triggered/perpetuated by many different pathogens much the same way as
the common cold or hepatitis. Or the problem, as acknowledge by the
authors, could lie in the immune system where there is an uncommon
reaction to common pathogens. Although the symptom of chronic fatigue
is referred to throughout the paper, the reference section lists
chronic fatigue syndrome studies so apparently the authors are using
two different terms to mean the same thing.
They also used the Chalder Fatigue Scale which has been shown to have
a ceiling effect where pathological fatigue is not measured. However,
the researchers acknowledged the need to include severity as a
variable saying in part, "We also
designed two categories of more serious fatigue. =E2=80=98Severe fatigue=E2=
=80=99 was
de=EF=AC=81ned as the combination of chronic fatigue and a total fatigue sc=
ore
of of greater than or equal to a score of 23, and =E2=80=98consistent fatig=
ue=E2=80=99
as chronic fatigue combined with fatigue present at least 75% of the
time.
They also acknowledged the need for subgroups in both CFS and IBS as well.
Infectious Diseases
Nearly Half of Giardiasis Patients Report Fatigue or IBS at 3 Years
By: JENNIE SMITH, Internal Medicine News Digital Network
People exposed to the protozoan Giardia lamblia are at increased risk
of having irritable bowel syndrome and chronic fatigue years after
their gastrointestinal infections have been treated, a team of
Norwegian researchers has found.
Although other types of acute gastrointestinal infections have been
associated with ongoing disorders including both fatigue and irritable
bowel syndrome (IBS), the finding challenges the assumption that acute
giardiasis, once treated, does not cause long-term complications.
Among a cohort of people who became ill during a 2004 outbreak of
giardiasis in the Norwegian city of Bergen, nearly half reported
having chronic fatigue, IBS, or both 3 years later. Prescription data
from the time of the outbreak, which was traced to a contaminated
reservoir, suggested that the vast majority of those affected had been
treated with metronidazole. Giardiasis is not endemic in Norway.
For their research, published online Sept. 12 in the journal Gut
(doi:10.1136/gutjnl-2011-300220), Dr. Knut-Arne Wensaas of the
University of Bergen and Uni Health in Bergen, and his colleagues,
collected data using validated questionnaires from 817 patients who
had laboratory-confirmed G. lamblia infection in 2004, and 1,128 age-
and sex-matched controls (mean age, 36; about 66% female) not infected
in that outbreak.
Of the exposed cases, 46.1% reported IBS at 3 years, compared with 14%
in the control group, for a relative risk of 3.4 (95% CI, 2.9-3.8)
after adjustment for potential confounding factors. The same
percentage =E2=80=93 46.1% =E2=80=93 of the exposed group reported chronic =
fatigue,
compared with 12% of controls (adjusted RR, 4.0; 95% CI, 3.5-4.5).
Despite the study=E2=80=99s observational design, the association between
prior infection and the two disorders was seen as so strong, Dr.
Wensaas said in an interview, that "it suggests a causal relationship"
that warrants further investigation.
In the exposed group, 62.6% of those with IBS had chronic fatigue, as
did 30.6% of those without IBS, compared with 32% and 9% for controls.
That the two disorders, IBS and chronic fatigue, were found to occur
together more frequently among those with previous giardiasis
suggested that there could be commonalities in the pathogenesis of
giardiasis, IBS, and chronic fatigue. One possible link, the
researchers hypothesized, is an immune response involving T
lymphocytes.
While a majority of cases were women, sex was not seen as an effect
modifier for IBS or for chronic fatigue. The prevalence of IBS was
higher among women than men in both the exposed group (48.9% vs.
40.8%) and the control group (15.9% vs. 10.4%).
The authors noted that their definition of IBS was based on the Rome
III criteria: "recurrent abdominal pain or discomfort at least 3 days
a month in the past 3 months and associated with at least two of three
criteria related to defecation (onset associated with a change in
frequency or form of stool, or improvement with defecation)."
Dr. Wensaas said that the idea for the study came in part from his and
his colleagues=E2=80=99 clinical observations treating patients in Bergen i=
n
the years following the outbreak. A previous study, by another
research team, had also looked at the same outbreak and outcomes at a
2-year end point (Trans. R. Soc. Trop. Med. Hyg. 2009;103:530-2).
Dr. Wensaas, a general practitioner, said that not only had a large
number of patients presented with fatigue and/or IBS following their
giardiasis infections, but that they continued to have these symptoms
well past the 3-year end point of the study, suggesting that the
effects could continue even longer. Dr. Wensaas pointed to one
Canadian study that found an elevated risk for IBS at 8 years after
acute bacterial gastroenteritis (Gut 2010;59:605-11).
The investigators acknowledged as a weakness of their study the
potential for selection bias inherent in its observational design and
use of questionnaires. "There is a possibility that those having had
acute giardiasis will be more aware of symptoms and more likely to
find them abnormal than the controls, and thus report more
complaints," they wrote, noting also that the city of Bergen had
originally compensated those affected by the outbreak, potentially
encouraging exaggerated complaints.
An additional weakness reported was that chronic giardiasis could not
be ruled out among respondents.
Dr. Wensaas and his colleagues received funding for their study from
the city of Bergen and the Norwegian Medical Association=E2=80=99s Funds fo=
r
Research in General Practice; none of the study authors said they had
relevant financial disclosures.
The full study can be found here:
http://press.psprings.co.uk/gut/september/gut300220.pdf
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