Pathogens Research

Small life forms are a big research topic at EPA. Pathogens are tiny organisms, such as bacteria, fungi, protozoa, and viruses, that cause disease. They’re often found in water, frequently as a result of sewage discharges that contain fecal matter, septic tanks that leak, and animal feedlots that create polluted runoff. NRMRL develops scientific assessments and best practices to protect us from exposure to harmful levels of pathogens in drinking water.

One microorganism of concern is Cryptosporidium. This protozoan parasite enters our source water through sewage and animal waste. It causes cryptosporidiosis, a mild gastrointestinal disease whose most common symptom is watery diarrhea. Other symptoms are dehydration, weight loss, stomach cramps or pain, fever, nausea, and vomiting. Some people with cryptosporidiosis will have no symptoms at all. After becoming infected with the parasite, most people will begin to show signs of the disease within 2 to 10 days.

EPA regulates Cryptosporidium in our drinking water through the Interim Enhanced Surface Water Treatment Rule. This rule requires that at least 99 percent of Cryptosporidium protozoa be removed by filtered surface water systems serving 10,000 people or more. Systems without filtration must implement a watershed control program to protect source waters from contamination.

Giardia lamblia, another troublesome pathogen, also infects the gastrointestinal tract. It causes giardiasis, whose symptoms usually occur within 7 to 10 days of ingestion and include severe diarrhea and abdominal cramps. Other symptoms are bloating, fatigue, nausea, vomiting, and weight loss.

Waterborne giardiasis may occur as a result of disinfection problems or inadequate filtration procedures. EPA regulates Giardia in our drinking water by requiring water systems to disinfect or filter their water so that at least 99.9 percent of Giardia is physically removed or rendered harmless.

Small water distribution systems face unique challenges when it comes to protecting drinking water from Cryptosporidium and Giardia lamblia. So EPA’s pathogens research includes investigating the risk trade-offs with disinfection by-products and ways for small systems to control microbial pathogens.

Contact

Mark Rodgers (513) 569-7225

See Also

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