The Parts of ME: Does “Post Exertional Malaise (PEM)” exist in other diseases?

When the National Academy of Medicine (NAM, formerly the Institute of Medicine/IOM) released its recommendations for Systemic Exertion Intolerance Disease (SEID) as a replacement for “ME/CFS,” I saw a lot of people spreading this myth: That “post exertional malaise” (PEM) is what differentiates myalgic encephalomyelitis (M.E.) from other illnesses. This is not true, nor is this what’s explained in the NAM’s report. At most, the report says that the presence of PEM helps distinguish it from other conditions, while it is what best distinguishes “ME/CFS” from idiopathic chronic fatigue. PEM alone is not specific to M.E., Chronic fatigue syndrome (CFS), or SEID, just like unrefreshing sleep is not specific to any one disease.

What distinguishes M.E. from other illnesses is a chronic, severe, measurable loss of sustainable strength on exertion, alongside a detailed history which almost always includes a noticeable infectious onset. (Rarely, some may not realize they’ve been infected, but M.E. is always an acute-onset, acquired infectious disease process [1].)

The term “postexertional malaise” was first coined in the Fukuda definition for CFS (2) without any explanation as to what it actually meant. As we define post-exertional malaise today, it can mean many things, occur in many different diseases, and is usually described as a worsening of all symptoms in response to activities that were well-tolerated pre-illness, and accompanied by delayed recovery.

“Minimum exercise makes me tired”; “drained after mild activity”; “soreness after non-strenuous activities”; “dead feeling after exercise”; “mentally tired after slightest effort” (3).

“A few studies that compared ME/CFS with other diseases found that, although PEM was experienced by 19 to 20 percent of subjects with major depressive disorder (Hawk et al., 2006a; Komaroff et al., 1996b) and 52 percent of patients with multiple sclerosis (Komaroff et al., 1996b), it was still much more common in ME/CFS patients than in comparison groups. One study found that 64 percent of patients with major depressive disorder experienced PEM, but the authors did not describe how PEM was assessed (Zhang et al., 2010). As mentioned earlier, these prevalence estimates may vary depending on how PEM was defined and queried for, and thus need to be interpreted with caution” (3).

Dr. Lucinda Bateman, one of many contributors to the NAM’s paper “Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness,” reminds us of the limitations on PEM research:

“Post Exertional Malaise has basically been compared to healthy controls, but there are really very few studies–not just in this section but in all the other parameters–that compare the symptoms to other chronic illnesses. And that’s really needed so we understand where it fits in. Because I think there are other illnesses where people have a consequence of exercise or being upright, it just isn’t termed in quite that way” (4).

Even in the case of delayed recovery, this is something Lyme disease can cause: Whereas the T cell function of the immune system in healthy individuals will have returned to normal within 12 to 24 hours after exercise (5), [T-cell function in people with Lyme disease] will depress for 12 to 24+ hours after exercise” (6).

I’m offering these references so you can see others talking about PEM in the context of illnesses besides ME or CFS, including a quote by the late Rich Van K. after his own exploration. Read the descriptions below and see if they sound at all familiar to you.

From the Phoenix Rising ME/CFS boards (7):

“I don’t think that PEM is a classic lyme symptom, although I have been wondering the same myself. I’ve heard it said that it’s not, and that if you’re a lymie with PEM you have a babesia infection. It’s the babesia that causes PEM, I gather probably because your red blood cells can’t transport oxygen efficiently when it’s needed. … Interesting, because I had ‘ME’ diagnosis and suffer from PEM but recently found out it’s actually lyme I have” (7).

“I wanted to chime in on the Post-Exertional ‘Malaise’ symptom. It is true that it is not necessarily associated with lyme itself. But it is a VERY signature symptom of Babesiosis. I was able to exercise throughout my years of ‘CFS’ (which was episodic). However that changed in ’05 and I started having Post-Exertional ‘Malaise’. I was finally diagnosed as infected with lyme and babesia last year. I can really tell the difference in symptoms. Babesia really makes you feel worse with exercise. Regular antibiotics don’t work against Babesia which is a protozoan like malaria. So someone treated for lyme and not babesia will still have fatigue problems. Most of the people with lyme have more than one infection. Babesia is a very common co-infection” (8).

