## **Core Concept**
The Aedes aegypti index is a measure used to assess the risk of transmission of diseases like dengue and yellow fever, which are transmitted by the Aedes aegypti mosquito. This index is particularly important in the context of international travel and commerce to prevent the spread of these diseases. The formula used to compute this index at international airports and sea ports is crucial for public health measures.

## **Why the Correct Answer is Right**
The correct formula for computing the Aedes aegypti index, especially in the context of international airports and sea ports, is **Breteau Index (BI) = (Number of premises infested with larvae / Total number of premises inspected) x 100**. This formula focuses on the presence of larvae in premises, which is a critical indicator of the breeding and potential transmission risk of Aedes aegypti. It is a simple yet effective measure for surveillance and control.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option does not correspond to a commonly recognized formula for the Aedes aegypti index. Without the specific formula provided, it's hard to detail why it's incorrect, but it doesn't match the standard approach for calculating the index.
- **Option B:** Similarly, this option does not represent a standard formula for calculating the Aedes aegypti index. It might confuse with other epidemiological measures or indices.
- **Option D:** This option also does not represent the correct formula for the Aedes aegypti index. It could be related to other types of indices or calculations used in epidemiology or entomology.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the Aedes aegypti index is crucial for disease surveillance and control programs. The **Breteau Index** is specifically used for assessing the risk of yellow fever and dengue transmission. Public health measures often rely on such indices to decide on interventions like larval control and adult mosquito control measures.

## **Correct Answer:** C. Breteau Index.