<a href=https://explorable.com/cause-and-effect>Establishing Cause and Effect</a>. Cause and effect is one of the most commonly misunderstood concepts in science and is often misused by lawyers, the media, politicians and even scientists themselves, in an attempt to add legitimacy to research.
You can't catch cancer from anyone, in any way. Cancer is not contagious. You can't catch HIV/AIDS just by touching somebody. The AIDS virus is not found in sweat. Yes, you can catch a cold, or the flu by shaking hands with someone if you then put your hands on/near a mucous membrane (eyes, nose, mouth).
Tremors are usually caused by problems with areas of the brain that control movements. Neurological problems can cause tremors, but they can also be caused by metabolic problems and toxins (such as alcohol) that affect the brain and nervous system. Shaking hands and tremor can also be a side effect of medications. Shaking hands can occur as a solitary manifestation or can be accompanied by tremor or neurological disturbances in other parts of the body. Depending upon the underlying cause, shaking hands can be mild or severe, temporary or chronic. Shaking hands can occur at rest or during directed movements.