19th century jumping frenchmen could have been suffering from an autoimmune disease

Maine lumberjack jumping disease
http://en.wikipedia.org/wiki/Jumping_Frenchmen_of_Maine
The startle reflex is located in the brain stem.

Could this have been an autoimmune disease of the brain stem?

Autoimmune cross-targeting hypothesis: a virus marks the inside of a cell while a larger infection marks the outside and the combination triggers autoimmune disease.  The immune system is instructed to destroy both the inside and the outside of the target.

Legionnaire outside and the Borna virus inside the brain stem cells?

Legionnaires disease is an issue in the Maine area.
http://www.pressherald.com/2011/11/29/legionnaires-disease-cases-jump-in-state-new-england_2011-11-29/

Legionnaire and neurological connections exist
http://www.ncbi.nlm.nih.gov/pubmed/15026520
http://www.ncbi.nlm.nih.gov/pubmed/22998348

Note that the startle reflex is in the brain stem where legionnaire can infect

Brain stem and legionnaire
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC491213/
http://www.ncbi.nlm.nih.gov/pubmed/2954126
http://www.ncbi.nlm.nih.gov/pubmed/16501905

borna virus typically thrives in the brain stem and infects both birds and mammals
http://www.ncbi.nlm.nih.gov/pubmed/7789150
but bird are said to be the "carriers"
http://www.2ndchance.info/MacawWastingSyndr-Berg2001.pdf