By Igor Koralnik, MD
“I take care of HIV-infected people who have neurological problems and I do research on progressive multifocal leukoencephalopathy.” This is my typical answer to the question: “What kind of a doctor are you? “Which most often elicits raised eyebrows, puzzled looks and a polite, “Oh, this is so interesting! Now what is it that you are actually doing?”
Most people know that neurologists take care of patients with stroke, seizure, Parkinson’s or Alzheimer’s, but few are aware of the multiple neurological complications of HIV infection. Even fewer have ever heard of progressive multifocal leukoencephalopathy or PML.
So I tell them that I got interested in this area when I was a med student at the beginning of the HIV epidemic. During my first forays on the wards, I saw so many young people coming down with all kinds of neurological diseases of the brain, spinal cord and nerves. Those diseases were either caused directly by HIV, or by other opportunistic infectious agents that took advantage of the patients’ lower immune defense caused by AIDS. This is when I decided to specialize in the neurological complications of HIV, and, by extension, to the care of patients with infections of the nervous system.
The paradox of PML
One of these infectious agents is JC virus, named according to the initials of a patient with PML. After his death, researchers in the U.S. isolated the virus from his brain. JC virus is a fascinating paradox: innocuous in healthy people, it resides in the majority of us as a lifelong infection in the kidneys and gets excreted in the urine without causing any disease; deadly in immunosuppressed individuals, it destroys the white matter of the brain in multiple areas, causing a variety of neurological deficits including paralysis, blindness, language dysfunction and seizures. There is no specific treatment for JC virus. Only half of patients who develop PML survive more than one year.