Myalgic Encephalomyelitis is a complex and severely disabling illness which presents many symptoms. It has had many names, but is now generally called ME or CFIDS (Chronic Fatigue and Immune Dysfunction Syndrome) although it is still known by its older name Chronic Fatique Syndrome (CFS). This accounts for the fact that a number of support organizations incorporated "CFS" into their name.

Equine Encephalomyelitis (Sleeping Sickness, Blind Staggers, Brain Fever) is a viral disease that results in inflammation of the brain's vascular system. This seasonal disease is transmitted by mosquitoes and has an acute onset that is fatal. It affects all ages and types of horses. The horse is a dead end host and cannot pass this virus to another horse. Birds and rodents serve as reservoirs for the virus.