Cryptosporidium hominis
Johnson et al. 2005 · 254 nm
Test conditions & context
Type Protozoan cyst / oocyst
Medium Water
Test wavelength 254 nm
Particle size 5000 nm
Author Johnson et al.
Year 2005
UV-C dose–response (D-values)
A D-value is the UV-C dose (in mJ/cm²) needed for a given log-reduction. D90 = 90 % inactivation = 1-log; D99 = 99 % = 2-log; D99.9 = 99.9 % = 3-log, and so on. Values come from the cited study under its specific test conditions.
Reduction log Dose (mJ/cm²)
D90 90 % 1-log 3 mJ/cm²
D99 99 % 2-log 5.8 mJ/cm²
Morphology & UV-C resistance
Morphology class Protozoan cyst
Oocyst with a thick wall — UV-sensitive, but chlorine- and ozone-resistant → UV is the preferred inactivation method.
Primary source
Johnson et al. (2005). iuva.org/resources/Resource%20Documents/Malayeri-Fluence%20Required%20to%20Achieve%20Incremental%20Log%20Inactivation%20of%20Bacteria%2C%20Protozoa%2C%20Viruses%20and%20Algae.pdf