By Jodi Bassett, 2010:
M.E. is an infectious neurological disease and represents a major attack on the central nervous system (CNS) – and an associated injury of the immune system – by the chronic effects of a viral infection. There is also transient and/or permanent damage to many other organs and bodily systems (and so on) in M.E. M.E. affects the body systemically.
Even minor levels of physical and cognitive activity, sensory input and orthostatic stress beyond a M.E. patient’s individual post-illness limits causes a worsening of the severity of the illness (and of symptoms) which can persist for days, weeks or months or longer.
In addition to the risk of relapse, repeated or severe (individually determined) overexertion can also cause permanent damage (eg. to the heart), disease progression and/or death in M.E. (See the sections below for more information.)
It is the combination of the chronicity, the dysfunctions, and the instability, the lack of dependability of these functions, that creates the high level of disability in M.E.
It is also worth noting that of the CNS dysfunctions, cognitive dysfunction is one of the most disabling characteristics of M.E.