Investigating Disease Outbreaks Associated with AFOs Focus: Waterborne Exposures

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Investigating Disease Outbreaks Associated with
AFOsFocus Waterborne Exposures

• Gunther Craun, Gunther F. Craun Associates,
  Staunton, VA
• Rebecca Calderon, National Health and
  Environmental Effects Research Laboratory, EPA,
  RTP, NC

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Linking Exposure and Illness

• Epidemiologic methods are well established and
  available
• Outbreaks
• Endemic Illness

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Waterborne Outbreak Data

• Waterborne outbreak surveillance since 1971 by
  EPA and CDC
• Information can help identify problems that may
  need regulation or changes in monitoring and
  current operational practices.

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Important limitations when reviewing waterborne
outbreak data

• Outbreaks voluntarily reported
• Not all Waterborne outbreaks are recognized
• good surveillance is needed to detect an
  outbreak

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Disease Pyramid
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Important limitations continued

• Not all waterborne outbreaks are thoroughly
  investigated
• The primary objective of the investigation is to
  determine why people are becoming ill and how to
  stop the illness

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Important limitations continued

• Thorough investigation requires a
  multidisciplinary investigation team
• epidemiologists, engineers, microbiologists,
  laboratory capabilities
• should investigate sources of contamination as
  well as water system deficiencies

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Zoonotic Waterborne Outbreaks Reported, 1971-2000
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Protozoan Waterborne Outbreaks

• Giardia or Cryptosporidium caused most outbreaks
  of identified etiology in community water
  systems.
• N. fowleri, Schistosomatidae, Giardia, and
  Cryptosporidium were identified in untreated
  recreational water outbreaks.

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Waterborne Outbreaks Zoonotic Bacteria

• Campylobacter, Salmonella, E. coli, and Yersinia
  caused outbreaks in drinking water
  systemsprimarily in groundwater systems.
• E. coli 0157H7 and 0121H19 and Leptospira
  caused almost half of the outbreaks associated
  with untreated recreational water.

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Contamination Sources

• Most WBDO investigations focused on specific
  events (e.g., heavy rains or surface water entry
  into wells seepage of sewage) and water
  treatment deficiencies (e.g., interruption of
  disinfection) that may have been responsible for
  the outbreak

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Contamination Sources

• several outbreak investigations noted that the
  likely source of water contamination was wild or
  domestic animals including cattle and pigs
• Information was not available in the reports to
  determine whether AFOs contributed to water
  contamination

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Contamination Sources

• drinking water outbreaks of zoonotic agents were
  also associated with
• sewage and surface water entering groundwater
  sources
• contamination of distribution system piping and
  storage

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Contamination Sources

• recreational water outbreaks were also associated
  with
• poor bather hygiene and septic tank discharges

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What is Needed to Assess Outbreak Risks
Associated with AFOs

• Better surveillance to detect possible outbreaks
• More complete investigations of sources of
  contamination
• Improved laboratory capabilities to provide
  information about additional zoonotic agents and
  possible animal sources