Note: This is the second article in an ongoing series. Make sure to check out the following articles once you’re finished with this one!
What Causes Chronic Fatigue Syndrome? – Part I: Understanding Fatigue
What Causes Chronic Fatigue Syndrome? – Part III: Genetics
What Causes Chronic Fatigue Syndrome? – Part IV: Hormones
What Causes Chronic Fatigue Syndrome? – Part V: A Functional Medicine Approach
Many report chronic fatigue syndrome to have begun after a bad flu or mono. Could chronic fatigue be caused by an infection with the Epstein-Barr virus?
Chronic fatigue syndrome presents very similarly to that of a viral infection. Thus it’s no surprise that doctors and scientists have suspected that CFS is caused by some sort of infection. The most popular of which is the Epstein-Barr virus (EBV). You probably know the EBV virus as the common cause of mononucleosis (mono).
Unfortunately, this theory quickly unravels as many patients with chronic fatigue syndrome have not ever had mono. Their labs for antibodies towards the Ebstein-Barr virus come back negative. So, researchers broadened their hypothesis, if chronic fatigue is not caused solely by the Epstein-Barr virus, then there must be another type of chronic fatigue syndrome! One caused by a viral infection, the other caused by a non-viral infection.
Let me be crystal clear, at the time of this writing, there have not been any medical studies that show a direct, causative link between chronic fatigue syndrome and viral or non-viral infections (including mono). With that said, there are correlations between certain types of infections and chronic fatigue syndrome. This post will explore the most common viral and non-viral infections associated with chronic fatigue syndrome.
Mono & chronic fatigue syndrome
The Epstein-Barr virus (EBV) is also known as Human Herpesvirus 4 (HHV-4). You may know it as the cause of mononucleosis (mono. or, the kissing disease). Though the Epstein-Barr virus only causes mononucleosis 30-50% of the time and only during adolescence. (1) The EBV is transferred via oral saliva. This is why it is commonly known as the kissing disease. It is thought that nearly 90% of adults in North America have been infected with the EBV at some time. (2)
Do you know what the symptoms of mono include? Here’s a short list:
- Fatigue
- Sore throat
- Fever
- Swollen lymph nodes &/or tonsils
- Headaches
The above symptoms are very similar to those found in chronic fatigue syndrome. Even more interesting, many people with chronic fatigue remark that their symptoms occurred after a mono infection.
With such a strong correlation in both symptoms and onset, could the Epstein-Barr virus be a potential cause of chronic fatigue syndrome?
Studies were done in the late eighties and early nineties convinced researchers that the EBV (Epstein-Barr Virus) played a causative role in chronic fatigue syndrome. (3, 4) As research progressed, doctors and scientists learned that while EBV (and to a lesser extent, mono) is certainly correlated with chronic fatigue syndrome, it is not causal.
It’s incredibly important to differentiate correlation from causation. Causation implies that the change in one variable is the cause of the change in another variable. If mono (or, the EBV) caused chronic fatigue, you would see close to 100% of the people who contracted mono then go on to develop chronic fatigue syndrome. I’m confident you can think of a friend who has got infected with mono but never went on to develop chronic fatigue syndrome.
Mono is certainly correlated with chronic fatigue syndrome. A higher percentage of those infected with the Epstein-Barr virus go on to develop chronic fatigue syndrome that those who are never affected. (5) Some patients with chronic fatigue syndrome also show elevated antibodies to the Epstein-Barr virus. This implies their immune system was infected with the virus at some point. However, these links are just correlated. Correlation implies a connection. But it’s not enough of a link to be causal.
The Enterovirus and chronic fatigue syndrome
Enteroviruses are a group or genus of viruses that infect humans by way of the intestines. You’ve probably heard of the enterovirus by way of polio. Polio is one of many different types of enteroviruses. In fact, researchers have identified 71 different types of human enteroviruses. (6)
Similar to the Epstein-Barr virus, the symptoms of the non-polio strain of enterovirus infection include:
- Sore throat
- Body and muscle aches
- Vomiting
- Fever
- Skin rash
One study found that nearly all patients (76%) with chronic fatigue syndrome had immune system markers (IgM) of a previous enterovirus infection. (7) Though another study found that there was almost no connection between chronic fatigue syndrome and enterovirus infections. (8)
Other studies argued that testing immune system activation (IgM or IgG) markers for the enterovirus were not an accurate way to determine whether or not an infection had occurred. These studies used a testing method called polymerase chain reaction (PCR). PCR looks for the RNA or genetic marker of the enterovirus in tissues instead of examining the immune system. One study found 53% of those with chronic fatigue syndrome had PCR markers for the enterovirus. (9) But a follow-up study by the same researchers from only 6% higher rate of infection between those with chronic fatigue syndrome and healthy controls. (10)
Are you confused yet?
