Evaluation of altered environmental conditions as a decontamination approach for nonspore‐forming biological agents

Abstract

Aims The purpose of this study was to evaluate the effects of altered environmental conditions on the persistence of Francisella tularensis bacteria and Venezuelan equine encephalitis virus (VEEV), on two material types. Methods and Results Francisella tularensis (F.t.) and VEEV were inoculated (c. 1 × 108 colony‐forming units or PFU), dried onto porous and nonporous fomites (glass and paper), and exposed to combinations of altered environmental conditions ranging from 22 to 60°C and 30 to 75% relative humidity (RH). Viability of test organism was assessed after contact times ranging from 30 min to 10 days. Inactivation rates of F.t. and VEEV increased as both temperature and/or RH were increased. Greater efficacy was observed for paper as compared to glass for both test organisms. Conclusions The use of elevated temperature and RH increased rate of inactivation for both organisms and greater than six log reduction was accomplished in as little as 6 h by elevating temperature to approximately 60°C. Significance and Impact of the Study These results provide information for inactivation of nonspore‐forming select agents using elevated temperature and humidity which may aid incident commanders following a biological contamination incident by providing alternative methods for remediation.

Evaluation of environmental conditions as a decontamination approach for SARS-CoV-2 when applied to common library, archive and museum-related materials

“…This study has also confirmed that storage under warm conditions will increase the rate of natural attenuation and reduce the time required to achieve LOQ by 0-3 days based on material type, and conversely, under cold storage conditions, the attenuation rate steeply declines. These findings are consistent with similar research efforts where the ability to achieve 6 LR or greater for Venezuelan Equine Encephalitic virus on both porous and non-porous materials was achieved in 6-12 h as compared to control samples held at ambient temperatures showing minimal LR after 96 h. (Richter et al, 2019). More recently, the half-life of SARS-CoV-2 virus on non-porous fomites stored at 24°C ranged from 6.3 to 18.6 h; however, by increasing the temperature to 35°C, the half-life was reduced to 1.0 to 8.9 (Biryukov et al, 2020).…”

“…While statistical analysis was not conducted, the survival of SARS-CoV-2 virus and the porosity of the material type did not result in any obvious paired effect that has been previously observed for other similar environmental persistence evaluations (e.g. porous materials result in slower reduction in viability while non-porous materials result in faster reduction; Richter et al, 2019). cover) were evaluated at ambient temperature conditions in a stacked configuration, to reflect routine storage conditions of the materials common in library facilities.…”

“…The survival or persistence of biological organisms in the environment has been previously studied and is largely influenced by the climate and the materials with which these biological organisms are in contact (Biryukov et al, 2020 ; Calfee & Wendling, 2012 ; Casanova et al, 2010 ; Chin et al, 2020 ; Kampf et al, 2020 ; Richter et al, 2019 ; Rogers et al, 2016 ; Wood et al, 2015 ; Wood et al, 2018 ). Environmental factors that may impact the viability of bacteria and the infectivity of viruses in the environment include temperature, humidity, ultraviolet (UV) radiation and desiccation (Sinclair et al, 2008 ).…”

Persistence of Pathogens on Inanimate Surfaces: A Narrative Review

“…The longest survival was seen at 38 ± 2 °C and 41 ± 5% relative humidity: both strains were still detectable after 10 days on glass. On paper, Schu4 was inactivated after 96 h and LVS after 24 h [ 139 ].…”

Evaluating the Environmental Persistence and Inactivation of MS2 Bacteriophage and the Presumed Ebola Virus Surrogate Phi6 Using Low Concentration Hydrogen Peroxide Vapor

“…In addition to calculating an LR value for each test condition and time point, we have determined inactivation rates (as D -values) for positive controls and the coupons exposed to HPV. D -values are commonly used to quantify the rate of inactivation of a microbial population, over several time points and are expressed as the time in h to reach 1 LR from the initially recovered PFU amount. , For brevity, these calculated D -values for each phage and test condition, as well as further information on the statistical methods and their detailed results, are found in the Supporting Information (SI). The D -values were calculated as the ratio of the shorter of the number of hours to achieve complete decontamination (i.e., when the phage was not detected) or the end of the decontamination test period; divided by the difference between the log recovery of the phage at the time point and the log recovery at time zero.…”