Occurrence and removal efficiency of parasitic protozoa in Swedish wastewater treatment plants
Journal article, 2017

Giardia intestinalis, Cryptosporidium spp., Entamoeba histolytica and Dientamoeba fragilis are parasitic protozoa and causative agents of gastroenteritis in humans. G. intestinalis and Cryptosporidium spp. in particular are the most common protozoa associated with waterborne outbreaks in high-income countries. Surveillance of protozoan prevalence in wastewater and evaluation of wastewater treatment removal efficiencies of protozoan pathogens is therefore imperative for assessment of human health risk. In this study, influent and effluent wastewater samples from three wastewater treatment plants in Sweden were collected over nearly one year and assessed for prevalence of parasitic protozoa. Quantitative real-time PCR using primers specific for the selected protozoa Cryptosporidium spp., G. intestinalis, E. histolytica, Entamoeba dispar and D. fragilis was used for protozoan DNA detection and assessment of wastewater treatment removal efficiencies. Occurrence of G. intestinalis, E. dispar and D. fragilis DNA was assessed in both influent (44, 30 and 39 out of 51 samples respectively) and effluent wastewater (14, 9 and 33 out of 51 samples respectively) in all three wastewater treatment plants. Mean removal efficiencies of G. intestinalis, E. dispar and D. fragilis DNA quantities, based on all three wastewater treatment plants studied varied between 67 and 87%, 37–75% and 20–34% respectively. Neither E. histolytica nor Cryptosporidium spp. were detected in any samples. Overall, higher quantities of protozoan DNA were observed from February to June 2012. The high prevalence of protozoa in influent wastewater indicates the need for continued monitoring of these pathogens in wastewater-associated aquatic environments to minimise the potential risk for human infection.


Parasitic contamination



Removal efficiency


Björn Berglund

Linköping University

O. Dienus

County Hospital Ryhov

Ekaterina Sokolova

Chalmers, Civil and Environmental Engineering, Water Environment Technology

Emma Berglind

County Hospital Ryhov

Andreas Matussek

County Hospital Ryhov

Karolinska University Hospital

Thomas Pettersson

Chalmers, Civil and Environmental Engineering, Water Environment Technology

Per Eric Lindgren

County Hospital Ryhov

Linköping University

Science of the Total Environment

0048-9697 (ISSN) 1879-1026 (eISSN)

Vol. 598 821-827

Subject Categories

Infectious Medicine

Water Treatment

Environmental Sciences



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