A mental or psychiatric disorder is a psychological pattern reflected in behavior that is generally not considered part of normal development. Generally, mental illness is defined by a combination of how a person feels, acts, thinks or perceives, and can be associated with particular functions of the brain that causes the sufferer to be hostile to or disruptive of the established social order and engaging in behavior that violates accepted mores. The danger is that the mentally afflicted believe their condition, regardless how severe, is normal and that anyone who disagrees with them is their mortal enemy including their allies; such is the current iteration of the Republican Party.
It is reasonable to assume that racism, extremist religion, and disbelief in reality are manifestations of Republican psychiatric disorders and they are particularly rampant in the extremist tea party wing. It is generally agreed by mental health experts that mental illness is not contagious, but they have not yet conducted in depth studies into the plague ravaging the Republican Party. It is unfair to blame the lunacy rampant in Republican ranks solely on delusional teabaggers because what was once regarded as extreme is the new normal for the GOP from the leadership to freshman representatives in Congress and state legislatures. It is true there are a small number of Republicans who have not yet fallen victim to teabagger insanity, but they are being called upon by the psychologically demented to either get out or they will be replaced.