If you had the seeds of pestilence in your body you would not have a more active contagion that you have in your tempers, tastes, and principles. Simply to be in this world, whatever you are, is to exert an influence, compared with which mere language and persuasion are feeble.
The deadliest contagion is majority opinion.
A well-informed mind is the best security against the contagion of folly and of vice. The vacant mind is ever on the watch for relief, and ready to plunge into error, to escape from the languor of idleness. - Ann Radcliffe
Religion reminds me of a lace condom. While lovingly crafted, it’s not designed for pleasure; unless inflated with fervour, it collapses; one size does not fit all; and no matter how many times you dunk it in holy water, it will not prevent misconceptions or contagion. - Lowestoft Thellow
Having knowledge of an unethical act and allowing it to continue can spread a contagion that can affect multiple beings in society - Bertrand Russell