Pathogens• Ways livestock agriculture may increase pathogens

in the environment– Indirect effects on water– Direct contamination in water

• Drinking

• Irrigation

– Antibiotic resistance in microorganisms– Direct contamination in air

• Indirect effects on pathogens in water– Effect Blooms of toxic algaeExcess N Pfiesteria piscidida Toxinsor P (Red tides in marine Contact causes environments) confusion, memory loss and gastrointestinal problems Cyanobacteria Toxins (called blue-green algae Can kill livestock in fresh water)– Control

• Reduction of N and P excretion and losses during storage and application

• Direct pathogen contamination of water– Major microorganisms of concern Effects (Particularly severe in very young, elderly, or individuals with compromised immunity)

• Protozoa Cryptosporidium parvum Severe diarrhea, vomiting Giardia fatigue, dehydration• Bacteria E. Coli O157:H7 Bloody diarrhea, dehydration, kidney failure• Viruses Bovine rotavirus Diarrhea

Bovine coronavirus– Number of cases

US Outbreaks (1989-96)

Drinking water Recreational water Surface Ground Natural Pool Cryptosporidium parvum 4 4 2 11 Giardia 12 6 4 5 E. Coli O157:H7 0 3 7 1

– Reasons for problems these organisms• The organisms or their reproductive forms are shed by

infected animals in large numbers• The organisms survive and remain infectious in the

environment for long periods– Some are resistant to water treatment

• E. Coli O157:H7 can multiply outside the host if adequate nutrition

• Low dose needed for infection• Wide range of animal hosts

– Other potentially harmful bacteria in the environment• Campylobacter• Listeria monocytogenes• Salmonella• Mycobacterium paratuberculosis

– Causes Johne’s Disease– Association with Crohn’s disease in humans

– Risk is largely unknown• Most studies on water

quality have demonstrated that poor manure management increases fecal coliforms in water supplies

• Relationship between fecal coliforms and pathogens has not been established

• Difficult to separate contamination from humans, domestic animals and wild animals

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• Pathogenic organisms– Cryptosporidium parvum

• Life cycle (1 – 8 days) Oocysts consumed by host animal (Contain 4 sporozoites)

Sporozoites released in intestine

Sporozoites invade intestinal cells and reproduce in cells

New sporozoites invade new cells Oocysts released in feces Damage intestinal cells

Severe diarrhea• Oocysts in 39 to 87% of US surface waters

• Hosts– Species

» Humans» Domestic livestock (Cattle, sheep, goats, swine,

horses)» Companion animals (Dogs, cats)» Wildlife (Mice, Raccoons)

– Age» Calves 50% of calves shed oocysts between 1-3 weeks Few shed in cattle > 6 months» Swine Shed oocysts during nursing and weanling stages» Foals Shed oocysts up to 19 weeks» Sheep Adult ewes will shed oocysts around lambing

• Viability characteristics– Resistant to most public water treatments– Very susceptible to drying

» 2 hours of dryness is lethal– Very susceptible to high temperatures

» >100oF– Susceptible to freezing temperatures

» Freezing for 10 days reduced viability by 90%– Susceptible to pH>9.0

» Public water treatment plants often treat water to pH 12.0– Oocysts remain in upper soil unless transported to ground

water with macropore flow

– Giardia• Life cycle (7-9 days) Cysts ingested (Contain trophozoites)

Trophozoites attach to Severe upper small intestine diarrhea

Produce cysts

Cysts released Cysts release more in feces trophozoites• Cysts are present in most surface waters• Hosts

– Species» All mammals, some birds, reptiles, and amphibians

– Age» Occurs at all ages, but most common in animals that are

less than 6 months• Viability characteristics

– Similar to Cryptosporidium• No evidence of human infection from domestic livestock

– Escherichia Coli O157:H7• A potentially deadly bacteria

– Causes bloody disease, dehydration and kidney failure– Particularly hazardous to young, elderly, and compromised

immune systems– Infection can occur with as few as 10 cells

• Life cycle– E. Coli O157 is consumed from water troughs or moist rations

» Can survive in water trough for 4 months– E. Coli only present in cattle for 1 to 2 months

» More frequent in cattle fed high grain dietsFeeding forage at the end of

finishing will decrease numbersRole of distillers grains???

» More common in summer than winter» More frequent in cattle that are 3 – 18 months old than

mature cows» More frequent in large herds

– Excreted in feces as viable bacteria– Capable of multiplying in the environment

» Dependent on nutrients » Usually decrease over time

• Viability– E. Coli O157:H7 are killed by chlorine, high

temperature, drying, aerobic storage

• At this time, few cases of direct human infection through water– Contamination of spinach believed to occur from

irrigation water with a feedlot ½ mile away» E. Coli may be transported by flow, adhesion of

soil particles or motility.

