Epstein-Barr Virus

Evidence for Role in Chronic Fatigue Syndrome

A woman clutches her throat.
Epstein-Barr causes mononucleosis, which is characterized by a sore throat. Image Source/Getty Images

The Epstein-Barr virus (EBV) is a member of the herpesvirus family and one of the most common human viruses. The Epstein-Barr virus (EBV) has long been tentatively connected to chronic fatigue syndrome (ME/CFS.) Some researchers say it's an important causal factor while others say it's not involved with this disease.

Those who believe it is connected often talk about reactivation. EBV is in the herpesvirus family.

All herpesviruses stay in your system forever, but generally remain dormant most of the time. When they do become active, specialized cells in the immune system, including B-cells and T-cells, typically don't have a problem knocking them back down again.

Most people aren't even aware that this process is going on. That's because B- and T-cells, in a healthy immune system, remember the virus and can rapidly assemble an army of antibodies to keep it in check.

If the immune system isn't working correctly, though, it could theoretically allow the virus to gain a foothold at levels that once again make you sick. That's called reactivation.

Evidence of Reactivation

Research published in 2014 shores up the hypothesis of EBV reactivation as a possible cause of some cases of ME/CFS.

In this study, scientists found evidence that the B- and T-cells of many people with this disease were unable to remember EBV, meaning a reactivated virus would be better able to thrive, reproduce, and cause symptoms.

Researchers found this impaired cellular memory in the immune systems of 76 percent of the more than 400 study participants. That's an impressive percentage.

Along with showing what may cause and sustain some cases of ME/CFS, researchers say this work could lead to a long-sought diagnostic marker.

More About the Epstein-Barr Virus

EBV is a nasty bug.

It's best known for causing infectious mononucleosis, called mono or the "kissing disease." Symptoms of mono include:

  • severe fatigue
  • sore throat
  • headache
  • fever
  • muscle aches
  • swollen lymph nodes
  • sensitivity to light
  • shortness of breath

Recovery from mono is known to take a long time, and recurrences are marked by extreme fatigue.

Some researchers have long believed it's no coincidence that those are also symptoms of ME/CFS. However, a large portion of the population carries EBV and only a small number of those people develop ME/CFS. That has confounded attempts to explain how EBV could contribute to the illness.

This study appears to overcome that problem, though, providing an answer to that question. It doesn't answer questions about why some people's immune systems seem to be blind to this particular virus, though. That's a topic for future research.

Previous Studies

Other studies have shown that a significant number of juvenile ME/CFS cases followed mono, and many adolescents whom doctors deem unrecovered from mono fit the ME/CFS diagnostic criteria. It seems that the harder EBV hits, the more likely it is to cause prolonged illness. (Read more about these findings from Cort Johnson at Health Rising.)

In addition to mono, EBV is linked to certain types of cancer, which could explain the higher incidence of cancer-related illness and death some ME/CFS experts have observed. EBV may also play a role in multiple sclerosis. Some research also suggests it can mimic acute leukemia.

With this new discovery of impaired cellular memory, we may have filled a significant gap in knowledge about how EBV could be triggering ME/CFS and contributing to on-going symptoms.

While more work is needed to verify this study, it could prompt more doctors to prescribe anti-viral medications (such as valacyclovir or valganciclovir) for ME/CFS patients with high EBV levels.


Chhabra P, Law AD, Sharma U, et al. Epstein-barr virus infection masquerading as acute leukemia: a report of two cases and review of literature. Indian journal of hematology & blood transfusion. 2014 Mar;30(1):26-8.

Loebel M, Strohschein K, Giannini C, et al. Deficient EBV-specific B- and T-cell response in patients with chronic fatigue syndrome. PLoS One. 2014 Jan 15;9(1):e85387. eCollection 2014.