Oregon Wastewater Surveillance

The primary objective of this pilot wastewater surveillance project in collaboration with the Oregon health Authority is to develop methods to monitor Cryptosporidium in wastewater and to monitor several diverse Oregon communities over time to assess the utility of Cryptosporidium wastewater surveillance.

Cryptosporidium is a parasitic protozoa which belongs to the phylum Apicomplexa and the subgroup coccidia. Cryptosporidium is a major enteric pathogen of public health concern and globally recognized as a significant cause of waterborne diseases. With C. parvum and C. hominis causing most human cases, cryptosporidiosis can be asymptomatic or can cause self-limiting gastroenteritis in immunocompetent individuals. However, among immunocompromised individuals, cryptosporidiosis can be severe, protracted, and sometimes fatal. Transmission to humans is most commonly through contact with contaminated water (drinking or recreational contact) and, to a lesser extent, zoonotic transmission from contact with an infected animal. Livestock, especially calves, are the main reservoirs of Cryptosporidium parvum. The pathogen is commonly found in lakes and rivers that contribute to water supplies. Under optimal conditions, oocysts can remain infectious in the environment for over six months and are resistant to chlorination, thus standard chemical disinfection is ineffective.

Oregon is at a particularly high risk of a possible cryptosporidiosis outbreak due to contaminated drinking water. Approximately one million Oregonians in the Portland metro area are provided unfiltered drinking water from the Bull Run Watershed, creating an increased risk for cryptosporidiosis outbreaks. Additionally, current clinical-based surveillance for cryptosporidiosis is estimated to identify <2% of cases due to asymptomatic and mildly symptomatic infections as well as voluntary case reporting by clinicians. As infected individuals shed 107-109 Cryptosporidium oocysts per bowel movement, wastewater surveillance of Cryptosporidium may be an effective public health tool to identify cryptosporidiosis outbreaks and notify public works of potential drinking water contamination.