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Questions arising from research priorities related to pathogen vectors and pathways.

 
Research priority Research questions
1.1. Pathogen fates: barren vs. vegetated systems. Vegetated zones capture and infiltrate more coliforms than bare soils, but how do different soil, pathogen, and vegetation types contribute to pathogen capture and infiltration (Roodsari et al., 2005) and can this reduce ground water quality (Thiagarajan et al., 2007)?
1.2. Pathogen pathways: crop production, harvesting, packing. Survival, treatment, and cross-contamination issues during packing have been characterized (Coetzer, 2006; Fonseca, 2006), but how do specific cultivar types, conditions, growth stages, pathogen densities, and soil textures, affect pathogen uptake or surface adherence (Solomon et al., 2006)?
1.3. Pathogen persistence: growing and harvested crop. Though most available data are derived from controlled environments, E. coli O157:H7 appear able to survive from seedling stage to harvest under field conditions (Islam et al., 2004). How can the total influence of the many separate variables associated with field conditions best be applied to predict pathogen survival (Delaquis et al., 2007)? Are there agronomic practices that can improve sanitizer efficiencies post-harvest (Fonseca, 2006)?
1.4. Pathogen vectors: large and small animals. Genetic fingerprinting can be used to track specific pathogen strains through different species (Liebana et al., 2003) and to identify sources of fecal contamination (Graves et al., 2007; Jiang et al., 2007; Meays et al., 2004; Somarelli et al., 2007). How significant are specific factors affecting the transmission of existing and emerging diseases through wildlife, livestock (Daszak et al., 2007; Gortazar et al., 2007), insects (Conn et al., 2007), and gastropods (Sproston et al., 2006)? How important or effective are rodent and reptile controls (Beuchat, 2006; Meerburg and Kijlstra, 2007)? Can habitat removal concentrate wildlife to an extent that promotes zoonotic diseases (Daszak et al., 2000)?
1.5. Pathogen fate: storm flows, floods, impoundments. Now that genetic fingerprinting can be used to trace movement of specific pathogen strains in water (Cooley et al., 2007) and to quantify risk models (Ferguson et al., 2003), how do mass-balance and kinetics data for specific pathogens compare to those of indicator organisms, which have received more study (Ferguson et al., 2003; Pachepsky et al., 2006)?
1.6. E. coli O157:H7: influence of animal husbandry techniques. Sound husbandry helps control zoonoses (Collins and Wall, 2004). How valid are simulation results suggesting that, used together, vaccinations, probiotics, modified diets, and hygiene improvements substantially reduce E. coli O157:H7 (Vosough Ahmadi et al., 2007).
1.7. Pathogen development and export: range management strategies. E. coli and fecal coliforms can grow in fresh manure and survive longer under cool, shaded conditions (Meays et al., 2005; Van Kessel et al., 2007). Many water quality management practices (MPs) for range management are similar to those used for crops and similarly need work to quantify their effectiveness with respect to both pathogens and indicator organisms (Agouridis et al., 2005; Knox et al., 2007; Oliver et al., 2007). Also, can manure deposit patterns (Tate et al., 2003) be managed to reduce pathogen exports?



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Questions arising from research priorities related to mitigation and management practices.

 
Research priority Research questions
2.1. Pathogens fates: after capture with management practices (MPs). A broadly stated priority. See Priorities 1.1, 1.4, 1.5, 2.2, and 2.4. Also, what is the likely fate of pathogens excreted within MPs by fauna that are visiting or inhabiting them? Can MP choices apply evolutionary pressures to pathogens that increase their persistence and their virulence (Walther and Ewald, 2004)?
2.2. Pathogens in sediments: growth and survival factors. Sediments can protect and nourish certain pathogens, including E. coli O157:H7, and later release them to surface and ground water (Crabill et al., 1999; Gagliardi and Karns, 2000; Jamieson et al., 2004 To what extent can the parameters that determine the growth or survival of pathogens be quantified?
2.3. Pathogens in sediments: assessment for landspreading E. coli may adapt to become native soil organisms (Ishii et al., 2006). What is the potential for pathogens to similarly adapt to inhabit sediments? How will sediment properties affect the export potential of sequestered pathogens (Guber et al., 2007; Kay et al., 2007)? Can tests and risk assessment approaches that consider pathogens in water or biosolids be adapted to determine when sediments are safe to use (Gale, 2005; Keeling et al., 2007; Shuval et al., 1997; Westrell et al., 2004)?
2.4. Pathogens in tailwater: assessment for irrigation. Water reuse guidelines call for undetectable levels of viable pathogens in irrigation water applied to fresh vegetables, but what information is needed as to the presence and variability of human pathogens in tailwater to develop a risk-based approach for determining when or how testing should be conducted (Hamilton et al., 2006; Mena, 2006; USEPA and U.S. AID, 2004)? How should standards be adjusted to account for different irrigation methods (Bernstein et al., 2007; Bihn and Gravani, 2006)?
2.5. Irrigation water treatment. What biological or energetic treatment methods, such as wetlands and ultraviolet radiation, are most practical and cost efficient for co-management (Berry et al., 2007; Hill, 2003; Karim et al., 2004)? What technologies are currently in use (Mena, 2006)?
2.6. Pathogens in manures and composts. What manure properties, such as pH or fiber content, may contribute to pathogen persistence (Franz et al., 2005)? How much time is needed between a manure applications and harvests under specific management conditions (Bihn and Gravani, 2006)? Composting inactivates pathogens (Larney et al., 2003), but what industry quality control standards are needed to assure proper heating and avoid cross-contamination (Wichuk and McCartney, 2007)?