Environmentally Transmitted Pathogens

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Environmentally Transmitted Pathogens
Jeanette Thurston-Enriquez
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To Take Away

• Waterborne outbreaks not only impact human health
  but also the economy
• Ag runoff from manured land can carry human
  enteric pathogens
• Pathogenic bacteria are not the ONLY threats
• Should not only be concerned with DW
  suppliesrecreational, irrigation, shellfish
  harvesting
• Commonly applied bacterial indicators may not
  reflect human health threats

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Waterborne Disease in the U.S.

• lt20 drinking and recreational water outbreaks/yr
• estimated to be 10-100 x higher

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Water Sources That Can Be Threatened By
Waterborne Pathogens
Recreational
Irrigation
Drinking
Seafood
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Etiological Agents of Waterborne Disease,
United States, 1991-2000
Drinking Water
gt425,000 illnesses 1993, Milwaukee, 403,000
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Drinking Water Outbreaks

• Milwaukee, 1993
• Municipal wastewater contamination of surface
  water
• Cryptosporidium parvum
• gt400,000 cases, 4400 hospitalizations
• gt50 fatalities
• Walkerton, 2001
• Agricultural runoff to groundwater supply
• Escherichia coli O157H7 Campylobacter
• gt2000 cases
• 7 fatalities

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Etiological Agents of Waterborne Disease,
United States, 1991-2000
Recreational Outbreaks Surface Water
gt4500 illnesses
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Recreational Water Outbreaks

• Cryptosporidium and pools/spas
• Naegleria in ponds, puddles, lakes
• Usually fatal
• Pathogenic bacteria in freshwater (E. coli
  O157H7, Shigella, etc)
• 1991-2000
• 19 outbreaks/yr
• 1689 illnesses/yr

• 1999
• Clark County, Washington
• Lake
• E. coli O157H7
• 1041 cases, 65 hospitalized
• no fatalities

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Foodborne Outbreaks Associated with Contaminated
Water

• Fresh Produce
• 1996, Cyclospora, Guatemala/multi-state
• Raspberries
• Contaminated irrigation water suspected as
  pathogen source
• gt1400 illnesses
• Ice
• 1999, Norwalk virus, Anchorage AK
• Contaminated water used to make ice
• 400 illnesses, 1 fatality

• Shellfish
• 1991, China, Hepatitis A
• Fecal pollution of clam harvesting water
• gt290,000 illnesses
• Food Processing
• 1990, S. Carolina/multi-state, Salmonella
• Tomatoes
• Contamination of water bath used by packer
• 174 illnesses

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Costs of Contaminated Water

• Medical Expenses
• Time lost from work/Loss of productivity
• Miscellaneous supplies
• Legal expenses
• Changes in current practices
• Water municipalitiestreatment
• Individual consumer changes-POUs
• Loss of consumer confidence

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Enteric vs. Non-Enteric Pathogens Implicated in
Waterborne Disease Outbreaks 1991-2000
Recreational/Surface Water
Drinking water
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Examples of Enteric Pathogens that Threaten
Water Supplies
Bacteria
Protozoan Parasites
Campylobacter
Cryptosporidium
Shigella
Giardia
Escherichia coli
Salmonella
Enteric Viruses
Noroviruses
Emerging Pathogens
Enteroviruses
Microsporidia
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Enteric Pathogen Illness

• Fecal-oral route
• Wide range of disease
• Diarrhea to respiratory disease, paralysis,
  encephalitis, hepatitis
• Usually mild and self-limiting
• Medical attention not usually sought
• Severe illness in some cases
• Economic Costs
• Mild disease 280
• Severe disease 8000

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Enteric PathogensContributing Factors for
Environmental Persistence and Transmission

• High numbers shed in feces
• Increased survival
• Low infectious dose
• Increased resistance to disinfection/treatment
• Multiple routes of transmission
• Animal and human infections

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Microbiological Water Quality AssessmentIndicato
r Microorganisms

• Drinking water
• Total coliforms
• lt5 positive (presence/absence)
• E. coli
• zero

• Recreational water
• Primary contact (bathing beaches)
• E. coli 126 CFU/100ml
• Secondary Contact
• 2o 5X 1o contact standards

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Criteria for Ideal Indicators

• useful for all water types
• present whenever pathogen present
• longer survival than hardiest pathogen
• no multiplication in water
• easy and low cost detection method
• be a member of the intestinal micro flora of warm
  blooded animals
• relationship between indicator and degree of
  fecal pollution

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Deficiencies in Use of Microbial Indicators

• Indicator absence ? pathogen absence
• Indicator presence ? pathogen presence
• Regrowth in aquatic environments
• Regrowth in distribution systems
• Suppression by high background bacterial growth
• Not indicative of a health threat
• No relationship between enteric viruses or
  protozoan pathogens

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Failure of Water Testing Indicator
Microorganisms

• 35 of gastrointestinal illness was estimated to
  be attributable to the consumption of drinking
  water meeting current water quality standards
• (Payment et al., 1991)
• Outbreaks
• Drinking water Milwaukee (indicators absent)
  (1993)
• Recreational water E. coli O157H7 (indicators
  did not exceed stds) (1999)

Escherichia coli
Enterococci
Fecal coliforms
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Barriers Against Waterborne Disease

• Drinking water and wastewater treatment
• Disinfection
• Filtration
• Water testing
• Surface water monitoring/Source water protection
• Point-of-use devicesdisinfect/filter
• Disinfectant use in recreational water (pool and
  spa)

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Conclusions Impact of Pathogens in Water

• Human and Animal Health ? Economy
• Many Pathogen and Water Sources (human,
  livestock, wildlife, domestic animals)
• Water and food supplies
• Multiple routes for pathogen transmission
  dissemination
• Water Quality Assessment has not been a reliable
  indication of a disease threat

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Information Gaps Needs

• METHODOLOGIES
• Viable/infectious, detection, enumeration
• PATHOGEN FATE AND SURVIVAL
• Established emerging pathogens
• Appropriate indicators
• Environment treatment
• INDICATOR MICROORGANISMS
• Relationship to human health risk?
• Established emerging pathogens

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Information Gaps Needs

• WATER TREATMENT
• Efficacy vulnerabilities
• LIVESTOCK MANAGEMENT PRACTICES
• Pathogen transport to water
• Pathogen reduction by manure management practices
• LOW-COST REDUCTION STRATEGIES
• Manure management, surface water protection,
  water treatment alternatives, emergency relief
  efforts, etc.
• RISK ASSESSMENTS