• Factors affecting extent of pathogen problem– Size of loading dose

• Percentage of herd infected• Frequency on manure addition to storage• Amount of dilution

– Length of storage– Manure treatment

• Anerobic > Aerobic > Compost– Storage characteristics

• Aerobic/anerobic• Drying• Temperature• Freeze/thaw• pH• Nutrients• Inhibitors

– Form of organisms excreted• Cysts or oocysts > vegetative forms

– Routes of pathogen contamination• Run-off from bare lots• Direct deposit in pastures or lots• Run-off from manure application

– Vegetation on land application• Tall forage reduces run-off

– Prevents microorganisms from reaching water sources• Tall forage provides shade and moisture

– Increases survivability– Soil of land application area

• Organic or clay soils trap protozoa and bacteria• E. Coli can move rapidly through saturated soils or soils with

macropores

• Control of pathogen transport from livestock units– Prevent import of pathogen onto farm

• Feed feedstuffs not contaminated with feces from rodents or other livestock– Prevent infestation of rodents or other wild or domestic

animals in feed storage areas– Purchase feeds from sources that prevent fecal

contamination of feedstuffs• Provide water sources with low risk of pathogen

contamination– Keep livestock out of streams and ponds

» Provide alternate water sources– Divert precipitation run-off from livestock facilities

• Purchase livestock from sources with good health management– Avoid purchases from sales barns– Separate and quarantine new animals

• Avoid transport of manure onto farm– Have visitors wear plastic boots– Thoroughly clean tires on vehicles

– Prevent amplification and proliferation of organisms on farm• Frequent cleaning and drying of housing units

– Particularly maternity areas• Use separate implements for feeding and cleaning• Frequent cleaning of equipment

– Tires and blades• Provide feed and water free of fecal contamination from

livestock, pets, rodents, wildlife, and humans• No feeding of wasted adult feed to young livestock• Segregate calves by age

– Prevent contact of calves < 3 months with older cattle• Prevent run-off from entering or leaving areas housing young

animals– Limiting pathogen proliferation during manure storage

• Store manure from animals less than 6 months separate from mature animals and spread on non-hydrologically sensitive areas– If calf manure can’t be stored in area that restricts leaching

or run-off, mix it with manure from mature cattle and apply by Best Management Practices (Dilutes organisms)

• Composting at 140oF will kill most pathogenic organisms and cysts

– Prevention of pathogen contamination by manure application• Application methods

– Incorporation into the soil» Particularly effective during wet weather» Reduces risk of contamination of water sources by: Adsorption of organisms to soil particles Filtration of organisms Attack by predator organisms Freeze-thaw activity

– Surface application» Effective in dry weather» Reduces risk by: Drying UV light

• Hydrologic considerations– Avoid manure application in major water flow paths– Should consider:

» Soil permeability» Slope steepness» Flood plains» Flow paths

• Grassland manure application considerations– Manure should be stored for at least 60 days– Manure should be applied at least 30 days before grazing– Grass should be short when manure is applied– Pastures fertilized with manure should only be grazed by

mature animals– Preventing export of pathogens from farm

• Control run-off from livestock facilities– Particularly facilities housing young animals– Place cow winter feeding areas away from streams

• Utilize buffer strips– Grass strips lining sides of streams or ponds– Width

» > 4.5 m from field with manure application» > 10 – 20 m from animal feeding operations

– Effective as part of a group of Best Management Practices» Should not be relied on as only practice

• Proper grazing management– Use of rotational grazing

» More uniform distribution of manure– Avoid over-grazing– Limit or prevent access of water bodies to animals

• Release of antibiotic resistant microorganisms into the environment– Numerous antibiotics fed at subtherapeutic levels

to promote growth and feed efficiency• Chlortetracycline, Oxytetracycline, Penicillin, Bacitracin,

Tylosin

– Actions• Prevent subclinical disease• Increases nutrient absorption• Improves metabolic processes

– Increases rate of protein synthesis

– Problem• Selection of organisms that are resistant to antibiotics

– Concern for penicillin, tetracyclines, and erythromycin

• Organisms released from non-sealed lagoons and from surface-applied manure

– Recommend• Proper use of antibiotics

– Don’t use antibiotics as a substitute for good management

– Rotate antibiotics used on operation

• Proper manure storage– No run-off or leakage

• Proper manure application– Minimize run-off

• Direct contamination of the air– Endotoxin• Lipopolysaccharide component of the cell wall

of gram-negative bacteria• Problem in confinements, not in outside

environment• Health effects on works in confinement

buildings– Cough– Chest tightness– Headache– Fever– Flu-like symptoms

• Control dust control measures