RIO DE JANEIRO — Fears that a new, multidrug-resistant, rapidly progressing strain of HIV-1 had surfaced in New York City have been alleviated, with medical researchers reporting that they have tracked down the most likely source of the infection.
Concerns have existed since February, when officials from the New York City Department of Health and Mental Hygiene announced that a middle-aged man had purportedly been infected with a unique, highly virulent strain of HIV.
The New York City patient had rapidly progressed to late-stage HIV infection, with a CD4 cell count of 60 cells/mcL within 20 months of infection.
But viral testing suggested that the New York City patient was infected by a Connecticut man whose disease has followed a more typical clinical course, said Gary Blick, M.D., medical and research director of Circle Medical LLC in Norwalk, Conn.
“The Connecticut man's virus is a 99.5% pol[ymerase] gene match to that of the New York City man. They're essentially identical,” Dr. Blick reported at the International AIDS Society Conference on HIV Pathogenesis and Treatment.
The man from Connecticut, referred to as “Patient Zero,” and the New York City man have acknowledged having had unprotected sex together after using crystal methamphetamine in October 2004.
Since Patient Zero has become compliant with highly active antiretroviral treatment, he has had a stable CD4 count and viral load.
“He is not a rapidly progressive patient,” Dr. Blick said.
So why did the New York City man's disease progress so quickly?
Most likely, his behavior is the culprit, Dr. Blick commented. The New York City patient admitted not only to being promiscuous, but also to being a heavy user of crystal methamphetamine, a street drug that lowers inhibitions and increases risky sexual behavior. Genetic susceptibility also may have played a role.
Mark A. Wainberg, Ph.D., director of the McGill University AIDS Centre, Montreal, pointed out that having multiple sex partners and repeatedly using crystal “meth” may pummel the immune system, facilitating infection with multidrug-resistant HIV.
Dr. Wainberg said that these findings should end talk of a new HIV strain.
“It's a well-done analysis that shows the strains are virtually identical,” he explained.