Are you kidding? Did you forget that almost 1 million US soldiers visited Cambodia, Laos, and Vietnam in the 1960's and 1970's?
OH! and only just over 100,000 US citizens visit Indonesia, Malaysia, Thailand, Sri Lanka, and Hong Kong each year.
Anyone who claims that F. buskii does not exist in South Carolina is either ignorant or a unabashed liar. Their larvae have been found living in snails in the waters of South Carolina which is not South East Asia as far as I can tell.