The reported number of zoonotic diseases varies a bit according to sources, but most report there are approximately 200. Also, zoonoses constitute greater than 60% of all known infectious diseases and approximately 75% of emerging infectious diseases.
This should come as no surprise since humans are part of the animal kingdom and are genetically similar to many other animals. The human genome shows 99% similarity to great apes and 95% similarity to pigs. Transmission can be from both wild and domestic animals. Many factors can make such disease transmission likely, and these will be discussed later in the course.
