Through the air with water droplets that a breathed, sneezed, or coughed out.
Another option is:
Though water. The bacteria gets into water, and when animals or humans drink it, then they become sick from the bacteria.
This is especially an issue in places where clean, filtered water isn’t always an available option.
And then the animals that pick up the disease get eaten by people. We saw this during Covid. Because the bats carried the disease, and then people went to eat them, so they picked up the disease due to the animals not being cooked properly. So that’s one of the reasons it spread so quickly throughout Asia.