> If there was something like Lead Poisoning going around, information spreads so quickly we'd know about it. The first infection with HIV-1 subgroup M is pres

> If there was something like Lead Poisoning going around, information spreads so quickly we'd know about it. The first infection with HIV-1 subgroup M is presumed to have happened in the 1920s yet it took decades until the 1981 Pneumocystis Pneumonia article in MMWR. Only then people really started looking and discovered that the virus had been circulating for decades. HIV has an extremely long period where it slowly destroys your immune system but you personally feel mostly fine. Only years later you develop AIDS and then die from an opportunistic infection. Diseases with such long incubation periods are extremely hard to identify and it's even harder to identify their cause. We still don't know the cause for Alzheimer's disease for example. It's entirely possible that some aspects of a technology we use today causes such a disease but we'll only discover it 20 years down the line. Admittedly it's hard to test for such effects.