Researchers have identified a mysterious new disease that has left scores of people in Asia and some in the United States with AIDS-like symptoms even though they are not infected with HIV.
The patients' immune systems become damaged, leaving them unable to fend off germs as healthy people do. What triggers this isn't known, but the disease does not seem to be contagious.
This is another kind of acquired immune deficiency that is not inherited and occurs in adults, but doesn't spread the way AIDS does through a virus, said Dr. Sarah Browne, a scientist at the National Institute of Allergy and Infectious Diseases.
She helped lead the study with researchers in Thailand and Taiwan where most of the cases have been found since 2004. Their report is in today's New England Journal of Medicine.
"This is absolutely fascinating. I've seen probably at least three patients in the last 10 years or so" who might have had this, said Dr. Dennis Maki, an infectious disease specialist at the University of Wisconsin in Madison.
It's still possible that an infection of some sort could trigger the disease, even though the disease itself doesn't seem to spread person-to-person, he said.
The disease develops around age 50 on average but does not run in families, which makes it unlikely that a single gene is responsible, Browne said. Some patients have died of overwhelming infections, including some Asians now living in the U.S., although Browne could not estimate how many.
AIDS is a specific disease, and it stands for acquired immune deficiency syndrome. That means the immune system becomes impaired during someone's lifetime, rather than from inherited gene defects like the "bubble babies" who are born unable to fight off germs.
The virus that causes AIDS — HIV — destroys T-cells, key soldiers of the immune system that fight germs. The new disease doesn't affect those cells, but causes a different kind of damage. Browne's study of more than 200 people in Taiwan and Thailand found that most of those with the disease make substances called autoantibodies that block interferon-gamma, a chemical signal that helps the body clear infections.
Researchers are calling this new disease an "adult-onset" immunodeficiency syndrome because it develops later in life and they don't know why or how.