What is a common concern associated with fleas?

Fleas are indeed a concern because they are known carriers of diseases, including the plague, which has historically caused significant mortality. The transmission occurs when fleas feed on infected hosts, such as rodents, and later bite humans, thereby transmitting the infectious agents. This vector relationship is critical in understanding the public health implications of flea infestations, especially in areas where the plague is still a potential risk.

In contrast, fleas do not transmit rabies, as rabies is primarily spread through the bites of infected animals, mainly mammals like bats and dogs, rather than through insect vectors. Although fleas can bite humans, their bites can cause irritation and allergic reactions, which can be harmful to individuals rather than being benign. Additionally, fleas are not known to frequently die from light exposure; they are more resilient and have adapted to live in dark, hidden environments like cracks and crevices in homes. Thus, the association of fleas with carrying the plague makes option B the most accurate regarding common concerns.