Microbicides play critical roles in infection prevention and control of Ebola virus by decontaminating high-touch environmental surfaces (HITES), interrupting the virus-HITES-hands nexus. We evaluated the efficacy of formulations containing different microbicidal actives for inactivating Ebola virus–Makona strain (EBOV/Mak) on stainless-steel carriers per ASTM E2197-11. Formulations of sodium hypochlorite (NaOCl) (0.05–1%), ethanol (70%), chloroxylenol (PCMX) (0.12–0.48% by weight) in hard water, and a ready-to-use disinfectant spray with 58% ethanol (EDS), were tested at contact times of 0, or 0.5 to 10 min at ambient temperature. EBOV/Mak was inactivated (> 6 log10) by 70% ethanol after contact times ≥ 2.5 min, by 0.5% and 1% NaOCl or EDS (> 4 log10) at contact times ≥ 5 min, and by 0.12–0.48% PCMX (> 4.2 log10) at contact times ≥ 5 min. Residual infectious virus in neutralized samples was assessed by passage on cells and evaluation for viral cytopathic effect. No infectious virus was detected in cells inoculated with EBOV/Mak exposed to NaOCl (0.5% or 1%), PCMX (0.12% to 0.48%), or EDS for ≥ 5 min. These results demonstrate ≥ 6 log10 inactivation of EBOV/Mak dried on prototypic surfaces by EDS or formulations of NaOCl (≥ 0.5%), PCMX (≥ 0.12%), or 70% ethanol at contact times ≥ 5 min. Sci Rep Sci Rep 1579 scirep 101563288 Scientific Reports 2045-2322 Nature Publishing Group PMC7498580 PMC7498580.1 7498580 7498580 32943689 10.1038/s41598-020-71736-x 71736 1 Article Efficacy of microbicides for inactivation of Ebola–Makona virus on a non-porous surface: a targeted hygiene intervention for reducing virus spread Cutts Todd A. 1 2 Robertson Catherine 1 2 Theriault Steven S. 3 Nims Raymond W. 4 Kasloff Samantha B. 1 2 Rubino Joseph R. 5 Ijaz M. We evaluated the efficacy of formulations containing different microbicidal actives for inactivating Ebola virus–Makona strain (EBOV/Mak) on stainless-steel carriers per ASTM E2197-11. Formulations of sodium hypochlorite (NaOCl) (0.05–1%), ethanol (70%), chloroxylenol (PCMX) (0.12–0.48% by weight) in hard water, and a ready-to-use disinfectant spray with 58% ethanol (EDS), were tested at contact times of 0, or 0.5 to 10 min at ambient temperature. EBOV/Mak was inactivated (> 6 log 10 ) by 70% ethanol after contact times ≥ 2.5 min, by 0.5% and 1% NaOCl or EDS (> 4 log 10 ) at contact times ≥ 5 min, and by 0.12–0.48% PCMX (> 4.2 log 10 ) at contact times ≥ 5 min. For instance, objects in the vicinity of infected patients (including IV insertion site, patient’s skin, mattress, clothes, blanket, digestive losses bucket, IV drip stand, floor, and healthcare workers’ personal protective equipment) have been shown to be contaminated with Ebola virus RNA 5 . Considering this, an important intervention for limiting viral dissemination may involve the use of an effective virucidal agent for disinfecting surfaces contaminated with Ebola virus, thereby mitigating the risk of transmission of the virus to healthy individuals, including health-care workers. The Ebola virus is a member of the Filoviridae family, and is an enveloped virus. As such, the Ebola virus should be relatively susceptible to a variety of microbicidal inactivation approaches 6 . In view of the lethality of the virus, the United States Centers for Disease Control and Prevention (CDC) offers the following guidance 7 : “…selection of a disinfection product with a higher potency than what is normally required for an enveloped virus is being recommended at this time. EPA-registered hospital disinfectants with label claims against non-enveloped viruses (noroviruses, rotavirus, adenovirus, poliovirus) are broadly antiviral and capable of inactivating both enveloped and non-enveloped viruses.” The United States Environmental Protection Agency (EPA) requires that claims for efficacy of a product for an emerging enveloped virus include that the product be approved for inactivating at least one large or one small non-enveloped virus 8 . The virucidal efficacy of microbicides for Ebola virus is usually determined in studies involving virus suspended in a liquid matrix. The low minimum infectious dose of the Ebola virus in humans (estimated to be 1 to 10 infectious units) 13 , 14 and the lethality (~ 41%) of the associated hemorrhagic disease 15 mean that risk mitigation in the form of surface decontamination must be effective beyond the typical expectation of a 3–4 log 10 reduction in viral titer. The US Environmental Protection Agency (EPA) stated in its 2012 disinfectant product guidance 16 that “The product should demonstrate complete inactivation of the virus at all dilutions. That is, some residual infectious virus may be allowed. In the case of the Ebola virus, we believe that the efficacy of a We therefore expect that the efficacy data obtained here for the Makona variant should apply also to other outbreak variants of Ebola virus. Sodium hypochlorite 0.5% solutions are recommended by the CDC 18 as an example of a suitable disinfectant solution for hemorrhagic fever viruses. Smither et al. 19 use a similar experimental design (i.e., a combination of TCID 50 assay and passage of neutralized solutions in flasks to rule out residual infectious virus) to study the disinfection of Ebola virus Yambuku-Ecran (EBOV-Ecran) on aluminum carriers by 0.75% NaOCl in tap water for 10 min contact time. These four disinfectants display sufficient inactivation efficacy for Ebola virus at reasonably short contact times that may be practically achieved in the field. Use of these disinfectants for surface decontamination in the field or in healthcare settings therefore has the potential to reduce infectious Ebola virus load on those surfaces and to reduce spread of virus from infected to non-infected individuals. Methods Methods for the previously reported Ebola variant carrier inactivation studies involving ethanol and sodium hypochlorite were described in Cook et al. 11 and have not been reproduced here.

Infectious diseases can be transmitted via fomites (contaminated surfaces/objects); disinfection can interrupt this transmission route. However, disinfection guidelines for low-resource outbreak settings are inconsistent and not evidence-based. A systematic review of surface disinfection efficacy studies was conducted to inform low-resource outbreak guideline development. Due to variation in experimental procedures, outcomes were synthesized in a narrative summary focusing on chlorine-based disinfection against 7 pathogens with potential to produce outbreaks in low-resource settings (Mycobacterium tuberculosis, Vibrio cholerae, Salmonella spp., hepatitis A virus, rotavirus, norovirus, and Ebola virus). Data were extracted from 89 laboratory studies and made available, including 20 studies on relevant pathogens used in combination with surrogate data to determine minimum target concentration × time ("CT") factors. Stainless steel (68%) and chlorine-based disinfectants (56%) were most commonly tested. No consistent trend was seen in the influence of chlorine concentration and exposure time on disinfection efficacy. Disinfectant application mode; soil load; and surface type were frequently identified as influential factors in included studies. This review highlights that surface disinfection efficacy estimates are strongly influenced by each study's experimental conditions. We therefore recommend laboratory testing to be followed by field-based testing/monitoring to ensure effectiveness is achieved in situ.