“Hi, all. I posed the question to a group that includes quite a few ILADS docs and leaders of Lyme support groups. I got several responses, and the consensus was that PEM/PEF is the norm in ‘chronic Lyme’ patients, though there are some who do not have it. Of course ‘chronic Lyme’ includes the coinfections that are often associated with Lyme disease per se, so it could be due to comorbid Babesiosis. Best regards, Rich” (7).

From the LymeNet support forums: “Disabling fatigue which lasts for days or more occurs after exerting myself in normal physical or mental activities. I know that this is a hallmark of Chronic Fatigue Syndrome, but wondered if it occurs in Lyme” (9).

Yes it does. I believe Babesia (a common co-infection) can also cause these problems. I think it is not uncommon in chronic infections. Lyme can cause dysautonomia. I think that is a big part of why people have post exertional fatigue. I was diagnosed with CFS and fibromyalgia which turned out to be lyme.

This is a sign of babesiosis which is a coinfection of lyme disease.

“Yes, it does. I don’t know what you consider ‘normal’ physical activities, but with any form of CFS or Lyme, aerobic workouts should not happen, period. High stress situations should also be avoided as much as possible. I’m beginning to form the opinion that there are two kinds of Chronic Fatigue Syndrome: Diagnosed Lyme and Undiagnosed Lyme. All the other viruses and coinfections tag along for the ride.”

“Q: Can Lyme Disease cause Post-Exertional Malaise? Absolutely. First, it’s very serious toxic infection. That’s a huge ‘Bingo’ right there. Huge. Infection causes fatigue. Many other reasons are given above and also see the links here for MITOCHONDRIAL dysfunction…”

Post exertional malaise: Prior to treatment and during the beginning of treatment I had it BAD BAD BAD!!! Now I can do a bit more but there are still days when I lie down after doing some things and have malaise…[b]ut prior to treatment–GOSH!! it was so bad I’d just whimper. So I think with treatment some of this will let up for you. It’s so awful and confusing. And like others I had the stupid fibromyalgia diagnoses and even Parkinsons.

Both Lyme disease and Babesiosis rates are rising rapidly, with Lyme in specific infecting 300,000 new people in the US alone–a number the CDC admits is ten times what they originally predicted; it is one of the fastest spreading infectious diseases in both the US and Western Europe, and it is the fastest growing vector-borne infectious disease in the United States (10). In some places the rates of babesiosis have also increased tenfold (11), even though you don’t need a tick bite to contract it: Babesia has been the number one transfusion-transmitted infection in the US for years (12), and may account for many transfusion-related cases of “M.E.”

Fewer than 50% of people with Lyme disease recall a tick bite, fewer than 50% of those people recall a rash, and if you think testing is good enough, you’re absolutely wrong: The ELISA test has only a 50-65% detection rate (10) and Western Blots have been shown to miss almost 1 out of every 3 cases (later proven by culture) (13, 14). For these reasons, Lyme disease can be a clinical diagnosis, where a positive test is not required in order to begin a trial treatment if there is a high likelihood of infection, such as the presence of the “bull’s-eye rash” or other classic symptoms in an endemic region. Some physicians will use antibiotics to stimulate the immune system, counteracting the bacteria’s immunosuppressive defenses (15) and causing tests to become positive if Borrelia burgdorferi is present; this technique is known as an “antibiotic pulse.”

In the UK, Lyme diseases cases are “surging,” already double from 2004, and in England, there were already 111% more cases of Lyme disease in just the first nine months of 2015 than all of 2014 combined (16). Lyme is also the most common tick-borne disease in Germany, where very conservative estimates suggest 60,000 new cases per year (17). Despite over 1,000 cases reported in over 400 locations, officials in Australia have yet to alert the public or even admit the disease has spread to their country (18); 55% of respondents to a 2012 survey by the Lyme Disease Association of Australia were co-infected with babesia (19).

