Background: The current disease outbreak caused by the Ebola virus Makona variant (EBOV/Mak) has led to unprecedented morbidity and lethality given its geographic reach and sustained transmission. Sodium hypochlorite and ethanol are well-accepted decontamination agents, however little published evidence supports the selection of appropriate concentrations and contact times. The present study addresses the environmental robustness of EBOV/Mak and evaluates the effectiveness of sodium hypochlorite and ethanol as disinfectants. Methods: EBOV/Mak was suspended in a simulated organic soil load and dried onto surfaces. Viability was measured at 1 hour, 24 hours, 72 hours, and 192 hours. For the evaluation of disinfectants, EBOV/Mak in a simulated organic soil was dried onto stainless steel carriers and disinfected with 0.01% (v/v), 0.1% (v/v), 0.5% (v/v) and 1% (v/v) sodium hypochlorite solutions or 67% (v/v) ethanol at contact times of 1, 5 or 10 minutes. Results: EBOV/Mak persisted longer on steel and plastic surfaces (192 hours) than cotton (<24 hours). Dilute sodium hypochlorite (0.01% and 0.1%) showed little antiviral action, whereas 0.5% and 1% sodium hypochlorite solutions demonstrated recoverable virus at one minute but sterilized surfaces in five minutes. Disinfection with 67% ethanol did not fully clear infectious virions from 3/9 carriers at 1 minute but sterilized all carriers at 5 and 10 minutes. Conclusions: Sodium hypochlorite and ethanol effectively decontaminate EBOV/Mak suspended in a simulated organic load; however, selection of concentration and contact time proves critical.

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.