Physical and emotional diseases have a spiritual expression. It is task of the shaman to grasp and locate the spiritual nature of suffer.

This nature is shown to the shaman in a form he perceives as disgusting to recognize it as sickness. This disease will be removed by pulling it out of the body. This process is called "shamanic extraction".

If somebody is ill with a localized ailment - like a certain form of cancer, shoulder pain or emotional suffer at heart - than there is the high possibility the person is suffering by a "spiritual intruder". 

Spiritual intruders are alien energy pattern nested in the body of the patient. The shaman takes this "negative" effecting energy out (extracting) and places it in nature where it will be neutralized.

The same applies to maledictions (curses) thrown at the body with harmful intent (even over long distances). Energy itself is always neutral, there is no such thing as good or bad, light or dark energy. What is harmful is the intention, the purpose behind the energy. Removing them is the task of the shaman.