Knowledge and Know-How Acquisition for an Efficient Risk Assessment of Waterborne Pathogens in the Drinking Water of Luxembourg - KAWA

Coordinating Institution: CRP Gabriel Lippmann
Contracting Partner(s): Administration de la Gestion de l'Eau
Other Partner(s): UniversIty Louis Pasteur Strasbourg (F)
From: 01/07/2005
To: 31/08/2008
Budget: 848,716.00€
Contact(s): Cauchie Henry-Michel

Progress Summary 2008

The KAWA project aimed to acquire new knowledge and develop innovative know-how to perform an adequate risk assessment on the major non-bacterial pathogens in the drinking water of Luxembourg. Viruses, parasitic protozoa and toxic cyanobacteria were chosen as target pathogens on the basis of their frequent occurrence, their pathogenicity at low doses and the gap of knowledge concerning them compared to bacteria. The last eight months of the projects were dedicated to the monitoring of enteroviruses, Giardia and Cryptosporidium (oo)cysts in some strategic water resources in Luxembourg. Results confirmed the presence of both parasites in the reservoir of Esch-sur-Sûre, especially during the winter period. After statistic correlation tests, E.coli appeared to be a reliable indicator for Giardia and Cryptosporidium. No (oo)cyst could be detected in the treated water (Plant outlet). A detailed spatio-temporal analysis of the parasite dynamics in the reservoirs of the Upper Sûre and in the main contributing rivers has been carried out from February to August 2008. This study highlighted large variations in the occurrence of parasites as a function of the chosen sampling programme. Parasite density can present a ten-fold variation at one sampling across three days. This is in relation to the rains that wash parasite from surrounding soils during rainy events. Moreover, parasites appeared to be preferentially located at 2 meters depth. This depth most probably corresponds to the position where the survival of the (oo)cysts is the highest. Higher in the water column, ultraviolet radiation decreases certainly the viability of (oo)cysts. A good correlation has also been observed spatially between the parasite density and the density of Escherichia coli and intestinal enterococci, confirming the possible use of these microbial parameters as indicators of parasite contamination in reservoirs.

The data acquired in 2008 were used to define a PhD thesis that will focus on the definition of a procedure to determine the optimal sampling of parasites in surface waters. This PhD thesis has started in January 2009. On the other hand, the protocol for the simultaneous concentration of parasites and viruses from large volumes of water has been validated and applied to various groundwaters in Luxembourg and in France. This protocol combines a filtration of the water on a pleated membrane with a porosity of 1 µm, an ultrafiltration on PES membranes with a cut-off of 30 kDa and an ultracentrifugation at 45,000 g. It allowed the detection of viruses and pathogens at very low densities.

Refereed Scientific Publications:
  • Helmi K., S. Skraber, C. Gantzer, R. Willame, L. Hoffmann & H.M. Cauchie (2008) – Interactions of Cryptosporidium parvum, Giardia lamblia, vaccinal poliovirus type 1, and bacteriophages ΦX174 and MS2 with a drinking water biofilm and a wastewater biofilm. Applied and Environmental Microbiology 74 (7): 2079-2088.
  • Willame R., I. Thys, V. Jacquet, M. Berbanck, H.M. Cauchie & L. Hoffmann (2008) – Environmental variables involved in the development of bloom-forming cyanobacteria in a meso-eutrophic reservoir. Algological Studies 126: 227-247.
Project Website:

Figure 1: Sampling of large water volumes (> 100 litres) for the determination of the density of pathogenic parasites in the Esch-sur-Sûre reservoir

Figure 2: Ultrafiltration device alowing the concentration of large volumes of drinking water (> 1,000 litres) for the monitoring of pathogenic viruses