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Even “Minor” Infections Can Cause Chronic Fatigue Syndrome (ME/CFS)

Giardia hasn’t historically ranked high as a potential cause of chronic fatigue syndrome (ME/CFS). Some anecdotal reports suggest that a Giardia outbreak may have occurred prior to the Incline Village ME/CFS outbreak in the 1980’s. More recently, Corinne Blandino’s severe, decades long case of ME/CFS – which originated with an exposure to Giardia at work – demonstrated how devastating a case of Giardia triggered ME/CFS can be.

Giardia long lasting effects

Giardia is thought of as a minor infection – but it can have long lasting effects.

It wasn’t until city in Norway got exposed to Giardia in 2004, however, that Giardia, a protozoa, became one of the pathogens definitively linked with chronic fatigue syndrome (ME/CFS). Large studies (n=1254) examining the aftermath of the outbreak in a public water system in Bergen found that five years later, almost 50% of those originally infected still had symptoms of irritable bowel syndrome and/or chronic fatigue (post-infectious chronic fatigue).

“Other patients suffer a severe, long lasting illness, for which treatment is ineffectual, and even after the parasite has finally been eliminated, some sequelae persist, affecting quality of life and continuing to cause the patient discomfort or pain” (LJ Robertson et al, 2010)

Five percent suffered from fatigue severe enough for them to lose employment or be unable to continue their education. Interestingly, all had taken anti-parasitic drugs and all had apparently cleared the pathogen from their systems.  Five years later, 30% were deemed to have an ME/CFS-like illness and almost 40% had irritable bowel syndrome  (IBS).

“Minor” Infection – Sometimes Serious Results

By all accounts Giardia shouldn’t be doing this. Giardia is not normally considered a serious infection. Most people have some diarrhea and pass the bug quickly – and if they don’t, antibiotics are usually (but not always) effective. Giardia, seemingly, produces the kind of “minor” infection that our medical system doesn’t spend much time on.

The Mayo Clinic reports that Giardia infection (giardiasis) is one of the most common causes of waterborne illness in the United States. The parasites are found in backcountry streams and lakes throughout the U.S., but can also be found in municipal water supplies, swimming pools, whirlpool spas and wells. Giardia infection can be transmitted through food and person-to-person contact.

Research studies are slowly revealing that the effects of even vanquished Giardia infections can be long lasting for some. The Mayo Clinic reports that intestinal problems such as lactose intolerance  may be present long after the parasites are gone. (Even though half a dozen studies have been published on the Bergen outbreak, Mayo fails to note that long term issues with fatigue and pain (or ME/CFS) may result).

The Bergen studies indicate, however, that this rather common infection worldwide can cause long term and even at times debilitating fatigue as well. The takeaway lesson from the Bergen studies is that one doesn’t need to have mono, Ross-River virus or Valley fever or any of several serious infections to get seriously afflicted. As Dr. Chia has been saying about enteroviruses for years, any minor infection has the potential to cause ME/CFS in the right person.

The Galland-Giardia Chronic Fatigue Syndrome (ME/CFS) Connection

The Norwegians wrongly reported that they were the first to associate fatigue with Giardia infections, but they couldn’t be blamed for thinking so. Way back in 1989, an integrative doctor named Dr. Galland suggested that Giardia infections were associated with ME/CFS. That year, Galland reported at a scientific conference that Giardia might be more common in ME/CFS than expected. Using a new test, Galland found active Giardia infection in 46 per cent of his chronic fatigue syndrome (ME/CFS) patients. (Galland noted that many of his patients may have picked up the bug during travel to foreign countries).

