manure-borne pathogens: impact of animal agriculture on microbial water quality jeanette a....
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Manure-borne Pathogens:Impact of Animal Agriculture on Microbial Water Quality
Jeanette A. Thurston-Enriquez
USDA-ARS
Public Health and Animal Waste
• Animal waste agents – Infectious
• bacteria, viruses, protozoa
– Chemical • nutrients, endocrine disrupters, antimicrobials
Manure-borne Pathogens of Concern
Antibiotic Resistant Bacteria
Protozoan Parasites Pathogenic Bacteria
Viruses
Fungi
In order to determine the human health impact of
manure-borne pathogens we need to evaluate:
• Occurrence• Survival/Persistence• Dissemination/
Transport
Manure, Manure Management Systems, & Surrounding
Environment: Water, Air, Soil
Other Health-Related Microorganisms
• Fecal Indicator Microorganisms– What?
• Traditionally, bacteria of fecal origin
– Total and fecal coliforms– Escherichia coli
– Why?• Indicators of fecal contamination• Recreational and drinking water
quality regulations• Faster, cheaper, easier detection
Waterborne Disease in the U.S.
• 12-20 outbreaks/yr– 10-100 x higher
• ~900,000 cases of waterborne microbial infections
• Up to 900 deaths• >70% in >55 yrs
RUNOFF RUNOFF
Contamination Routes
Well head impacts
Urban and storm waterWWTP
overflowSeptic tankleakage
Agriculture
Recreation
Wildlife
Groundwater
Infiltrationpercolation Discharge
Manure Dissemination
• Land application• Aerosol generation• Leakage or overflow from storage
lagoons or treatment ponds• Runoff from feed yards, manure-
applied land, pasture land, etc.
Holding Pond
Surface Water
Groundwater
Runoff and Aerosol Deposition
Manure storage
Manure Land Application
Well head impacts
Outbreak Source: Animal Ag.
Walkerton, 2001– Land-applied cattle manure– Agricultural runoff to groundwater
supply– Escherichia coli O157:H7 &
Campylobacter– >2000 cases– 7 fatalities
Contributing Factors for Environmental Persistence and
Transmission ofEnteric Pathogens
• High numbers shed in feces• Increased survival• Low infectious dose• Increased resistance to
disinfection/treatment• Multiple routes of
transmission• Animal and human infections
Potential Routes of Human Exposure to
Pathogens– Waterborne
• Drinking and recreational water– Foodborne (can be related to waterborne)
• Direct contact, irrigation water, ingestion of contaminated produce
– Direct Contact– Aerosol Transmission
• Transport to water supplies or food crops• Inhalation of aerosols • Contact
Possible Pathogen Transmission by
Aerosols• Direct transmission or deposition
onto food crops, fomites, or water
Livestock Spray IrrigationBiosolids Land
Application
Barriers Against Waterborne Disease• Drinking water and wastewater
treatment– Disinfection & Filtration
• Surface water monitoring/Source water protection
• Point-of-use devices—disinfect/filter
• Protection of recreational waters•Contaminant monitoring•Designation of specific uses
Limiting Microbial Transport:Aerosols
• Top spray vs. drop spray• Keep tractor speed low; scrape moist soil• Low wind speed • Wind direction
Pen scrapingLand application
Microbial Reduction Prior to Land Application:
Constructed Wetlands
• Alternative waste management and treatment technology• Bacterial reduction: >80 % (prior to plant establishment)• Protozoan parasite reduction: >60 % (prior to plant
establishment)
Manure-borne Pathogen Information Gaps
• Environmental Loading
• Environmental Fate
• Treatment Effectiveness
• Alternative Treatments/Tech.
• Detection Methods– Viability– Sensitivity– Specificity
• Emerging Pathogens• **Risk Assessments
– Requires above information