Re: Ebola Transmission Discussion
Re: Ebola Transmission Discussion
Public Health Agency of Canada
EBOLA VIRUS
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INFECTIOUS DOSE: 1 - 10 aerosolized organisms are sufficient to cause infection in humans (21).
MODE OF TRANSMISSION: In an outbreak, it is hypothesized that the first patient becomes infected as a result of contact with an infected animal (15). Person-to-person transmission occurs via close personal contact with an infected individual or their body fluids during the late stages of infection or after death (1, 2, 15, 27). Nosocomial infections can occur through contact with infected body fluids due to the reuse of unsterilized syringes, needles, or other medical equipment contaminated with these fluids (1, 2). Humans may be infected by handling sick or dead non-human primates and are also at risk when handling the bodies of deceased humans in preparation for funerals, suggesting possible transmission through aerosol droplets (2, 6, 28). In the laboratory, infection through small-particle aerosols has been demonstrated in primates, and
airborne spread among humans is strongly suspected, although it has not yet been conclusively demonstrated (1, 6, 13). The importance of this route of transmission is not clear. Poor hygienic conditions can aid the spread of the virus (6).
INCUBATION PERIOD: Two to 21 days, more often 4 - 9 days (1, 13, 14).
COMMUNICABILITY: Communicable as long as blood, secretions, organs, or semen contain the virus. Ebola virus has been isolated from semen 61 days after the onset of illness, and transmission through semen has occurred 7 weeks after clinical recovery (1, 2).
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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.
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SOURCES/SPECIMENS: Blood, serum, urine, respiratory and throat secretions, semen, and organs or their homogenates from human or animal hosts (1, 2, 35). Human or animal hosts, including non-human primates, may represent a further source of infection (35).
PRIMARY HAZARDS: Accidental parenteral inoculation, respiratory exposure to infectious aerosols and droplets, and/or direct contact with broken skin or mucous membranes (35).
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Date Modified: 2014-08-01
http://www.phac-aspc.gc.ca/lab-bio/res/psds-ftss/ebola-eng.php