In 1990 Galland published a paper “Giardia lamblia infection as a cause of chronic fatigue.” in the Journal of Nutritional Medicine. (The paper never appeared on PubMed, the main English research database, apparently because of the journal it was published in. Citations from present and past journals devoted to ME/CFS have never appeared in PubMed either.)

chronic fatigue - giardia

Galland found the most devastating long term symptom after a Giardi infection was not gut pain but fatigue

Interestingly, given the involvement of a pathogenic gut protazoan, the patients’ gut symptoms were relatively minor; it was their fatigue, muscle pain, muscle weakness, flu-like feelings, sweats and enlarged lymph nodes that stood out. Galland reported that treating the infection alleviated the fatigue in over 80% of his patients and removed the digestive complaints in 90%. In 1998 Galland reported that one outbreak of Giardia, in Placerville, California, “was followed by an epidemic of Chronic Fatigue Syndrome, which swept through the town’s residents”.

Galland found that a longer than usual treatment regimen was often necessary to clear the body of the bug. Instead of the normal five-day treatment, his average treatment regimen lasted three weeks and could extend to eight.  He has also reported treatment successes involving other parasites (Entamoeba hystolytica, Cyrptosporidium) and other diseases such as rheumatoid arthritis.

In 2011, Galland hadn’t let up on the ME/CFS/giardia/intestinal parasite angle, reporting that a woman with severe fatigue and dizziness (but not many gut symptoms) who had tested positive for Giardia slowly recovered under his anti-parasitic protocol. Citing a Johns Hopkins study indicating that 20 percent of healthy controls had antibodies to Giardia, Galland suggested that Giardia infections were much more common, particularly in small town water systems (such as Incline Village?), than previously suspected.

Giardia is probably not a common cause of ME/CFS: Dr. Peterson said he regularly tests for it but rarely finds it – but because it is usually treatable, it’s a test that probably everyone, particularly those who got ill after foreign travel, should get.

The biggest question for the ME/CFS community (and the Lyme community), though, is why, as with other infections, some people who get enough treatment to make the pathogen disappear are still ill.

Back to the Norwegians

Galland may have generated some buzz in integrative medicine circles, but it took the Norwegian researchers to get Giardia and ME/CFS on the map in the research world. Tests revealing increased numbers of cytotoxic (i.e. killer) T-cells indicated an immune system on the alert for a pathogen.  (Similar findings occur in herpesvirus and cytomegalovirus infections, infectious mononucleosis, etc.)

With the Norwegian studies indicating that depression and anxiety weren’t the culprits in the ME/CFS outbreak, several hypotheses popped up:

  • The Sneaky Pathogen theory – The pathogen wasn’t gone at all, it was laying low. Poor immune surveillance was allowing low, undetectable levels of the bug to produce low-grade inflammation that was causing fatigue, abdominal distress and other symptoms.
  • The Hit and Run Gut Attack Theory #1 – Before it was overcome, the water-borne pathogen permanently damaged the lining of the intestines causing problems with gut permeability, hypersensitivity, bacterial overgrowth, immune reactions (fatigue, etc.) and irritable bowel syndrome.
  • The Hit and Run Gut Attack Theory #2 – the pathogen triggered the activation of mast cells in the gut causing fatigue, hypersensitivity, IBS and other symptoms.

The Latest Study

Giardia-specific cellular immune responses in post-giardiasis chronic fatigue syndrome, Kurt Hanevik1, 2Email authorView ORCID ID profile, Einar Kristoffersen1, 3, Kristine Mørch1, 2, Kristin Paulsen Rye1, Steinar Sørnes1, Staffan Svärd4, Øystein Bruserud1 and Nina Langeland1, 2 BMC Immunology 201718:5 DOI: 10.1186/s12865-017-0190-3

The latest Norwegian study attempted to explain the lingering fatigue and other problems by testing immune responses (T-cell proliferation assay, T cell activation and cytokine release analysis) to Giardia in 20 Giardia exposed fatigued individuals, 10 Giardia exposed non-fatigued individuals and 10 healthy unexposed individuals were recruited as controls.

