Digitally Detecting Waterborne Illnesses

By Marguerite Huber

Toxoplasma gondii oocysts

Toxoplasma gondii oocysts

The smaller something is, the harder it is to find. Just try finding a needle in a haystack, or low concentrations of pathogens such as Toxoplasma gondii (T. gondii) and Cryptosporidium in drinking water. These two human pathogens are the leading causes of protozoan waterborne illnesses (toxoplasmosis and cryptosporidiosis), so they are something the drinking water industries are working hard to monitor.

To understand exposure risks associated with T. gondii and Cryptosporidium, sensitive and accurate detection and clinical diagnostic tools must be in place. The lack of such tools make environmental monitoring for these parasites challenging.

One of the biggest issues with monitoring human pathogens is that if it is environmentally transmitted (such as through drinking water), its concentrations can be very low, making it difficult to detect with current water monitoring practices.

EPA researchers have recognized that detection is the biggest challenge. They are working to help bring current methods–which rely on a technique known as polymerase chain reaction (PCR) that amplifies genetic material (DNA) for further analysis—into the digital age. They have designed software to assess the performance and detection limits of digital PCR (dPCR) to accurately quantify low concentration levels of T. gondii and Cryptosporidium.

Dr. Eric Villegas, a scientist working on the project explains, “Digital PCR can perform up to a million reactions in the same amount of time that standard techniques take, improving how we model the detection of waterborne pathogens.”

This capability of dPCR offers a whole new set of opportunities, including greater statistical power to detect if the pathogen is present and, if so, to determine its concentration. “The software that we developed assesses the quality of the data collected and determines the concentration of pathogens with high precision and accuracy,” researcher Dr. Scott Keely, explains. Ultimately, this approach will provide additional sensitivity for quick and accurate diagnosis of parasite infections.

Overall, this research will detect pathogens better and faster than existing methods, which will allow policymakers, drinking water utilities, and managers to scrutinize available data, analyze it with confidence, and learn what type of data to collect in the future. Most importantly, it will help minimize any health risk related to drinking and recreational water quality by providing decision-makers with methods and tools that decrease the amount of time to reach decisions regarding the management of water bodies or other sources of drinking water where these pathogens are of potential concern.

About the Author: Marguerite Huber is a Student Contractor with EPA’s Science Communications Team.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

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Concentrated Effort, Universal Need

Potomac River BasinNearly 6 million people live in the drainage area of the Potomac River which stretches 14,670 square miles across four states and the District of Columbia. 86% of these people get their drinking water from public water suppliers which use the Potomac River, its tributaries and surrounding ground water as their source water. And with an average flow before withdrawal of 7 billion gallons/day, it may be an understatement to say: it’s a big deal!

Luckily, this has not gone unnoticed. Organized in 2004, the Potomac River Basin Drinking Water Source Protection Partnership (DWSPP) has been working to better understand and address the risks that may negatively affect the quality of drinking water in the Potomac River basin. The Partnership is a voluntary association of 20 water suppliers and government agencies whose mission is the protection of their source water supplies in the basin. Some of the biggest interests of the Partnership are:

• Tracking research on low levels of emerging  contaminants to determine their persistence in the environment and their potential threats to human health and the environment

• Early warning/emergency response to events and conditions which may threaten the safety of the water supply

• Urban issues such as the impact of roadway salts on drinking water sources

• Agriculture issues such as the potential contribution of pathogens. One example of this is Cryptosporidium, which may cause water-borne disease

Broad source water programs like the Partnership’s are significant because they extend beyond the treatment element and provide an invaluable multi-barrier approach to drinking water protection. With concerns like those above (and more) in both urban and rural areas, this collaborative approach should open the eyes of residents in watersheds everywhere.

So what should you do? Educate yourself on the issues the Potomac DWSPP is working on by visiting their website and be sure to take a look at specific information about special topics or workgroup activities. You may also find information like how to properly dispose of pharmaceuticals, as well as other ways you too can ensure safe drinking water for your area.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action, and EPA does not verify the accuracy or science of the contents of the blog.

Please share this post. However, please don't change the title or the content. If you do make changes, don't attribute the edited title or content to EPA or the author.