How is the Breteau Index calculated and what does it indicate?

• A. BI = number of positive houses per 100 containers inspected; indicates overall mosquito density.
• B. BI = total containers examined per 100 houses; indicates water-holding containers count.
• C. BI = number of positive containers per 100 houses inspected; indicates container-breeding infestation level.
• D. BI = number of breeding sites per square kilometer; indicates density.

Answer: (C)

The Breteau Index measures how widespread container-breeding mosquitoes are by counting how many containers with larvae or pupae are found per 100 houses inspected. Positive containers are those that actually harbor immature mosquitoes. The calculation is the number of positive containers divided by the number of houses inspected, multiplied by 100. This index reflects the infestation level of breeding sites in the area, helping guide targeted source reduction. It isn’t about the total number of containers, the number of houses with larvae per container, or density per area, which is why other formulations don’t fit.