The study did not find increased immune responses to Giardia (including T-cell activation or cytokine responses) in the post-infectious Giardia group. The still ill Giardia patients did, however, have higher levels of a key immune marker called sCD40L implicated in inflammation and in severe symptom flares in ME/CFS patients after exercise.

giardia question chronic fatigue syndrome

No one knows why 5-10% of the post-giardiasis patients are still sick

Why these patients – five years after their Giardia infection was resolved – are still ill remains a mystery, but the link between Giardia infections and subsequent chronic illnesses is growing.  A higher incidence of Giardia infection was recently found in lupus. Just this year, a study found an association between Giardia infection and the subsequent development of arthritis.  A 4,000 person study recently confirmed an association between Giardia infection and the development of irritable bowel syndrome.  That study’s findings were buttressed by an earlier study indicating that Giardia induces gut hypersensitivity in rats long after the parasite had been cleared.

How Giardia is setting some people up for subsequent illnesses such as ME/CFS, arthritis, lupus or IBS isn’t entirely clear.  It is clear, though, that particularly virulent strains of Giardia that cause more damage might be involved.  Giardiasis can damage the microvilli of the intestines and promote inflammation. Eight months after the apparent resolution of Giardia, signs of gut inflammation were present in almost 50% of the Bergen cohort. (That high number suggested that the Bergen cohort may have been hit by a particularly virulent strain of Giardia.)  Protracted levels of gut inflammation resulting in systemic inflammation – as some suspect is present in ME/CFS – could explain the fatigue and other problems that remained.

“Host responses” may be important as well. Reduced levels of gut arginine at the time of infection may result in more gut damage. Although T-cells are the big guns in the immune response to pathogens, one study suggested that one’s gut microbiome makeup played a bigger factor in preventing/allowing a serious infection to occur.

Some findings in the Norwegian Giardia outbreak mirror others seen in post-infectious ME/CFS illness states. Greater illness severity, whether characterized by increased symptom severity, more time spent in bed and/or a more difficult time ridding the body of the infection have been found to predispose people with infectious mononucleosis or giardiasis to coming down with ME/CFS.  Being female is another risk factor.

Prior illnesses may make a difference as well. Prior gut symptoms increased the risk of fatigue, etc., after a giardia infection but, interestingly, not more gut problems. This indicated, as has been shown before, that a lack of gut symptoms does not necessarily rule out the gut as a central factor in disease.

The Post-Infectious Cohort

Whether the pathogen involved is Ross-River virus, Q-fever, Epstein-Barr Virus, Giardia or other gut pathogens such as Campylobacter, Salmonella, Shigella, Escherichia coli and Trichinella spiralis, a year or so later, from 5-10% of those afflicted are still ill. Infections, whether cleared or not, clearly can have long-term consequences.  The link between infectious mononucleosis and multiple sclerosis is a classic example. Dozens of studies indicate that having infectious mononucleosis increases one’s risk of later coming down with multiple sclerosis.

The Simmaron Research Foundation is continuing its efforts to examine the role unusual infections may play in ME/CFS with its support of the Konnie Knox study examining the role that vector-borne (bird/insect borne) infections may play in ME/CFS.


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  • Simas

    July 5, 2017 at 7:57 pm - Reply

    Wow, this is very interesting. I have to admit that I find this hypothesis, the most interesting:
    “The Hit and Run Gut Attack Theory #2 – the pathogen triggered the activation of mast cells in the gut causing fatigue, hypersensitivity, IBS and other symptoms.”
    I’ve even found one case study recently that describes a patient who maintained remission from idiopathic anaphylaxis(extreme mast cell activation of unknown cause) as long as her B-cells were depleted! Isn’t that interesting considering rituximab’s efficacy in CFS?

    • Cort Johnson

      July 6, 2017 at 3:30 pm - Reply

      Fluge and Mella are going to pop the code on the big Rituximab trial in Oct I think it is – and we should know sometime next year.

  • Thomas

    July 5, 2017 at 11:15 pm - Reply

    One small detail: You wrote: «a small community in Norway».
    That «small community was Bergen, one of the biggest cities in Norway (at that time I suppose approx 250.000) However ir was an outbreak in the center of Bergen.

