As Encephalitis is a carrier disease, a perfectly healthy person who is infected but shows no symptoms may infect another person. As your uncle was an Electric Tramcar Conductor he was ideally placed to be exposed to any infection going. I can remember the trams in Sunderland, and at peak times they were packed full, with not much room between the seats, and the upstairs was always full of cigarette smoke. The conductors had to go to each passenger in turn to take their fare and issue tickets, so he was always in close proximity to them. Regards Stan Mapstone