Waterborne pathogens represent a major concern for human and animal health making monitoring of water essential to prevent outbreaks. Sample preparation is critical to assess a spatio-temporally representative volume of water and identify pathogens present at low concentrations, with filtration being the commonly adopted approach. Numerous different filter types and operational strategies have been investigated to consistently improve the low recovery rates of pathogens, with work now investigating creation of automated sampling systems.
Previous work has often focused on chemical strategies for maximising recovery rates during the elution from the filter. However, novel physical methods, like the use of megasonic sonication offer great potential for effective pathogen removal from filters. Compared to ultrasound assisted agitation, megasonic sonication, which operates at a higher excitation energy frequency, offers a gentler and more thorough process for elution with lower risk of pathogen damage during the process. Megasonic exposure of Cryptosporidium oocysts has been demonstrated to preserve their viability. This mode of elution enables the downstream identification of pathogen infectivity since viability and species information cannot be extracted from damaged or destroyed pathogens.
Here we investigate the use of megasonic elution to improve the recovery rates of Cryptosporidium in two different filtration set-ups: firstly dead-end filtration using a Rexeed filter and secondly, tangential flow filtration using a Fresenius filter. The results demonstrate that recovery rates are increased by around 50% for both set-ups highlighting the potential of megasonic elution in this application.