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. 2019 Jul;24(29):1800546.
doi: 10.2807/1560-7917.ES.2019.24.29.1800546.

Dientamoeba fragilis - the most common intestinal protozoan in the Helsinki Metropolitan Area, Finland, 2007 to 2017

Jukka-Pekka Pietilä  1 , Taru Meri  2 , Heli Siikamäki  1 , Elisabet Tyyni  3 , Anne-Marie Kerttula  3 , Laura Pakarinen  1 , T Sakari Jokiranta  4   5 , Anu Kantele  1   6
Affiliations

Dientamoeba fragilis - the most common intestinal protozoan in the Helsinki Metropolitan Area, Finland, 2007 to 2017

Jukka-Pekka Pietilä et al. Euro Surveill. 2019 Jul.

Abstract

BackgroundDespite the global distribution of the intestinal protozoan Dientamoeba fragilis, its clinical picture remains unclear. This results from underdiagnosis: microscopic screening methods either lack sensitivity (wet preparation) or fail to reveal Dientamoeba (formalin-fixed sample).AimIn a retrospective study setting, we characterised the clinical picture of dientamoebiasis and compared it with giardiasis. In addition, we evaluated an improved approach to formalin-fixed samples for suitability in Dientamoeba diagnostics.MethodsThis study comprised four parts: (i) a descriptive part scrutinising rates of Dientamoeba findings; (ii) a methodological part analysing an approach to detect Dientamoeba-like structures in formalin samples; (iii) a clinical part comparing demographics and symptoms between patients with dientamoebiasis (n = 352) and giardiasis (n = 272), and (iv) a therapeutic part (n = 89 patients) investigating correlation between faecal eradication and clinical improvement.ResultsThe rate of Dientamoeba findings increased 20-fold after introducing criteria for Dientamoeba-like structures in formalin-fixed samples (88.9% sensitivity and 83.3% specificity). A further increase was seen after implementing faecal PCR. Compared with patients with giardiasis, the symptoms in the Dientamoeba group lasted longer and more often included abdominal pain, cramping, faecal urgency and loose rather than watery stools. Resolved symptoms correlated with successful faecal eradication (p < 0.001).ConclusionsPreviously underdiagnosed, Dientamoeba has become the most frequently recorded pathogenic enteroparasite in Finland. This presumably results from improved diagnostics with either PCR or detection of Dientamoeba-like structures in formalin-fixed samples, an approach applicable also in resource-poor settings. Symptoms of dientamoebiasis differ slightly from those of giardiasis; patients with distressing symptoms require treatment.

Keywords: Dientamoeba fragilis; Giardia; dientamoebiasis; intestinal; parasite; protozoan.

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Conflict of interest statement

Conflict of interest: None declared.

Figures

Figure 1
Figure 1
Annual numbers of new Dientamoeba and Giardia findings and number of faecal samples investigated at HUSLAB, Helsinki, Finland 2007–2017 (n = 189,723 samples)
Figure 2
Figure 2
Study design for a retrospective investigation of patients with positive stool findings of Dientamoeba and Giardia, Helsinki Metropolitan Area, Finland, 2007–2012 (n = 624)
Figure 3
Figure 3
Identification of Dientamoeba fragilis from formalin-fixed faecal samples, Helsinki Metropolitan Area, Finland, March 2015 (n = 8)
See this image and copyright information in PMC

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