Typically pork is considered to be one of the more risky meats to eat when it is not cooked thoroughly, simply because of all the bacteria that tend to be on it. When you make sure that your pork is cooked all the way, you will greatly reduce your risk of suffering any ill affects whatsoever.
It is okay to eat pork that is slightly pink in the middle, though it should be cooked all the way. The reason that it is recommended that you not eat pork rare is because it tends to carry with it more bacteria that most other types of meat, which is why you should make sure it is cooked thoroughly before eating it.