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 Thursday'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.
Kim Nguyen, 62, a seamstress from
Vietnam who has lived in Tennessee since 1975, was gravely ill when she
sought help for a persistent fever, infections throughout her bones and
other bizarre symptoms in 2009. She had been sick off and on for
several years and had visited Vietnam in 1995 and again in early 2009.
"She was wasting away from this
systemic infection" that at first seemed like tuberculosis but wasn't,
said Dr. Carlton Hays Jr., a family physician at the Jackson Clinic in
Jackson, Tenn. "She's a small woman to begin with, but when I first saw
her, her weight was 91 pounds, and she lost down to 69 pounds."
Nguyen (pronounced "when") was
referred to specialists at the National Institutes of Health who had
been tracking similar cases. She spent nearly a year at an NIH hospital
in Bethesda, Md., and is there now for monitoring and further treatment.
"I feel great now," she said
Wednesday. But when she was sick, "I felt dizzy, headaches, almost fell
down," she said. "I could not eat anything."
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.
Blocking that signal leaves
people like those with AIDS — vulnerable to viruses, fungal infections
and parasites, but especially micobacteria, a group of germs similar to
tuberculosis that can cause severe lung damage. 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.
"Fundamentally, we do not know what's causing them to make these antibodies," Browne said.
Antibiotics aren't always
effective, so doctors have tried a variety of other approaches,
including a cancer drug that helps suppress production of antibodies.
The disease quiets in some patients once the infections are tamed, but
the faulty immune system is likely a chronic condition, researchers
believe.
The fact that nearly all the
patients so far have been Asian or Asian-born people living elsewhere
suggests that genetic factors and something in the environment such as
an infection may trigger the disease, researchers conclude.
The first cases turned up in 2004 and Browne's study enrolled about 100 people in six months.
"We know there are many others out there," including many cases mistaken as tuberculosis in some countries, she said.