Worldwide, most people with Lyme disease suffer from coinfections, things like babesiosis that may also be vector-borne (ticks, mosquitoes, biting flies, fleas, even lice) and complicate treatment and recovery. Dr. Carsten Nicolaus, ILADS member (International Lyme and Associated Diseases Society) and Medical and Executive Director of the BCA Clinic in Germany, says 90% of the patients that visit him have co-infections, the most common of which are Bartonella (~40%) and Anaplasmosis/Human Granulocytic Ehrlichiosis (~30%). As is typical, his patients regularly present with other infections such as Chlamydia pneumoniae, Mycoplasma pneumoniae, EBV, and CMV (20), the latter of which are well-known to cause substantially worsened symptoms after exertion.

Someone studying or otherwise trying to help people with ME and CFS cannot afford to dismiss the severity and pertinence of this information. We might be fighting an uphill battle, but researchers in particular cannot afford to not understand something that shares so many symptoms with the illnesses they are studying. How much further could we advance if an ILADS physician were a consultant on all major CFS research? And without comparison studies, how do we really know someone with chronic Lyme disease, babesiosis, EBV, CMV, similar chronic relapsing infections, or other diseases that impair the mitochondria, wouldn’t give similar or even the same results as “ME/CFS” patients if they were subjected to the two-day cardiopulmonary exercise tests (21, 22, 23), tests which claim to identify a type of PEM “unique” to “ME/CFS”?

Right now, quite simply, we don’t know. What we do know, and what I hope I’ve demonstrated, is that post exertional malaise is not solely associated with chronic fatigue syndrome, or myalgic encephalomyelitis.

a rainbow at night

See also:

Resources for Lyme Disease and Co-infections

Support Forums:
Finding a Lyme Literate Medical Doctor, or LLMD:
If you know of other reputable labs in your country, support forums, or ways to find an LLMD in your area that aren’t listed here–even if it’s just a link to a list on another site–comment below or contact me and I’ll gladly add them here for all readers.


1. Hyde, B. (2007, January 29). The Nightingale Definition of Myalgic Encephalomyelitis (M.E.). Retrieved December 7, 2015, from
2. Fukuda, K., Straus, S. E., Hickie, I., Sharpe, M. C., Dobbins, J. G., & Komaroff, A. (1994). The chronic fatigue syndrome: a comprehensive approach to its definition and study. Annals of Internal Medicine, 121(12), 953-959.
3. Committee on the Diagnostic Criteria for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome, Board on the Health of Select Populations, & Institute of Medicine. (2015). Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness. Retrieved December 7, 2015, from
4. “New Clinical Definitions for ME/CFS” Dr. Lucinda Bateman. (2015, March 8). Retrieved December 7, 2015, from
5. Gleeson, M., Bishop, N. C. (2005). The T cell and NK cell immune response to exercise. Annals of Transplantation, 10(4), 44-49.
6. Burrascano Jr., J. (2008, October). Advanced Topics in Lyme Disease: Diagnostic Hints and Treatment Guidelines for Lyme and Other Tick Borne Illnesses. Retrieved December 7, 2015, from
7. Just found out I have active lyme disease. I am stunned. Help! (2012, July 28). Retrieved December 7, 2015, from
8. Lyme Disease and XMRV. (2012, July 31). Retrieved December 7, 2015, from
9. Can Lyme Disease cause Post-Exertional Malaise? (n.d.). Retrieved December 7, 2015, from archive &cd=4&hl=en&ct=clnk&gl=us
10. Lyme Disease Quick Facts. (n.d.). Retrieved December 7, 2015, from
11. Cape Cod a hot spot for babesiosis from ticks. (2015, March 1). Retrieved December 7, 2015, from
12. Joiner, J. (2015, May 8). Hospitals Knowingly Dispense Poisoned Blood. Retrieved December 7, 2015, from
13. Basic Information about Lyme Disease. (n.d.). Retrieved December 7, 2015, from
14. Lyme disease is a clinical diagnosis, based on your medical history, symptoms and exposure to ticks. (n.d.). Retrieved December 7, 2015, from
15. Twenty studies revealing immunosuppression from Lyme disease. (2015, August 10). Retrieved December 7, 2015, from
16. Jowit, J. (2015, December 4). Surge in acute cases of Lyme disease in Britain spurs ministers to act. Retrieved December 7, 2015, from
17. Paddock, C., & Telford III, S. (2010). Through a Glass, Darkly: The Global Incidence of Tick-borne Diseases. Critical Needs and Gaps in Understanding Prevention, Amelioration, and Resolution of Lyme and Other Tick-Borne Diseases: The Short-Term and Long-Term Outcomes. Retrieved December 7, 2015, from Files/Disease/TickBorne/01-Global-Incidence-of-Tick-borne-disease.pdf
18. The stats – Lyme Disease Association of Australia. (n.d.). Retrieved December 7, 2015, from
19. Lyme disease: Australian patient experience in 2012. (2012, November). Retrieved December 7, 2015, from
20. Rubin, C. (2013, October 29). The Global Search for Education: Germany – Ticks. Retrieved December 7, 2015, from
21. Keller, B., Pryor, J., & Giloteaux, L. (2014). Inability of myalgic encephalomyelitis/chronic fatigue syndrome patients to reproduce VO2peak indicates functional impairment. Journal of Translational Medicine, 12, 104.
22. Vermeulen, R., Kurk, R., Visser, F., Sluiter, W., & Scholte, H. (2010). Patients with chronic fatigue syndrome performed worse than controls in a controlled repeated exercise study despite a normal oxidative phosphorylation capacity. Journal of Translational Medicine, 8, 93.
23. Snell, C., Stevens, S., Davenport, T., & Ness, J. (2013). Discriminative validity of metabolic and workload measurements for identifying people with chronic fatigue syndrome. Physical Therapy, 93(11), 1484-1492.


