The answer to a recent question on the Law Stack Exchange ("Is it illegal to sell duck eggs in Austria?") establishes that fresh duck eggs are (or were) illegal to sell in Austria without a number of conspicuous safety warnings. (The rules in question were definitely in force from at least 1947 until at least 2006, but possibly also earlier and/or later.) The law requires sellers to do the following:
Mark the eggs themselves, using indelible, foodsafe ink, with the warning, "Duck egg! Boil!"
Mark the container in which the eggs are sold with the warning, "Duck eggs! Boil for at least 8 minutes or bake in an oven!"
Display a large sign in the premises near where the duck eggs are sold, with the warning, "To prevent damage to health, duck eggs must not be eaten raw or soft-boiled, nor used to make puddings, mayonnaise, egg dishes, fried eggs, pancakes, omelettes, etc. Before consumption they must be boiled for at least 8 minutes, or baked completely through in an oven."
I have bought duck eggs in other countries and never encountered such warnings. Is it true that duck eggs require food safety precautions over and above those for chicken eggs? If so, what's the reason that duck eggs are so unsafe? If not, is there some specific, documented reason why the Austrian authorities may have been (mis)led to believe that duck eggs posed a health hazard? (For example, were there possibly flawed scientific studies in the past pointing to duck eggs being dangerous? Or was there some well-publicized scandal concerning unsanitary conditions at Austrian duck farms?)