Aedes aegypti index near pos should be less than –

**Core Concept**
The Aedes aegypti index is a measure of the density of Aedes aegypti mosquitoes in a given area, typically expressed as the number of mosquitoes per person. This index is crucial in assessing the risk of dengue fever transmission. A high Aedes aegypti index indicates a higher risk of dengue fever outbreaks.

**Why the Correct Answer is Right**
The correct answer is based on the World Health Organization's (WHO) guidelines for controlling dengue fever. The Aedes aegypti index near a positive dengue fever case should be less than 1, indicating effective mosquito control measures are in place. This threshold helps prevent further transmission of the disease. The Aedes aegypti mosquito is the primary vector for dengue fever, and controlling its population is essential in reducing the risk of outbreaks.

**Why Each Wrong Option is Incorrect**
* **Option A:** A higher index, such as 5 or 10, would indicate a higher risk of dengue fever transmission, not a reduced risk.
* **Option B:** There is no specific numerical value for the Aedes aegypti index near a positive dengue fever case; however, the WHO recommends an index of less than 1 as a general guideline.
* **Option C:** An index of 0 would indicate no Aedes aegypti mosquitoes present, which is unlikely in areas where dengue fever is endemic.

**Clinical Pearl / High-Yield Fact**
The Aedes aegypti index is a key indicator of dengue fever transmission risk. Regular monitoring and control measures, such as larval control and adult mosquito elimination, are essential in reducing the Aedes aegypti index and preventing dengue fever outbreaks.

**Correct Answer: D. 1**