How are the viruses causing dementia transmitted? Are dementia patients safe to be around?

The consequences of dementia from a low level of chronic viral presence in the brain do not make the person a biohazard to others. That low-level presence is not transmissible through ordinary person-to-person contact, so it would be most unfortunate if this revelation results in any kind of discrimination against sufferers of dementia out of fear of contracting the condition. It is uniformly the case that the virus is more a remnant from an earlier acute illness, often decades before the onset of dementia symptoms. During that acute phase is when there is a window of infectivity because there will be higher levels of virus being produced and possibly shed into the environment, as happens with influenza, or spread through intimate contact as with infectious mononucleosis, the so-called "kissing disease," caused by Epstein-Barr virus. So the viruses responsible are simply in circulation, largely infecting young people. Most will recover within days or weeks from any symptoms, but some will retain virus in the body as a chronic low-level infection without symptoms that are visible, and over time, especially with the reawakening of underlying karmic vulnerability in concert with age-related decline, many times will cause what appears to be a new illness, noticeable as a decline in cognition.