This is going to sound incredibly callous, because, well, it is: If Apple (NASDAQ:AAPL) CEO Steve Jobs is once again in poor health, shareholders have a right to know. Not when he's ready to tell, or when the doctors are confident of a good prognosis, but now.

To be fair, we don't know whether Jobs is sick or not. I'm hoping not. Jobs is the genius who helped to spawn my more-than-20-year love affair with all things Mac.

But the question is worth asking. Fortune asked it last month, on the heels of his appearance at Apple's Worldwide Developers Conference. "Why does Steve Jobs look so thin?" the headline read. Questions regarding cancer naturally followed; Jobs has already escaped from its clutches once. A spokesperson for the iEmpire responded by telling The Wall Street Journal that he was recovering from "a common bug."

I hope that's true. In a life-imitates-art moment, Jobs revealed in an email in July of 2004 that he had undergone weekend surgery to remove a tumor. "I will be recuperating during the month of August, and expect to return to work in September," the message read. To me, it was eerily reminiscent of the old Aaron Sorkin TV series The West Wing, in which fictitious president Jed Bartlet is forced to reveal that he has a form of multiple sclerosis.

I'm glad Jobs beat cancer the first time around. The Big C has a habit of plaguing my family. My mom had it, two of my uncles have had it, and my grandfather died from it. I'm sympathetic.

But none of that changes the cold truth that Jobs is worth billions to Apple shareholders. We know because, when reports of his strikingly thin appearance on stage at WWDC surfaced, Apple’s share price dropped almost 5% in two days.

Contrast that with other tech firms. Bill Gates just retired from Microsoft (NASDAQ:MSFT), but investors didn't care -- at least, not until Mr. Softy missed estimates by a penny. (Boo-freaking-hoo.)

Cisco (NASDAQ:CSCO), EMC (NYSE:EMC), IBM (NYSE:IBM), Intel (NASDAQ:INTC) -- none of the other big tech firms face this issue. Well, perhaps one: Oracle (NASDAQ:ORCL), with iconic CEO Larry Ellison.

Oracle, interestingly, offers the clearest example of what's wrong with Apple right now. Ellison has two extremely strong lieutenants in Safra Catz and Charles Phillips. Who's backstopping Jobs? No one knows.

Be well, Steve. But please also be prepared. You owe your shareholders at least that much.

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