Occurrence and potential health risk of Cryptosporidium and Giardia in different water catchments in Belgium.

Human wastewater and livestock can contribute to contamination of surface water with Cryptosporidium and Giardia. In countries where a substantial proportion of drinking water is produced from surface water, e.g., Belgium, this poses a constant threat on drinking water safety. Our objective was to monitor the presence of Cryptosporidium and Giardia in different water catchment sites in Belgium and to discriminate between (oo)cysts from human or animal origin using genotyping. Monthly samples were collected from raw water and purified drinking water at four catchment sites. Cryptosporidium and Giardia were detected using USEPA method 1623 and positive samples were genotyped. No contamination was found in purified water at any site. In three catchments, only low numbers of (oo)cysts were recovered from raw water samples (<1/liter), but raw water samples from one catchment site were frequently contaminated with Giardia (92 %) and Cryptosporidium (96 %), especially in winter and spring. Genotyping of Giardia in 38 water samples identified the presence of Giardia duodenalis assemblage AI, AII, BIV, BIV-like, and E. Cryptosporidium andersoni, Cryptosporidium suis, Cryptosporidium horse genotype, Cryptosporidium parvum, and Cryptosporidium hominis were detected. The genotyping results suggest that agriculture may be a more important source of surface water contamination than human waste in this catchment. In catchment sites with contaminated surface water, such as the Blankaart, continuous monitoring of treated water for the presence of Cryptosporidium and Giardia would be justified and (point) sources of surface water contamination should be identified.

Giardia muris infection in mice is associated with a protective interleukin 17A response and induction of peroxisome proliferator-activated receptor alpha.

The protozoan parasite Giardia duodenalis (Giardia lamblia) is one of the most commonly found intestinal pathogens in mammals, including humans. In the current study, a Giardia muris-mouse model was used to analyze cytokine transcription patterns and histological changes in intestinal tissue at different time points during infection in C57BL/6 mice. Since earlier work revealed the upregulation of peroxisome proliferator-activated receptors (PPARs) in Giardia-infected calves, a second aim was to investigate the potential activation of PPARs in the intestines of infected mice. The most important observation in all mice was a strong upregulation of il17a starting around 1 week postinfection. The significance of interleukin 17A (IL-17A) in orchestrating a protective immune response was further demonstrated in an infection trial or experiment using IL-17 receptor A (IL-17RA) knockout (KO) mice: whereas in wild-type (WT) mice, cyst secretion dropped significantly after 3 weeks of infection, the IL-17RA KO mice were unable to clear the infection. Analysis of the intestinal response further indicated peroxisome proliferator-activated receptor alpha (PPARα) induction soon after the initial contact with the parasite, as characterized by the transcriptional upregulation of ppara itself and several downstream target genes such as pltp and cpt1. Overall, PPARα did not seem to have any influence on the immune response against G. muris, since PPARα KO animals expressed il-17a and could clear the infection similar to WT controls. In conclusion, this study shows for the first time the importance of IL-17 production in the clearance of a G. muris infection together with an early induction of PPARα. The effect of the latter, however, is still unclear.