An AIDS-like disease which attacks the immune system has swept Asia and parts of the U.S. in a bizarre pattern, bewildering doctors and researchers.

The disease, which doesn’t appear to be contagious, doesn’t spread through a virus, unlike AIDS. So far, it has targeted adults over 50, mostly those of Asian descent. And while doctors are still trying to get a handle on what causes it, they have so far ruled out the possibility that it originates in a single gene since it doesn’t run in family blood lines. They do, however, believe an infection of some kind could trigger the onset of the disease; but because almost all the patients to date have either been Asian or of Asian descent, doctors believe the key to figuring out the cause lies in genetics.

One other key element to the disease is the odd way it has of striking late in life; unlike those who are born with the inability to fight off germs, this illness affects a healthy immune system and breaks it down. That’s what makes it so scary.

Victims of the disease often suffer from headaches, dizziness, bone infections, and weight loss–among other things–which can look like tuberculosis. If not caught in time, it can be a wasting disease, working on the body as efficiently as the AIDS virus without the damage AIDS causes to T-cells.

For now, a weak immune system is something patients will likely have to endure for the rest of their lives. But when caught quickly enough, antibiotics and even certain cancer drugs have proven beneficial in clearing up the dangerous infections brought on by the disease.