Incidence of a disease is 4 per 1000 of population with duration of 2 years. Calculate the prevalence?
**Core Concept**
The incidence of a disease is the number of new cases that develop within a specified time period, whereas prevalence is the total number of cases (new and existing) present in the population at a given time. Prevalence is a measure of the burden of a disease in a population, and it is influenced by both the incidence and the duration of the disease.
**Why the Correct Answer is Right**
To calculate the prevalence, we need to multiply the incidence by the duration of the disease. The formula for prevalence is: Prevalence = Incidence × Duration. In this case, the incidence is 4 per 1000 population, and the duration is 2 years. Therefore, Prevalence = 4/1000 × 2 = 8/1000 or 0.8%.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option does not take into account the duration of the disease, which is a critical factor in calculating prevalence.
* **Option B:** This option incorrectly multiplies the incidence by the reciprocal of the duration, which would give a different result.
* **Option C:** This option does not provide a numerical answer, making it an incorrect choice.
* **Option D:** This option is missing, so we cannot evaluate its correctness.
**Clinical Pearl / High-Yield Fact**
When calculating prevalence, remember that it is a measure of the total burden of a disease in a population, taking into account both new and existing cases. This is in contrast to incidence, which only measures the number of new cases.
**Correct Answer: C. 0.8%.**