Inactivation of Enteric Adenovirus and Feline Calicivirus by Carbon Dioxide

Jeanette A. Thurston-Enriquez, University of Nebraska - Lincoln
Charles N. Haas, Drexel University, Philadelphia, Pennsylvania
Joseph Jacangelo, Montgomery Watson Harza, Lovettsville, Virginia
Charles P. Gerba, University of Arizona, Tucson, Arizona

Document Type Article

Published in APPLIED AND ENVIRONMENTAL MICROBIOLOGY, June 2005, p. 3100–3105.

Abstract

Chlorine dioxide (ClO₂) inactivation experiments were conducted with adenovirus type 40 (AD40) and feline calicivirus (FCV). Experiments were carried out in buffered, disinfectant demand-free water under high- and low-pH and -temperature conditions. Ct values (the concentration of ClO₂ multiplied by contact time with the virus) were calculated directly from bench-scale experiments and from application of the efficiency factor Hom (EFH) model. AD40 Ct ranges for 4-log inactivation (Ct_99.99%) at 5°C were >0.77 to <1.53 mg/liter x min and >0.80 to <1.59 mg/liter x min for pH 6 and 8, respectively. For 15°C AD40 experiments, >0.49 to <0.74 mg/liter x min and <0.12 mg/liter x min Ct_99.99% ranges were observed for pH 6 and 8, respectively. FCV Ct_99.99% ranges for 5°C experiments were >20.20 to <30.30 mg/liter x min and >0.68 mg/liter x min for pH 6 and 8, respectively. For 15°C FCV experiments, Ct_{99.99% ranges were >4.20 to <6.72 and <0.18 mg/liter x min for pH 6 and 8, respectively. Viral inactivation was higher at pH 8 than at pH 6 and at 15°C than at 5°C. Comparison of Ct values and inactivation curves demonstrated that the EFH model described bench-scale experiment data very well. Observed bench-scale Ct99.99% ranges and EFH model Ct99.99%values demonstrated that FCV is more resistant to ClO2 than AD40 for the conditions studied. U.S. Environmental Protection Agency guidance manual Ct99.99% values are higher than Ct99.99% values calculated from bench-scale experiments and from EFH model application.}