Reprinted with the kind permission of Simmaron Research 
By Cort Johnson
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.
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 ?nally 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).
The Giardia ‘Syndrome’ Strikes: Norwegian Studies Suggest ‘Minor Bugs’ May Commonly Trigger Chronic Fatigue Syndrome As Well 
“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.)
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.
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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.
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.