12 thoughts on “The Parts of ME: Does “Post Exertional Malaise (PEM)” exist in other diseases?

  1. Kit, I don’t know how you organize all this information. It’s tough enough to process reading it let alone writing it. Brava!

    Glad you wrote about this because I’ve been wondering how you identify your illness. You have been diagnosed with Chronic Lyme disease and above many people express that CFS/ME is caused by Lyme disease. Do you believe your ME was caused by your Lyme? If so, I wonder about treating ME because, like FM and MS, it doesn’t have a “cure,” but Lyme disease is treatable. So, if you can cure the Lyme, would it cure your ME?

    Also, is it possible that it’s “just” Lyme and not ME?

    I ask because I wonder how you differentiate between the two?

    Also, I find others identifying as having Lyme and CFS and/or Fibromyalgia and, at least in my case, I believe FM was a misdiagnosis for me. That once I clear the Lyme and its coinfections (I have Babesiosis), I will regain my health.

    Lastly, disabling fatigue is my worst symptom. I don’t seem to have severe PEM. My energy waxes and wanes. One day I may be able to walk the dog a mile and on another day, I can’t even get out of the house. It makes no sense, but doesn’t seem to correspond to exercise. Any thoughts?

    I know lot’s of questions, but I’ve been curious about them since I read your very first post.



  2. Question regarding your question “And without comparison studies, how do we really know someone with chronic Lyme disease, babesiosis, EBV, CMV, similar chronic relapsing infections, or other diseases that impair the mitochondria, wouldn’t give similar or even the same results as “ME/CFS” patients if they were subjected to the two-day cardiopulmonary exercise tests (21, 22, 23), tests which claim to identify a type of PEM “unique” to “ME/CFS”?”

    How do we know someone with ME/CFS doesn’t have chronic Lyme disease? The testing is so difficult (offering false negatives) and expensive, I wonder how many people diagnosed with ME are even tested?


    1. Right. Just like having MS or cancer doesn’t mean you can’t also catch Lyme, having M.E. doesn’t protect you from tick bites (or flea bites). Anyone can contract Lyme disease and its co-infections. I know that better than most. I contracted Lyme disease four years after M.E.–it was actually because the M.E. went into remission that I felt well enough to go fishing, and get that tick in my scalp that stay attached for three days!