    • Cort Johnson

      July 6, 2017 at 4:00 am - Reply

      Definitely not a small city! I don’t know where I got that from and will change that.

  • weyland

    July 6, 2017 at 10:47 am - Reply

    I’ve yet to see a convincing argument for how an intestinal-only parasite could cause encephalomyelitis of the brain. My bet is that giardia is a red herring in these outbreak cases. What it indicates is sewage contamination of potable water supplies. The Bergen outbreak was linked to a sewage spill into the water supply. The Placerville outbreak was also linked to water supply quality issues. There was a sewage spill at an Incline Village pump station very near the time of the outbreaks there. If you get sewage in your water, you’re not going to just get giardia, you’re going to also get a heavy concentration of enteroviruses which are already confirmed to cause myalgic encephalomyelitis. I’ve read the case reports for the Bergen outbreak and they never even tested the patients for enteroviruses. Giardia is what stood out to them because it’s easily recovered from stool and it’s not endemic to Norway so it was probably introduced into the sewage and then water by foreign visitors.

    • Cort Johnson

      July 6, 2017 at 3:28 pm - Reply

      Thanks. I had heard that there may have been a problem with water at Incline. Then its possible that an enterovirus infection was present but never resolved (are there any drugs for it?; does anyone ever test for them) or that it triggered some process which results in ME/CFS.

      • strawberry

        July 7, 2017 at 9:04 pm - Reply

        Thank you both weyland and Cort! If that info is true, it could be the reasoning behind my illness also. I have been ill basically since my daughter’s birth (22 years) and I had to give a “stool sample” late term pregnancy due to a water main break and contamination. I don’t remember being treated for parasites, but I can’t remember much that long ago. Thanks for the memory flash back. I will add that to my timeline!

        • Cort Johnson

          July 8, 2017 at 4:15 pm - Reply

          Thanks Strawberry and good luck!

  • Carl

    July 6, 2017 at 3:55 pm - Reply

    I’d like to suggest a fourth hypothesis. I know three people including myself that have ME/CFS. I contracted mine after Hep C and the others after Lyme disease. What all three of us as well as the giardia patients have in common is that we were all treated with high potency antibiotics for an extended periods. In my case, my doctor initially misdiagnosed me with a stubborn sinus infection and treated me with a strong antibiotic for 6 months. In addition to ME/CFS, I and my two friends also have SIBO. It’s possible that the antibiotics killed off our good bacteria and now we have candida and bacterial overgrowths that are causing all sorts of immune and physiological problems. My energy improves after taking antifungals and antibiotics followed by probiotic and prebiotic supplements. Unfortunately in my case, SIBO tends to return after several months regardless of continued diet and supplements for gut health. I am homozygous for SNP variants for MTHFR C677T, CBS, and MAO A and perhaps those SNP variants impair my ability to maintain healthy gut flora. A few practitioners have made this hypothesis in their web sites, but without much supporting research. What’s interesting to me is that I cannot tolerate any form of folate or B12 and only small doses of Co-Q10. I have tried Dr. Ben’s recommendations for preventing methylfolate side effects without success. D-ribose and NADH are the only supplements that improve my energy. Further study would be appreciated. Thanks.

    • Cort Johnson

      July 6, 2017 at 6:36 pm - Reply

      What an interesting story you have Carl. Have you checked out Dr. Siebecker’s site? She has herbal approaches to SIBO…Check out these blogs for more.

