Below - a history of travel; Below - 1918 to 2000 viruses; Clearly - as more travel means become available, viruses spread with that. Even the Black Death spread because of modern travel to that age. If physical disease spreads with means of travel... Does mental disease also spread via means of travel? The Internet was mass introduced in the late 1990s. Prior to that - access to information was limited. As network capabilities grew and technology advanced - that access to information became instant. Suicide is the worst symptom of mental disease and has increased right along with Internet accessibility.