Disinfecting Ebola: New Questions
By Meryl Nass, M.D. Dr. Nass is a board-certified internist and a biological warfare epidemiologist and expert in anthrax. Nass publishes Anthrax Vaccine.
I previously recommended alcohol hand rub (usually 70% ethyl or isopropyl alcohol) to kill Ebola on hands and gloves, which CDC recommends, along with soap and water.
From more reading, I no longer feel this is adequate, as it appears alcohol has not been tested on Ebola, and because other environmental tests have found Ebola to be hardier than one would have guessed (see Canadian discussion below).
According to the manufacturer of a popular brand of alcohol hand sanitizer, Purell:
Are PURELL® products effective against Ebola?
As we have already noted, CDC speaks with forked tongue on Ebola, presumably because of the imperative to appear fully prepared, when it isn’t. The following CDC document, which discusses how to decontaminate surfaces (not skin), admits that although Ebola is an enveloped virus, it may require stronger measures for decontamination than the enveloped viruses we are used to dealing with in hospitals. Instead, CDC recommends we treat Ebola like we would treat Norovirus, which is not killed with alcohol rub.
- Use a U.S. Environmental Protection Agency (EPA)-registered hospital disinfectant with a label claim for a non-enveloped virus (e.g., norovirus, rotavirus, adenovirus, poliovirus) to disinfect environmental surfaces in rooms of patients with suspected or confirmed Ebola virus infection. Although there are no products with specific label claims against the Ebola virus, enveloped viruses such as Ebola are susceptible to a broad range of hospital disinfectants used to disinfect hard, non-porous surfaces. In contrast, non-enveloped viruses are more resistant to disinfectants. As a precaution, selection of a disinfectant 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 (e.g., norovirus, rotavirus, adenovirus, poliovirus) are broadly antiviral and capable of inactivating both enveloped and non-enveloped viruses…
- For large spills, a chemical disinfectant with sufficient potency is needed to overcome the tendency of proteins in blood and other body substances to neutralize the disinfectant’s active ingredient. An EPA-registered hospital disinfectant with label claims for non-enveloped viruses (e.g., norovirus, rotavirus, adenovirus, poliovirus) and instructions for cleaning and decontaminating surfaces or objects soiled with blood or body fluids should be used according to those instructions.
CDC also recommends sodium hypochlorite “wipes” for cleaning collections of infectious fluids. This may not be adequate either.“Wipes” are convenient because they usually do not drip, or splash, which could spread viral contamination. However, virus is killed as a function of the amount and concentration of the active ingredient, the concentration of virus, and the amount of time the two are in contact, as well as interfering substances that may be present. Simply wiping a surface will not necessarily inactivate all virus on the surface. Nor will a quick spraying when the active ingredient evaporates rapidly.
The Canadian public health agency emphasizes that time is needed to kill the virus, not simply contact with a disinfectant that rapidly evaporates, like alcohol. Their guidance says the following:
“SUSCEPTIBILITY TO DISINFECTANTS: Ebolavirus is susceptible to 3% acetic acid, 1% glutaraldehyde, alcohol-based products, and dilutions (1:10-1:100 for ≥10 minutes) of 5.25% household bleach (sodium hypochlorite), and calcium hypochlorite (bleach powder)
cleaning to remove visible stains followed by contact with a 1:100
dilution of 5.25% household bleach for more than 10 minutes.
Filoviruses have been reported capable to survive for weeks in blood
and can also survive on contaminated surfaces, particularly at low
temperatures (4°C) 52. 61
contaminated surfaces (plastic, metal or glass) at room temperature . 61
In another study, Ebolavirus dried onto glass, polymeric silicone
rubber, or painted aluminum alloy is able to survive in the dark for
several hours under ambient conditions (between 20°C and 25°C and 30–40%
relative humidity) (amount of virus reduced to 37% after 15.4 hours),
but is less stable than some other viral hemorrhagic fevers (Lassa) . When dried in tissue culture media onto glass and stored at 4 °C, Zaire ebolavirus survived for over 50 days 53. 61
on observations in nature. This information is intended to be used to
support local risk assessments in a laboratory setting.
concludes that the risk of transmission is low when recommended
infection control guidelines for viral hemorrhagic fevers are followed . 64
Infection control protocols included decontamination of floors with
0.5% bleach daily and decontamination of visibly contaminated surfaces
with 0.05% bleach as necessary…
Allow aerosols to settle and, wearing protective clothing, gently cover
spill with paper towels and apply suitable disinfectant, starting at
the perimeter and working towards the centre. Allow sufficient contact
time before clean-up.
Decontaminate all materials for disposal from the containment
laboratory by steam sterilisation, chemical disinfection, incineration
or by gaseous methods. Contaminated materials include both liquid and
Of course, the obvious question is why hasn’t CDC or EPA or OSHA or DOD tested Ebola against all usual/available disinfectants so we do not have
to guess. Can Sanjay or another TV doc find out for us?