I call it the Secret Knowledge.

Meaning that body of information not everyone has, known only to those few people who had the good sense to go off the beaten path and seek it. It is information you’ll never see in your “newspapers” or “network news” or any other place overly concerned with verifiable “facts” and reliable “sources.” It will not come to you through a university “study,” peer-reviewed “article,” renowned “expert,” government “agency” or any other such traditional bastion of authority.

No, the Secret Knowledge is the truth behind the truth, the real facts behind the facts “they” want you to believe. It unveils the conspiracies beneath the facade suckers mistake for real life. Not incidentally, the Secret Knowledge will always confirm your worst fears.

I don’t know when the mania for Secret Knowledge began. Maybe it was when the Rev. Martin Luther King Jr. and the Kennedys were killed, and some of us could not shake a gnawing suspicion that the stories we were told were not the whole truth. Maybe it was when a man walked on the moon, and it was so amazing, some of us refused to believe it had happened. Maybe it was when Watergate shattered public trust. Maybe it was when “The X-Files” fed a shivering unease that we inhabited a world of lies within lies.

But if we can’t say for certain when the mania began, the fact that it’s here is beyond dispute. Indeed, it has spread like, well … measles.

As you have no doubt heard, that highly contagious and sometimes deadly disease, which this country declared eradicated 15 years ago, has returned. According to the Centers for Disease Control and Prevention, there were fewer than 50 cases in 2002, and 644 last year. Already this year, there have been over 100 cases.

Authorities say much of this resurgence is due to the refusal of a growing number of parents to vaccinate their kids. The parents think the shots are dangerous, citing a 1998 study by a British doctor who claimed to have found a link between vaccinations and autism. As it turns out, that study was debunked and retracted, and the doctor lost his license. But the alleged link lives on, fueled by Jenny McCarthy, who has become a front woman of sorts for the anti-vaccination movement.

It is an Internet Age paradox: We have more information than ever before, and yet, seem to know less. Indeed, in the Internet Age, it can be fairly said nothing is ever truly, finally knowable — authoritative testimony always subject to contradiction by some blogger grinding axes, some graduate of Google U, somebody who heard from somebody who heard from somebody who heard.

And let us pause here to cast shame on would-be presidents Chris Christie and Rand Paul, who both said last week that vaccinations should be a matter of parental choice, a particularly craven bit of pandering that ignores a simple principle you’d think we’d all support: Your right to make irresponsible decisions about your child ends at my right to safeguard my child’s health. But in an era of designer facts and homemade truth, maybe there are no simple principles any more.

As a disease once thought over and done with comes back like some ‘90s boy band, this much seems obvious: Secret Knowledge is just ignorance by another name.