Pathogens

1
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

2

• Indirect effects on pathogens in water
• Effect
• Blooms of toxic
  algae
• Excess N Pfiesteria piscidida
  Toxins
• or 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

3

• 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 O157H7
  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

4

• 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 O157H7 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 Johnes Disease
• Association with Crohns disease in humans

5

• 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

6

• 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

7

• 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 gt 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

8

• Viability characteristics
• Resistant to most public water treatments
• Very susceptible to drying
• 2 hours of dryness is lethal
• Very susceptible to high temperatures
• gt100oF
• Susceptible to freezing temperatures
• Freezing for 10 days reduced viability by 90
• Susceptible to pHgt9.0
• Public water treatment plants often treat water
  to pH 12.0
• Oocysts remain in upper soil unless transported
  to ground water with macropore flow

9

• 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

10

• Escherichia Coli O157H7
• 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 diets
• Feeding forage at the end of finishing will
  decrease numbers
• Role 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

11

• Viability
• E. Coli O157H7 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.

12

• 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 gt Aerobic gt Compost
• Storage characteristics
• Aerobic/anerobic
• Drying
• Temperature
• Freeze/thaw
• pH
• Nutrients
• Inhibitors
• Form of organisms excreted
• Cysts or oocysts gt vegetative forms
• Routes of pathogen contamination

13

• 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

14

• 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

15

• 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 lt 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 cant 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

16

• 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

17

• 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
• gt 4.5 m from field with manure application
• gt 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

18

• 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

19

• Recommend
• Proper use of antibiotics
• Dont 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

20

• 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