      Many people are only given a CFS or ME diagnosis because their doctor can’t think of anything else and they’re basing it on overly broad criteria, so it’s important to know WHY you’re getting that diagnosis: For legal reasons, even though your doctor knows what real ME is? Or because they’re at a dead end; i.e. you’ve been given a label but still not a real diagnosis?

      You raise an excellent point, and I was actually thinking of this earlier but too mentally fatigued to fit it in:

      How DO we know that the people IN those cardiopulomonary studies who did so poorly, didn’t actually have, or additionally have, chronic infections? The results do tie into the muscle fatigue aspect of ME, and coupled with history can be very helpful in diagnosis, but. That doesn’t mean others misdiagnosed with ME or CFS but actually having infection, wouldn’t have also had those scores on day two. For all we know the people tested DID have infections and just didn’t know it! I haven’t checked their methodologies to predict the likelihood of them using classic ME patients in the studies vs a mixed ME/CFS cohort.

      I think everyone diagnosed with M.E. and CFS needs to be tested, especially in endemic region. As I learned first hand, with so many similar symptoms it could take years before someone realizes something is “off” (like a repeating symptom pattern or increasing nerve damage), and the sooner someone finds out, the better.


  3. Thanks for your work on this. It’s really frustrating to me that the key feature (muscle weakness on mild exertion) of the disease has been completely lost over time and replaced with a new key feature (PEM), one that was never emphasized as being unique or important in Ramsay’s original description of ME. I did not realize that the PEM concept came from Fukuda initially but that makes sense. The CCC and ICC definitions are irrevocable tainted by CFS concepts, even though they claim to be describing ME. I believe they are only appropriating the name in order to move away from the stigma of the CFS name, but they don’t describe any of the key features of true ME.

    I think there has been a dangerous and improper conflation of ME and vector borne infections in the past few years. I believe doctors such as KDM are partly to blame for this by claiming that the majority of their ME patients have been diagnosed with a vector borne infection. This doesn’t mean that those infections cause ME, it means that those patients were misdiagnosed with ME. If you have a Borrelia infection then you have Lyme disease, if you have a Babesia infection then you have babesiosis, and so on. No doubt these people are extremely sick with symptoms like chronic fatigue and post exertional malaise, but that doesn’t mean they have ME. I also believe that people are abandoning the chronic lyme concept due to the stigma attached to it and are finding it easier to adopt the “ME/CFS” diagnostic label instead, unfortunately this just further distorts what ME and even CFS were meant to describe and will eventually distort research due to mixed cohorts.

    If you read Ramsay’s book, and then read the individual papers written about the very well documented outbreaks of ME, it’s quite clear that ME, as Ramsay and others described prior to 1988, is a very specific post viral consequence and probably involves only a small handful of viruses, those capable of producing persistent non-lytic CNS infection in key areas such as the hypothalamus, brain stem, and spinal cord. I think that we need to reject SEID and abandon the CCC/ICC version of ME and return to the historical description of the disease because it was the most accurate, being produced by careful examination of patients from 1955 until 1986, and not tainted in any way by the concept of CFS.

    Liked by 1 person

  4. I had no idea babesiosis did not require a tick bite. Most of the time I see it listed as strictly a tick-related disease. I had a terrible Lone Star Tick bite last year, and I think that’s caused some lasting problems; although, I don’t think it’s associated with Lyme. As for mosquitos, I’ve clocked nearly 20 bites/day during our worst rainy summers, and that was with repellant. Getting ready to pull some invasive ivy from the yard to reduce their habitat.

    Liked by 1 person

    1. Lone Star Ticks can transmit a Southern version of Lyme called STARI, as well as Ehrlichiosis, Tularemia, Rickettsia (bacteria)…all kinds of things. If you got sicker after the bite, see an LLMD who will know what to test for and how to administer treatment to avoid progressive and/or long-lasting damage.

      Liked by 1 person

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