Since C. parvum oocysts are spherical objects of ∼ 5 m diameter, they are clearly observed in brightfield microscopy. With the LTRS instrument we can thereby trap a single C. parvum oocyst and acquire a Raman spectrum. Oocysts can be trapped and moved in three dimensions using only 2.5 mW of laser power (reducing to approximately 1.5 mW in the sample), indicating that they have a rather high index of refraction for light at 785 nm. However, we used 60 mW of laser power and integrated the collected Raman scattered light for 20 seconds over Raman wavenumber 600 -1780 cm -1 . The short integration time at this power did not affect the appearance of an oocyst in the microscope nor the acquired Raman spectrum, indicating no thermal damage, which is of importance to consider since a high dose might damage the trapped object . In total, we measured n = 100 viable and neutralized oocysts respectively, and averaged their spectra into representative graphs as shown in Figure . The high resolution of our experimental setup shows that oocyst spectra consist of several distinct Raman peaks.