The cholera bactery evolves which means it changes the way it works. So if you are vaccinated, the bactery will evolve itself in such a way that your body doesn't reject it.
It is a perfect example of a natural selection.
(I'm not sure if this is the exact answer that you are looking for.)
That they are <span>caused by microorganisms.</span>
Honestly, dog-walking and dog-sitting is a really great job and <span>it is also really fun and rewarding</span>. The average wage for a Dog Walker is $13.27 per hour. Therefore, being a freelancer, I would love to spend my spare time on the dog walk.
Usually, I spend an hour, every morning, jogging. This suits me and I can earn some extra cash too, besides my fitness.