      Cheaper, Safer, Better: the Herbal Approach To Small Intestinal Bacterial Overgrowth –

      • Carl

        July 6, 2017 at 7:03 pm - Reply

        Thanks for the suggestion, Cort. However, I started out with an herbal and diet approach to SIBO for 6 months without any improvement. Perhaps a complicating factor for me is that after the 6-month antibiotic treatment, I had Nissan Fundoplication to treat the real problem of GERD. Laparoscopic operations, including Nissen Fundoplication, have been linked to stubborn cases of SIBO possibly due to adhesions. P.S. I also have had no detectable Hep C for the last 15 years and recent extensive lab tests have shown no elevated immune system response. Although my doctor is familiar with genetic SNP problems and SIBO, he’s baffled by the fact that small doses (200 mcg/week for a couple of weeks) of methylfolate have doubled the severity of my CFS over the past 6 months. Moderate exercise used to lessen my fatigue, whereas since I took a few doses of methyfolate, moderate exercise just crushes me. Other supplements recommended by Dr. Ben have either worsened my CFS or have had no effect. My next step is to focus on my SIBO. Thanks for the suggestion.

        • Laurajnyc

          July 27, 2017 at 6:05 am - Reply

          Carl, I had the same experience with methylfolate. No matter how small I started, it was awful. Like it hollowed out my mood and remaining energy. Activated b6, b2 and tyrosine helped repair my mood.

    • Issie

      July 8, 2017 at 9:29 am - Reply

      I have MTHFR and other methylation issues too. My doc says that unless you have high homocysteine levels, your probably don’t need to supplement to with folate as your body would be compensating for the mutation. I had to stay off folate for 2 weeks before having it checked and it’s perfectly normal. I had trouble trying to take the supplement to too.


  • Cort Johnson

    July 6, 2017 at 7:08 pm - Reply

    Phil emailed me this. He said I could pass it on

    “I have FM, not CFS (although I was certainly terribly fatigued a lot of the time) but I certainly suffered a Giardia infection episode at about the right time to have major explanatory power for everything that followed.

    I refilled my water bottle when on a mountain-bike ride, from a stream that at the time was not known to be contaminated. It would have been recorded that I had contracted Giardia under these circumstances, and I noticed a few years later in the media, that public warnings were being issued about that stream.

    I wonder if this can be fitted in to my hypothesis that FM (in my case and most people’s case) is the result of a metabolic or renal system dysfunction that fails to clear toxins (both external toxins and post-exertion toxins), that end up lingering in the myofascial ground substance and making muscle fibres “stick” in low-level contracted positions. Plus adjacent bands of muscle fibre at complex junctions of multiple muscles, stick against each other resulting in “pinching” pains.

    I still suggest that a Giardia infection is one factor among two or more factors that unlucky people happened to experience at the same time. Maybe one of the factors is hereditary. There must be an explanation why most members of the population get exposed to the same things and don’t get CFS or FM.

    In my case, a Cadmium toxic-level exposure must have occurred at a similar time, plus high job stress. I do say that muscles tensed all day under stressful conditions, are far more likely to end up with the “sticky” dysfunctions I am describing.

    I wish researchers would stop wasting resources on looking for “central nervous system” dysfunctions as the cause of FM. The CNS dysfunction is obviously going to be present in anyone who has been suffering prolonged actual physical pain, and it is obvious that this is where the CNS dysfunction originates in people with FM. Not in the CNS itself, but in the existence of actual physical pain. Massage therapists have been able to feel the abnormalities in the muscles all along. I think it is the height of arrogance for medical “experts” to be still writing the condition off as a “head” issue. “Cognitive Behavioural Therapy” as “treatment” is about as unjust as the way soldiers with shell-shock were sometimes treated 100 years ago (“lack of moral fibre”, etc).

  • Issie

    July 8, 2017 at 9:47 am - Reply

    I recently have had the complete workup protocol of Shoemaker and have all the markers for CIRS. One of the treatments I was put on – believe it or not – is used to kill Giardia and it is also used as an antiviral. It’s called Alinia. It’s very expensive and cheapest I could find in the states was to have it compounded. Which was good idea because I didn’t like some other the fillers that is in the original medicine. The plan is 3 to 6 months on it. She also gave me supplements for babesia and herbals for possible yeast. Having had a toxic mold exposure and also finding a type mold/fungus in a thyroid biopsy that is similar to Valley Fever – there is also treatment for that. We must be on the right track because the herxing is with me now. I take that as a good sign.

