How has the process of globalization created a threat to world health ?

The process of globalization managed to connect people from all over the world, and enabling them to travel easily at pretty much every spot on the planet. While this is very good when it comes to traveling, sharing ideas, technology, trade, it is actually very bad and dangerous when it comes to diseases. Because the people are able to travel all around the world, someone who has traveled to another continent can catch a deadly and very infections disease, and when that person returns back home it will spread it around on the other people in his/hers homeland, causing a pandemic and maybe resulting in death of millions of people.