Chicago ? A troubling case in which a high-risk organ donor infected four patients with the AIDS virus and hepatitis has led medical ethicists to warn that patients need to know more about whose organs they’re getting.

Public health officials said Tuesday the Chicago case is the first known instance of HIV transmission through organ transplants since 1986.

It’s also the first-ever known instance in which one organ donor has spread hepatitis C and HIV at the same time, said Dr. Matt Kuehnert of the federal Centers for Disease Control and Prevention.

The CDC and other public health officials are investigating the Chicago cases.

But they emphasized that the risk of getting any disease from transplanted organs is less than 0.01 percent. Noting that more than 400,000 transplants have occurred nationwide in the past two decades, they called the transplant system safe.

But it’s not 100 percent safe: Standard testing failed to detect HIV in the Chicago case. People waiting for organs should be told as much pertinent information as possible about potential donors, said University of Pennsylvania medical ethicist Art Caplan.