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Water: Unregulated Contaminant Monitoring Program

Aeromonas detection: what does it mean?

1. What is Aeromonas?
2. Where do Aeromonas come from?
3. Do Aeromonas cause human disease?
4. Who can get Aeromonas infections?
5. What is EPA doing about Aeromonas?
6. How do Aeromonas get into the distrution system?
7. What do I do now? Does my utility have to report this information to the consumers?


1. What is Aeromonas?
Aeromonas
is a genus of bacteria that is ubiquitous in the environment. It is present in all types of water worldwide as well as food and soil. There are approximately 16 different species in this genus, the best known of which is Aeromonas hydrophila. Physiologically, Aeromonas are similar to bacteria in the coliform group and can be isolated from similar environments.

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2. Where do Aeromonas come from?
Aeromonas
are commonly isolated from a variety of aquatic environments, including freshwater, estuarine, brackish, and salt waters. Aeromonas is a normal part of the microflora found in these waters, and its presence does not indicate the water has been polluted. These organisms have also been isolated from a variety of foods, including red meats (beef, pork, lamb), poultry, produce, fish, and shellfish.

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3. Do Aeromonas cause human disease?
Some members of this group of bacteria have been implicated in human disease, although not all strains appear to be pathogenic to humans. Aeromonas infections are typically acquired through two routes, either through ingestion or through exposure of open wounds. The primary clinical diseases from Aeromonas infections are gastroenteritis and bacterial septicemia. Aeromonas-related gastroenteritis is generally a self-limiting watery diarrhea lasting a few days to a few weeks. In individuals with weakened or impaired immune systems, this diarrhea can be chronic and severe (meaning a significant loss of water from the body.) Aeromonas septicemia (a serious condition where bacteria are present throughout the body) generally occurs from wound infections or from gastroenteritis in individuals with weakened immune systems. Aeromonas infections are treatable with antibiotics.

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4. Who can get Aeromonas infections?
It appears that all people are susceptible to gastroenteritis caused by Aeromonas, although it is most frequently observed in young children (under 5 years of age) and older adults (over 60 years of age). People with compromised immune systems and individuals suffering from leukemia, carcinoma, diabetes, hepatitis, and cirrhosis or those being treated with immunosuppressive drugs or who are undergoing cancer chemotherapy may be susceptible to systemic infections caused by Aeromonas.

The Centers for Disease Control and Prevention (CDC) states that the frequency of Aeromonas infections in the United States is unknown and that most cases have been sporadic, individual cases rather than associated with large outbreaks.

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5. What is EPA doing about Aeromonas?
Because these bacteria are common in natural waters and because it is generally accepted that some strains of Aeromonas can be pathogenic to humans, the U.S. EPA conducted occurrence monitoring for Aeromonas bacteria in selected drinking water utilities in 2003. Currently, the U.S. EPA is evaluating the data received from this monitoring and is identifying the species of Aeromonas isolated throughout this monitoring period. This information will be used in a risk assessment evaluation to determine whether Aeromonas bacteria should be proposed for regulation in drinking water.

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6. How do Aeromonas get into the distribution system?
As stated above, Aeromonas occur naturally in freshwaters. Such waters are frequently used as raw sources for treated drinking water. In general, Aeromonas bacteria are killed by the levels of chlorine disinfection used in water treatment facilities. Aeromonas associated with particles in raw waters may evade treatment/disinfection and so enter a distribution system in this manner. A break in a distribution system pipe may also allow untreated water/sewage to enter a system. Once in the system the bacteria may find environments conducive to their survival, especially when temperature and nutrient levels are elevated and when chlorine residuals are low (e.g. in the remote parts of the distribution system and in biofilm material on the inside of pipes).

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7. What do I do now? Does my utility have to report this information to the consumers?
YES. The Consumer Confidence Report (CCR) Rule requires community water systems (CWSs) to report unregulated contaminant monitoring results whenever such contaminants are detected. If your public water system (PWS) has not had any detections, no CCR reporting requirements apply, but Public Notification (PN) Rule requirements, declaring that the data are available, must still be met (see last paragraph below).

The CCR is an annual drinking water quality report that gives PWS customers fundamental information about their drinking water. The centerpiece of the CCR is a table displaying the levels of detected contaminants, including unregulated contaminants, in finished water. For each detected unregulated contaminant, including Aeromonas, the table must display the average of any monitoring results from the year and the range of detections. A PWS may briefly explain in the CCR why it is monitoring for unregulated contaminants. The explanation may read as follows: 


Unregulated contaminants are those for which EPA has not established drinking water standards. The purpose of unregulated contaminant monitoring is to assist EPA in determining the occurrence of unregulated contaminants in drinking water and whether future regulation is warranted.

EPA has published both a guidance document developed the CCRwriter and CCRiWriter, software to help water suppliers create their consumer confidence reports.

In addition to CCR requirements, PWSs must also meet the requirements of the Public Notification (PN) Rule. This regulation applies to all PWSs, and requires those PWSs that are subject to the UCMR to notify the public that unregulated contaminant monitoring results are available. EPA's Public Notification Handbook provides instructions and includes templates that water suppliers can use for various types of public notices.

For more information: (ALL ABOUT PDF FILES) Exit EPA Disclaimer

For questions, please contact:
Dan Hautman
U.S. Environmental Protection Agency
Office of Ground Water and Drinking Water
Technical Support Center
26 West Martin Luther King Dr, MS-140
Cincinnati, Ohio 45268
(513) 569-7274

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