To summarize, the enterovirus (like the Epstein-Barr virus) may be a trigger for chronic fatigue syndrome but there is not enough evidence to conclude that is causal.
Candida and yeast infections effect on chronic fatigue syndrome
Candida is a broad category of yeast species (in scientific terms, its called a genus). Candida (and its many subtypes) is the most common fungal infection on the planet. (11) Candida Albicans is the most common species to cause infection in humans. You may know candida as the yeast species that causes oral thrush. Candida infections are most common after long-term antibiotic use. (12)
During the 90’s and the early 2000’s, natural health practitioners jumped on the Candida bandwagon. They thought that Candida was the cause of every chronic illness. Meanwhile, the conventional medical system believed Candida to be a normal resident of the digestive tract. And thus it couldn’t possibly be causing illness. As with most things, the truth is likely somewhere between the two extremes.
During the Candida heyday, it was thought that an overgrowth of this yeast species could cause chronic fatigue syndrome. One study showed there was an increase in the stool of those with chronic fatigue syndrome. (12) Candida infections of the gastrointestinal tract were shown to cause the following symptoms:
- Belching
- Bloating
- Indigestion
- Nausea
- Diarrhea
- Gas
While not closely related to the common symptoms of chronic fatigue syndrome, the above symptoms are commonly listed in those with irritable bowel syndrome (IBS). And we know that those with fibromyalgia or chronic fatigue have a much higher prevalence of gut-related symptoms.
Much like the Epstein-Barr and enterovirus, reducing the cause of chronic fatigue syndrome down to one species of yeast is not likely to bring about a solution. Candida may very well contribute and/or correlate to chronic fatigue syndrome. Though it is safe to say that it is not causal.
Human herpesvirus 6 and chronic fatigue syndrome
The Human Herpesvirus-6A and Herpesvirus-6B (HHV-6) are two of the nine herpes viruses known to infect humans. Most humans who acquire the virus do so early in life. (13) Infection of via the HHV-6 commonly presents with a condition called roseola. Roseola presents with a high fever and a pink rash across the skin.
The HHV-6 has been shown to trigger chronic fatigue syndrome in some patients. (14) We must be careful to differentiate the terms trigger and cause. While the HHV-6 and many of the other infections listed above may trigger chronic fatigue syndrome it has not be shown that any of the infections listed cause chronic fatigue syndrome. If the HHV-6 caused chronic fatigue syndrome, then we would be able to cause chronic fatigue in a healthy individual simply by exposing them to the HHV-6 virus. This has not been shown to be the case. Many healthy individuals have been exposed to the HHV-6 virus and experience no symptoms of fatigue afterward.
Is chronic fatigue triggered by an infection?
Throughout this post, I’ve illustrated how the most common infections associated with chronic fatigue syndrome do not possess enough evidence to be listed as causal. The common element among all these infections is that many seem to trigger chronic fatigue syndrome. Another way to think about the relationship between infectious agents and chronic fatigue syndrome is as follows:
Infections pull the trigger on chronic fatigue syndrome. But what is it that loads the gun?
Could the gun be loaded by your genetics? Hormones? Environment?
Continue reading this series of posts that explore what really is causing chronic fatigue syndrome.
What Causes Chronic Fatigue Syndrome? – Part I: Understanding Fatigue
What Causes Chronic Fatigue Syndrome? – Part III: Genetics
What Causes Chronic Fatigue Syndrome? – Part IV: Hormones
What Causes Chronic Fatigue Syndrome? – Part V: A Functional Medicine Approach
Want to know more than your doctor about what causes chronic fatigue syndrome? Click here.
