Amyotrophic lateral sclerosis, the most common of five forms of motor neuron disease, is associated with echovirus (an enterovirus) infection of the central nervous system, and with retrovirus activity (it is not known whether this retrovirus activity arises from a human endogenous retrovirus, or from an exogenous retrovirus).
Depression is associated with cytomegalovirus and West Nile virus, and the protozoan parasite Toxoplasma gondii. It is thought that depression may be precipitat... more