Transport and survival of Cryptosporidium Parvum Oocysts in Soil Columns Following Applications of Raw and Separated Liquid Slurry

The widespread waterborne pathogen Cryptosporidium parvum is primarily transmitted to humans via contaminated drinking and recreational water. Nearly all drinking water in Denmark is groundwater, but this can be contaminated with oocysts from application of contaminated manure to the field. Oocysts transport to groundwater requires that the oocysts are transported through soil and bedrock to the water table. The purpose of this study was to determine the potential transport of the protozoan pathogen C. parvum through soil to land drains and, subsequently water courses in a laboratory setup using simulated rainfall and six 20 cm long replicate intact soil columns. Two types of contaminated slurry, namely raw slurry and the separated liquid fraction of the slurry were applied ten cm into the soil, following irrigation once a week over a four week period. C. parvum oocysts were detected in the leachates from soil columns to which Cryptosporidium positive slurry had been injected. Although recovery rates were low, regardless of slurry type, C. parvum oocysts were detected from all soil columns. Variations in the leachate patterns were recorded between soil columns added raw and liquid slurry respectively with significantly more oocysts in leachate from the latter. At the end of the study soil columns were destructively sampled to establish the location of remaining oocysts within the soil. Distribution within the soil was almost similar in all the soil columns, with the majority of oocysts found in the first section were the slurry was applied and with numbers decreasing with increasing depth.