percentage. This ratio provides a useful metric for comparing the lethality of different diseases and for assessing the effectiveness of public health interventions.
**Why Each Wrong Option is Incorrect**
* **Option A:** This is not a recognized index for measuring disease lethality. It may be a distractor to test the student's knowledge of disease epidemiology.
* **Option B:** This option is not a standard measure of disease severity. It may be a distractor to test the student's understanding of disease statistics.
* **Option C:** This is not a valid index for measuring disease lethality. It may be a distractor to test the student's knowledge of disease surveillance.
**Clinical Pearl / High-Yield Fact**
The Case Fatality Rate (CFR) is a critical metric in disease epidemiology, as it helps public health officials prioritize interventions and allocate resources effectively. A high CFR often indicates a more severe disease, while a low CFR may suggest a more benign or manageable condition.
**Correct Answer:** C.