Tommy Morrison, once the heavyweight boxing champion of the world, died of AIDS last month. His case, however, was not typical for someone with HIV: He and his wife, Trisha, denied he had the infection to the bitter end. In fact, not only did they deny that Morrison was infected, they denied that HIV causes AIDS at all. And it’s not even clear that they think the condition called AIDS actually exists.

Their tripartite denial makes the story a bit tricky to follow at times, though taken one by one, there is a credible context to at least some of their claims: Morrison’s pursuit of a negative test in the 1990s to allow him back into the ring is a reasonable business decision for a boxer with few other marketable skills. And let’s face it—a thorough grasp of the pathophysiology of a progressive immunodeficiency caused by CD4 cell loss over time can be a heavy lift. But the Morrisons’ vigorous denial that AIDS is caused by a transmissible virus, called HIV, falls well outside mainstream thinking. In their nonbelief, however, they are not alone.

Indeed, the world of HIV deniers (also called AIDS deniers or HIV/AIDS deniers) has been around almost as long as the disease itself. The size of their ranks in 2013 is difficult to estimate, given the Internet’s natural ability to overestimate based on enthusiasm, but it surely numbers in the thousands. Their varied paths to denialism make these people unique among non-reality-based groups. Take the anti-vaccination activists: At their core is a clutch of parents worried about their kids. Any parent knows that parenthood can be a rationality-free zone. Or the anti-global warming agnostics: They seem more like a front group for Big Oil or at least Chamber of Commerce boosterism than a group of wide-eyed (non)believers willing to take a life-and-death stand on principle. Even the anti-evolution zealots are just expressing their deliberately blind faith in a deity, and the blinder, the better.

In contrast, the HIV deniers are an oddball collection of prissy scientists, right-wing moralizers, standard big-government paranoids, and those still very spooked by the idea that men have sex with men. There are no TV stars in their midst, no money, much less Big Money; they have neither conventions nor house organs—even Fox News sits at a safe remove. Indeed, they have no real political agenda except perhaps a limp suspicion that science is corrupt and scientists are even more corrupt and that all those taxpayer billions could be better spent on a real disease.

Read it at Slate.