The Disinfection Characteristics of Ebola Virus Outbreak Variants

Abstract

The recent Ebola virus outbreak in West Africa has forced experts to re-evaluate their understanding of how to best disinfect areas contaminated with infectious bodily fluids. Recent research has found that Ebola virus remains viable in blood for 7–10 days making appropriate disinfection crucial to infection control. We sought to determine if the three most important outbreak variants of Zaire ebolavirus (Mayinga, Kikwit and Makona) exhibit separate phenotypes when challenged with a range of sodium hypochlorite (NaOCl) concentrations or 70% ethanol (EtOH) at average West African temperature. The time dependent killing of Ebola virus was evaluated by measuring infectious virus and viral RNA (vRNA), to determine if RNA detection is a viable method for decontamination measurement in areas without high containment laboratory access. Makona was less susceptible to weaker concentrations of NaOCl (0.05 and 0.1%) than Mayinga and Kikwit. At the recommended concentration of NaOCl (≥0.5%) all of the variants were inert after 5 minutes of contact time. Similarly, all variants were inactivated by 70% EtOH after 2.5 minutes, only Makona was detected at 1 minute. In multiple instances, high amounts of vRNA was detected in the absence of infectious virus, suggesting that it does not serve as an accurate measure of remaining infectivity after cleansing.

Determining the Efficacy, Safety and Suitability of Disinfectants to Prevent Emerging Infectious Disease Transmission

“…Summary: Overall, a 15-min exposure to 0.5% chlorine (independently of chlorine type, surface, pre-cleaning practices and organic matter) was found to reduce surface contamination by an Ebola virus surrogate to non-detectable levels. These results are consistent with recent results from small-scale studies using the Ebola virus [18].…”

Efficacy of microbicides for inactivation of Ebola–Makona virus on a non-porous surface: a targeted hygiene intervention for reducing virus spread

“…The Vero E6 cultures were inoculated with undiluted neutralized samples and passaged twice. +, viral CPE observed; −, viral CPE not observed, or no cytotoxicity observed for N + NaOCl (neutralizer + NaOCl cytotoxicity control) (modified from Cook et al 11 ). www.nature.com/scientificreports/ log 10 reduction in viral titer on each surface beyond the cytotoxic level. "…”

“…Cook et al 11 previously examined the efficacy of 70% ethanol and several concentrations of sodium hypochlorite against three variants of the Ebola virus (Mayinga, Kikwit, and Makona). The authors found that the Makona variant was somewhat less susceptible to the lower concentrations of sodium hypochlorite, while being similarly susceptible to 70% ethanol and higher concentrations of sodium hypochlorite 11 . We therefore expect that the efficacy data obtained here for the Makona variant should apply also to other outbreak variants of Ebola virus.…”

“…solutions for inactivating EBOV/Mak dried within an organic load on stainless steel carriers was evaluated 11 per ASTM E2197-11 9 . Efficacy was evaluated 11 at four NaOCl concentrations (0.05%, 0.1%, 0.5%, and 1%) in hard water, with contact times of 1, 2.5, 5, 7.5, and 10 min at ambient temperature (~ 27 °C).…”

“…Use of hard water as diluent was included in the study design to simulate water hardness in the field. We have compared the efficacy data recently collected for para-chloro-meta-xylenol (PCMX) and a formulated disinfectant spray containing 58% ethanol (EDS) to data published previously 11 , at the same testing facility and using the same methodology, for 70% ethanol and for varying concentrations of sodium hypochlorite (NaOCl). We have reported both sets of results within this article in order to facilitate direct comparisons of virucidal efficacy for the various microbicidal actives.…”