    One thing I learned that I didn’t know is folate and fish oil feeds mold. Magnesium, calcium help to build biofilm. So I had to do some supplement adjustments and cut out things I was using. I’m no worse for leaving them off.

    She also had me raise the headboard my bed. I always slept with pillows under me to get my head up. She didn’t want that as it causes you to bend at the waist. That interferes with circulation. So we got some wooden risers to raise the head of the bed. It does seem to be helping my circulation and I don’t wake up with a headache.


  • zzz

    July 10, 2017 at 9:55 am - Reply

    Well, this sounds like me, all right. I spent two years in Nepal and India from 1988 to 1990, where I got a number of giardia infections that were cleared up by antibiotics. However, within four months of returning to the U.S., I came down with full-blown ME/CFS. Neither giardia or even general GI symptoms were present at the time.

    It wasn’t until 2006 – 16 years later – that I started getting what appeared to be a recurrence of my giardia symptoms, which were like nothing else I had experienced, and therefore easily identified. A standard one-day treatment of tinidazole got rid of the symptoms completely, but only for a day. Subsequent treatments had no effect.

    Tests for giardia turned up negative, so my infectious disease doctor declared that I had IBS, and that I should learn to live with it. He refused to prescribe antibiotics. I didn’t believe him, and instead found antibiotic treatments for refractory giardiasis (albendazole plus either tinidazole or azithromycin) which I used over the next 18 months to eradicate my symptoms. These symptoms have not returned, thought the heavy doses of antibiotics have had some unrelated long lasting side effects.

    So based on my experience, I vote for “The Sneaky Pathogen theory”, even though none of my doctors believe such a thing was possible. And I have no doubt that giardia can be a potent trigger for ME/CFS.

    For the record, I knew plenty of other people who had spent substantial periods of time in Nepal and India, invariably getting giardia somewhere along the way, and a large proportion of these people eventually developed ME/CFS.

    • Cort Johnson

      July 12, 2017 at 2:57 pm - Reply

      Fascinating zzz, I had giardia a couple of years before I got ill and tested positive for it later…

    • Christian S

      July 14, 2017 at 5:14 pm - Reply

      My current issues stem from a trip to India, though I have a suspicion that my anti malarial drug and an herbal anti bacterial regimen after I got home have contributed to my symptom progression. That being said, I have had Giardia from local hiking trips and no long lasting effects , except perhaps subsurface changes in gut makeup. I think the India trip was, for me, a confluence of multiple factors that contributed to overall severity. I am currently working on trying to detox from heavy metals , in case that Is a contributing factor. The gut issues are far more complex and will require likely a more comprehensive approach…

  • Laurajnyc

    July 27, 2017 at 6:24 am - Reply

    Great article. I absolutely believe I have a resident infection somewhere. Probably in the gut as I think my SIBO antibiotics tipped me into CFS.
    Also Dr. Galland’s website says he is located 2 blocks away from me! Will call tomorrow.

  • Aidan

    January 16, 2018 at 11:50 am - Reply

    I have now seen countless patients diagnosed with ME/CFS IBS Fibro EDS MACS test Positive to (GAD) Antibodies for (SPS) Stiff Person Syndrome & what Dr. Peterson mentioned he tested countless for Giardia & they were Negative. On water supply, a friend of mine is an Engineer in water supply Company apparently the entire water table under Philadelphia is contaminated with Radiation from Japan & they put chemicals in the water but it does nothing…Giardia is not any Cause that is certain

  • Owen

    August 13, 2019 at 12:42 pm - Reply

    Hi Zzz are you able to expand on the protocol you used when treating yourself using albendazole and azithromycin? I am convinced I have a giardia type infection and want to explore treatment using these two drugs. Any help is much appreciated. Thanks, Owen