I'm sure there will be variation depending on what the contaminated item or surface is made of - linens, I could imagine, would remain dangerous for longer than a door-knob. But if the items are not decontaminated in some way, how long can the virus survive outside a host?
This really depends on the environment, one study (listed below as reference 1) found that the Ebola virus can survive under ideal conditions on flat surfaces in the dark for up to six days - see the figure from the same publication.
However, the virus is quite sensitive to UV radiation (see reference 2 for all the details) and most viral particles are likely to get inactivated within relatively short time. It might still be possible to get positive tests for Ebola from really sensitive PCR-based tests, but these are most likely not infectious anymore. The CDC lists common bleach (or any other routinely used disinfected) as a good way to get rid of Ebola viruses.
I found this safety sheet in the topic.
SECTION IV – STABILITY AND VIABILITY
DRUG SUSCEPTIBILITY: Unknown. S-adenosylhomocysteine hydrolase inhibitors have been found to have complete mortality protection in mice infected with a lethal dose of Ebola virus (30).
DRUG RESISTANCE: There are no known antiviral treatments available for human infections.
SUSCEPTIBILITY TO DISINFECTANTS: Ebola virus is susceptible to sodium hypochlorite, lipid solvents, phenolic disinfectants, peracetic acid, methyl alcohol, ether, sodium deoxycholate, 2% glutaraldehyde, 0.25% Triton X-100, β-propiolactone, 3% acetic acid (pH 2.5), formaldehyde and paraformaldehyde, and detergents such as SDS (20, 21, 31-34).
PHYSICAL INACTIVATION: Ebola are moderately thermolabile and can be inactivated by heating for 30 minutes to 60 minutes at 60ºC, boiling for 5 minutes, gamma irradiation (1.2 x106 rads to 1.27 x106 rads), and/or UV radiation (3, 6, 20, 32, 33).
SURVIVAL OUTSIDE HOST: The virus can survive in liquid or dried material for a number of days (23). Infectivity is found to be stable at room temperature or at 4°C for several days, and indefinitely stable at -70°C (6, 20). Infectivity can be preserved by lyophilisation.
However there are no references on the site, so I checked the data provided. According to scientific articles it is trusty, however these articles are related to not the current West African strain, so it can be slightly different.
Clinical specimens from patients infected with Lassa, Ebola, or Marburg virus may present a serious biohazard to laboratory workers. We have examined the effects of heat, alteration of pH, and gamma radiation on these viruses in human blood and on the electrolytes, enzymes, and coagulation factors measured in laboratory tests that are important in the care of an infected patient. Heating serum at 60 degrees C for 1 h reduced high titers of these viruses to noninfectious levels without altering the serum levels of glucose, blood urea nitrogen, and electrolytes. Dilution of blood in 3% acetic acid, diluent for a leukocyte count, inactivated all of these viruses. All of the methods tested for viral inactivation markedly altered certain serum proteins, making these methods unsuitable for samples that are to be tested for certain enzyme levels and coagulation factors.
- 1984 - Physicochemical inactivation of Lassa, Ebola, and Marburg viruses and effect on clinical laboratory analyses.
Ebola, Lassa, Venezuelan equine encephalitis, and Sindbis viruses were dried onto solid surfaces, incubated for various time periods under controlled conditions of temperature and relative humidity, and quantitatively eluted from surfaces, and viral titers in the recovered samples were determined. The viral inactivation kinetics that were obtained indicated that viral resistance to natural inactivation in the dark follows (in decreasing order of stability) alphavirus > Lassa virus > Ebola virus. The findings reported in this study on the natural decay in the dark should assist in understanding the biophysical properties of enveloped RNA viruses outside the host and in estimating the persistence of viruses in the environment during epidemics or after an accidental or intentional release.
- 2010 - Persistence in darkness of virulent alphaviruses, Ebola virus, and Lassa virus deposited on solid surfaces
Our study has shown that Lake Victoria marburgvirus (MARV) and Zaire ebolavirus (ZEBOV) can survive for long periods in different liquid media and can also be recovered from plastic and glass surfaces at low temperatures for over 3 weeks. The decay rates of ZEBOV and Reston ebolavirus (REBOV) plus MARV within a dynamic aerosol were calculated. ZEBOV and MARV had similar decay rates, whilst REBOV showed significantly better survival within an aerosol.