Why do some animals have natural immunity to certain diseases?

Some animals have evolved natural immunity to certain diseases through genetic adaptation. For example, certain species of bats are able to carry viruses like Ebola and rabies without succumbing to them, possibly due to immune system adaptations that prevent the virus from causing harm. Similarly, many animals that live in environments with constant exposure to parasites, like the naked mole rat, have developed resistance to infections that would be deadly to other species. Evolutionary pressures favor these animals, allowing them to survive in environments where others might not.