Everything You Should Know About Progressive Multifocal Leukoencephalopathy (PML) Virus

What Is Progressive Multifocal Leukoencephalopathy?

Progressive multifocal leukoencephalopathy (PML) is a degenerative brain disorder caused by the human immunodeficiency virus (HIV). PML is a neurodegenerative disease that causes the death of neurons in areas of the brain responsible for memory, attention, thinking skills, judgment and problem solving abilities. The primary symptom of PML is dementia. It is characterized by loss of cognitive ability and personality changes.

The most common signs of PML are:

Memory problems, such as forgetting things or having difficulty concentrating;

Difficulty with learning new tasks;

Fluctuating moods, which may include depression, irritability and anxiety; and/or

Social withdrawal.

Other symptoms of PML include:

Sensitivity to light;

Dilated pupils; and/or


The symptoms of PML are similar to those seen in Alzheimer’s Disease (AD), but it is not clear if they are due to AD or other factors. Some studies have shown that the risk of developing Parkinson’s Disease increases with age.

HIV (Human Immunodeficiency Virus) is a virus that attacks specific cells of the human immune system. Over time, HIV infection can destroy so many of these immune cells that the body can no longer fight off common illnesses like the cold or flu. This greatly increases the risk of developing secondary bacterial and fungal infections that do not usually cause serious illness in people with healthy immune systems. It is a virus that can lead to acquired immunodeficiency syndrome (AIDS), which affects your body’s ability to fight off other infections.

A person has AIDS when their CD4 cell count drops below 200. CD4 cells or T-cells are a type of lymphocyte, or white blood cell, that fight infection in the body. The lower the CD4 cell count, the weaker the immune system becomes. A healthy person has a CD4 cell count above 1,000.

It is possible for a person with a high CD4 cell count to get HIV, but they are less likely to develop AIDS and less likely to pass on the virus to someone else.

HIV is spread in three ways:

through direct contact with infected blood;

from mother to child during pregnancy, birth or breastfeeding; and

through sexual contact with an infected partner.

HIV is different from the herpes simplex virus and the virus that causes genital warts. Both of these types of viruses can also be spread through sexual contact, but they do not cause acquired immunodeficiency syndrome.

If you have been diagnosed with HIV you should:

Tell your sexual partner(s) so that they can get tested. You should also tell anyone you have had a sexual relationship within the last six months. A person can have HIV and not know it.

Get a complete physical to check for symptoms of other infections that are common in people with weakened immune systems, such as tuberculosis (TB).

Take prescribed drugs exactly as directed. Drugs can slow or help stop the progress of HIV infection. They may also help you feel better and improve your quality of life.

You should ask your doctor which drugs are right for you. The first line of defense is a drug called AZT or zidovudine. Other drugs called nucleoside analogues are also used.

It is possible to take advantage of experimental treatments and drugs still in the testing phase. It is important that you ask your doctor if any are appropriate for you.

Infections can be very serious in people with HIV. You may need a special antibiotics called “protease inhibitors”.

Sources & references used in this article:

Progressive multifocal leukoencephalopathy and anti‐CD20 monoclonal antibodies: What do we know after 20 years of rituximab by D Focosi, M Tuccori, F Maggi – Reviews in medical virology, 2019 – Wiley Online Library

Evaluation of patients treated with natalizumab for progressive multifocal leukoencephalopathy by TA Yousry, EO Major, C Ryschkewitsch… – … England Journal of …, 2006 – Mass Medical Soc

Distribution of nonintegrated DNA from JC papovavirus in organs of patients with progressive multifocal leukoencephalopathy by BW Grinnell, BL Padgett… – Journal of Infectious …, 1983 – academic.oup.com