The concept of "being sick" is almost as foreign as the thought of "being poor" to an Argentium: it's virtually nonexistent.

Elio and his siblings have all gotten sick at five different points in their respective lives - all of which are related to either growing pains, overexertion, or immediate yet extensive changes in their Aura resulting in their cultivation breakthroughs. Generally-speaking, if you count them fathering the best healthcare system in the world, their immune system is many times stronger than an average person's due to a combination of genetics, regulated physical activity, medical specialization, and the permeating effects of their Aura resulting from its temperance over the course of their lives. So diseases and illnesses that would severely hamper anyone else would at best be a seen as a mild convenience to an Argentium.

However, the proper protocol for any Argentium with a malady is to quarantine themselves for at least 24 hours; during that time, they would call on one of their various doctors under their charge to thoroughly examine them (usually as a house call), and proceed to follow their instructions after receiving a prognosis. Typically, this means dietary restrictions, timely medicinal intakes, and forbidding any and all kinds of strenuous activity - which most of them are prone to do.