# Presentation: 346622

## Investigating Disease Outbreaks Associated with AFOsFocus: Waterborne Exposures

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

## Linking Exposure and Illness  

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

## Slide 3

## 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.

## Important limitations when reviewing waterborne outbreak data

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

## Disease Pyramid

## 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

## 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

## Zoonotic Waterborne Outbreaks Reported, 1971-2000

|  | Percent of outbreaks |
| --- | --- |
| Drinking Water | 49% (n=189) |
| Untreated Recreational Water  | 79% (n=43) |

**Notes:**

	51% of the reported waterborne outbreaks resulted in gastroenteritis of undetermined etiology. Of the outbreaks of known etiology, slightly less than half of the drinking water outbreaks and more than three-quarters of the outbreaks associated with untreated recreational water were caused by zoonotic pathogens.

## 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.

**Notes:**
	Current EPA regulations have reduced drinking water outbreaks of giardiasis and cryptosporidiosis. Since 1991, drinking water outbreaks of cryptosporidiosis decreased by more than half while untreated recreational water outbreaks increased by three-fold. 
	N. flowleri, a naturally occurring environment protozoan, caused most of the outbreaks in untreated recreational waters.

## Waterborne Outbreaks Zoonotic Bacteria 

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

**Notes:**
	Zoonotic bacteria caused fewer outbreaks than zoonotic protozoa.

## 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

## 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

## 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

## Contamination Sources

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

## 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