Multiple sclerosis (MS) and other conditions affecting the immune system can activate the John Cunningham (JC) virus, causing a potentially life threatening infection.
The JC virus is common, and most people don’t know they carry it.
The JC virus can be activated when a person’s immune system is compromised because of an illness or immunosuppressive medication.
The virus can then be carried into the brain. It infects the white matter of the brain and attacks the cells responsible for making myelin, the protective coating that covers and protects nerve cells.
This infection is called progressive multifocal leukoencephalopathy (PML). PML can be fatal.
Read on to learn more about the JC virus and the risks for people with MS.
Anywhere from 50% to 90% of humans have JC virus antibodies. The average person carrying the JC virus will never know it and is unlikely to experience any side effects.
However, if you have MS, you’re more likely to experience potentially serious complications, such as PML.
The JC virus often attacks when a person’s immune system is at its weakest. A weakened immune system can no longer fight off invading viruses. It’s the perfect opportunity for the JC virus to awaken, cross the blood-brain barrier, and begin attacking the brain.
People with MS are at an increased risk for PML because their immune system is often compromised as a result of the condition.
Further compounding the problem, several MS medications can also compromise the immune system.
Immunosuppressant medications can increase the likelihood that a person with MS will develop PML after exposure to the JC virus. Examples of these immunosuppressant medications include:
- azathioprine (Azasan, Imuran)
- cyclophosphamide
- dimethyl fumarate (Tecfidera)
- methotrexate
- mitoxantrone (Novantrone)
In
This JC virus-detecting test can determine whether a person has been exposed to the virus and whether it’s present in their body.
A positive test doesn’t mean that a person with MS will definitely develop PML, but only JCV-positive people can develop PML. Knowing that the test is JCV-positive indicates to your doctor that they should monitor for PML.
If your doctor recommends testing and the test is negative, you may require more frequent blood tests to check for the JC virus antibodies and
Talk with your doctor about how often you should be tested for JC virus antibodies. Regular testing will help you detect the infection faster. The sooner it’s detected, the sooner you can begin treatment.
Learn about tests used in MS.
Talk with your doctor about your risk for developing PML and how the medications you’re taking might affect that risk.
They may want to conduct an ELISA before you begin taking immunosuppressive medication. If this is the case, talk with them about having the ELISA blood test first. If your result comes back negative, you’re less likely to develop PML.
If your results come back positive, talk with your doctor about the risks of taking the medication and the likelihood you’ll develop PML.
A positive test may require that you and your doctor re-evaluate your treatment plan.
Learn more treatments for MS.
You should contact your doctor as soon as you have concerns about the JC virus or PML.
The doctor may order tests to confirm the presence of JC virus antibodies. If the test detects the antibodies, your doctor may re-evaluate your current treatment plan in case any of your current medications, such as immunosuppressives, may increase your risk of PML.
If you have symptoms of PML, you should seek immediate medical help. The symptoms can develop over a number of
Symptoms can vary depending on the area and severity of the damage but may include:
- clumsiness
- progressive weakness
- vision changes
- speech changes
- personality changes
It’s important to note that these symptoms are similar to those of an MS flare. You should contact your doctor if you notice new or worsening symptoms.
Many people carry the John Cunningham (JC) virus, but it does not usually cause any symptoms. However, if you have a weakened immune system due to multiple sclerosis (MS), you are more at risk of developing potentially serious complications, namely progressive multifocal leukoencephalopathy (PML).
Immunosuppressive medications for treating MS can also increase the risk of PML.
Your doctor can order blood tests to check for the presence of JC virus antibodies. If the test is positive, they may order regular MRIs to monitor for signs of PML.
If you have MS, you can discuss the possible risk of PML with your doctor. They can advise on how frequently they recommend tests for monitoring, and they may make changes to your treatment plan if the test is positive for JC virus antibodies.