parasite posteruegw
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Dientamoeba fragilis and Blastocystis: Two parasites the irritable bowel might be missing
A population-based follow-up study of subjects with and without gastrointestinal symptomsKrogsgaard LR1, Engsbro AL 1, 2, Stensvold CR3, Nielsen HV3, Bytzer P1
1: Department of Medicine, Section of Gastroenterology, Køge Sygehus. 2: Department of Microbiology, Hvidovre Hospital, 3: Unit of Mycology and Parasitology, Statens Serum Institut
Introduction Several studies have demonstrated that the parasites D. fragilis and
Blastocystis are frequently found in patients with irritable bowel syndrome
(IBS) and suggests that those infested might by misdiagnosed with IBS.
However, previous studies have all lacked a well-defined asymptomatic control
group and the pathogenecity of the parasites is still not settled. We
hypothesised that intestinal parasites may be associated with symptoms of IBS
and studied this in a prospective follow-up study.
Results In 2010, stool samples were analyzed from 328 subjects.
Intestinal parasites were found in 44,5% (n=146) of all. Subjects with IBS were
significantly less likely to harbor parasites than the asymptomatic background
population (figure 2). Harboring parasites was not associated with gender. D.
fragilis was found in 30,1% of all subjects; significantly more prevalent in controls
compared to IBS subjects (figure 2). Blastocystis was found in 18,9% of all subjects
and more often in controls (figure 2).
Conclusion
In an asymptomatic adult background population 50% harbor intestinal parasites,
this is significantly more compared to subjects with IBS symptoms. Harboring D.
fragilis or Blastocystis does not influence the development or disappearance of IBS
symptoms over 1 year. Further studies will contribute to clarify their role, if any, in
IBS symptom development over a longer period of time.
Methodology In 2010, members of a web-panel, representative of the Danish population
aged 18-49 years (females 50%), were invited by e-mail to fill out a
questionnaire. 6.112 responded to the questionnaire based on the Rome III
criteria for IBS.
Stool samples were requested from 499 subjects. Two consecutive stool
samples were tested for parasites (microscopy, culture for Blastocystis and
real-time PCR for D. fragilis, Cryptosporidium spp., Entamoeba histolytica and
dispar and G. intestinalis).
The questionnaire was repeated after 1 year in responders from the first
survey. Stool sampling were requested once again from those giving samples
sin 2010.
In 2011, follow-up was completed in 275/328 (83,8%) subjects, who gave stool
samples in 2010 (106 IBS subjects and 169 controls). In both IBS subjects and
controls there were no significant differences in development of GI symptoms over
1 year between those with and without parasites (p>0,1), nor when analyzed for D.
fragilis or Blastocystis separately ( se figure 3 and 4) .
Webpanel: 19.567 Responders: 6.112
Asked for stool
samples: 499• 201 IBS
• 298 controls
Stool samples
collected from: 328• 124 IBS
• 204 controls
Figure 1. Flow chart
Figure 3. Symptom development over 1 year according to Dientamoeba fragilis (DF) status 2010. Bars show symptom status in 2011.
Contact: Laura Rindom Krogsgaard. Email: [email protected]
DF positive DF negative
62 56
27 26
12 18
Symptoms of IBS in 2010
Continously IBSUnspecific GI symptomsAsymptomatic
p> 0,1
DF positive DF negative0%
20%40%60%80%
100%
68 62
27 32
5 6
Asymptomatic in 2010
Continously asymptomaticUnspecific GI symptomsIBS
p> 0,1
Dientamoeba fragilis Blastocystis0
10
20
30
40
50
60
35.5
23.4
14.5
50
34.8
22
IBS Controls%
p=0,01
p=0,03
p=0,09
Figure 2. Prevalence of intestinal parasites in IBS subjects and controls
All parasites B positive B negative0%
20%40%60%80%
100%
60 65
35 29
5 6
Asymptomatic in 2010
Continously asymptomaticUnspecific GI symptomsIBS
p> 0,1
B positive B negative
67 56
2028
13 17
Symptoms of IBS in 2010
Continously IBSUnspecific GI symptomsAsymptomatic
p> 0,1
Figure 4. Symptom development over 1 year according to Blastocystis (B) status 2010. Bars show symptom status in 2011.