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Title: Transport, Fate, and Infectivity of Cryptosporidium parvum Oocysts Released from Manure and Leached through Macroporous Soil

Author
item Boyer, Douglas
item KUCZYNSKA, EWA - FRMRLY ARS VISITING SY
item Fayer, Ronald

Submitted to: Environmental Geology and Water Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/25/2008
Publication Date: 8/17/2009
Citation: Boyer, D.G., Kuczynska, E., Fayer, R. 2009. Transport, Fate, and Infectivity of Cryptosporidium parvum Oocysts Released from Manure and Leached through Macroporous Soil. Environmental Geology and Water Sciences. 58(5):1011-1019.

Interpretive Summary: A major mode of transmission of Cryptosporidium parvum, a widespread waterborne pathogen, is via contaminated drinking and recreational waters. Cryptosporidium transport to surface water can occur by deposition of manure directly in the water or by wash off in surface runoff. Cryptosporidium transport to groundwater is less straightforward and requires that oocysts move through soil and bedrock to reach the water table. The purpose of this study was to determine the relative concentration and infectivity of Cryptosporidium released from manure and leached through columns of undisturbed, macroporous soil common to the central Appalachian karst and recovered in drainage water. Modeling the fate of oocysts in this system over time can provide baseline data for evaluating real world events. Twenty to thirty percent of oocysts released from manure leached to the bottoms of undisturbed soil columns. Less than 5 percent of released oocysts leached to the bottom of disturbed soil columns. Cryptosporidium survival studies using mice showed that about 85 percent of Cryptosporidium were infective at the beginning of leaching experiments. The infectivity decreased to about 20 percent after twelve weeks of leaching from soil columns maintained at 10 degrees C. This study demonstrated that leaching is an important mechanism of oocyst transport in soils where infiltration capacities are high and long, continuous macropores exist.

Technical Abstract: A major mode of transmission of Cryptosporidium parvum, a widespread waterborne pathogen, is via contaminated drinking and recreational waters. Oocyst transport to surface water can occur by deposition of manure directly in the water or by wash off in surface runoff. Oocyst transport to groundwater is less straightforward and requires that oocysts move through soil and bedrock to reach the water table. The purpose of this study was to determine the relative concentration and infectivity of C. parvum oocysts released from manure and leached through columns of undisturbed, macroporous soil common to the central Appalachian karst and recovered in drainage water. Modeling the fate of oocysts in this system over time can provide baseline data for evaluating real world events. Twenty to thirty percent of oocysts released from manure leached to the bottoms of undisturbed soil columns. Less than 5 percent of released oocysts leached to the bottom of disturbed soil columns. Oocyst survival studies using BALB/c neonatal suckling mice showed that about 85 percent of oocysts were infective at the beginning of leaching experiments. The oocyst infectivity decreased to about 20 percent after twelve weeks of leaching from soil columns maintained at 10 degrees C. This study demonstrated that leaching is an important mechanism of oocyst transport in soils where infiltration capacities are high and long, continuous macropores exist. Cool (10 degrees) temperatures appear to increase survivability and maintain infectivity of many oocysts for three months or longer. Cool temperatures also appear to increase rates of release of oocysts from manure and leaching through soil. However, it is unclear if the temperature effect is related to decomposition of oocysts or to attachment/detachment processes.