Why are diseases more communicable within a species (e.g. human-to-human) than intraspecies (e.g. bird-to-human)?

Question

Why are diseases more communicable within a species (e.g. human-to-human) than intraspecies (e.g. bird-to-human)?

In: Biology

Answer 1

Think of viruses like computer viruses. They exploit security holes. But a computer virus that works on Macs will have a hard time working on Windows.