Prevalence of Intestinal Parasitoses in a Non-Endemic Setting during a 10-Year Period (2011–2020): A Focus on Dientamoeba fragilis

Abstract

Dientamoeba fragilis is a cosmopolitan and neglected protozoan. Although little is known concerning its pathogenicity and its true prevalence worldwide, its role as enteric pathogen is emerging, as the occurrence of dientamoebiasis has increased also in industrialised countries. This study investigated the occurrence and prevalence of intestinal parasites, focusing on D. fragilis in a 10-year period (2011–2020) in a single tertiary-care hospital located in Northern Italy. A statistical evaluation of the correlation between dientamoebiasis and specific signs other than gastrointestinal-related ones was performed. The laboratory diagnosis was performed on 16,275 cases of suspected intestinal parasitoses. Intestinal parasites were detected in 3254 cases, 606 of which were associated to D. fragilis, which represented 18.6% (606/3254) of all the intestinal parasitoses with a 3.7% (606/16,275) prevalence and an increasing trend during the last five years (2011–2015: 2.8% vs. 2016–2020: 4.8%). D. fragilis was commonly detected in foreigners, especially those from developing countries, as well as in children; prevalence was equal in males and females. With regard to the clinical aspect, the only putative sign statistically related to dientamoebiasis was anal pruritus. Despite the controversial epidemiological knowledges on dientamoebiasis, the prevalence of D. fragilis found in this study highlights the need to consider this parasite in any differential diagnosis of gastrointestinal disease.

Food and Drinking Water as Sources of Pathogenic Protozoans: An Update

“…The lack of reports for D. fragilis and P. hominis reflects the poorly defined pathogenicity of these species so further investigation into the occurrence of symptomatic cases after the consumption of contaminated food or water should be considered [21,284,286].…”

“…Most studies on this protozoan parasite were conducted in industrialized countries and prevalence values ranged between 0.3% and 82.9%. The few studies available for developing countries reported prevalence values between 0% and 60.6% [39,284]. Spreading by the fecal-oral route is most likely though zoonotic transmission was also suggested since D. fragilis was detected in pigs, cats, and dogs [21].…”

“…Recently, a cyst stage was discovered and its transmission and association of the protozoan with symptomatic disease was shown in a rat model [285]. Acquisition together with pinworms (Enterobius vermicularis) was also suggested [284]. The advent of PCR methods to replace microscopy methods which do not allow a definitive diagnosis determined an apparent increase in D. fragilis prevalence and the proportion of asymptomatic carriage, ranging between 11% and 39%, raised doubts on its pathogenicity [21].…”

A Cross-Sectional Study on the Occurrence of the Intestinal Protist, Dientamoeba fragilis, in the Gut-Healthy Volunteers and Their Animals

“…Our results show a prevalence of 24% in gut-healthy people in different age groups, which is slightly lower than in the above-mentioned studies. Interestingly, a ten-year study conducted at the University Hospital of Parma demonstrated an almost comparable prevalence of D. fragilis (i.e., 20%) in patients with gastrointestinal symptoms [ 3 ]. Following data from patient cohorts and healthy subjects, the incidence of D. fragilis seems to be more or less comparable.…”

“…Dientamoeba fragilis is a human intestinal protist with cosmopolitan distribution and prevalence ranging from 0.2% to 82% (reviewed in [ 1 , 2 , 3 ]). Most studies addressing its occurrence are from high-income countries and surprisingly, less is known from low-income countries [ 1 , 2 , 4 ].…”