What factor increases the risk of malaria transmission in urban areas?

High population density is a significant factor that increases the risk of malaria transmission in urban areas. This is because a dense population provides a larger pool of potential hosts for the malaria parasite, as malaria is transmitted through the bite of Anopheles mosquitoes, which can thrive in areas with ample human activity. The more individuals present in a given area, the higher the likelihood of mosquitoes encountering and biting infected individuals, leading to a greater chance for the disease to spread.

Additionally, urban environments can offer suitable breeding conditions for mosquitoes, especially in areas where stagnant water accumulates, such as in poorly managed drainage systems, containers, and other man-made environments. High population density also means increased travel and movement of people, which can facilitate the spread of malaria from one area to another.

In contrast, the use of air conditioning can actually reduce mosquito activity within buildings, and fewer outdoor activities may diminish the likelihood of individuals encountering mosquitoes. Cold climate regions are generally not conducive to the survival of the mosquitoes that transmit malaria, significantly reducing the risk of transmission. Thus, high population density stands out as the primary contributing factor to increased malaria transmission in urban settings.