Dr. Jerri Bartholomew (OSU Microbiology) used quantitative PCR to detect pathogens in aquatic ecosystems.  Water sampling is a more recent approach to test for aquatic pathogens such as bacteria and myxozoan parasites.  Water is collected by hand or with an automatic sampler.   Samples are filtered and the DNA is extracted.  Molecular methods such as quantitative PCR are used to determine the identity and abundance of pathogens.  Data is usally obtained more quickly than with sentinel fish exposure data, and has a higher detection threshold.  A combined approach of water sampling and sentinel fish exposures is used to relate abundance of waterborne stages with fish health.  Using PCR, the genotype of the parasite present in the water can also be identified which helps determine the risks to specific fish species.

Hallett, S.L. and Bartholomew, J.L.  2006.  Application of a real-time PCR assay to detect and quantify the myxozoan parasite Ceratomyxa shasta in river water samples.  Dis. Aquat. Organ. 71(2):109-118.