Bats are considered good disease vectors for several reasons. One of the main reasons is that they are able to host a large number of viruses and other pathogens without becoming sick themselves, due to their unique immune system. This means that they can serve as a reservoir for many diseases, and can transmit them to other animals or humans that come into contact with their bodily fluids, such as saliva, urine, and feces.

Additionally, bats are highly mobile and can travel long distances, which allows them to spread diseases across large areas. They also tend to live in large groups in close proximity to each other, which can facilitate the spread of diseases among their populations.

Finally, many species of bats are known to have close contact with humans, either because they roost in human-made structures or because they are hunted or consumed as food. This can increase the risk of disease transmission from bats to humans.